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qemu/block.c
Max Reitz 1046779e64 block: Ignore loosening perm restrictions failures 
We generally assume that loosening permission restrictions can never
fail.  We have seen in the past that this assumption is wrong.  This has
led to crashes because we generally pass &error_abort when loosening
permissions.

However, a failure in such a case should actually be handled in quite
the opposite way: It is very much not fatal, so qemu may report it, but
still consider the operation successful.  The only realistic problem is
that qemu may then retain permissions and thus locks on images it
actually does not require.  But again, that is not fatal.

To implement this behavior, we make all functions that change
permissions and that pass &error_abort to the initiating function
(bdrv_check_perm() or bdrv_child_check_perm()) evaluate the
@loosen_restrictions value introduced in the previous patch.  If it is
true and an error did occur, we abort the permission update, discard the
error, and instead report success to the caller.

bdrv_child_try_set_perm() itself does not pass &error_abort, but it is
the only public function to change permissions.  As such, callers may
pass &error_abort to it, expecting dropping permission restrictions to
never fail.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2019-06-18 16:41:10 +02:00

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/*
* QEMU System Emulator block driver
*
* Copyright (c) 2003 Fabrice Bellard
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "block/trace.h"
#include "block/block_int.h"
#include "block/blockjob.h"
#include "block/nbd.h"
#include "block/qdict.h"
#include "qemu/error-report.h"
#include "module_block.h"
#include "qemu/module.h"
#include "qapi/error.h"
#include "qapi/qmp/qdict.h"
#include "qapi/qmp/qjson.h"
#include "qapi/qmp/qnull.h"
#include "qapi/qmp/qstring.h"
#include "qapi/qobject-output-visitor.h"
#include "qapi/qapi-visit-block-core.h"
#include "sysemu/block-backend.h"
#include "sysemu/sysemu.h"
#include "qemu/notify.h"
#include "qemu/option.h"
#include "qemu/coroutine.h"
#include "block/qapi.h"
#include "qemu/timer.h"
#include "qemu/cutils.h"
#include "qemu/id.h"
#ifdef CONFIG_BSD
#include <sys/ioctl.h>
#include <sys/queue.h>
#ifndef __DragonFly__
#include <sys/disk.h>
#endif
#endif
#ifdef _WIN32
#include <windows.h>
#endif
#define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states =
QTAILQ_HEAD_INITIALIZER(graph_bdrv_states);
static QTAILQ_HEAD(, BlockDriverState) all_bdrv_states =
QTAILQ_HEAD_INITIALIZER(all_bdrv_states);
static QLIST_HEAD(, BlockDriver) bdrv_drivers =
QLIST_HEAD_INITIALIZER(bdrv_drivers);
static BlockDriverState *bdrv_open_inherit(const char *filename,
const char *reference,
QDict *options, int flags,
BlockDriverState *parent,
const BdrvChildRole *child_role,
Error **errp);
/* If non-zero, use only whitelisted block drivers */
static int use_bdrv_whitelist;
#ifdef _WIN32
static int is_windows_drive_prefix(const char *filename)
{
return (((filename[0] >= 'a' && filename[0] <= 'z') ||
(filename[0] >= 'A' && filename[0] <= 'Z')) &&
filename[1] == ':');
}
int is_windows_drive(const char *filename)
{
if (is_windows_drive_prefix(filename) &&
filename[2] == '\0')
return 1;
if (strstart(filename, "\\\\.\\", NULL) ||
strstart(filename, "//./", NULL))
return 1;
return 0;
}
#endif
size_t bdrv_opt_mem_align(BlockDriverState *bs)
{
if (!bs || !bs->drv) {
/* page size or 4k (hdd sector size) should be on the safe side */
return MAX(4096, getpagesize());
}
return bs->bl.opt_mem_alignment;
}
size_t bdrv_min_mem_align(BlockDriverState *bs)
{
if (!bs || !bs->drv) {
/* page size or 4k (hdd sector size) should be on the safe side */
return MAX(4096, getpagesize());
}
return bs->bl.min_mem_alignment;
}
/* check if the path starts with "<protocol>:" */
int path_has_protocol(const char *path)
{
const char *p;
#ifdef _WIN32
if (is_windows_drive(path) ||
is_windows_drive_prefix(path)) {
return 0;
}
p = path + strcspn(path, ":/\\");
#else
p = path + strcspn(path, ":/");
#endif
return *p == ':';
}
int path_is_absolute(const char *path)
{
#ifdef _WIN32
/* specific case for names like: "\\.\d:" */
if (is_windows_drive(path) || is_windows_drive_prefix(path)) {
return 1;
}
return (*path == '/' || *path == '\\');
#else
return (*path == '/');
#endif
}
/* if filename is absolute, just return its duplicate. Otherwise, build a
path to it by considering it is relative to base_path. URL are
supported. */
char *path_combine(const char *base_path, const char *filename)
{
const char *protocol_stripped = NULL;
const char *p, *p1;
char *result;
int len;
if (path_is_absolute(filename)) {
return g_strdup(filename);
}
if (path_has_protocol(base_path)) {
protocol_stripped = strchr(base_path, ':');
if (protocol_stripped) {
protocol_stripped++;
}
}
p = protocol_stripped ?: base_path;
p1 = strrchr(base_path, '/');
#ifdef _WIN32
{
const char *p2;
p2 = strrchr(base_path, '\\');
if (!p1 || p2 > p1) {
p1 = p2;
}
}
#endif
if (p1) {
p1++;
} else {
p1 = base_path;
}
if (p1 > p) {
p = p1;
}
len = p - base_path;
result = g_malloc(len + strlen(filename) + 1);
memcpy(result, base_path, len);
strcpy(result + len, filename);
return result;
}
/*
* Helper function for bdrv_parse_filename() implementations to remove optional
* protocol prefixes (especially "file:") from a filename and for putting the
* stripped filename into the options QDict if there is such a prefix.
*/
void bdrv_parse_filename_strip_prefix(const char *filename, const char *prefix,
QDict *options)
{
if (strstart(filename, prefix, &filename)) {
/* Stripping the explicit protocol prefix may result in a protocol
* prefix being (wrongly) detected (if the filename contains a colon) */
if (path_has_protocol(filename)) {
QString *fat_filename;
/* This means there is some colon before the first slash; therefore,
* this cannot be an absolute path */
assert(!path_is_absolute(filename));
/* And we can thus fix the protocol detection issue by prefixing it
* by "./" */
fat_filename = qstring_from_str("./");
qstring_append(fat_filename, filename);
assert(!path_has_protocol(qstring_get_str(fat_filename)));
qdict_put(options, "filename", fat_filename);
} else {
/* If no protocol prefix was detected, we can use the shortened
* filename as-is */
qdict_put_str(options, "filename", filename);
}
}
}
/* Returns whether the image file is opened as read-only. Note that this can
* return false and writing to the image file is still not possible because the
* image is inactivated. */
bool bdrv_is_read_only(BlockDriverState *bs)
{
return bs->read_only;
}
int bdrv_can_set_read_only(BlockDriverState *bs, bool read_only,
bool ignore_allow_rdw, Error **errp)
{
/* Do not set read_only if copy_on_read is enabled */
if (bs->copy_on_read && read_only) {
error_setg(errp, "Can't set node '%s' to r/o with copy-on-read enabled",
bdrv_get_device_or_node_name(bs));
return -EINVAL;
}
/* Do not clear read_only if it is prohibited */
if (!read_only && !(bs->open_flags & BDRV_O_ALLOW_RDWR) &&
!ignore_allow_rdw)
{
error_setg(errp, "Node '%s' is read only",
bdrv_get_device_or_node_name(bs));
return -EPERM;
}
return 0;
}
/*
* Called by a driver that can only provide a read-only image.
*
* Returns 0 if the node is already read-only or it could switch the node to
* read-only because BDRV_O_AUTO_RDONLY is set.
*
* Returns -EACCES if the node is read-write and BDRV_O_AUTO_RDONLY is not set
* or bdrv_can_set_read_only() forbids making the node read-only. If @errmsg
* is not NULL, it is used as the error message for the Error object.
*/
int bdrv_apply_auto_read_only(BlockDriverState *bs, const char *errmsg,
Error **errp)
{
int ret = 0;
if (!(bs->open_flags & BDRV_O_RDWR)) {
return 0;
}
if (!(bs->open_flags & BDRV_O_AUTO_RDONLY)) {
goto fail;
}
ret = bdrv_can_set_read_only(bs, true, false, NULL);
if (ret < 0) {
goto fail;
}
bs->read_only = true;
bs->open_flags &= ~BDRV_O_RDWR;
return 0;
fail:
error_setg(errp, "%s", errmsg ?: "Image is read-only");
return -EACCES;
}
/*
* If @backing is empty, this function returns NULL without setting
* @errp. In all other cases, NULL will only be returned with @errp
* set.
*
* Therefore, a return value of NULL without @errp set means that
* there is no backing file; if @errp is set, there is one but its
* absolute filename cannot be generated.
*/
char *bdrv_get_full_backing_filename_from_filename(const char *backed,
const char *backing,
Error **errp)
{
if (backing[0] == '\0') {
return NULL;
} else if (path_has_protocol(backing) || path_is_absolute(backing)) {
return g_strdup(backing);
} else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) {
error_setg(errp, "Cannot use relative backing file names for '%s'",
backed);
return NULL;
} else {
return path_combine(backed, backing);
}
}
/*
* If @filename is empty or NULL, this function returns NULL without
* setting @errp. In all other cases, NULL will only be returned with
* @errp set.
*/
static char *bdrv_make_absolute_filename(BlockDriverState *relative_to,
const char *filename, Error **errp)
{
char *dir, *full_name;
if (!filename || filename[0] == '\0') {
return NULL;
} else if (path_has_protocol(filename) || path_is_absolute(filename)) {
return g_strdup(filename);
}
dir = bdrv_dirname(relative_to, errp);
if (!dir) {
return NULL;
}
full_name = g_strconcat(dir, filename, NULL);
g_free(dir);
return full_name;
}
char *bdrv_get_full_backing_filename(BlockDriverState *bs, Error **errp)
{
return bdrv_make_absolute_filename(bs, bs->backing_file, errp);
}
void bdrv_register(BlockDriver *bdrv)
{
QLIST_INSERT_HEAD(&bdrv_drivers, bdrv, list);
}
BlockDriverState *bdrv_new(void)
{
BlockDriverState *bs;
int i;
bs = g_new0(BlockDriverState, 1);
QLIST_INIT(&bs->dirty_bitmaps);
for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
QLIST_INIT(&bs->op_blockers[i]);
}
notifier_with_return_list_init(&bs->before_write_notifiers);
qemu_co_mutex_init(&bs->reqs_lock);
qemu_mutex_init(&bs->dirty_bitmap_mutex);
bs->refcnt = 1;
bs->aio_context = qemu_get_aio_context();
qemu_co_queue_init(&bs->flush_queue);
for (i = 0; i < bdrv_drain_all_count; i++) {
bdrv_drained_begin(bs);
}
QTAILQ_INSERT_TAIL(&all_bdrv_states, bs, bs_list);
return bs;
}
static BlockDriver *bdrv_do_find_format(const char *format_name)
{
BlockDriver *drv1;
QLIST_FOREACH(drv1, &bdrv_drivers, list) {
if (!strcmp(drv1->format_name, format_name)) {
return drv1;
}
}
return NULL;
}
BlockDriver *bdrv_find_format(const char *format_name)
{
BlockDriver *drv1;
int i;
drv1 = bdrv_do_find_format(format_name);
if (drv1) {
return drv1;
}
/* The driver isn't registered, maybe we need to load a module */
for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
if (!strcmp(block_driver_modules[i].format_name, format_name)) {
block_module_load_one(block_driver_modules[i].library_name);
break;
}
}
return bdrv_do_find_format(format_name);
}
static int bdrv_format_is_whitelisted(const char *format_name, bool read_only)
{
static const char *whitelist_rw[] = {
CONFIG_BDRV_RW_WHITELIST
};
static const char *whitelist_ro[] = {
CONFIG_BDRV_RO_WHITELIST
};
const char **p;
if (!whitelist_rw[0] && !whitelist_ro[0]) {
return 1; /* no whitelist, anything goes */
}
for (p = whitelist_rw; *p; p++) {
if (!strcmp(format_name, *p)) {
return 1;
}
}
if (read_only) {
for (p = whitelist_ro; *p; p++) {
if (!strcmp(format_name, *p)) {
return 1;
}
}
}
return 0;
}
int bdrv_is_whitelisted(BlockDriver *drv, bool read_only)
{
return bdrv_format_is_whitelisted(drv->format_name, read_only);
}
bool bdrv_uses_whitelist(void)
{
return use_bdrv_whitelist;
}
typedef struct CreateCo {
BlockDriver *drv;
char *filename;
QemuOpts *opts;
int ret;
Error *err;
} CreateCo;
static void coroutine_fn bdrv_create_co_entry(void *opaque)
{
Error *local_err = NULL;
int ret;
CreateCo *cco = opaque;
assert(cco->drv);
ret = cco->drv->bdrv_co_create_opts(cco->filename, cco->opts, &local_err);
error_propagate(&cco->err, local_err);
cco->ret = ret;
}
int bdrv_create(BlockDriver *drv, const char* filename,
QemuOpts *opts, Error **errp)
{
int ret;
Coroutine *co;
CreateCo cco = {
.drv = drv,
.filename = g_strdup(filename),
.opts = opts,
.ret = NOT_DONE,
.err = NULL,
};
if (!drv->bdrv_co_create_opts) {
error_setg(errp, "Driver '%s' does not support image creation", drv->format_name);
ret = -ENOTSUP;
goto out;
}
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_create_co_entry(&cco);
} else {
co = qemu_coroutine_create(bdrv_create_co_entry, &cco);
qemu_coroutine_enter(co);
while (cco.ret == NOT_DONE) {
aio_poll(qemu_get_aio_context(), true);
}
}
ret = cco.ret;
if (ret < 0) {
if (cco.err) {
error_propagate(errp, cco.err);
} else {
error_setg_errno(errp, -ret, "Could not create image");
}
}
out:
g_free(cco.filename);
return ret;
}
int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp)
{
BlockDriver *drv;
Error *local_err = NULL;
int ret;
drv = bdrv_find_protocol(filename, true, errp);
if (drv == NULL) {
return -ENOENT;
}
ret = bdrv_create(drv, filename, opts, &local_err);
error_propagate(errp, local_err);
return ret;
}
/**
* Try to get @bs's logical and physical block size.
* On success, store them in @bsz struct and return 0.
* On failure return -errno.
* @bs must not be empty.
*/
int bdrv_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
{
BlockDriver *drv = bs->drv;
if (drv && drv->bdrv_probe_blocksizes) {
return drv->bdrv_probe_blocksizes(bs, bsz);
} else if (drv && drv->is_filter && bs->file) {
return bdrv_probe_blocksizes(bs->file->bs, bsz);
}
return -ENOTSUP;
}
/**
* Try to get @bs's geometry (cyls, heads, sectors).
* On success, store them in @geo struct and return 0.
* On failure return -errno.
* @bs must not be empty.
*/
int bdrv_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
{
BlockDriver *drv = bs->drv;
if (drv && drv->bdrv_probe_geometry) {
return drv->bdrv_probe_geometry(bs, geo);
} else if (drv && drv->is_filter && bs->file) {
return bdrv_probe_geometry(bs->file->bs, geo);
}
return -ENOTSUP;
}
/*
* Create a uniquely-named empty temporary file.
* Return 0 upon success, otherwise a negative errno value.
*/
int get_tmp_filename(char *filename, int size)
{
#ifdef _WIN32
char temp_dir[MAX_PATH];
/* GetTempFileName requires that its output buffer (4th param)
have length MAX_PATH or greater. */
assert(size >= MAX_PATH);
return (GetTempPath(MAX_PATH, temp_dir)
&& GetTempFileName(temp_dir, "qem", 0, filename)
? 0 : -GetLastError());
#else
int fd;
const char *tmpdir;
tmpdir = getenv("TMPDIR");
if (!tmpdir) {
tmpdir = "/var/tmp";
}
if (snprintf(filename, size, "%s/vl.XXXXXX", tmpdir) >= size) {
return -EOVERFLOW;
}
fd = mkstemp(filename);
if (fd < 0) {
return -errno;
}
if (close(fd) != 0) {
unlink(filename);
return -errno;
}
return 0;
#endif
}
/*
* Detect host devices. By convention, /dev/cdrom[N] is always
* recognized as a host CDROM.
*/
static BlockDriver *find_hdev_driver(const char *filename)
{
int score_max = 0, score;
BlockDriver *drv = NULL, *d;
QLIST_FOREACH(d, &bdrv_drivers, list) {
if (d->bdrv_probe_device) {
score = d->bdrv_probe_device(filename);
if (score > score_max) {
score_max = score;
drv = d;
}
}
}
return drv;
}
static BlockDriver *bdrv_do_find_protocol(const char *protocol)
{
BlockDriver *drv1;
QLIST_FOREACH(drv1, &bdrv_drivers, list) {
if (drv1->protocol_name && !strcmp(drv1->protocol_name, protocol)) {
return drv1;
}
}
return NULL;
}
BlockDriver *bdrv_find_protocol(const char *filename,
bool allow_protocol_prefix,
Error **errp)
{
BlockDriver *drv1;
char protocol[128];
int len;
const char *p;
int i;
/* TODO Drivers without bdrv_file_open must be specified explicitly */
/*
* XXX(hch): we really should not let host device detection
* override an explicit protocol specification, but moving this
* later breaks access to device names with colons in them.
* Thanks to the brain-dead persistent naming schemes on udev-
* based Linux systems those actually are quite common.
*/
drv1 = find_hdev_driver(filename);
if (drv1) {
return drv1;
}
if (!path_has_protocol(filename) || !allow_protocol_prefix) {
return &bdrv_file;
}
p = strchr(filename, ':');
assert(p != NULL);
len = p - filename;
if (len > sizeof(protocol) - 1)
len = sizeof(protocol) - 1;
memcpy(protocol, filename, len);
protocol[len] = '\0';
drv1 = bdrv_do_find_protocol(protocol);
if (drv1) {
return drv1;
}
for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); ++i) {
if (block_driver_modules[i].protocol_name &&
!strcmp(block_driver_modules[i].protocol_name, protocol)) {
block_module_load_one(block_driver_modules[i].library_name);
break;
}
}
drv1 = bdrv_do_find_protocol(protocol);
if (!drv1) {
error_setg(errp, "Unknown protocol '%s'", protocol);
}
return drv1;
}
/*
* Guess image format by probing its contents.
* This is not a good idea when your image is raw (CVE-2008-2004), but
* we do it anyway for backward compatibility.
*
* @buf contains the image's first @buf_size bytes.
* @buf_size is the buffer size in bytes (generally BLOCK_PROBE_BUF_SIZE,
* but can be smaller if the image file is smaller)
* @filename is its filename.
*
* For all block drivers, call the bdrv_probe() method to get its
* probing score.
* Return the first block driver with the highest probing score.
*/
BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size,
const char *filename)
{
int score_max = 0, score;
BlockDriver *drv = NULL, *d;
QLIST_FOREACH(d, &bdrv_drivers, list) {
if (d->bdrv_probe) {
score = d->bdrv_probe(buf, buf_size, filename);
if (score > score_max) {
score_max = score;
drv = d;
}
}
}
return drv;
}
static int find_image_format(BlockBackend *file, const char *filename,
BlockDriver **pdrv, Error **errp)
{
BlockDriver *drv;
uint8_t buf[BLOCK_PROBE_BUF_SIZE];
int ret = 0;
/* Return the raw BlockDriver * to scsi-generic devices or empty drives */
if (blk_is_sg(file) || !blk_is_inserted(file) || blk_getlength(file) == 0) {
*pdrv = &bdrv_raw;
return ret;
}
ret = blk_pread(file, 0, buf, sizeof(buf));
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not read image for determining its "
"format");
*pdrv = NULL;
return ret;
}
drv = bdrv_probe_all(buf, ret, filename);
if (!drv) {
error_setg(errp, "Could not determine image format: No compatible "
"driver found");
ret = -ENOENT;
}
*pdrv = drv;
return ret;
}
/**
* Set the current 'total_sectors' value
* Return 0 on success, -errno on error.
*/
int refresh_total_sectors(BlockDriverState *bs, int64_t hint)
{
BlockDriver *drv = bs->drv;
if (!drv) {
return -ENOMEDIUM;
}
/* Do not attempt drv->bdrv_getlength() on scsi-generic devices */
if (bdrv_is_sg(bs))
return 0;
/* query actual device if possible, otherwise just trust the hint */
if (drv->bdrv_getlength) {
int64_t length = drv->bdrv_getlength(bs);
if (length < 0) {
return length;
}
hint = DIV_ROUND_UP(length, BDRV_SECTOR_SIZE);
}
bs->total_sectors = hint;
return 0;
}
/**
* Combines a QDict of new block driver @options with any missing options taken
* from @old_options, so that leaving out an option defaults to its old value.
*/
static void bdrv_join_options(BlockDriverState *bs, QDict *options,
QDict *old_options)
{
if (bs->drv && bs->drv->bdrv_join_options) {
bs->drv->bdrv_join_options(options, old_options);
} else {
qdict_join(options, old_options, false);
}
}
static BlockdevDetectZeroesOptions bdrv_parse_detect_zeroes(QemuOpts *opts,
int open_flags,
Error **errp)
{
Error *local_err = NULL;
char *value = qemu_opt_get_del(opts, "detect-zeroes");
BlockdevDetectZeroesOptions detect_zeroes =
qapi_enum_parse(&BlockdevDetectZeroesOptions_lookup, value,
BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF, &local_err);
g_free(value);
if (local_err) {
error_propagate(errp, local_err);
return detect_zeroes;
}
if (detect_zeroes == BLOCKDEV_DETECT_ZEROES_OPTIONS_UNMAP &&
!(open_flags & BDRV_O_UNMAP))
{
error_setg(errp, "setting detect-zeroes to unmap is not allowed "
"without setting discard operation to unmap");
}
return detect_zeroes;
}
/**
* Set open flags for a given discard mode
*
* Return 0 on success, -1 if the discard mode was invalid.
*/
int bdrv_parse_discard_flags(const char *mode, int *flags)
{
*flags &= ~BDRV_O_UNMAP;
if (!strcmp(mode, "off") || !strcmp(mode, "ignore")) {
/* do nothing */
} else if (!strcmp(mode, "on") || !strcmp(mode, "unmap")) {
*flags |= BDRV_O_UNMAP;
} else {
return -1;
}
return 0;
}
/**
* Set open flags for a given cache mode
*
* Return 0 on success, -1 if the cache mode was invalid.
*/
int bdrv_parse_cache_mode(const char *mode, int *flags, bool *writethrough)
{
*flags &= ~BDRV_O_CACHE_MASK;
if (!strcmp(mode, "off") || !strcmp(mode, "none")) {
*writethrough = false;
*flags |= BDRV_O_NOCACHE;
} else if (!strcmp(mode, "directsync")) {
*writethrough = true;
*flags |= BDRV_O_NOCACHE;
} else if (!strcmp(mode, "writeback")) {
*writethrough = false;
} else if (!strcmp(mode, "unsafe")) {
*writethrough = false;
*flags |= BDRV_O_NO_FLUSH;
} else if (!strcmp(mode, "writethrough")) {
*writethrough = true;
} else {
return -1;
}
return 0;
}
static char *bdrv_child_get_parent_desc(BdrvChild *c)
{
BlockDriverState *parent = c->opaque;
return g_strdup(bdrv_get_device_or_node_name(parent));
}
static void bdrv_child_cb_drained_begin(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
bdrv_do_drained_begin_quiesce(bs, NULL, false);
}
static bool bdrv_child_cb_drained_poll(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
return bdrv_drain_poll(bs, false, NULL, false);
}
static void bdrv_child_cb_drained_end(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
bdrv_drained_end(bs);
}
static void bdrv_child_cb_attach(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
bdrv_apply_subtree_drain(child, bs);
}
static void bdrv_child_cb_detach(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
bdrv_unapply_subtree_drain(child, bs);
}
static int bdrv_child_cb_inactivate(BdrvChild *child)
{
BlockDriverState *bs = child->opaque;
assert(bs->open_flags & BDRV_O_INACTIVE);
return 0;
}
static bool bdrv_child_cb_can_set_aio_ctx(BdrvChild *child, AioContext *ctx,
GSList **ignore, Error **errp)
{
BlockDriverState *bs = child->opaque;
return bdrv_can_set_aio_context(bs, ctx, ignore, errp);
}
static void bdrv_child_cb_set_aio_ctx(BdrvChild *child, AioContext *ctx,
GSList **ignore)
{
BlockDriverState *bs = child->opaque;
return bdrv_set_aio_context_ignore(bs, ctx, ignore);
}
/*
* Returns the options and flags that a temporary snapshot should get, based on
* the originally requested flags (the originally requested image will have
* flags like a backing file)
*/
static void bdrv_temp_snapshot_options(int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
*child_flags = (parent_flags & ~BDRV_O_SNAPSHOT) | BDRV_O_TEMPORARY;
/* For temporary files, unconditional cache=unsafe is fine */
qdict_set_default_str(child_options, BDRV_OPT_CACHE_DIRECT, "off");
qdict_set_default_str(child_options, BDRV_OPT_CACHE_NO_FLUSH, "on");
/* Copy the read-only and discard options from the parent */
qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
qdict_copy_default(child_options, parent_options, BDRV_OPT_DISCARD);
/* aio=native doesn't work for cache.direct=off, so disable it for the
* temporary snapshot */
*child_flags &= ~BDRV_O_NATIVE_AIO;
}
/*
* Returns the options and flags that bs->file should get if a protocol driver
* is expected, based on the given options and flags for the parent BDS
*/
static void bdrv_inherited_options(int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
int flags = parent_flags;
/* Enable protocol handling, disable format probing for bs->file */
flags |= BDRV_O_PROTOCOL;
/* If the cache mode isn't explicitly set, inherit direct and no-flush from
* the parent. */
qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE);
/* Inherit the read-only option from the parent if it's not set */
qdict_copy_default(child_options, parent_options, BDRV_OPT_READ_ONLY);
qdict_copy_default(child_options, parent_options, BDRV_OPT_AUTO_READ_ONLY);
/* Our block drivers take care to send flushes and respect unmap policy,
* so we can default to enable both on lower layers regardless of the
* corresponding parent options. */
qdict_set_default_str(child_options, BDRV_OPT_DISCARD, "unmap");
/* Clear flags that only apply to the top layer */
flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_COPY_ON_READ |
BDRV_O_NO_IO);
*child_flags = flags;
}
const BdrvChildRole child_file = {
.parent_is_bds = true,
.get_parent_desc = bdrv_child_get_parent_desc,
.inherit_options = bdrv_inherited_options,
.drained_begin = bdrv_child_cb_drained_begin,
.drained_poll = bdrv_child_cb_drained_poll,
.drained_end = bdrv_child_cb_drained_end,
.attach = bdrv_child_cb_attach,
.detach = bdrv_child_cb_detach,
.inactivate = bdrv_child_cb_inactivate,
.can_set_aio_ctx = bdrv_child_cb_can_set_aio_ctx,
.set_aio_ctx = bdrv_child_cb_set_aio_ctx,
};
/*
* Returns the options and flags that bs->file should get if the use of formats
* (and not only protocols) is permitted for it, based on the given options and
* flags for the parent BDS
*/
static void bdrv_inherited_fmt_options(int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
child_file.inherit_options(child_flags, child_options,
parent_flags, parent_options);
*child_flags &= ~(BDRV_O_PROTOCOL | BDRV_O_NO_IO);
}
const BdrvChildRole child_format = {
.parent_is_bds = true,
.get_parent_desc = bdrv_child_get_parent_desc,
.inherit_options = bdrv_inherited_fmt_options,
.drained_begin = bdrv_child_cb_drained_begin,
.drained_poll = bdrv_child_cb_drained_poll,
.drained_end = bdrv_child_cb_drained_end,
.attach = bdrv_child_cb_attach,
.detach = bdrv_child_cb_detach,
.inactivate = bdrv_child_cb_inactivate,
.can_set_aio_ctx = bdrv_child_cb_can_set_aio_ctx,
.set_aio_ctx = bdrv_child_cb_set_aio_ctx,
};
static void bdrv_backing_attach(BdrvChild *c)
{
BlockDriverState *parent = c->opaque;
BlockDriverState *backing_hd = c->bs;
assert(!parent->backing_blocker);
error_setg(&parent->backing_blocker,
"node is used as backing hd of '%s'",
bdrv_get_device_or_node_name(parent));
bdrv_refresh_filename(backing_hd);
parent->open_flags &= ~BDRV_O_NO_BACKING;
pstrcpy(parent->backing_file, sizeof(parent->backing_file),
backing_hd->filename);
pstrcpy(parent->backing_format, sizeof(parent->backing_format),
backing_hd->drv ? backing_hd->drv->format_name : "");
bdrv_op_block_all(backing_hd, parent->backing_blocker);
/* Otherwise we won't be able to commit or stream */
bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET,
parent->backing_blocker);
bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM,
parent->backing_blocker);
/*
* We do backup in 3 ways:
* 1. drive backup
* The target bs is new opened, and the source is top BDS
* 2. blockdev backup
* Both the source and the target are top BDSes.
* 3. internal backup(used for block replication)
* Both the source and the target are backing file
*
* In case 1 and 2, neither the source nor the target is the backing file.
* In case 3, we will block the top BDS, so there is only one block job
* for the top BDS and its backing chain.
*/
bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE,
parent->backing_blocker);
bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET,
parent->backing_blocker);
bdrv_child_cb_attach(c);
}
static void bdrv_backing_detach(BdrvChild *c)
{
BlockDriverState *parent = c->opaque;
assert(parent->backing_blocker);
bdrv_op_unblock_all(c->bs, parent->backing_blocker);
error_free(parent->backing_blocker);
parent->backing_blocker = NULL;
bdrv_child_cb_detach(c);
}
/*
* Returns the options and flags that bs->backing should get, based on the
* given options and flags for the parent BDS
*/
static void bdrv_backing_options(int *child_flags, QDict *child_options,
int parent_flags, QDict *parent_options)
{
int flags = parent_flags;
/* The cache mode is inherited unmodified for backing files; except WCE,
* which is only applied on the top level (BlockBackend) */
qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT);
qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH);
qdict_copy_default(child_options, parent_options, BDRV_OPT_FORCE_SHARE);
/* backing files always opened read-only */
qdict_set_default_str(child_options, BDRV_OPT_READ_ONLY, "on");
qdict_set_default_str(child_options, BDRV_OPT_AUTO_READ_ONLY, "off");
flags &= ~BDRV_O_COPY_ON_READ;
/* snapshot=on is handled on the top layer */
flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_TEMPORARY);
*child_flags = flags;
}
static int bdrv_backing_update_filename(BdrvChild *c, BlockDriverState *base,
const char *filename, Error **errp)
{
BlockDriverState *parent = c->opaque;
bool read_only = bdrv_is_read_only(parent);
int ret;
if (read_only) {
ret = bdrv_reopen_set_read_only(parent, false, errp);
if (ret < 0) {
return ret;
}
}
ret = bdrv_change_backing_file(parent, filename,
base->drv ? base->drv->format_name : "");
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not update backing file link");
}
if (read_only) {
bdrv_reopen_set_read_only(parent, true, NULL);
}
return ret;
}
const BdrvChildRole child_backing = {
.parent_is_bds = true,
.get_parent_desc = bdrv_child_get_parent_desc,
.attach = bdrv_backing_attach,
.detach = bdrv_backing_detach,
.inherit_options = bdrv_backing_options,
.drained_begin = bdrv_child_cb_drained_begin,
.drained_poll = bdrv_child_cb_drained_poll,
.drained_end = bdrv_child_cb_drained_end,
.inactivate = bdrv_child_cb_inactivate,
.update_filename = bdrv_backing_update_filename,
.can_set_aio_ctx = bdrv_child_cb_can_set_aio_ctx,
.set_aio_ctx = bdrv_child_cb_set_aio_ctx,
};
static int bdrv_open_flags(BlockDriverState *bs, int flags)
{
int open_flags = flags;
/*
* Clear flags that are internal to the block layer before opening the
* image.
*/
open_flags &= ~(BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING | BDRV_O_PROTOCOL);
return open_flags;
}
static void update_flags_from_options(int *flags, QemuOpts *opts)
{
*flags &= ~(BDRV_O_CACHE_MASK | BDRV_O_RDWR | BDRV_O_AUTO_RDONLY);
if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) {
*flags |= BDRV_O_NO_FLUSH;
}
if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_DIRECT, false)) {
*flags |= BDRV_O_NOCACHE;
}
if (!qemu_opt_get_bool_del(opts, BDRV_OPT_READ_ONLY, false)) {
*flags |= BDRV_O_RDWR;
}
if (qemu_opt_get_bool_del(opts, BDRV_OPT_AUTO_READ_ONLY, false)) {
*flags |= BDRV_O_AUTO_RDONLY;
}
}
static void update_options_from_flags(QDict *options, int flags)
{
if (!qdict_haskey(options, BDRV_OPT_CACHE_DIRECT)) {
qdict_put_bool(options, BDRV_OPT_CACHE_DIRECT, flags & BDRV_O_NOCACHE);
}
if (!qdict_haskey(options, BDRV_OPT_CACHE_NO_FLUSH)) {
qdict_put_bool(options, BDRV_OPT_CACHE_NO_FLUSH,
flags & BDRV_O_NO_FLUSH);
}
if (!qdict_haskey(options, BDRV_OPT_READ_ONLY)) {
qdict_put_bool(options, BDRV_OPT_READ_ONLY, !(flags & BDRV_O_RDWR));
}
if (!qdict_haskey(options, BDRV_OPT_AUTO_READ_ONLY)) {
qdict_put_bool(options, BDRV_OPT_AUTO_READ_ONLY,
flags & BDRV_O_AUTO_RDONLY);
}
}
static void bdrv_assign_node_name(BlockDriverState *bs,
const char *node_name,
Error **errp)
{
char *gen_node_name = NULL;
if (!node_name) {
node_name = gen_node_name = id_generate(ID_BLOCK);
} else if (!id_wellformed(node_name)) {
/*
* Check for empty string or invalid characters, but not if it is
* generated (generated names use characters not available to the user)
*/
error_setg(errp, "Invalid node name");
return;
}
/* takes care of avoiding namespaces collisions */
if (blk_by_name(node_name)) {
error_setg(errp, "node-name=%s is conflicting with a device id",
node_name);
goto out;
}
/* takes care of avoiding duplicates node names */
if (bdrv_find_node(node_name)) {
error_setg(errp, "Duplicate node name");
goto out;
}
/* Make sure that the node name isn't truncated */
if (strlen(node_name) >= sizeof(bs->node_name)) {
error_setg(errp, "Node name too long");
goto out;
}
/* copy node name into the bs and insert it into the graph list */
pstrcpy(bs->node_name, sizeof(bs->node_name), node_name);
QTAILQ_INSERT_TAIL(&graph_bdrv_states, bs, node_list);
out:
g_free(gen_node_name);
}
static int bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv,
const char *node_name, QDict *options,
int open_flags, Error **errp)
{
Error *local_err = NULL;
int i, ret;
bdrv_assign_node_name(bs, node_name, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
bs->drv = drv;
bs->read_only = !(bs->open_flags & BDRV_O_RDWR);
bs->opaque = g_malloc0(drv->instance_size);
if (drv->bdrv_file_open) {
assert(!drv->bdrv_needs_filename || bs->filename[0]);
ret = drv->bdrv_file_open(bs, options, open_flags, &local_err);
} else if (drv->bdrv_open) {
ret = drv->bdrv_open(bs, options, open_flags, &local_err);
} else {
ret = 0;
}
if (ret < 0) {
if (local_err) {
error_propagate(errp, local_err);
} else if (bs->filename[0]) {
error_setg_errno(errp, -ret, "Could not open '%s'", bs->filename);
} else {
error_setg_errno(errp, -ret, "Could not open image");
}
goto open_failed;
}
ret = refresh_total_sectors(bs, bs->total_sectors);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not refresh total sector count");
return ret;
}
bdrv_refresh_limits(bs, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
assert(bdrv_opt_mem_align(bs) != 0);
assert(bdrv_min_mem_align(bs) != 0);
assert(is_power_of_2(bs->bl.request_alignment));
for (i = 0; i < bs->quiesce_counter; i++) {
if (drv->bdrv_co_drain_begin) {
drv->bdrv_co_drain_begin(bs);
}
}
return 0;
open_failed:
bs->drv = NULL;
if (bs->file != NULL) {
bdrv_unref_child(bs, bs->file);
bs->file = NULL;
}
g_free(bs->opaque);
bs->opaque = NULL;
return ret;
}
BlockDriverState *bdrv_new_open_driver(BlockDriver *drv, const char *node_name,
int flags, Error **errp)
{
BlockDriverState *bs;
int ret;
bs = bdrv_new();
bs->open_flags = flags;
bs->explicit_options = qdict_new();
bs->options = qdict_new();
bs->opaque = NULL;
update_options_from_flags(bs->options, flags);
ret = bdrv_open_driver(bs, drv, node_name, bs->options, flags, errp);
if (ret < 0) {
qobject_unref(bs->explicit_options);
bs->explicit_options = NULL;
qobject_unref(bs->options);
bs->options = NULL;
bdrv_unref(bs);
return NULL;
}
return bs;
}
QemuOptsList bdrv_runtime_opts = {
.name = "bdrv_common",
.head = QTAILQ_HEAD_INITIALIZER(bdrv_runtime_opts.head),
.desc = {
{
.name = "node-name",
.type = QEMU_OPT_STRING,
.help = "Node name of the block device node",
},
{
.name = "driver",
.type = QEMU_OPT_STRING,
.help = "Block driver to use for the node",
},
{
.name = BDRV_OPT_CACHE_DIRECT,
.type = QEMU_OPT_BOOL,
.help = "Bypass software writeback cache on the host",
},
{
.name = BDRV_OPT_CACHE_NO_FLUSH,
.type = QEMU_OPT_BOOL,
.help = "Ignore flush requests",
},
{
.name = BDRV_OPT_READ_ONLY,
.type = QEMU_OPT_BOOL,
.help = "Node is opened in read-only mode",
},
{
.name = BDRV_OPT_AUTO_READ_ONLY,
.type = QEMU_OPT_BOOL,
.help = "Node can become read-only if opening read-write fails",
},
{
.name = "detect-zeroes",
.type = QEMU_OPT_STRING,
.help = "try to optimize zero writes (off, on, unmap)",
},
{
.name = BDRV_OPT_DISCARD,
.type = QEMU_OPT_STRING,
.help = "discard operation (ignore/off, unmap/on)",
},
{
.name = BDRV_OPT_FORCE_SHARE,
.type = QEMU_OPT_BOOL,
.help = "always accept other writers (default: off)",
},
{ /* end of list */ }
},
};
/*
* Common part for opening disk images and files
*
* Removes all processed options from *options.
*/
static int bdrv_open_common(BlockDriverState *bs, BlockBackend *file,
QDict *options, Error **errp)
{
int ret, open_flags;
const char *filename;
const char *driver_name = NULL;
const char *node_name = NULL;
const char *discard;
QemuOpts *opts;
BlockDriver *drv;
Error *local_err = NULL;
assert(bs->file == NULL);
assert(options != NULL && bs->options != options);
opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
qemu_opts_absorb_qdict(opts, options, &local_err);
if (local_err) {
error_propagate(errp, local_err);
ret = -EINVAL;
goto fail_opts;
}
update_flags_from_options(&bs->open_flags, opts);
driver_name = qemu_opt_get(opts, "driver");
drv = bdrv_find_format(driver_name);
assert(drv != NULL);
bs->force_share = qemu_opt_get_bool(opts, BDRV_OPT_FORCE_SHARE, false);
if (bs->force_share && (bs->open_flags & BDRV_O_RDWR)) {
error_setg(errp,
BDRV_OPT_FORCE_SHARE
"=on can only be used with read-only images");
ret = -EINVAL;
goto fail_opts;
}
if (file != NULL) {
bdrv_refresh_filename(blk_bs(file));
filename = blk_bs(file)->filename;
} else {
/*
* Caution: while qdict_get_try_str() is fine, getting
* non-string types would require more care. When @options
* come from -blockdev or blockdev_add, its members are typed
* according to the QAPI schema, but when they come from
* -drive, they're all QString.
*/
filename = qdict_get_try_str(options, "filename");
}
if (drv->bdrv_needs_filename && (!filename || !filename[0])) {
error_setg(errp, "The '%s' block driver requires a file name",
drv->format_name);
ret = -EINVAL;
goto fail_opts;
}
trace_bdrv_open_common(bs, filename ?: "", bs->open_flags,
drv->format_name);
bs->read_only = !(bs->open_flags & BDRV_O_RDWR);
if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, bs->read_only)) {
if (!bs->read_only && bdrv_is_whitelisted(drv, true)) {
ret = bdrv_apply_auto_read_only(bs, NULL, NULL);
} else {
ret = -ENOTSUP;
}
if (ret < 0) {
error_setg(errp,
!bs->read_only && bdrv_is_whitelisted(drv, true)
? "Driver '%s' can only be used for read-only devices"
: "Driver '%s' is not whitelisted",
drv->format_name);
goto fail_opts;
}
}
/* bdrv_new() and bdrv_close() make it so */
assert(atomic_read(&bs->copy_on_read) == 0);
if (bs->open_flags & BDRV_O_COPY_ON_READ) {
if (!bs->read_only) {
bdrv_enable_copy_on_read(bs);
} else {
error_setg(errp, "Can't use copy-on-read on read-only device");
ret = -EINVAL;
goto fail_opts;
}
}
discard = qemu_opt_get(opts, BDRV_OPT_DISCARD);
if (discard != NULL) {
if (bdrv_parse_discard_flags(discard, &bs->open_flags) != 0) {
error_setg(errp, "Invalid discard option");
ret = -EINVAL;
goto fail_opts;
}
}
bs->detect_zeroes =
bdrv_parse_detect_zeroes(opts, bs->open_flags, &local_err);
if (local_err) {
error_propagate(errp, local_err);
ret = -EINVAL;
goto fail_opts;
}
if (filename != NULL) {
pstrcpy(bs->filename, sizeof(bs->filename), filename);
} else {
bs->filename[0] = '\0';
}
pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), bs->filename);
/* Open the image, either directly or using a protocol */
open_flags = bdrv_open_flags(bs, bs->open_flags);
node_name = qemu_opt_get(opts, "node-name");
assert(!drv->bdrv_file_open || file == NULL);
ret = bdrv_open_driver(bs, drv, node_name, options, open_flags, errp);
if (ret < 0) {
goto fail_opts;
}
qemu_opts_del(opts);
return 0;
fail_opts:
qemu_opts_del(opts);
return ret;
}
static QDict *parse_json_filename(const char *filename, Error **errp)
{
QObject *options_obj;
QDict *options;
int ret;
ret = strstart(filename, "json:", &filename);
assert(ret);
options_obj = qobject_from_json(filename, errp);
if (!options_obj) {
error_prepend(errp, "Could not parse the JSON options: ");
return NULL;
}
options = qobject_to(QDict, options_obj);
if (!options) {
qobject_unref(options_obj);
error_setg(errp, "Invalid JSON object given");
return NULL;
}
qdict_flatten(options);
return options;
}
static void parse_json_protocol(QDict *options, const char **pfilename,
Error **errp)
{
QDict *json_options;
Error *local_err = NULL;
/* Parse json: pseudo-protocol */
if (!*pfilename || !g_str_has_prefix(*pfilename, "json:")) {
return;
}
json_options = parse_json_filename(*pfilename, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
/* Options given in the filename have lower priority than options
* specified directly */
qdict_join(options, json_options, false);
qobject_unref(json_options);
*pfilename = NULL;
}
/*
* Fills in default options for opening images and converts the legacy
* filename/flags pair to option QDict entries.
* The BDRV_O_PROTOCOL flag in *flags will be set or cleared accordingly if a
* block driver has been specified explicitly.
*/
static int bdrv_fill_options(QDict **options, const char *filename,
int *flags, Error **errp)
{
const char *drvname;
bool protocol = *flags & BDRV_O_PROTOCOL;
bool parse_filename = false;
BlockDriver *drv = NULL;
Error *local_err = NULL;
/*
* Caution: while qdict_get_try_str() is fine, getting non-string
* types would require more care. When @options come from
* -blockdev or blockdev_add, its members are typed according to
* the QAPI schema, but when they come from -drive, they're all
* QString.
*/
drvname = qdict_get_try_str(*options, "driver");
if (drvname) {
drv = bdrv_find_format(drvname);
if (!drv) {
error_setg(errp, "Unknown driver '%s'", drvname);
return -ENOENT;
}
/* If the user has explicitly specified the driver, this choice should
* override the BDRV_O_PROTOCOL flag */
protocol = drv->bdrv_file_open;
}
if (protocol) {
*flags |= BDRV_O_PROTOCOL;
} else {
*flags &= ~BDRV_O_PROTOCOL;
}
/* Translate cache options from flags into options */
update_options_from_flags(*options, *flags);
/* Fetch the file name from the options QDict if necessary */
if (protocol && filename) {
if (!qdict_haskey(*options, "filename")) {
qdict_put_str(*options, "filename", filename);
parse_filename = true;
} else {
error_setg(errp, "Can't specify 'file' and 'filename' options at "
"the same time");
return -EINVAL;
}
}
/* Find the right block driver */
/* See cautionary note on accessing @options above */
filename = qdict_get_try_str(*options, "filename");
if (!drvname && protocol) {
if (filename) {
drv = bdrv_find_protocol(filename, parse_filename, errp);
if (!drv) {
return -EINVAL;
}
drvname = drv->format_name;
qdict_put_str(*options, "driver", drvname);
} else {
error_setg(errp, "Must specify either driver or file");
return -EINVAL;
}
}
assert(drv || !protocol);
/* Driver-specific filename parsing */
if (drv && drv->bdrv_parse_filename && parse_filename) {
drv->bdrv_parse_filename(filename, *options, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return -EINVAL;
}
if (!drv->bdrv_needs_filename) {
qdict_del(*options, "filename");
}
}
return 0;
}
static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q,
uint64_t perm, uint64_t shared,
GSList *ignore_children,
bool *tighten_restrictions, Error **errp);
static void bdrv_child_abort_perm_update(BdrvChild *c);
static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared);
static void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
uint64_t *shared_perm);
typedef struct BlockReopenQueueEntry {
bool prepared;
bool perms_checked;
BDRVReopenState state;
QSIMPLEQ_ENTRY(BlockReopenQueueEntry) entry;
} BlockReopenQueueEntry;
/*
* Return the flags that @bs will have after the reopens in @q have
* successfully completed. If @q is NULL (or @bs is not contained in @q),
* return the current flags.
*/
static int bdrv_reopen_get_flags(BlockReopenQueue *q, BlockDriverState *bs)
{
BlockReopenQueueEntry *entry;
if (q != NULL) {
QSIMPLEQ_FOREACH(entry, q, entry) {
if (entry->state.bs == bs) {
return entry->state.flags;
}
}
}
return bs->open_flags;
}
/* Returns whether the image file can be written to after the reopen queue @q
* has been successfully applied, or right now if @q is NULL. */
static bool bdrv_is_writable_after_reopen(BlockDriverState *bs,
BlockReopenQueue *q)
{
int flags = bdrv_reopen_get_flags(q, bs);
return (flags & (BDRV_O_RDWR | BDRV_O_INACTIVE)) == BDRV_O_RDWR;
}
/*
* Return whether the BDS can be written to. This is not necessarily
* the same as !bdrv_is_read_only(bs), as inactivated images may not
* be written to but do not count as read-only images.
*/
bool bdrv_is_writable(BlockDriverState *bs)
{
return bdrv_is_writable_after_reopen(bs, NULL);
}
static void bdrv_child_perm(BlockDriverState *bs, BlockDriverState *child_bs,
BdrvChild *c, const BdrvChildRole *role,
BlockReopenQueue *reopen_queue,
uint64_t parent_perm, uint64_t parent_shared,
uint64_t *nperm, uint64_t *nshared)
{
assert(bs->drv && bs->drv->bdrv_child_perm);
bs->drv->bdrv_child_perm(bs, c, role, reopen_queue,
parent_perm, parent_shared,
nperm, nshared);
/* TODO Take force_share from reopen_queue */
if (child_bs && child_bs->force_share) {
*nshared = BLK_PERM_ALL;
}
}
/*
* Check whether permissions on this node can be changed in a way that
* @cumulative_perms and @cumulative_shared_perms are the new cumulative
* permissions of all its parents. This involves checking whether all necessary
* permission changes to child nodes can be performed.
*
* Will set *tighten_restrictions to true if and only if new permissions have to
* be taken or currently shared permissions are to be unshared. Otherwise,
* errors are not fatal as long as the caller accepts that the restrictions
* remain tighter than they need to be. The caller still has to abort the
* transaction.
* @tighten_restrictions cannot be used together with @q: When reopening, we may
* encounter fatal errors even though no restrictions are to be tightened. For
* example, changing a node from RW to RO will fail if the WRITE permission is
* to be kept.
*
* A call to this function must always be followed by a call to bdrv_set_perm()
* or bdrv_abort_perm_update().
*/
static int bdrv_check_perm(BlockDriverState *bs, BlockReopenQueue *q,
uint64_t cumulative_perms,
uint64_t cumulative_shared_perms,
GSList *ignore_children,
bool *tighten_restrictions, Error **errp)
{
BlockDriver *drv = bs->drv;
BdrvChild *c;
int ret;
assert(!q || !tighten_restrictions);
if (tighten_restrictions) {
uint64_t current_perms, current_shared;
uint64_t added_perms, removed_shared_perms;
bdrv_get_cumulative_perm(bs, &current_perms, &current_shared);
added_perms = cumulative_perms & ~current_perms;
removed_shared_perms = current_shared & ~cumulative_shared_perms;
*tighten_restrictions = added_perms || removed_shared_perms;
}
/* Write permissions never work with read-only images */
if ((cumulative_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) &&
!bdrv_is_writable_after_reopen(bs, q))
{
if (!bdrv_is_writable_after_reopen(bs, NULL)) {
error_setg(errp, "Block node is read-only");
} else {
uint64_t current_perms, current_shared;
bdrv_get_cumulative_perm(bs, &current_perms, &current_shared);
if (current_perms & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) {
error_setg(errp, "Cannot make block node read-only, there is "
"a writer on it");
} else {
error_setg(errp, "Cannot make block node read-only and create "
"a writer on it");
}
}
return -EPERM;
}
/* Check this node */
if (!drv) {
return 0;
}
if (drv->bdrv_check_perm) {
return drv->bdrv_check_perm(bs, cumulative_perms,
cumulative_shared_perms, errp);
}
/* Drivers that never have children can omit .bdrv_child_perm() */
if (!drv->bdrv_child_perm) {
assert(QLIST_EMPTY(&bs->children));
return 0;
}
/* Check all children */
QLIST_FOREACH(c, &bs->children, next) {
uint64_t cur_perm, cur_shared;
bool child_tighten_restr;
bdrv_child_perm(bs, c->bs, c, c->role, q,
cumulative_perms, cumulative_shared_perms,
&cur_perm, &cur_shared);
ret = bdrv_child_check_perm(c, q, cur_perm, cur_shared, ignore_children,
tighten_restrictions ? &child_tighten_restr
: NULL,
errp);
if (tighten_restrictions) {
*tighten_restrictions |= child_tighten_restr;
}
if (ret < 0) {
return ret;
}
}
return 0;
}
/*
* Notifies drivers that after a previous bdrv_check_perm() call, the
* permission update is not performed and any preparations made for it (e.g.
* taken file locks) need to be undone.
*
* This function recursively notifies all child nodes.
*/
static void bdrv_abort_perm_update(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
BdrvChild *c;
if (!drv) {
return;
}
if (drv->bdrv_abort_perm_update) {
drv->bdrv_abort_perm_update(bs);
}
QLIST_FOREACH(c, &bs->children, next) {
bdrv_child_abort_perm_update(c);
}
}
static void bdrv_set_perm(BlockDriverState *bs, uint64_t cumulative_perms,
uint64_t cumulative_shared_perms)
{
BlockDriver *drv = bs->drv;
BdrvChild *c;
if (!drv) {
return;
}
/* Update this node */
if (drv->bdrv_set_perm) {
drv->bdrv_set_perm(bs, cumulative_perms, cumulative_shared_perms);
}
/* Drivers that never have children can omit .bdrv_child_perm() */
if (!drv->bdrv_child_perm) {
assert(QLIST_EMPTY(&bs->children));
return;
}
/* Update all children */
QLIST_FOREACH(c, &bs->children, next) {
uint64_t cur_perm, cur_shared;
bdrv_child_perm(bs, c->bs, c, c->role, NULL,
cumulative_perms, cumulative_shared_perms,
&cur_perm, &cur_shared);
bdrv_child_set_perm(c, cur_perm, cur_shared);
}
}
static void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
uint64_t *shared_perm)
{
BdrvChild *c;
uint64_t cumulative_perms = 0;
uint64_t cumulative_shared_perms = BLK_PERM_ALL;
QLIST_FOREACH(c, &bs->parents, next_parent) {
cumulative_perms |= c->perm;
cumulative_shared_perms &= c->shared_perm;
}
*perm = cumulative_perms;
*shared_perm = cumulative_shared_perms;
}
static char *bdrv_child_user_desc(BdrvChild *c)
{
if (c->role->get_parent_desc) {
return c->role->get_parent_desc(c);
}
return g_strdup("another user");
}
char *bdrv_perm_names(uint64_t perm)
{
struct perm_name {
uint64_t perm;
const char *name;
} permissions[] = {
{ BLK_PERM_CONSISTENT_READ, "consistent read" },
{ BLK_PERM_WRITE, "write" },
{ BLK_PERM_WRITE_UNCHANGED, "write unchanged" },
{ BLK_PERM_RESIZE, "resize" },
{ BLK_PERM_GRAPH_MOD, "change children" },
{ 0, NULL }
};
char *result = g_strdup("");
struct perm_name *p;
for (p = permissions; p->name; p++) {
if (perm & p->perm) {
char *old = result;
result = g_strdup_printf("%s%s%s", old, *old ? ", " : "", p->name);
g_free(old);
}
}
return result;
}
/*
* Checks whether a new reference to @bs can be added if the new user requires
* @new_used_perm/@new_shared_perm as its permissions. If @ignore_children is
* set, the BdrvChild objects in this list are ignored in the calculations;
* this allows checking permission updates for an existing reference.
*
* See bdrv_check_perm() for the semantics of @tighten_restrictions.
*
* Needs to be followed by a call to either bdrv_set_perm() or
* bdrv_abort_perm_update(). */
static int bdrv_check_update_perm(BlockDriverState *bs, BlockReopenQueue *q,
uint64_t new_used_perm,
uint64_t new_shared_perm,
GSList *ignore_children,
bool *tighten_restrictions,
Error **errp)
{
BdrvChild *c;
uint64_t cumulative_perms = new_used_perm;
uint64_t cumulative_shared_perms = new_shared_perm;
assert(!q || !tighten_restrictions);
/* There is no reason why anyone couldn't tolerate write_unchanged */
assert(new_shared_perm & BLK_PERM_WRITE_UNCHANGED);
QLIST_FOREACH(c, &bs->parents, next_parent) {
if (g_slist_find(ignore_children, c)) {
continue;
}
if ((new_used_perm & c->shared_perm) != new_used_perm) {
char *user = bdrv_child_user_desc(c);
char *perm_names = bdrv_perm_names(new_used_perm & ~c->shared_perm);
if (tighten_restrictions) {
*tighten_restrictions = true;
}
error_setg(errp, "Conflicts with use by %s as '%s', which does not "
"allow '%s' on %s",
user, c->name, perm_names, bdrv_get_node_name(c->bs));
g_free(user);
g_free(perm_names);
return -EPERM;
}
if ((c->perm & new_shared_perm) != c->perm) {
char *user = bdrv_child_user_desc(c);
char *perm_names = bdrv_perm_names(c->perm & ~new_shared_perm);
if (tighten_restrictions) {
*tighten_restrictions = true;
}
error_setg(errp, "Conflicts with use by %s as '%s', which uses "
"'%s' on %s",
user, c->name, perm_names, bdrv_get_node_name(c->bs));
g_free(user);
g_free(perm_names);
return -EPERM;
}
cumulative_perms |= c->perm;
cumulative_shared_perms &= c->shared_perm;
}
return bdrv_check_perm(bs, q, cumulative_perms, cumulative_shared_perms,
ignore_children, tighten_restrictions, errp);
}
/* Needs to be followed by a call to either bdrv_child_set_perm() or
* bdrv_child_abort_perm_update(). */
static int bdrv_child_check_perm(BdrvChild *c, BlockReopenQueue *q,
uint64_t perm, uint64_t shared,
GSList *ignore_children,
bool *tighten_restrictions, Error **errp)
{
int ret;
ignore_children = g_slist_prepend(g_slist_copy(ignore_children), c);
ret = bdrv_check_update_perm(c->bs, q, perm, shared, ignore_children,
tighten_restrictions, errp);
g_slist_free(ignore_children);
if (ret < 0) {
return ret;
}
if (!c->has_backup_perm) {
c->has_backup_perm = true;
c->backup_perm = c->perm;
c->backup_shared_perm = c->shared_perm;
}
/*
* Note: it's OK if c->has_backup_perm was already set, as we can find the
* same child twice during check_perm procedure
*/
c->perm = perm;
c->shared_perm = shared;
return 0;
}
static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared)
{
uint64_t cumulative_perms, cumulative_shared_perms;
c->has_backup_perm = false;
c->perm = perm;
c->shared_perm = shared;
bdrv_get_cumulative_perm(c->bs, &cumulative_perms,
&cumulative_shared_perms);
bdrv_set_perm(c->bs, cumulative_perms, cumulative_shared_perms);
}
static void bdrv_child_abort_perm_update(BdrvChild *c)
{
if (c->has_backup_perm) {
c->perm = c->backup_perm;
c->shared_perm = c->backup_shared_perm;
c->has_backup_perm = false;
}
bdrv_abort_perm_update(c->bs);
}
int bdrv_child_try_set_perm(BdrvChild *c, uint64_t perm, uint64_t shared,
Error **errp)
{
Error *local_err = NULL;
int ret;
bool tighten_restrictions;
ret = bdrv_child_check_perm(c, NULL, perm, shared, NULL,
&tighten_restrictions, &local_err);
if (ret < 0) {
bdrv_child_abort_perm_update(c);
if (tighten_restrictions) {
error_propagate(errp, local_err);
} else {
/*
* Our caller may intend to only loosen restrictions and
* does not expect this function to fail. Errors are not
* fatal in such a case, so we can just hide them from our
* caller.
*/
error_free(local_err);
ret = 0;
}
return ret;
}
bdrv_child_set_perm(c, perm, shared);
return 0;
}
int bdrv_child_refresh_perms(BlockDriverState *bs, BdrvChild *c, Error **errp)
{
uint64_t parent_perms, parent_shared;
uint64_t perms, shared;
bdrv_get_cumulative_perm(bs, &parent_perms, &parent_shared);
bdrv_child_perm(bs, c->bs, c, c->role, NULL, parent_perms, parent_shared,
&perms, &shared);
return bdrv_child_try_set_perm(c, perms, shared, errp);
}
void bdrv_filter_default_perms(BlockDriverState *bs, BdrvChild *c,
const BdrvChildRole *role,
BlockReopenQueue *reopen_queue,
uint64_t perm, uint64_t shared,
uint64_t *nperm, uint64_t *nshared)
{
if (c == NULL) {
*nperm = perm & DEFAULT_PERM_PASSTHROUGH;
*nshared = (shared & DEFAULT_PERM_PASSTHROUGH) | DEFAULT_PERM_UNCHANGED;
return;
}
*nperm = (perm & DEFAULT_PERM_PASSTHROUGH) |
(c->perm & DEFAULT_PERM_UNCHANGED);
*nshared = (shared & DEFAULT_PERM_PASSTHROUGH) |
(c->shared_perm & DEFAULT_PERM_UNCHANGED);
}
void bdrv_format_default_perms(BlockDriverState *bs, BdrvChild *c,
const BdrvChildRole *role,
BlockReopenQueue *reopen_queue,
uint64_t perm, uint64_t shared,
uint64_t *nperm, uint64_t *nshared)
{
bool backing = (role == &child_backing);
assert(role == &child_backing || role == &child_file);
if (!backing) {
int flags = bdrv_reopen_get_flags(reopen_queue, bs);
/* Apart from the modifications below, the same permissions are
* forwarded and left alone as for filters */
bdrv_filter_default_perms(bs, c, role, reopen_queue, perm, shared,
&perm, &shared);
/* Format drivers may touch metadata even if the guest doesn't write */
if (bdrv_is_writable_after_reopen(bs, reopen_queue)) {
perm |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
}
/* bs->file always needs to be consistent because of the metadata. We
* can never allow other users to resize or write to it. */
if (!(flags & BDRV_O_NO_IO)) {
perm |= BLK_PERM_CONSISTENT_READ;
}
shared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
} else {
/* We want consistent read from backing files if the parent needs it.
* No other operations are performed on backing files. */
perm &= BLK_PERM_CONSISTENT_READ;
/* If the parent can deal with changing data, we're okay with a
* writable and resizable backing file. */
/* TODO Require !(perm & BLK_PERM_CONSISTENT_READ), too? */
if (shared & BLK_PERM_WRITE) {
shared = BLK_PERM_WRITE | BLK_PERM_RESIZE;
} else {
shared = 0;
}
shared |= BLK_PERM_CONSISTENT_READ | BLK_PERM_GRAPH_MOD |
BLK_PERM_WRITE_UNCHANGED;
}
if (bs->open_flags & BDRV_O_INACTIVE) {
shared |= BLK_PERM_WRITE | BLK_PERM_RESIZE;
}
*nperm = perm;
*nshared = shared;
}
static void bdrv_replace_child_noperm(BdrvChild *child,
BlockDriverState *new_bs)
{
BlockDriverState *old_bs = child->bs;
int i;
assert(!child->frozen);
if (old_bs && new_bs) {
assert(bdrv_get_aio_context(old_bs) == bdrv_get_aio_context(new_bs));
}
if (old_bs) {
/* Detach first so that the recursive drain sections coming from @child
* are already gone and we only end the drain sections that came from
* elsewhere. */
if (child->role->detach) {
child->role->detach(child);
}
if (old_bs->quiesce_counter && child->role->drained_end) {
int num = old_bs->quiesce_counter;
if (child->role->parent_is_bds) {
num -= bdrv_drain_all_count;
}
assert(num >= 0);
for (i = 0; i < num; i++) {
child->role->drained_end(child);
}
}
QLIST_REMOVE(child, next_parent);
}
child->bs = new_bs;
if (new_bs) {
QLIST_INSERT_HEAD(&new_bs->parents, child, next_parent);
if (new_bs->quiesce_counter && child->role->drained_begin) {
int num = new_bs->quiesce_counter;
if (child->role->parent_is_bds) {
num -= bdrv_drain_all_count;
}
assert(num >= 0);
for (i = 0; i < num; i++) {
bdrv_parent_drained_begin_single(child, true);
}
}
/* Attach only after starting new drained sections, so that recursive
* drain sections coming from @child don't get an extra .drained_begin
* callback. */
if (child->role->attach) {
child->role->attach(child);
}
}
}
/*
* Updates @child to change its reference to point to @new_bs, including
* checking and applying the necessary permisson updates both to the old node
* and to @new_bs.
*
* NULL is passed as @new_bs for removing the reference before freeing @child.
*
* If @new_bs is not NULL, bdrv_check_perm() must be called beforehand, as this
* function uses bdrv_set_perm() to update the permissions according to the new
* reference that @new_bs gets.
*/
static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs)
{
BlockDriverState *old_bs = child->bs;
uint64_t perm, shared_perm;
bdrv_replace_child_noperm(child, new_bs);
/*
* Start with the new node's permissions. If @new_bs is a (direct
* or indirect) child of @old_bs, we must complete the permission
* update on @new_bs before we loosen the restrictions on @old_bs.
* Otherwise, bdrv_check_perm() on @old_bs would re-initiate
* updating the permissions of @new_bs, and thus not purely loosen
* restrictions.
*/
if (new_bs) {
bdrv_get_cumulative_perm(new_bs, &perm, &shared_perm);
bdrv_set_perm(new_bs, perm, shared_perm);
}
if (old_bs) {
/* Update permissions for old node. This is guaranteed to succeed
* because we're just taking a parent away, so we're loosening
* restrictions. */
bool tighten_restrictions;
int ret;
bdrv_get_cumulative_perm(old_bs, &perm, &shared_perm);
ret = bdrv_check_perm(old_bs, NULL, perm, shared_perm, NULL,
&tighten_restrictions, NULL);
assert(tighten_restrictions == false);
if (ret < 0) {
/* We only tried to loosen restrictions, so errors are not fatal */
bdrv_abort_perm_update(old_bs);
} else {
bdrv_set_perm(old_bs, perm, shared_perm);
}
/* When the parent requiring a non-default AioContext is removed, the
* node moves back to the main AioContext */
bdrv_try_set_aio_context(old_bs, qemu_get_aio_context(), NULL);
}
}
/*
* This function steals the reference to child_bs from the caller.
* That reference is later dropped by bdrv_root_unref_child().
*
* On failure NULL is returned, errp is set and the reference to
* child_bs is also dropped.
*
* The caller must hold the AioContext lock @child_bs, but not that of @ctx
* (unless @child_bs is already in @ctx).
*/
BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
const char *child_name,
const BdrvChildRole *child_role,
AioContext *ctx,
uint64_t perm, uint64_t shared_perm,
void *opaque, Error **errp)
{
BdrvChild *child;
Error *local_err = NULL;
int ret;
ret = bdrv_check_update_perm(child_bs, NULL, perm, shared_perm, NULL, NULL,
errp);
if (ret < 0) {
bdrv_abort_perm_update(child_bs);
bdrv_unref(child_bs);
return NULL;
}
child = g_new(BdrvChild, 1);
*child = (BdrvChild) {
.bs = NULL,
.name = g_strdup(child_name),
.role = child_role,
.perm = perm,
.shared_perm = shared_perm,
.opaque = opaque,
};
/* If the AioContexts don't match, first try to move the subtree of
* child_bs into the AioContext of the new parent. If this doesn't work,
* try moving the parent into the AioContext of child_bs instead. */
if (bdrv_get_aio_context(child_bs) != ctx) {
ret = bdrv_try_set_aio_context(child_bs, ctx, &local_err);
if (ret < 0 && child_role->can_set_aio_ctx) {
GSList *ignore = g_slist_prepend(NULL, child);;
ctx = bdrv_get_aio_context(child_bs);
if (child_role->can_set_aio_ctx(child, ctx, &ignore, NULL)) {
error_free(local_err);
ret = 0;
g_slist_free(ignore);
ignore = g_slist_prepend(NULL, child);;
child_role->set_aio_ctx(child, ctx, &ignore);
}
g_slist_free(ignore);
}
if (ret < 0) {
error_propagate(errp, local_err);
g_free(child);
bdrv_abort_perm_update(child_bs);
return NULL;
}
}
/* This performs the matching bdrv_set_perm() for the above check. */
bdrv_replace_child(child, child_bs);
return child;
}
/*
* This function transfers the reference to child_bs from the caller
* to parent_bs. That reference is later dropped by parent_bs on
* bdrv_close() or if someone calls bdrv_unref_child().
*
* On failure NULL is returned, errp is set and the reference to
* child_bs is also dropped.
*
* If @parent_bs and @child_bs are in different AioContexts, the caller must
* hold the AioContext lock for @child_bs, but not for @parent_bs.
*/
BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs,
BlockDriverState *child_bs,
const char *child_name,
const BdrvChildRole *child_role,
Error **errp)
{
BdrvChild *child;
uint64_t perm, shared_perm;
bdrv_get_cumulative_perm(parent_bs, &perm, &shared_perm);
assert(parent_bs->drv);
bdrv_child_perm(parent_bs, child_bs, NULL, child_role, NULL,
perm, shared_perm, &perm, &shared_perm);
child = bdrv_root_attach_child(child_bs, child_name, child_role,
bdrv_get_aio_context(parent_bs),
perm, shared_perm, parent_bs, errp);
if (child == NULL) {
return NULL;
}
QLIST_INSERT_HEAD(&parent_bs->children, child, next);
return child;
}
static void bdrv_detach_child(BdrvChild *child)
{
if (child->next.le_prev) {
QLIST_REMOVE(child, next);
child->next.le_prev = NULL;
}
bdrv_replace_child(child, NULL);
g_free(child->name);
g_free(child);
}
void bdrv_root_unref_child(BdrvChild *child)
{
BlockDriverState *child_bs;
child_bs = child->bs;
bdrv_detach_child(child);
bdrv_unref(child_bs);
}
void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child)
{
if (child == NULL) {
return;
}
if (child->bs->inherits_from == parent) {
BdrvChild *c;
/* Remove inherits_from only when the last reference between parent and
* child->bs goes away. */
QLIST_FOREACH(c, &parent->children, next) {
if (c != child && c->bs == child->bs) {
break;
}
}
if (c == NULL) {
child->bs->inherits_from = NULL;
}
}
bdrv_root_unref_child(child);
}
static void bdrv_parent_cb_change_media(BlockDriverState *bs, bool load)
{
BdrvChild *c;
QLIST_FOREACH(c, &bs->parents, next_parent) {
if (c->role->change_media) {
c->role->change_media(c, load);
}
}
}
/* Return true if you can reach parent going through child->inherits_from
* recursively. If parent or child are NULL, return false */
static bool bdrv_inherits_from_recursive(BlockDriverState *child,
BlockDriverState *parent)
{
while (child && child != parent) {
child = child->inherits_from;
}
return child != NULL;
}
/*
* Sets the backing file link of a BDS. A new reference is created; callers
* which don't need their own reference any more must call bdrv_unref().
*/
void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
Error **errp)
{
bool update_inherits_from = bdrv_chain_contains(bs, backing_hd) &&
bdrv_inherits_from_recursive(backing_hd, bs);
if (bdrv_is_backing_chain_frozen(bs, backing_bs(bs), errp)) {
return;
}
if (backing_hd) {
bdrv_ref(backing_hd);
}
if (bs->backing) {
bdrv_unref_child(bs, bs->backing);
}
if (!backing_hd) {
bs->backing = NULL;
goto out;
}
bs->backing = bdrv_attach_child(bs, backing_hd, "backing", &child_backing,
errp);
/* If backing_hd was already part of bs's backing chain, and
* inherits_from pointed recursively to bs then let's update it to
* point directly to bs (else it will become NULL). */
if (bs->backing && update_inherits_from) {
backing_hd->inherits_from = bs;
}
out:
bdrv_refresh_limits(bs, NULL);
}
/*
* Opens the backing file for a BlockDriverState if not yet open
*
* bdref_key specifies the key for the image's BlockdevRef in the options QDict.
* That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
* itself, all options starting with "${bdref_key}." are considered part of the
* BlockdevRef.
*
* TODO Can this be unified with bdrv_open_image()?
*/
int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
const char *bdref_key, Error **errp)
{
char *backing_filename = NULL;
char *bdref_key_dot;
const char *reference = NULL;
int ret = 0;
bool implicit_backing = false;
BlockDriverState *backing_hd;
QDict *options;
QDict *tmp_parent_options = NULL;
Error *local_err = NULL;
if (bs->backing != NULL) {
goto free_exit;
}
/* NULL means an empty set of options */
if (parent_options == NULL) {
tmp_parent_options = qdict_new();
parent_options = tmp_parent_options;
}
bs->open_flags &= ~BDRV_O_NO_BACKING;
bdref_key_dot = g_strdup_printf("%s.", bdref_key);
qdict_extract_subqdict(parent_options, &options, bdref_key_dot);
g_free(bdref_key_dot);
/*
* Caution: while qdict_get_try_str() is fine, getting non-string
* types would require more care. When @parent_options come from
* -blockdev or blockdev_add, its members are typed according to
* the QAPI schema, but when they come from -drive, they're all
* QString.
*/
reference = qdict_get_try_str(parent_options, bdref_key);
if (reference || qdict_haskey(options, "file.filename")) {
/* keep backing_filename NULL */
} else if (bs->backing_file[0] == '\0' && qdict_size(options) == 0) {
qobject_unref(options);
goto free_exit;
} else {
if (qdict_size(options) == 0) {
/* If the user specifies options that do not modify the
* backing file's behavior, we might still consider it the
* implicit backing file. But it's easier this way, and
* just specifying some of the backing BDS's options is
* only possible with -drive anyway (otherwise the QAPI
* schema forces the user to specify everything). */
implicit_backing = !strcmp(bs->auto_backing_file, bs->backing_file);
}
backing_filename = bdrv_get_full_backing_filename(bs, &local_err);
if (local_err) {
ret = -EINVAL;
error_propagate(errp, local_err);
qobject_unref(options);
goto free_exit;
}
}
if (!bs->drv || !bs->drv->supports_backing) {
ret = -EINVAL;
error_setg(errp, "Driver doesn't support backing files");
qobject_unref(options);
goto free_exit;
}
if (!reference &&
bs->backing_format[0] != '\0' && !qdict_haskey(options, "driver")) {
qdict_put_str(options, "driver", bs->backing_format);
}
backing_hd = bdrv_open_inherit(backing_filename, reference, options, 0, bs,
&child_backing, errp);
if (!backing_hd) {
bs->open_flags |= BDRV_O_NO_BACKING;
error_prepend(errp, "Could not open backing file: ");
ret = -EINVAL;
goto free_exit;
}
if (implicit_backing) {
bdrv_refresh_filename(backing_hd);
pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
backing_hd->filename);
}
/* Hook up the backing file link; drop our reference, bs owns the
* backing_hd reference now */
bdrv_set_backing_hd(bs, backing_hd, &local_err);
bdrv_unref(backing_hd);
if (local_err) {
error_propagate(errp, local_err);
ret = -EINVAL;
goto free_exit;
}
qdict_del(parent_options, bdref_key);
free_exit:
g_free(backing_filename);
qobject_unref(tmp_parent_options);
return ret;
}
static BlockDriverState *
bdrv_open_child_bs(const char *filename, QDict *options, const char *bdref_key,
BlockDriverState *parent, const BdrvChildRole *child_role,
bool allow_none, Error **errp)
{
BlockDriverState *bs = NULL;
QDict *image_options;
char *bdref_key_dot;
const char *reference;
assert(child_role != NULL);
bdref_key_dot = g_strdup_printf("%s.", bdref_key);
qdict_extract_subqdict(options, &image_options, bdref_key_dot);
g_free(bdref_key_dot);
/*
* Caution: while qdict_get_try_str() is fine, getting non-string
* types would require more care. When @options come from
* -blockdev or blockdev_add, its members are typed according to
* the QAPI schema, but when they come from -drive, they're all
* QString.
*/
reference = qdict_get_try_str(options, bdref_key);
if (!filename && !reference && !qdict_size(image_options)) {
if (!allow_none) {
error_setg(errp, "A block device must be specified for \"%s\"",
bdref_key);
}
qobject_unref(image_options);
goto done;
}
bs = bdrv_open_inherit(filename, reference, image_options, 0,
parent, child_role, errp);
if (!bs) {
goto done;
}
done:
qdict_del(options, bdref_key);
return bs;
}
/*
* Opens a disk image whose options are given as BlockdevRef in another block
* device's options.
*
* If allow_none is true, no image will be opened if filename is false and no
* BlockdevRef is given. NULL will be returned, but errp remains unset.
*
* bdrev_key specifies the key for the image's BlockdevRef in the options QDict.
* That QDict has to be flattened; therefore, if the BlockdevRef is a QDict
* itself, all options starting with "${bdref_key}." are considered part of the
* BlockdevRef.
*
* The BlockdevRef will be removed from the options QDict.
*/
BdrvChild *bdrv_open_child(const char *filename,
QDict *options, const char *bdref_key,
BlockDriverState *parent,
const BdrvChildRole *child_role,
bool allow_none, Error **errp)
{
BlockDriverState *bs;
bs = bdrv_open_child_bs(filename, options, bdref_key, parent, child_role,
allow_none, errp);
if (bs == NULL) {
return NULL;
}
return bdrv_attach_child(parent, bs, bdref_key, child_role, errp);
}
/* TODO Future callers may need to specify parent/child_role in order for
* option inheritance to work. Existing callers use it for the root node. */
BlockDriverState *bdrv_open_blockdev_ref(BlockdevRef *ref, Error **errp)
{
BlockDriverState *bs = NULL;
Error *local_err = NULL;
QObject *obj = NULL;
QDict *qdict = NULL;
const char *reference = NULL;
Visitor *v = NULL;
if (ref->type == QTYPE_QSTRING) {
reference = ref->u.reference;
} else {
BlockdevOptions *options = &ref->u.definition;
assert(ref->type == QTYPE_QDICT);
v = qobject_output_visitor_new(&obj);
visit_type_BlockdevOptions(v, NULL, &options, &local_err);
if (local_err) {
error_propagate(errp, local_err);
goto fail;
}
visit_complete(v, &obj);
qdict = qobject_to(QDict, obj);
qdict_flatten(qdict);
/* bdrv_open_inherit() defaults to the values in bdrv_flags (for
* compatibility with other callers) rather than what we want as the
* real defaults. Apply the defaults here instead. */
qdict_set_default_str(qdict, BDRV_OPT_CACHE_DIRECT, "off");
qdict_set_default_str(qdict, BDRV_OPT_CACHE_NO_FLUSH, "off");
qdict_set_default_str(qdict, BDRV_OPT_READ_ONLY, "off");
qdict_set_default_str(qdict, BDRV_OPT_AUTO_READ_ONLY, "off");
}
bs = bdrv_open_inherit(NULL, reference, qdict, 0, NULL, NULL, errp);
obj = NULL;
fail:
qobject_unref(obj);
visit_free(v);
return bs;
}
static BlockDriverState *bdrv_append_temp_snapshot(BlockDriverState *bs,
int flags,
QDict *snapshot_options,
Error **errp)
{
/* TODO: extra byte is a hack to ensure MAX_PATH space on Windows. */
char *tmp_filename = g_malloc0(PATH_MAX + 1);
int64_t total_size;
QemuOpts *opts = NULL;
BlockDriverState *bs_snapshot = NULL;
Error *local_err = NULL;
int ret;
/* if snapshot, we create a temporary backing file and open it
instead of opening 'filename' directly */
/* Get the required size from the image */
total_size = bdrv_getlength(bs);
if (total_size < 0) {
error_setg_errno(errp, -total_size, "Could not get image size");
goto out;
}
/* Create the temporary image */
ret = get_tmp_filename(tmp_filename, PATH_MAX + 1);
if (ret < 0) {
error_setg_errno(errp, -ret, "Could not get temporary filename");
goto out;
}
opts = qemu_opts_create(bdrv_qcow2.create_opts, NULL, 0,
&error_abort);
qemu_opt_set_number(opts, BLOCK_OPT_SIZE, total_size, &error_abort);
ret = bdrv_create(&bdrv_qcow2, tmp_filename, opts, errp);
qemu_opts_del(opts);
if (ret < 0) {
error_prepend(errp, "Could not create temporary overlay '%s': ",
tmp_filename);
goto out;
}
/* Prepare options QDict for the temporary file */
qdict_put_str(snapshot_options, "file.driver", "file");
qdict_put_str(snapshot_options, "file.filename", tmp_filename);
qdict_put_str(snapshot_options, "driver", "qcow2");
bs_snapshot = bdrv_open(NULL, NULL, snapshot_options, flags, errp);
snapshot_options = NULL;
if (!bs_snapshot) {
goto out;
}
/* bdrv_append() consumes a strong reference to bs_snapshot
* (i.e. it will call bdrv_unref() on it) even on error, so in
* order to be able to return one, we have to increase
* bs_snapshot's refcount here */
bdrv_ref(bs_snapshot);
bdrv_append(bs_snapshot, bs, &local_err);
if (local_err) {
error_propagate(errp, local_err);
bs_snapshot = NULL;
goto out;
}
out:
qobject_unref(snapshot_options);
g_free(tmp_filename);
return bs_snapshot;
}
/*
* Opens a disk image (raw, qcow2, vmdk, ...)
*
* options is a QDict of options to pass to the block drivers, or NULL for an
* empty set of options. The reference to the QDict belongs to the block layer
* after the call (even on failure), so if the caller intends to reuse the
* dictionary, it needs to use qobject_ref() before calling bdrv_open.
*
* If *pbs is NULL, a new BDS will be created with a pointer to it stored there.
* If it is not NULL, the referenced BDS will be reused.
*
* The reference parameter may be used to specify an existing block device which
* should be opened. If specified, neither options nor a filename may be given,
* nor can an existing BDS be reused (that is, *pbs has to be NULL).
*/
static BlockDriverState *bdrv_open_inherit(const char *filename,
const char *reference,
QDict *options, int flags,
BlockDriverState *parent,
const BdrvChildRole *child_role,
Error **errp)
{
int ret;
BlockBackend *file = NULL;
BlockDriverState *bs;
BlockDriver *drv = NULL;
BdrvChild *child;
const char *drvname;
const char *backing;
Error *local_err = NULL;
QDict *snapshot_options = NULL;
int snapshot_flags = 0;
assert(!child_role || !flags);
assert(!child_role == !parent);
if (reference) {
bool options_non_empty = options ? qdict_size(options) : false;
qobject_unref(options);
if (filename || options_non_empty) {
error_setg(errp, "Cannot reference an existing block device with "
"additional options or a new filename");
return NULL;
}
bs = bdrv_lookup_bs(reference, reference, errp);
if (!bs) {
return NULL;
}
bdrv_ref(bs);
return bs;
}
bs = bdrv_new();
/* NULL means an empty set of options */
if (options == NULL) {
options = qdict_new();
}
/* json: syntax counts as explicit options, as if in the QDict */
parse_json_protocol(options, &filename, &local_err);
if (local_err) {
goto fail;
}
bs->explicit_options = qdict_clone_shallow(options);
if (child_role) {
bs->inherits_from = parent;
child_role->inherit_options(&flags, options,
parent->open_flags, parent->options);
}
ret = bdrv_fill_options(&options, filename, &flags, &local_err);
if (local_err) {
goto fail;
}
/*
* Set the BDRV_O_RDWR and BDRV_O_ALLOW_RDWR flags.
* Caution: getting a boolean member of @options requires care.
* When @options come from -blockdev or blockdev_add, members are
* typed according to the QAPI schema, but when they come from
* -drive, they're all QString.
*/
if (g_strcmp0(qdict_get_try_str(options, BDRV_OPT_READ_ONLY), "on") &&
!qdict_get_try_bool(options, BDRV_OPT_READ_ONLY, false)) {
flags |= (BDRV_O_RDWR | BDRV_O_ALLOW_RDWR);
} else {
flags &= ~BDRV_O_RDWR;
}
if (flags & BDRV_O_SNAPSHOT) {
snapshot_options = qdict_new();
bdrv_temp_snapshot_options(&snapshot_flags, snapshot_options,
flags, options);
/* Let bdrv_backing_options() override "read-only" */
qdict_del(options, BDRV_OPT_READ_ONLY);
bdrv_backing_options(&flags, options, flags, options);
}
bs->open_flags = flags;
bs->options = options;
options = qdict_clone_shallow(options);
/* Find the right image format driver */
/* See cautionary note on accessing @options above */
drvname = qdict_get_try_str(options, "driver");
if (drvname) {
drv = bdrv_find_format(drvname);
if (!drv) {
error_setg(errp, "Unknown driver: '%s'", drvname);
goto fail;
}
}
assert(drvname || !(flags & BDRV_O_PROTOCOL));
/* See cautionary note on accessing @options above */
backing = qdict_get_try_str(options, "backing");
if (qobject_to(QNull, qdict_get(options, "backing")) != NULL ||
(backing && *backing == '\0'))
{
if (backing) {
warn_report("Use of \"backing\": \"\" is deprecated; "
"use \"backing\": null instead");
}
flags |= BDRV_O_NO_BACKING;
qdict_del(options, "backing");
}
/* Open image file without format layer. This BlockBackend is only used for
* probing, the block drivers will do their own bdrv_open_child() for the
* same BDS, which is why we put the node name back into options. */
if ((flags & BDRV_O_PROTOCOL) == 0) {
BlockDriverState *file_bs;
file_bs = bdrv_open_child_bs(filename, options, "file", bs,
&child_file, true, &local_err);
if (local_err) {
goto fail;
}
if (file_bs != NULL) {
/* Not requesting BLK_PERM_CONSISTENT_READ because we're only
* looking at the header to guess the image format. This works even
* in cases where a guest would not see a consistent state. */
file = blk_new(bdrv_get_aio_context(file_bs), 0, BLK_PERM_ALL);
blk_insert_bs(file, file_bs, &local_err);
bdrv_unref(file_bs);
if (local_err) {
goto fail;
}
qdict_put_str(options, "file", bdrv_get_node_name(file_bs));
}
}
/* Image format probing */
bs->probed = !drv;
if (!drv && file) {
ret = find_image_format(file, filename, &drv, &local_err);
if (ret < 0) {
goto fail;
}
/*
* This option update would logically belong in bdrv_fill_options(),
* but we first need to open bs->file for the probing to work, while
* opening bs->file already requires the (mostly) final set of options
* so that cache mode etc. can be inherited.
*
* Adding the driver later is somewhat ugly, but it's not an option
* that would ever be inherited, so it's correct. We just need to make
* sure to update both bs->options (which has the full effective
* options for bs) and options (which has file.* already removed).
*/
qdict_put_str(bs->options, "driver", drv->format_name);
qdict_put_str(options, "driver", drv->format_name);
} else if (!drv) {
error_setg(errp, "Must specify either driver or file");
goto fail;
}
/* BDRV_O_PROTOCOL must be set iff a protocol BDS is about to be created */
assert(!!(flags & BDRV_O_PROTOCOL) == !!drv->bdrv_file_open);
/* file must be NULL if a protocol BDS is about to be created
* (the inverse results in an error message from bdrv_open_common()) */
assert(!(flags & BDRV_O_PROTOCOL) || !file);
/* Open the image */
ret = bdrv_open_common(bs, file, options, &local_err);
if (ret < 0) {
goto fail;
}
if (file) {
blk_unref(file);
file = NULL;
}
/* If there is a backing file, use it */
if ((flags & BDRV_O_NO_BACKING) == 0) {
ret = bdrv_open_backing_file(bs, options, "backing", &local_err);
if (ret < 0) {
goto close_and_fail;
}
}
/* Remove all children options and references
* from bs->options and bs->explicit_options */
QLIST_FOREACH(child, &bs->children, next) {
char *child_key_dot;
child_key_dot = g_strdup_printf("%s.", child->name);
qdict_extract_subqdict(bs->explicit_options, NULL, child_key_dot);
qdict_extract_subqdict(bs->options, NULL, child_key_dot);
qdict_del(bs->explicit_options, child->name);
qdict_del(bs->options, child->name);
g_free(child_key_dot);
}
/* Check if any unknown options were used */
if (qdict_size(options) != 0) {
const QDictEntry *entry = qdict_first(options);
if (flags & BDRV_O_PROTOCOL) {
error_setg(errp, "Block protocol '%s' doesn't support the option "
"'%s'", drv->format_name, entry->key);
} else {
error_setg(errp,
"Block format '%s' does not support the option '%s'",
drv->format_name, entry->key);
}
goto close_and_fail;
}
bdrv_parent_cb_change_media(bs, true);
qobject_unref(options);
options = NULL;
/* For snapshot=on, create a temporary qcow2 overlay. bs points to the
* temporary snapshot afterwards. */
if (snapshot_flags) {
BlockDriverState *snapshot_bs;
snapshot_bs = bdrv_append_temp_snapshot(bs, snapshot_flags,
snapshot_options, &local_err);
snapshot_options = NULL;
if (local_err) {
goto close_and_fail;
}
/* We are not going to return bs but the overlay on top of it
* (snapshot_bs); thus, we have to drop the strong reference to bs
* (which we obtained by calling bdrv_new()). bs will not be deleted,
* though, because the overlay still has a reference to it. */
bdrv_unref(bs);
bs = snapshot_bs;
}
return bs;
fail:
blk_unref(file);
qobject_unref(snapshot_options);
qobject_unref(bs->explicit_options);
qobject_unref(bs->options);
qobject_unref(options);
bs->options = NULL;
bs->explicit_options = NULL;
bdrv_unref(bs);
error_propagate(errp, local_err);
return NULL;
close_and_fail:
bdrv_unref(bs);
qobject_unref(snapshot_options);
qobject_unref(options);
error_propagate(errp, local_err);
return NULL;
}
BlockDriverState *bdrv_open(const char *filename, const char *reference,
QDict *options, int flags, Error **errp)
{
return bdrv_open_inherit(filename, reference, options, flags, NULL,
NULL, errp);
}
/* Return true if the NULL-terminated @list contains @str */
static bool is_str_in_list(const char *str, const char *const *list)
{
if (str && list) {
int i;
for (i = 0; list[i] != NULL; i++) {
if (!strcmp(str, list[i])) {
return true;
}
}
}
return false;
}
/*
* Check that every option set in @bs->options is also set in
* @new_opts.
*
* Options listed in the common_options list and in
* @bs->drv->mutable_opts are skipped.
*
* Return 0 on success, otherwise return -EINVAL and set @errp.
*/
static int bdrv_reset_options_allowed(BlockDriverState *bs,
const QDict *new_opts, Error **errp)
{
const QDictEntry *e;
/* These options are common to all block drivers and are handled
* in bdrv_reopen_prepare() so they can be left out of @new_opts */
const char *const common_options[] = {
"node-name", "discard", "cache.direct", "cache.no-flush",
"read-only", "auto-read-only", "detect-zeroes", NULL
};
for (e = qdict_first(bs->options); e; e = qdict_next(bs->options, e)) {
if (!qdict_haskey(new_opts, e->key) &&
!is_str_in_list(e->key, common_options) &&
!is_str_in_list(e->key, bs->drv->mutable_opts)) {
error_setg(errp, "Option '%s' cannot be reset "
"to its default value", e->key);
return -EINVAL;
}
}
return 0;
}
/*
* Returns true if @child can be reached recursively from @bs
*/
static bool bdrv_recurse_has_child(BlockDriverState *bs,
BlockDriverState *child)
{
BdrvChild *c;
if (bs == child) {
return true;
}
QLIST_FOREACH(c, &bs->children, next) {
if (bdrv_recurse_has_child(c->bs, child)) {
return true;
}
}
return false;
}
/*
* Adds a BlockDriverState to a simple queue for an atomic, transactional
* reopen of multiple devices.
*
* bs_queue can either be an existing BlockReopenQueue that has had QSIMPLE_INIT
* already performed, or alternatively may be NULL a new BlockReopenQueue will
* be created and initialized. This newly created BlockReopenQueue should be
* passed back in for subsequent calls that are intended to be of the same
* atomic 'set'.
*
* bs is the BlockDriverState to add to the reopen queue.
*
* options contains the changed options for the associated bs
* (the BlockReopenQueue takes ownership)
*
* flags contains the open flags for the associated bs
*
* returns a pointer to bs_queue, which is either the newly allocated
* bs_queue, or the existing bs_queue being used.
*
* bs must be drained between bdrv_reopen_queue() and bdrv_reopen_multiple().
*/
static BlockReopenQueue *bdrv_reopen_queue_child(BlockReopenQueue *bs_queue,
BlockDriverState *bs,
QDict *options,
const BdrvChildRole *role,
QDict *parent_options,
int parent_flags,
bool keep_old_opts)
{
assert(bs != NULL);
BlockReopenQueueEntry *bs_entry;
BdrvChild *child;
QDict *old_options, *explicit_options, *options_copy;
int flags;
QemuOpts *opts;
/* Make sure that the caller remembered to use a drained section. This is
* important to avoid graph changes between the recursive queuing here and
* bdrv_reopen_multiple(). */
assert(bs->quiesce_counter > 0);
if (bs_queue == NULL) {
bs_queue = g_new0(BlockReopenQueue, 1);
QSIMPLEQ_INIT(bs_queue);
}
if (!options) {
options = qdict_new();
}
/* Check if this BlockDriverState is already in the queue */
QSIMPLEQ_FOREACH(bs_entry, bs_queue, entry) {
if (bs == bs_entry->state.bs) {
break;
}
}
/*
* Precedence of options:
* 1. Explicitly passed in options (highest)
* 2. Retained from explicitly set options of bs
* 3. Inherited from parent node
* 4. Retained from effective options of bs
*/
/* Old explicitly set values (don't overwrite by inherited value) */
if (bs_entry || keep_old_opts) {
old_options = qdict_clone_shallow(bs_entry ?
bs_entry->state.explicit_options :
bs->explicit_options);
bdrv_join_options(bs, options, old_options);
qobject_unref(old_options);
}
explicit_options = qdict_clone_shallow(options);
/* Inherit from parent node */
if (parent_options) {
flags = 0;
role->inherit_options(&flags, options, parent_flags, parent_options);
} else {
flags = bdrv_get_flags(bs);
}
if (keep_old_opts) {
/* Old values are used for options that aren't set yet */
old_options = qdict_clone_shallow(bs->options);
bdrv_join_options(bs, options, old_options);
qobject_unref(old_options);
}
/* We have the final set of options so let's update the flags */
options_copy = qdict_clone_shallow(options);
opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
qemu_opts_absorb_qdict(opts, options_copy, NULL);
update_flags_from_options(&flags, opts);
qemu_opts_del(opts);
qobject_unref(options_copy);
/* bdrv_open_inherit() sets and clears some additional flags internally */
flags &= ~BDRV_O_PROTOCOL;
if (flags & BDRV_O_RDWR) {
flags |= BDRV_O_ALLOW_RDWR;
}
if (!bs_entry) {
bs_entry = g_new0(BlockReopenQueueEntry, 1);
QSIMPLEQ_INSERT_TAIL(bs_queue, bs_entry, entry);
} else {
qobject_unref(bs_entry->state.options);
qobject_unref(bs_entry->state.explicit_options);
}
bs_entry->state.bs = bs;
bs_entry->state.options = options;
bs_entry->state.explicit_options = explicit_options;
bs_entry->state.flags = flags;
/* This needs to be overwritten in bdrv_reopen_prepare() */
bs_entry->state.perm = UINT64_MAX;
bs_entry->state.shared_perm = 0;
/*
* If keep_old_opts is false then it means that unspecified
* options must be reset to their original value. We don't allow
* resetting 'backing' but we need to know if the option is
* missing in order to decide if we have to return an error.
*/
if (!keep_old_opts) {
bs_entry->state.backing_missing =
!qdict_haskey(options, "backing") &&
!qdict_haskey(options, "backing.driver");
}
QLIST_FOREACH(child, &bs->children, next) {
QDict *new_child_options = NULL;
bool child_keep_old = keep_old_opts;
/* reopen can only change the options of block devices that were
* implicitly created and inherited options. For other (referenced)
* block devices, a syntax like "backing.foo" results in an error. */
if (child->bs->inherits_from != bs) {
continue;
}
/* Check if the options contain a child reference */
if (qdict_haskey(options, child->name)) {
const char *childref = qdict_get_try_str(options, child->name);
/*
* The current child must not be reopened if the child
* reference is null or points to a different node.
*/
if (g_strcmp0(childref, child->bs->node_name)) {
continue;
}
/*
* If the child reference points to the current child then
* reopen it with its existing set of options (note that
* it can still inherit new options from the parent).
*/
child_keep_old = true;
} else {
/* Extract child options ("child-name.*") */
char *child_key_dot = g_strdup_printf("%s.", child->name);
qdict_extract_subqdict(explicit_options, NULL, child_key_dot);
qdict_extract_subqdict(options, &new_child_options, child_key_dot);
g_free(child_key_dot);
}
bdrv_reopen_queue_child(bs_queue, child->bs, new_child_options,
child->role, options, flags, child_keep_old);
}
return bs_queue;
}
BlockReopenQueue *bdrv_reopen_queue(BlockReopenQueue *bs_queue,
BlockDriverState *bs,
QDict *options, bool keep_old_opts)
{
return bdrv_reopen_queue_child(bs_queue, bs, options, NULL, NULL, 0,
keep_old_opts);
}
/*
* Reopen multiple BlockDriverStates atomically & transactionally.
*
* The queue passed in (bs_queue) must have been built up previous
* via bdrv_reopen_queue().
*
* Reopens all BDS specified in the queue, with the appropriate
* flags. All devices are prepared for reopen, and failure of any
* device will cause all device changes to be abandoned, and intermediate
* data cleaned up.
*
* If all devices prepare successfully, then the changes are committed
* to all devices.
*
* All affected nodes must be drained between bdrv_reopen_queue() and
* bdrv_reopen_multiple().
*/
int bdrv_reopen_multiple(BlockReopenQueue *bs_queue, Error **errp)
{
int ret = -1;
BlockReopenQueueEntry *bs_entry, *next;
assert(bs_queue != NULL);
QSIMPLEQ_FOREACH(bs_entry, bs_queue, entry) {
assert(bs_entry->state.bs->quiesce_counter > 0);
if (bdrv_reopen_prepare(&bs_entry->state, bs_queue, errp)) {
goto cleanup;
}
bs_entry->prepared = true;
}
QSIMPLEQ_FOREACH(bs_entry, bs_queue, entry) {
BDRVReopenState *state = &bs_entry->state;
ret = bdrv_check_perm(state->bs, bs_queue, state->perm,
state->shared_perm, NULL, NULL, errp);
if (ret < 0) {
goto cleanup_perm;
}
/* Check if new_backing_bs would accept the new permissions */
if (state->replace_backing_bs && state->new_backing_bs) {
uint64_t nperm, nshared;
bdrv_child_perm(state->bs, state->new_backing_bs,
NULL, &child_backing, bs_queue,
state->perm, state->shared_perm,
&nperm, &nshared);
ret = bdrv_check_update_perm(state->new_backing_bs, NULL,
nperm, nshared, NULL, NULL, errp);
if (ret < 0) {
goto cleanup_perm;
}
}
bs_entry->perms_checked = true;
}
/* If we reach this point, we have success and just need to apply the
* changes
*/
QSIMPLEQ_FOREACH(bs_entry, bs_queue, entry) {
bdrv_reopen_commit(&bs_entry->state);
}
ret = 0;
cleanup_perm:
QSIMPLEQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
BDRVReopenState *state = &bs_entry->state;
if (!bs_entry->perms_checked) {
continue;
}
if (ret == 0) {
bdrv_set_perm(state->bs, state->perm, state->shared_perm);
} else {
bdrv_abort_perm_update(state->bs);
if (state->replace_backing_bs && state->new_backing_bs) {
bdrv_abort_perm_update(state->new_backing_bs);
}
}
}
cleanup:
QSIMPLEQ_FOREACH_SAFE(bs_entry, bs_queue, entry, next) {
if (ret) {
if (bs_entry->prepared) {
bdrv_reopen_abort(&bs_entry->state);
}
qobject_unref(bs_entry->state.explicit_options);
qobject_unref(bs_entry->state.options);
}
if (bs_entry->state.new_backing_bs) {
bdrv_unref(bs_entry->state.new_backing_bs);
}
g_free(bs_entry);
}
g_free(bs_queue);
return ret;
}
int bdrv_reopen_set_read_only(BlockDriverState *bs, bool read_only,
Error **errp)
{
int ret;
BlockReopenQueue *queue;
QDict *opts = qdict_new();
qdict_put_bool(opts, BDRV_OPT_READ_ONLY, read_only);
bdrv_subtree_drained_begin(bs);
queue = bdrv_reopen_queue(NULL, bs, opts, true);
ret = bdrv_reopen_multiple(queue, errp);
bdrv_subtree_drained_end(bs);
return ret;
}
static BlockReopenQueueEntry *find_parent_in_reopen_queue(BlockReopenQueue *q,
BdrvChild *c)
{
BlockReopenQueueEntry *entry;
QSIMPLEQ_FOREACH(entry, q, entry) {
BlockDriverState *bs = entry->state.bs;
BdrvChild *child;
QLIST_FOREACH(child, &bs->children, next) {
if (child == c) {
return entry;
}
}
}
return NULL;
}
static void bdrv_reopen_perm(BlockReopenQueue *q, BlockDriverState *bs,
uint64_t *perm, uint64_t *shared)
{
BdrvChild *c;
BlockReopenQueueEntry *parent;
uint64_t cumulative_perms = 0;
uint64_t cumulative_shared_perms = BLK_PERM_ALL;
QLIST_FOREACH(c, &bs->parents, next_parent) {
parent = find_parent_in_reopen_queue(q, c);
if (!parent) {
cumulative_perms |= c->perm;
cumulative_shared_perms &= c->shared_perm;
} else {
uint64_t nperm, nshared;
bdrv_child_perm(parent->state.bs, bs, c, c->role, q,
parent->state.perm, parent->state.shared_perm,
&nperm, &nshared);
cumulative_perms |= nperm;
cumulative_shared_perms &= nshared;
}
}
*perm = cumulative_perms;
*shared = cumulative_shared_perms;
}
/*
* Take a BDRVReopenState and check if the value of 'backing' in the
* reopen_state->options QDict is valid or not.
*
* If 'backing' is missing from the QDict then return 0.
*
* If 'backing' contains the node name of the backing file of
* reopen_state->bs then return 0.
*
* If 'backing' contains a different node name (or is null) then check
* whether the current backing file can be replaced with the new one.
* If that's the case then reopen_state->replace_backing_bs is set to
* true and reopen_state->new_backing_bs contains a pointer to the new
* backing BlockDriverState (or NULL).
*
* Return 0 on success, otherwise return < 0 and set @errp.
*/
static int bdrv_reopen_parse_backing(BDRVReopenState *reopen_state,
Error **errp)
{
BlockDriverState *bs = reopen_state->bs;
BlockDriverState *overlay_bs, *new_backing_bs;
QObject *value;
const char *str;
value = qdict_get(reopen_state->options, "backing");
if (value == NULL) {
return 0;
}
switch (qobject_type(value)) {
case QTYPE_QNULL:
new_backing_bs = NULL;
break;
case QTYPE_QSTRING:
str = qobject_get_try_str(value);
new_backing_bs = bdrv_lookup_bs(NULL, str, errp);
if (new_backing_bs == NULL) {
return -EINVAL;
} else if (bdrv_recurse_has_child(new_backing_bs, bs)) {
error_setg(errp, "Making '%s' a backing file of '%s' "
"would create a cycle", str, bs->node_name);
return -EINVAL;
}
break;
default:
/* 'backing' does not allow any other data type */
g_assert_not_reached();
}
/*
* TODO: before removing the x- prefix from x-blockdev-reopen we
* should move the new backing file into the right AioContext
* instead of returning an error.
*/
if (new_backing_bs) {
if (bdrv_get_aio_context(new_backing_bs) != bdrv_get_aio_context(bs)) {
error_setg(errp, "Cannot use a new backing file "
"with a different AioContext");
return -EINVAL;
}
}
/*
* Find the "actual" backing file by skipping all links that point
* to an implicit node, if any (e.g. a commit filter node).
*/
overlay_bs = bs;
while (backing_bs(overlay_bs) && backing_bs(overlay_bs)->implicit) {
overlay_bs = backing_bs(overlay_bs);
}
/* If we want to replace the backing file we need some extra checks */
if (new_backing_bs != backing_bs(overlay_bs)) {
/* Check for implicit nodes between bs and its backing file */
if (bs != overlay_bs) {
error_setg(errp, "Cannot change backing link if '%s' has "
"an implicit backing file", bs->node_name);
return -EPERM;
}
/* Check if the backing link that we want to replace is frozen */
if (bdrv_is_backing_chain_frozen(overlay_bs, backing_bs(overlay_bs),
errp)) {
return -EPERM;
}
reopen_state->replace_backing_bs = true;
if (new_backing_bs) {
bdrv_ref(new_backing_bs);
reopen_state->new_backing_bs = new_backing_bs;
}
}
return 0;
}
/*
* Prepares a BlockDriverState for reopen. All changes are staged in the
* 'opaque' field of the BDRVReopenState, which is used and allocated by
* the block driver layer .bdrv_reopen_prepare()
*
* bs is the BlockDriverState to reopen
* flags are the new open flags
* queue is the reopen queue
*
* Returns 0 on success, non-zero on error. On error errp will be set
* as well.
*
* On failure, bdrv_reopen_abort() will be called to clean up any data.
* It is the responsibility of the caller to then call the abort() or
* commit() for any other BDS that have been left in a prepare() state
*
*/
int bdrv_reopen_prepare(BDRVReopenState *reopen_state, BlockReopenQueue *queue,
Error **errp)
{
int ret = -1;
int old_flags;
Error *local_err = NULL;
BlockDriver *drv;
QemuOpts *opts;
QDict *orig_reopen_opts;
char *discard = NULL;
bool read_only;
bool drv_prepared = false;
assert(reopen_state != NULL);
assert(reopen_state->bs->drv != NULL);
drv = reopen_state->bs->drv;
/* This function and each driver's bdrv_reopen_prepare() remove
* entries from reopen_state->options as they are processed, so
* we need to make a copy of the original QDict. */
orig_reopen_opts = qdict_clone_shallow(reopen_state->options);
/* Process generic block layer options */
opts = qemu_opts_create(&bdrv_runtime_opts, NULL, 0, &error_abort);
qemu_opts_absorb_qdict(opts, reopen_state->options, &local_err);
if (local_err) {
error_propagate(errp, local_err);
ret = -EINVAL;
goto error;
}
/* This was already called in bdrv_reopen_queue_child() so the flags
* are up-to-date. This time we simply want to remove the options from
* QemuOpts in order to indicate that they have been processed. */
old_flags = reopen_state->flags;
update_flags_from_options(&reopen_state->flags, opts);
assert(old_flags == reopen_state->flags);
discard = qemu_opt_get_del(opts, BDRV_OPT_DISCARD);
if (discard != NULL) {
if (bdrv_parse_discard_flags(discard, &reopen_state->flags) != 0) {
error_setg(errp, "Invalid discard option");
ret = -EINVAL;
goto error;
}
}
reopen_state->detect_zeroes =
bdrv_parse_detect_zeroes(opts, reopen_state->flags, &local_err);
if (local_err) {
error_propagate(errp, local_err);
ret = -EINVAL;
goto error;
}
/* All other options (including node-name and driver) must be unchanged.
* Put them back into the QDict, so that they are checked at the end
* of this function. */
qemu_opts_to_qdict(opts, reopen_state->options);
/* If we are to stay read-only, do not allow permission change
* to r/w. Attempting to set to r/w may fail if either BDRV_O_ALLOW_RDWR is
* not set, or if the BDS still has copy_on_read enabled */
read_only = !(reopen_state->flags & BDRV_O_RDWR);
ret = bdrv_can_set_read_only(reopen_state->bs, read_only, true, &local_err);
if (local_err) {
error_propagate(errp, local_err);
goto error;
}
/* Calculate required permissions after reopening */
bdrv_reopen_perm(queue, reopen_state->bs,
&reopen_state->perm, &reopen_state->shared_perm);
ret = bdrv_flush(reopen_state->bs);
if (ret) {
error_setg_errno(errp, -ret, "Error flushing drive");
goto error;
}
if (drv->bdrv_reopen_prepare) {
/*
* If a driver-specific option is missing, it means that we
* should reset it to its default value.
* But not all options allow that, so we need to check it first.
*/
ret = bdrv_reset_options_allowed(reopen_state->bs,
reopen_state->options, errp);
if (ret) {
goto error;
}
ret = drv->bdrv_reopen_prepare(reopen_state, queue, &local_err);
if (ret) {
if (local_err != NULL) {
error_propagate(errp, local_err);
} else {
bdrv_refresh_filename(reopen_state->bs);
error_setg(errp, "failed while preparing to reopen image '%s'",
reopen_state->bs->filename);
}
goto error;
}
} else {
/* It is currently mandatory to have a bdrv_reopen_prepare()
* handler for each supported drv. */
error_setg(errp, "Block format '%s' used by node '%s' "
"does not support reopening files", drv->format_name,
bdrv_get_device_or_node_name(reopen_state->bs));
ret = -1;
goto error;
}
drv_prepared = true;
/*
* We must provide the 'backing' option if the BDS has a backing
* file or if the image file has a backing file name as part of
* its metadata. Otherwise the 'backing' option can be omitted.
*/
if (drv->supports_backing && reopen_state->backing_missing &&
(backing_bs(reopen_state->bs) || reopen_state->bs->backing_file[0])) {
error_setg(errp, "backing is missing for '%s'",
reopen_state->bs->node_name);
ret = -EINVAL;
goto error;
}
/*
* Allow changing the 'backing' option. The new value can be
* either a reference to an existing node (using its node name)
* or NULL to simply detach the current backing file.
*/
ret = bdrv_reopen_parse_backing(reopen_state, errp);
if (ret < 0) {
goto error;
}
qdict_del(reopen_state->options, "backing");
/* Options that are not handled are only okay if they are unchanged
* compared to the old state. It is expected that some options are only
* used for the initial open, but not reopen (e.g. filename) */
if (qdict_size(reopen_state->options)) {
const QDictEntry *entry = qdict_first(reopen_state->options);
do {
QObject *new = entry->value;
QObject *old = qdict_get(reopen_state->bs->options, entry->key);
/* Allow child references (child_name=node_name) as long as they
* point to the current child (i.e. everything stays the same). */
if (qobject_type(new) == QTYPE_QSTRING) {
BdrvChild *child;
QLIST_FOREACH(child, &reopen_state->bs->children, next) {
if (!strcmp(child->name, entry->key)) {
break;
}
}
if (child) {
const char *str = qobject_get_try_str(new);
if (!strcmp(child->bs->node_name, str)) {
continue; /* Found child with this name, skip option */
}
}
}
/*
* TODO: When using -drive to specify blockdev options, all values
* will be strings; however, when using -blockdev, blockdev-add or
* filenames using the json:{} pseudo-protocol, they will be
* correctly typed.
* In contrast, reopening options are (currently) always strings
* (because you can only specify them through qemu-io; all other
* callers do not specify any options).
* Therefore, when using anything other than -drive to create a BDS,
* this cannot detect non-string options as unchanged, because
* qobject_is_equal() always returns false for objects of different
* type. In the future, this should be remedied by correctly typing
* all options. For now, this is not too big of an issue because
* the user can simply omit options which cannot be changed anyway,
* so they will stay unchanged.
*/
if (!qobject_is_equal(new, old)) {
error_setg(errp, "Cannot change the option '%s'", entry->key);
ret = -EINVAL;
goto error;
}
} while ((entry = qdict_next(reopen_state->options, entry)));
}
ret = 0;
/* Restore the original reopen_state->options QDict */
qobject_unref(reopen_state->options);
reopen_state->options = qobject_ref(orig_reopen_opts);
error:
if (ret < 0 && drv_prepared) {
/* drv->bdrv_reopen_prepare() has succeeded, so we need to
* call drv->bdrv_reopen_abort() before signaling an error
* (bdrv_reopen_multiple() will not call bdrv_reopen_abort()
* when the respective bdrv_reopen_prepare() has failed) */
if (drv->bdrv_reopen_abort) {
drv->bdrv_reopen_abort(reopen_state);
}
}
qemu_opts_del(opts);
qobject_unref(orig_reopen_opts);
g_free(discard);
return ret;
}
/*
* Takes the staged changes for the reopen from bdrv_reopen_prepare(), and
* makes them final by swapping the staging BlockDriverState contents into
* the active BlockDriverState contents.
*/
void bdrv_reopen_commit(BDRVReopenState *reopen_state)
{
BlockDriver *drv;
BlockDriverState *bs;
BdrvChild *child;
bool old_can_write, new_can_write;
assert(reopen_state != NULL);
bs = reopen_state->bs;
drv = bs->drv;
assert(drv != NULL);
old_can_write =
!bdrv_is_read_only(bs) && !(bdrv_get_flags(bs) & BDRV_O_INACTIVE);
/* If there are any driver level actions to take */
if (drv->bdrv_reopen_commit) {
drv->bdrv_reopen_commit(reopen_state);
}
/* set BDS specific flags now */
qobject_unref(bs->explicit_options);
qobject_unref(bs->options);
bs->explicit_options = reopen_state->explicit_options;
bs->options = reopen_state->options;
bs->open_flags = reopen_state->flags;
bs->read_only = !(reopen_state->flags & BDRV_O_RDWR);
bs->detect_zeroes = reopen_state->detect_zeroes;
if (reopen_state->replace_backing_bs) {
qdict_del(bs->explicit_options, "backing");
qdict_del(bs->options, "backing");
}
/* Remove child references from bs->options and bs->explicit_options.
* Child options were already removed in bdrv_reopen_queue_child() */
QLIST_FOREACH(child, &bs->children, next) {
qdict_del(bs->explicit_options, child->name);
qdict_del(bs->options, child->name);
}
/*
* Change the backing file if a new one was specified. We do this
* after updating bs->options, so bdrv_refresh_filename() (called
* from bdrv_set_backing_hd()) has the new values.
*/
if (reopen_state->replace_backing_bs) {
BlockDriverState *old_backing_bs = backing_bs(bs);
assert(!old_backing_bs || !old_backing_bs->implicit);
/* Abort the permission update on the backing bs we're detaching */
if (old_backing_bs) {
bdrv_abort_perm_update(old_backing_bs);
}
bdrv_set_backing_hd(bs, reopen_state->new_backing_bs, &error_abort);
}
bdrv_refresh_limits(bs, NULL);
new_can_write =
!bdrv_is_read_only(bs) && !(bdrv_get_flags(bs) & BDRV_O_INACTIVE);
if (!old_can_write && new_can_write && drv->bdrv_reopen_bitmaps_rw) {
Error *local_err = NULL;
if (drv->bdrv_reopen_bitmaps_rw(bs, &local_err) < 0) {
/* This is not fatal, bitmaps just left read-only, so all following
* writes will fail. User can remove read-only bitmaps to unblock
* writes.
*/
error_reportf_err(local_err,
"%s: Failed to make dirty bitmaps writable: ",
bdrv_get_node_name(bs));
}
}
}
/*
* Abort the reopen, and delete and free the staged changes in
* reopen_state
*/
void bdrv_reopen_abort(BDRVReopenState *reopen_state)
{
BlockDriver *drv;
assert(reopen_state != NULL);
drv = reopen_state->bs->drv;
assert(drv != NULL);
if (drv->bdrv_reopen_abort) {
drv->bdrv_reopen_abort(reopen_state);
}
}
static void bdrv_close(BlockDriverState *bs)
{
BdrvAioNotifier *ban, *ban_next;
BdrvChild *child, *next;
assert(!bs->refcnt);
bdrv_drained_begin(bs); /* complete I/O */
bdrv_flush(bs);
bdrv_drain(bs); /* in case flush left pending I/O */
if (bs->drv) {
if (bs->drv->bdrv_close) {
bs->drv->bdrv_close(bs);
}
bs->drv = NULL;
}
QLIST_FOREACH_SAFE(child, &bs->children, next, next) {
bdrv_unref_child(bs, child);
}
bs->backing = NULL;
bs->file = NULL;
g_free(bs->opaque);
bs->opaque = NULL;
atomic_set(&bs->copy_on_read, 0);
bs->backing_file[0] = '\0';
bs->backing_format[0] = '\0';
bs->total_sectors = 0;
bs->encrypted = false;
bs->sg = false;
qobject_unref(bs->options);
qobject_unref(bs->explicit_options);
bs->options = NULL;
bs->explicit_options = NULL;
qobject_unref(bs->full_open_options);
bs->full_open_options = NULL;
bdrv_release_named_dirty_bitmaps(bs);
assert(QLIST_EMPTY(&bs->dirty_bitmaps));
QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) {
g_free(ban);
}
QLIST_INIT(&bs->aio_notifiers);
bdrv_drained_end(bs);
}
void bdrv_close_all(void)
{
assert(job_next(NULL) == NULL);
nbd_export_close_all();
/* Drop references from requests still in flight, such as canceled block
* jobs whose AIO context has not been polled yet */
bdrv_drain_all();
blk_remove_all_bs();
blockdev_close_all_bdrv_states();
assert(QTAILQ_EMPTY(&all_bdrv_states));
}
static bool should_update_child(BdrvChild *c, BlockDriverState *to)
{
GQueue *queue;
GHashTable *found;
bool ret;
if (c->role->stay_at_node) {
return false;
}
/* If the child @c belongs to the BDS @to, replacing the current
* c->bs by @to would mean to create a loop.
*
* Such a case occurs when appending a BDS to a backing chain.
* For instance, imagine the following chain:
*
* guest device -> node A -> further backing chain...
*
* Now we create a new BDS B which we want to put on top of this
* chain, so we first attach A as its backing node:
*
* node B
* |
* v
* guest device -> node A -> further backing chain...
*
* Finally we want to replace A by B. When doing that, we want to
* replace all pointers to A by pointers to B -- except for the
* pointer from B because (1) that would create a loop, and (2)
* that pointer should simply stay intact:
*
* guest device -> node B
* |
* v
* node A -> further backing chain...
*
* In general, when replacing a node A (c->bs) by a node B (@to),
* if A is a child of B, that means we cannot replace A by B there
* because that would create a loop. Silently detaching A from B
* is also not really an option. So overall just leaving A in
* place there is the most sensible choice.
*
* We would also create a loop in any cases where @c is only
* indirectly referenced by @to. Prevent this by returning false
* if @c is found (by breadth-first search) anywhere in the whole
* subtree of @to.
*/
ret = true;
found = g_hash_table_new(NULL, NULL);
g_hash_table_add(found, to);
queue = g_queue_new();
g_queue_push_tail(queue, to);
while (!g_queue_is_empty(queue)) {
BlockDriverState *v = g_queue_pop_head(queue);
BdrvChild *c2;
QLIST_FOREACH(c2, &v->children, next) {
if (c2 == c) {
ret = false;
break;
}
if (g_hash_table_contains(found, c2->bs)) {
continue;
}
g_queue_push_tail(queue, c2->bs);
g_hash_table_add(found, c2->bs);
}
}
g_queue_free(queue);
g_hash_table_destroy(found);
return ret;
}
void bdrv_replace_node(BlockDriverState *from, BlockDriverState *to,
Error **errp)
{
BdrvChild *c, *next;
GSList *list = NULL, *p;
uint64_t old_perm, old_shared;
uint64_t perm = 0, shared = BLK_PERM_ALL;
int ret;
/* Make sure that @from doesn't go away until we have successfully attached
* all of its parents to @to. */
bdrv_ref(from);
assert(qemu_get_current_aio_context() == qemu_get_aio_context());
bdrv_drained_begin(from);
/* Put all parents into @list and calculate their cumulative permissions */
QLIST_FOREACH_SAFE(c, &from->parents, next_parent, next) {
assert(c->bs == from);
if (!should_update_child(c, to)) {
continue;
}
if (c->frozen) {
error_setg(errp, "Cannot change '%s' link to '%s'",
c->name, from->node_name);
goto out;
}
list = g_slist_prepend(list, c);
perm |= c->perm;
shared &= c->shared_perm;
}
/* Check whether the required permissions can be granted on @to, ignoring
* all BdrvChild in @list so that they can't block themselves. */
ret = bdrv_check_update_perm(to, NULL, perm, shared, list, NULL, errp);
if (ret < 0) {
bdrv_abort_perm_update(to);
goto out;
}
/* Now actually perform the change. We performed the permission check for
* all elements of @list at once, so set the permissions all at once at the
* very end. */
for (p = list; p != NULL; p = p->next) {
c = p->data;
bdrv_ref(to);
bdrv_replace_child_noperm(c, to);
bdrv_unref(from);
}
bdrv_get_cumulative_perm(to, &old_perm, &old_shared);
bdrv_set_perm(to, old_perm | perm, old_shared | shared);
out:
g_slist_free(list);
bdrv_drained_end(from);
bdrv_unref(from);
}
/*
* Add new bs contents at the top of an image chain while the chain is
* live, while keeping required fields on the top layer.
*
* This will modify the BlockDriverState fields, and swap contents
* between bs_new and bs_top. Both bs_new and bs_top are modified.
*
* bs_new must not be attached to a BlockBackend.
*
* This function does not create any image files.
*
* bdrv_append() takes ownership of a bs_new reference and unrefs it because
* that's what the callers commonly need. bs_new will be referenced by the old
* parents of bs_top after bdrv_append() returns. If the caller needs to keep a
* reference of its own, it must call bdrv_ref().
*/
void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top,
Error **errp)
{
Error *local_err = NULL;
bdrv_set_backing_hd(bs_new, bs_top, &local_err);
if (local_err) {
error_propagate(errp, local_err);
goto out;
}
bdrv_replace_node(bs_top, bs_new, &local_err);
if (local_err) {
error_propagate(errp, local_err);
bdrv_set_backing_hd(bs_new, NULL, &error_abort);
goto out;
}
/* bs_new is now referenced by its new parents, we don't need the
* additional reference any more. */
out:
bdrv_unref(bs_new);
}
static void bdrv_delete(BlockDriverState *bs)
{
assert(bdrv_op_blocker_is_empty(bs));
assert(!bs->refcnt);
/* remove from list, if necessary */
if (bs->node_name[0] != '\0') {
QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list);
}
QTAILQ_REMOVE(&all_bdrv_states, bs, bs_list);
bdrv_close(bs);
g_free(bs);
}
/*
* Run consistency checks on an image
*
* Returns 0 if the check could be completed (it doesn't mean that the image is
* free of errors) or -errno when an internal error occurred. The results of the
* check are stored in res.
*/
static int coroutine_fn bdrv_co_check(BlockDriverState *bs,
BdrvCheckResult *res, BdrvCheckMode fix)
{
if (bs->drv == NULL) {
return -ENOMEDIUM;
}
if (bs->drv->bdrv_co_check == NULL) {
return -ENOTSUP;
}
memset(res, 0, sizeof(*res));
return bs->drv->bdrv_co_check(bs, res, fix);
}
typedef struct CheckCo {
BlockDriverState *bs;
BdrvCheckResult *res;
BdrvCheckMode fix;
int ret;
} CheckCo;
static void coroutine_fn bdrv_check_co_entry(void *opaque)
{
CheckCo *cco = opaque;
cco->ret = bdrv_co_check(cco->bs, cco->res, cco->fix);
aio_wait_kick();
}
int bdrv_check(BlockDriverState *bs,
BdrvCheckResult *res, BdrvCheckMode fix)
{
Coroutine *co;
CheckCo cco = {
.bs = bs,
.res = res,
.ret = -EINPROGRESS,
.fix = fix,
};
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_check_co_entry(&cco);
} else {
co = qemu_coroutine_create(bdrv_check_co_entry, &cco);
bdrv_coroutine_enter(bs, co);
BDRV_POLL_WHILE(bs, cco.ret == -EINPROGRESS);
}
return cco.ret;
}
/*
* Return values:
* 0 - success
* -EINVAL - backing format specified, but no file
* -ENOSPC - can't update the backing file because no space is left in the
* image file header
* -ENOTSUP - format driver doesn't support changing the backing file
*/
int bdrv_change_backing_file(BlockDriverState *bs,
const char *backing_file, const char *backing_fmt)
{
BlockDriver *drv = bs->drv;
int ret;
if (!drv) {
return -ENOMEDIUM;
}
/* Backing file format doesn't make sense without a backing file */
if (backing_fmt && !backing_file) {
return -EINVAL;
}
if (drv->bdrv_change_backing_file != NULL) {
ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt);
} else {
ret = -ENOTSUP;
}
if (ret == 0) {
pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: "");
pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: "");
pstrcpy(bs->auto_backing_file, sizeof(bs->auto_backing_file),
backing_file ?: "");
}
return ret;
}
/*
* Finds the image layer in the chain that has 'bs' as its backing file.
*
* active is the current topmost image.
*
* Returns NULL if bs is not found in active's image chain,
* or if active == bs.
*
* Returns the bottommost base image if bs == NULL.
*/
BlockDriverState *bdrv_find_overlay(BlockDriverState *active,
BlockDriverState *bs)
{
while (active && bs != backing_bs(active)) {
active = backing_bs(active);
}
return active;
}
/* Given a BDS, searches for the base layer. */
BlockDriverState *bdrv_find_base(BlockDriverState *bs)
{
return bdrv_find_overlay(bs, NULL);
}
/*
* Return true if at least one of the backing links between @bs and
* @base is frozen. @errp is set if that's the case.
* @base must be reachable from @bs, or NULL.
*/
bool bdrv_is_backing_chain_frozen(BlockDriverState *bs, BlockDriverState *base,
Error **errp)
{
BlockDriverState *i;
for (i = bs; i != base; i = backing_bs(i)) {
if (i->backing && i->backing->frozen) {
error_setg(errp, "Cannot change '%s' link from '%s' to '%s'",
i->backing->name, i->node_name,
backing_bs(i)->node_name);
return true;
}
}
return false;
}
/*
* Freeze all backing links between @bs and @base.
* If any of the links is already frozen the operation is aborted and
* none of the links are modified.
* @base must be reachable from @bs, or NULL.
* Returns 0 on success. On failure returns < 0 and sets @errp.
*/
int bdrv_freeze_backing_chain(BlockDriverState *bs, BlockDriverState *base,
Error **errp)
{
BlockDriverState *i;
if (bdrv_is_backing_chain_frozen(bs, base, errp)) {
return -EPERM;
}
for (i = bs; i != base; i = backing_bs(i)) {
if (i->backing) {
i->backing->frozen = true;
}
}
return 0;
}
/*
* Unfreeze all backing links between @bs and @base. The caller must
* ensure that all links are frozen before using this function.
* @base must be reachable from @bs, or NULL.
*/
void bdrv_unfreeze_backing_chain(BlockDriverState *bs, BlockDriverState *base)
{
BlockDriverState *i;
for (i = bs; i != base; i = backing_bs(i)) {
if (i->backing) {
assert(i->backing->frozen);
i->backing->frozen = false;
}
}
}
/*
* Drops images above 'base' up to and including 'top', and sets the image
* above 'top' to have base as its backing file.
*
* Requires that the overlay to 'top' is opened r/w, so that the backing file
* information in 'bs' can be properly updated.
*
* E.g., this will convert the following chain:
* bottom <- base <- intermediate <- top <- active
*
* to
*
* bottom <- base <- active
*
* It is allowed for bottom==base, in which case it converts:
*
* base <- intermediate <- top <- active
*
* to
*
* base <- active
*
* If backing_file_str is non-NULL, it will be used when modifying top's
* overlay image metadata.
*
* Error conditions:
* if active == top, that is considered an error
*
*/
int bdrv_drop_intermediate(BlockDriverState *top, BlockDriverState *base,
const char *backing_file_str)
{
BlockDriverState *explicit_top = top;
bool update_inherits_from;
BdrvChild *c, *next;
Error *local_err = NULL;
int ret = -EIO;
bdrv_ref(top);
if (!top->drv || !base->drv) {
goto exit;
}
/* Make sure that base is in the backing chain of top */
if (!bdrv_chain_contains(top, base)) {
goto exit;
}
/* This function changes all links that point to top and makes
* them point to base. Check that none of them is frozen. */
QLIST_FOREACH(c, &top->parents, next_parent) {
if (c->frozen) {
goto exit;
}
}
/* If 'base' recursively inherits from 'top' then we should set
* base->inherits_from to top->inherits_from after 'top' and all
* other intermediate nodes have been dropped.
* If 'top' is an implicit node (e.g. "commit_top") we should skip
* it because no one inherits from it. We use explicit_top for that. */
while (explicit_top && explicit_top->implicit) {
explicit_top = backing_bs(explicit_top);
}
update_inherits_from = bdrv_inherits_from_recursive(base, explicit_top);
/* success - we can delete the intermediate states, and link top->base */
/* TODO Check graph modification op blockers (BLK_PERM_GRAPH_MOD) once
* we've figured out how they should work. */
if (!backing_file_str) {
bdrv_refresh_filename(base);
backing_file_str = base->filename;
}
QLIST_FOREACH_SAFE(c, &top->parents, next_parent, next) {
/* Check whether we are allowed to switch c from top to base */
GSList *ignore_children = g_slist_prepend(NULL, c);
ret = bdrv_check_update_perm(base, NULL, c->perm, c->shared_perm,
ignore_children, NULL, &local_err);
g_slist_free(ignore_children);
if (ret < 0) {
error_report_err(local_err);
goto exit;
}
/* If so, update the backing file path in the image file */
if (c->role->update_filename) {
ret = c->role->update_filename(c, base, backing_file_str,
&local_err);
if (ret < 0) {
bdrv_abort_perm_update(base);
error_report_err(local_err);
goto exit;
}
}
/* Do the actual switch in the in-memory graph.
* Completes bdrv_check_update_perm() transaction internally. */
bdrv_ref(base);
bdrv_replace_child(c, base);
bdrv_unref(top);
}
if (update_inherits_from) {
base->inherits_from = explicit_top->inherits_from;
}
ret = 0;
exit:
bdrv_unref(top);
return ret;
}
/**
* Length of a allocated file in bytes. Sparse files are counted by actual
* allocated space. Return < 0 if error or unknown.
*/
int64_t bdrv_get_allocated_file_size(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
if (!drv) {
return -ENOMEDIUM;
}
if (drv->bdrv_get_allocated_file_size) {
return drv->bdrv_get_allocated_file_size(bs);
}
if (bs->file) {
return bdrv_get_allocated_file_size(bs->file->bs);
}
return -ENOTSUP;
}
/*
* bdrv_measure:
* @drv: Format driver
* @opts: Creation options for new image
* @in_bs: Existing image containing data for new image (may be NULL)
* @errp: Error object
* Returns: A #BlockMeasureInfo (free using qapi_free_BlockMeasureInfo())
* or NULL on error
*
* Calculate file size required to create a new image.
*
* If @in_bs is given then space for allocated clusters and zero clusters
* from that image are included in the calculation. If @opts contains a
* backing file that is shared by @in_bs then backing clusters may be omitted
* from the calculation.
*
* If @in_bs is NULL then the calculation includes no allocated clusters
* unless a preallocation option is given in @opts.
*
* Note that @in_bs may use a different BlockDriver from @drv.
*
* If an error occurs the @errp pointer is set.
*/
BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts,
BlockDriverState *in_bs, Error **errp)
{
if (!drv->bdrv_measure) {
error_setg(errp, "Block driver '%s' does not support size measurement",
drv->format_name);
return NULL;
}
return drv->bdrv_measure(opts, in_bs, errp);
}
/**
* Return number of sectors on success, -errno on error.
*/
int64_t bdrv_nb_sectors(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
if (!drv)
return -ENOMEDIUM;
if (drv->has_variable_length) {
int ret = refresh_total_sectors(bs, bs->total_sectors);
if (ret < 0) {
return ret;
}
}
return bs->total_sectors;
}
/**
* Return length in bytes on success, -errno on error.
* The length is always a multiple of BDRV_SECTOR_SIZE.
*/
int64_t bdrv_getlength(BlockDriverState *bs)
{
int64_t ret = bdrv_nb_sectors(bs);
ret = ret > INT64_MAX / BDRV_SECTOR_SIZE ? -EFBIG : ret;
return ret < 0 ? ret : ret * BDRV_SECTOR_SIZE;
}
/* return 0 as number of sectors if no device present or error */
void bdrv_get_geometry(BlockDriverState *bs, uint64_t *nb_sectors_ptr)
{
int64_t nb_sectors = bdrv_nb_sectors(bs);
*nb_sectors_ptr = nb_sectors < 0 ? 0 : nb_sectors;
}
bool bdrv_is_sg(BlockDriverState *bs)
{
return bs->sg;
}
bool bdrv_is_encrypted(BlockDriverState *bs)
{
if (bs->backing && bs->backing->bs->encrypted) {
return true;
}
return bs->encrypted;
}
const char *bdrv_get_format_name(BlockDriverState *bs)
{
return bs->drv ? bs->drv->format_name : NULL;
}
static int qsort_strcmp(const void *a, const void *b)
{
return strcmp(*(char *const *)a, *(char *const *)b);
}
void bdrv_iterate_format(void (*it)(void *opaque, const char *name),
void *opaque, bool read_only)
{
BlockDriver *drv;
int count = 0;
int i;
const char **formats = NULL;
QLIST_FOREACH(drv, &bdrv_drivers, list) {
if (drv->format_name) {
bool found = false;
int i = count;
if (use_bdrv_whitelist && !bdrv_is_whitelisted(drv, read_only)) {
continue;
}
while (formats && i && !found) {
found = !strcmp(formats[--i], drv->format_name);
}
if (!found) {
formats = g_renew(const char *, formats, count + 1);
formats[count++] = drv->format_name;
}
}
}
for (i = 0; i < (int)ARRAY_SIZE(block_driver_modules); i++) {
const char *format_name = block_driver_modules[i].format_name;
if (format_name) {
bool found = false;
int j = count;
if (use_bdrv_whitelist &&
!bdrv_format_is_whitelisted(format_name, read_only)) {
continue;
}
while (formats && j && !found) {
found = !strcmp(formats[--j], format_name);
}
if (!found) {
formats = g_renew(const char *, formats, count + 1);
formats[count++] = format_name;
}
}
}
qsort(formats, count, sizeof(formats[0]), qsort_strcmp);
for (i = 0; i < count; i++) {
it(opaque, formats[i]);
}
g_free(formats);
}
/* This function is to find a node in the bs graph */
BlockDriverState *bdrv_find_node(const char *node_name)
{
BlockDriverState *bs;
assert(node_name);
QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
if (!strcmp(node_name, bs->node_name)) {
return bs;
}
}
return NULL;
}
/* Put this QMP function here so it can access the static graph_bdrv_states. */
BlockDeviceInfoList *bdrv_named_nodes_list(Error **errp)
{
BlockDeviceInfoList *list, *entry;
BlockDriverState *bs;
list = NULL;
QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
BlockDeviceInfo *info = bdrv_block_device_info(NULL, bs, errp);
if (!info) {
qapi_free_BlockDeviceInfoList(list);
return NULL;
}
entry = g_malloc0(sizeof(*entry));
entry->value = info;
entry->next = list;
list = entry;
}
return list;
}
#define QAPI_LIST_ADD(list, element) do { \
typeof(list) _tmp = g_new(typeof(*(list)), 1); \
_tmp->value = (element); \
_tmp->next = (list); \
(list) = _tmp; \
} while (0)
typedef struct XDbgBlockGraphConstructor {
XDbgBlockGraph *graph;
GHashTable *graph_nodes;
} XDbgBlockGraphConstructor;
static XDbgBlockGraphConstructor *xdbg_graph_new(void)
{
XDbgBlockGraphConstructor *gr = g_new(XDbgBlockGraphConstructor, 1);
gr->graph = g_new0(XDbgBlockGraph, 1);
gr->graph_nodes = g_hash_table_new(NULL, NULL);
return gr;
}
static XDbgBlockGraph *xdbg_graph_finalize(XDbgBlockGraphConstructor *gr)
{
XDbgBlockGraph *graph = gr->graph;
g_hash_table_destroy(gr->graph_nodes);
g_free(gr);
return graph;
}
static uintptr_t xdbg_graph_node_num(XDbgBlockGraphConstructor *gr, void *node)
{
uintptr_t ret = (uintptr_t)g_hash_table_lookup(gr->graph_nodes, node);
if (ret != 0) {
return ret;
}
/*
* Start counting from 1, not 0, because 0 interferes with not-found (NULL)
* answer of g_hash_table_lookup.
*/
ret = g_hash_table_size(gr->graph_nodes) + 1;
g_hash_table_insert(gr->graph_nodes, node, (void *)ret);
return ret;
}
static void xdbg_graph_add_node(XDbgBlockGraphConstructor *gr, void *node,
XDbgBlockGraphNodeType type, const char *name)
{
XDbgBlockGraphNode *n;
n = g_new0(XDbgBlockGraphNode, 1);
n->id = xdbg_graph_node_num(gr, node);
n->type = type;
n->name = g_strdup(name);
QAPI_LIST_ADD(gr->graph->nodes, n);
}
static void xdbg_graph_add_edge(XDbgBlockGraphConstructor *gr, void *parent,
const BdrvChild *child)
{
typedef struct {
unsigned int flag;
BlockPermission num;
} PermissionMap;
static const PermissionMap permissions[] = {
{ BLK_PERM_CONSISTENT_READ, BLOCK_PERMISSION_CONSISTENT_READ },
{ BLK_PERM_WRITE, BLOCK_PERMISSION_WRITE },
{ BLK_PERM_WRITE_UNCHANGED, BLOCK_PERMISSION_WRITE_UNCHANGED },
{ BLK_PERM_RESIZE, BLOCK_PERMISSION_RESIZE },
{ BLK_PERM_GRAPH_MOD, BLOCK_PERMISSION_GRAPH_MOD },
{ 0, 0 }
};
const PermissionMap *p;
XDbgBlockGraphEdge *edge;
QEMU_BUILD_BUG_ON(1UL << (ARRAY_SIZE(permissions) - 1) != BLK_PERM_ALL + 1);
edge = g_new0(XDbgBlockGraphEdge, 1);
edge->parent = xdbg_graph_node_num(gr, parent);
edge->child = xdbg_graph_node_num(gr, child->bs);
edge->name = g_strdup(child->name);
for (p = permissions; p->flag; p++) {
if (p->flag & child->perm) {
QAPI_LIST_ADD(edge->perm, p->num);
}
if (p->flag & child->shared_perm) {
QAPI_LIST_ADD(edge->shared_perm, p->num);
}
}
QAPI_LIST_ADD(gr->graph->edges, edge);
}
XDbgBlockGraph *bdrv_get_xdbg_block_graph(Error **errp)
{
BlockBackend *blk;
BlockJob *job;
BlockDriverState *bs;
BdrvChild *child;
XDbgBlockGraphConstructor *gr = xdbg_graph_new();
for (blk = blk_all_next(NULL); blk; blk = blk_all_next(blk)) {
char *allocated_name = NULL;
const char *name = blk_name(blk);
if (!*name) {
name = allocated_name = blk_get_attached_dev_id(blk);
}
xdbg_graph_add_node(gr, blk, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_BACKEND,
name);
g_free(allocated_name);
if (blk_root(blk)) {
xdbg_graph_add_edge(gr, blk, blk_root(blk));
}
}
for (job = block_job_next(NULL); job; job = block_job_next(job)) {
GSList *el;
xdbg_graph_add_node(gr, job, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_JOB,
job->job.id);
for (el = job->nodes; el; el = el->next) {
xdbg_graph_add_edge(gr, job, (BdrvChild *)el->data);
}
}
QTAILQ_FOREACH(bs, &graph_bdrv_states, node_list) {
xdbg_graph_add_node(gr, bs, X_DBG_BLOCK_GRAPH_NODE_TYPE_BLOCK_DRIVER,
bs->node_name);
QLIST_FOREACH(child, &bs->children, next) {
xdbg_graph_add_edge(gr, bs, child);
}
}
return xdbg_graph_finalize(gr);
}
BlockDriverState *bdrv_lookup_bs(const char *device,
const char *node_name,
Error **errp)
{
BlockBackend *blk;
BlockDriverState *bs;
if (device) {
blk = blk_by_name(device);
if (blk) {
bs = blk_bs(blk);
if (!bs) {
error_setg(errp, "Device '%s' has no medium", device);
}
return bs;
}
}
if (node_name) {
bs = bdrv_find_node(node_name);
if (bs) {
return bs;
}
}
error_setg(errp, "Cannot find device=%s nor node_name=%s",
device ? device : "",
node_name ? node_name : "");
return NULL;
}
/* If 'base' is in the same chain as 'top', return true. Otherwise,
* return false. If either argument is NULL, return false. */
bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base)
{
while (top && top != base) {
top = backing_bs(top);
}
return top != NULL;
}
BlockDriverState *bdrv_next_node(BlockDriverState *bs)
{
if (!bs) {
return QTAILQ_FIRST(&graph_bdrv_states);
}
return QTAILQ_NEXT(bs, node_list);
}
BlockDriverState *bdrv_next_all_states(BlockDriverState *bs)
{
if (!bs) {
return QTAILQ_FIRST(&all_bdrv_states);
}
return QTAILQ_NEXT(bs, bs_list);
}
const char *bdrv_get_node_name(const BlockDriverState *bs)
{
return bs->node_name;
}
const char *bdrv_get_parent_name(const BlockDriverState *bs)
{
BdrvChild *c;
const char *name;
/* If multiple parents have a name, just pick the first one. */
QLIST_FOREACH(c, &bs->parents, next_parent) {
if (c->role->get_name) {
name = c->role->get_name(c);
if (name && *name) {
return name;
}
}
}
return NULL;
}
/* TODO check what callers really want: bs->node_name or blk_name() */
const char *bdrv_get_device_name(const BlockDriverState *bs)
{
return bdrv_get_parent_name(bs) ?: "";
}
/* This can be used to identify nodes that might not have a device
* name associated. Since node and device names live in the same
* namespace, the result is unambiguous. The exception is if both are
* absent, then this returns an empty (non-null) string. */
const char *bdrv_get_device_or_node_name(const BlockDriverState *bs)
{
return bdrv_get_parent_name(bs) ?: bs->node_name;
}
int bdrv_get_flags(BlockDriverState *bs)
{
return bs->open_flags;
}
int bdrv_has_zero_init_1(BlockDriverState *bs)
{
return 1;
}
int bdrv_has_zero_init(BlockDriverState *bs)
{
if (!bs->drv) {
return 0;
}
/* If BS is a copy on write image, it is initialized to
the contents of the base image, which may not be zeroes. */
if (bs->backing) {
return 0;
}
if (bs->drv->bdrv_has_zero_init) {
return bs->drv->bdrv_has_zero_init(bs);
}
if (bs->file && bs->drv->is_filter) {
return bdrv_has_zero_init(bs->file->bs);
}
/* safe default */
return 0;
}
bool bdrv_unallocated_blocks_are_zero(BlockDriverState *bs)
{
BlockDriverInfo bdi;
if (bs->backing) {
return false;
}
if (bdrv_get_info(bs, &bdi) == 0) {
return bdi.unallocated_blocks_are_zero;
}
return false;
}
bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs)
{
if (!(bs->open_flags & BDRV_O_UNMAP)) {
return false;
}
return bs->supported_zero_flags & BDRV_REQ_MAY_UNMAP;
}
void bdrv_get_backing_filename(BlockDriverState *bs,
char *filename, int filename_size)
{
pstrcpy(filename, filename_size, bs->backing_file);
}
int bdrv_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
BlockDriver *drv = bs->drv;
/* if bs->drv == NULL, bs is closed, so there's nothing to do here */
if (!drv) {
return -ENOMEDIUM;
}
if (!drv->bdrv_get_info) {
if (bs->file && drv->is_filter) {
return bdrv_get_info(bs->file->bs, bdi);
}
return -ENOTSUP;
}
memset(bdi, 0, sizeof(*bdi));
return drv->bdrv_get_info(bs, bdi);
}
ImageInfoSpecific *bdrv_get_specific_info(BlockDriverState *bs,
Error **errp)
{
BlockDriver *drv = bs->drv;
if (drv && drv->bdrv_get_specific_info) {
return drv->bdrv_get_specific_info(bs, errp);
}
return NULL;
}
void bdrv_debug_event(BlockDriverState *bs, BlkdebugEvent event)
{
if (!bs || !bs->drv || !bs->drv->bdrv_debug_event) {
return;
}
bs->drv->bdrv_debug_event(bs, event);
}
int bdrv_debug_breakpoint(BlockDriverState *bs, const char *event,
const char *tag)
{
while (bs && bs->drv && !bs->drv->bdrv_debug_breakpoint) {
bs = bs->file ? bs->file->bs : NULL;
}
if (bs && bs->drv && bs->drv->bdrv_debug_breakpoint) {
return bs->drv->bdrv_debug_breakpoint(bs, event, tag);
}
return -ENOTSUP;
}
int bdrv_debug_remove_breakpoint(BlockDriverState *bs, const char *tag)
{
while (bs && bs->drv && !bs->drv->bdrv_debug_remove_breakpoint) {
bs = bs->file ? bs->file->bs : NULL;
}
if (bs && bs->drv && bs->drv->bdrv_debug_remove_breakpoint) {
return bs->drv->bdrv_debug_remove_breakpoint(bs, tag);
}
return -ENOTSUP;
}
int bdrv_debug_resume(BlockDriverState *bs, const char *tag)
{
while (bs && (!bs->drv || !bs->drv->bdrv_debug_resume)) {
bs = bs->file ? bs->file->bs : NULL;
}
if (bs && bs->drv && bs->drv->bdrv_debug_resume) {
return bs->drv->bdrv_debug_resume(bs, tag);
}
return -ENOTSUP;
}
bool bdrv_debug_is_suspended(BlockDriverState *bs, const char *tag)
{
while (bs && bs->drv && !bs->drv->bdrv_debug_is_suspended) {
bs = bs->file ? bs->file->bs : NULL;
}
if (bs && bs->drv && bs->drv->bdrv_debug_is_suspended) {
return bs->drv->bdrv_debug_is_suspended(bs, tag);
}
return false;
}
/* backing_file can either be relative, or absolute, or a protocol. If it is
* relative, it must be relative to the chain. So, passing in bs->filename
* from a BDS as backing_file should not be done, as that may be relative to
* the CWD rather than the chain. */
BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs,
const char *backing_file)
{
char *filename_full = NULL;
char *backing_file_full = NULL;
char *filename_tmp = NULL;
int is_protocol = 0;
BlockDriverState *curr_bs = NULL;
BlockDriverState *retval = NULL;
if (!bs || !bs->drv || !backing_file) {
return NULL;
}
filename_full = g_malloc(PATH_MAX);
backing_file_full = g_malloc(PATH_MAX);
is_protocol = path_has_protocol(backing_file);
for (curr_bs = bs; curr_bs->backing; curr_bs = curr_bs->backing->bs) {
/* If either of the filename paths is actually a protocol, then
* compare unmodified paths; otherwise make paths relative */
if (is_protocol || path_has_protocol(curr_bs->backing_file)) {
char *backing_file_full_ret;
if (strcmp(backing_file, curr_bs->backing_file) == 0) {
retval = curr_bs->backing->bs;
break;
}
/* Also check against the full backing filename for the image */
backing_file_full_ret = bdrv_get_full_backing_filename(curr_bs,
NULL);
if (backing_file_full_ret) {
bool equal = strcmp(backing_file, backing_file_full_ret) == 0;
g_free(backing_file_full_ret);
if (equal) {
retval = curr_bs->backing->bs;
break;
}
}
} else {
/* If not an absolute filename path, make it relative to the current
* image's filename path */
filename_tmp = bdrv_make_absolute_filename(curr_bs, backing_file,
NULL);
/* We are going to compare canonicalized absolute pathnames */
if (!filename_tmp || !realpath(filename_tmp, filename_full)) {
g_free(filename_tmp);
continue;
}
g_free(filename_tmp);
/* We need to make sure the backing filename we are comparing against
* is relative to the current image filename (or absolute) */
filename_tmp = bdrv_get_full_backing_filename(curr_bs, NULL);
if (!filename_tmp || !realpath(filename_tmp, backing_file_full)) {
g_free(filename_tmp);
continue;
}
g_free(filename_tmp);
if (strcmp(backing_file_full, filename_full) == 0) {
retval = curr_bs->backing->bs;
break;
}
}
}
g_free(filename_full);
g_free(backing_file_full);
return retval;
}
void bdrv_init(void)
{
module_call_init(MODULE_INIT_BLOCK);
}
void bdrv_init_with_whitelist(void)
{
use_bdrv_whitelist = 1;
bdrv_init();
}
static void coroutine_fn bdrv_co_invalidate_cache(BlockDriverState *bs,
Error **errp)
{
BdrvChild *child, *parent;
uint64_t perm, shared_perm;
Error *local_err = NULL;
int ret;
BdrvDirtyBitmap *bm;
if (!bs->drv) {
return;
}
if (!(bs->open_flags & BDRV_O_INACTIVE)) {
return;
}
QLIST_FOREACH(child, &bs->children, next) {
bdrv_co_invalidate_cache(child->bs, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
}
/*
* Update permissions, they may differ for inactive nodes.
*
* Note that the required permissions of inactive images are always a
* subset of the permissions required after activating the image. This
* allows us to just get the permissions upfront without restricting
* drv->bdrv_invalidate_cache().
*
* It also means that in error cases, we don't have to try and revert to
* the old permissions (which is an operation that could fail, too). We can
* just keep the extended permissions for the next time that an activation
* of the image is tried.
*/
bs->open_flags &= ~BDRV_O_INACTIVE;
bdrv_get_cumulative_perm(bs, &perm, &shared_perm);
ret = bdrv_check_perm(bs, NULL, perm, shared_perm, NULL, NULL, &local_err);
if (ret < 0) {
bs->open_flags |= BDRV_O_INACTIVE;
error_propagate(errp, local_err);
return;
}
bdrv_set_perm(bs, perm, shared_perm);
if (bs->drv->bdrv_co_invalidate_cache) {
bs->drv->bdrv_co_invalidate_cache(bs, &local_err);
if (local_err) {
bs->open_flags |= BDRV_O_INACTIVE;
error_propagate(errp, local_err);
return;
}
}
for (bm = bdrv_dirty_bitmap_next(bs, NULL); bm;
bm = bdrv_dirty_bitmap_next(bs, bm))
{
bdrv_dirty_bitmap_set_migration(bm, false);
}
ret = refresh_total_sectors(bs, bs->total_sectors);
if (ret < 0) {
bs->open_flags |= BDRV_O_INACTIVE;
error_setg_errno(errp, -ret, "Could not refresh total sector count");
return;
}
QLIST_FOREACH(parent, &bs->parents, next_parent) {
if (parent->role->activate) {
parent->role->activate(parent, &local_err);
if (local_err) {
bs->open_flags |= BDRV_O_INACTIVE;
error_propagate(errp, local_err);
return;
}
}
}
}
typedef struct InvalidateCacheCo {
BlockDriverState *bs;
Error **errp;
bool done;
} InvalidateCacheCo;
static void coroutine_fn bdrv_invalidate_cache_co_entry(void *opaque)
{
InvalidateCacheCo *ico = opaque;
bdrv_co_invalidate_cache(ico->bs, ico->errp);
ico->done = true;
aio_wait_kick();
}
void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp)
{
Coroutine *co;
InvalidateCacheCo ico = {
.bs = bs,
.done = false,
.errp = errp
};
if (qemu_in_coroutine()) {
/* Fast-path if already in coroutine context */
bdrv_invalidate_cache_co_entry(&ico);
} else {
co = qemu_coroutine_create(bdrv_invalidate_cache_co_entry, &ico);
bdrv_coroutine_enter(bs, co);
BDRV_POLL_WHILE(bs, !ico.done);
}
}
void bdrv_invalidate_cache_all(Error **errp)
{
BlockDriverState *bs;
Error *local_err = NULL;
BdrvNextIterator it;
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
AioContext *aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
bdrv_invalidate_cache(bs, &local_err);
aio_context_release(aio_context);
if (local_err) {
error_propagate(errp, local_err);
bdrv_next_cleanup(&it);
return;
}
}
}
static bool bdrv_has_bds_parent(BlockDriverState *bs, bool only_active)
{
BdrvChild *parent;
QLIST_FOREACH(parent, &bs->parents, next_parent) {
if (parent->role->parent_is_bds) {
BlockDriverState *parent_bs = parent->opaque;
if (!only_active || !(parent_bs->open_flags & BDRV_O_INACTIVE)) {
return true;
}
}
}
return false;
}
static int bdrv_inactivate_recurse(BlockDriverState *bs)
{
BdrvChild *child, *parent;
bool tighten_restrictions;
uint64_t perm, shared_perm;
int ret;
if (!bs->drv) {
return -ENOMEDIUM;
}
/* Make sure that we don't inactivate a child before its parent.
* It will be covered by recursion from the yet active parent. */
if (bdrv_has_bds_parent(bs, true)) {
return 0;
}
assert(!(bs->open_flags & BDRV_O_INACTIVE));
/* Inactivate this node */
if (bs->drv->bdrv_inactivate) {
ret = bs->drv->bdrv_inactivate(bs);
if (ret < 0) {
return ret;
}
}
QLIST_FOREACH(parent, &bs->parents, next_parent) {
if (parent->role->inactivate) {
ret = parent->role->inactivate(parent);
if (ret < 0) {
return ret;
}
}
}
bs->open_flags |= BDRV_O_INACTIVE;
/* Update permissions, they may differ for inactive nodes */
bdrv_get_cumulative_perm(bs, &perm, &shared_perm);
ret = bdrv_check_perm(bs, NULL, perm, shared_perm, NULL,
&tighten_restrictions, NULL);
assert(tighten_restrictions == false);
if (ret < 0) {
/* We only tried to loosen restrictions, so errors are not fatal */
bdrv_abort_perm_update(bs);
} else {
bdrv_set_perm(bs, perm, shared_perm);
}
/* Recursively inactivate children */
QLIST_FOREACH(child, &bs->children, next) {
ret = bdrv_inactivate_recurse(child->bs);
if (ret < 0) {
return ret;
}
}
return 0;
}
int bdrv_inactivate_all(void)
{
BlockDriverState *bs = NULL;
BdrvNextIterator it;
int ret = 0;
GSList *aio_ctxs = NULL, *ctx;
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
AioContext *aio_context = bdrv_get_aio_context(bs);
if (!g_slist_find(aio_ctxs, aio_context)) {
aio_ctxs = g_slist_prepend(aio_ctxs, aio_context);
aio_context_acquire(aio_context);
}
}
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
/* Nodes with BDS parents are covered by recursion from the last
* parent that gets inactivated. Don't inactivate them a second
* time if that has already happened. */
if (bdrv_has_bds_parent(bs, false)) {
continue;
}
ret = bdrv_inactivate_recurse(bs);
if (ret < 0) {
bdrv_next_cleanup(&it);
goto out;
}
}
out:
for (ctx = aio_ctxs; ctx != NULL; ctx = ctx->next) {
AioContext *aio_context = ctx->data;
aio_context_release(aio_context);
}
g_slist_free(aio_ctxs);
return ret;
}
/**************************************************************/
/* removable device support */
/**
* Return TRUE if the media is present
*/
bool bdrv_is_inserted(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
BdrvChild *child;
if (!drv) {
return false;
}
if (drv->bdrv_is_inserted) {
return drv->bdrv_is_inserted(bs);
}
QLIST_FOREACH(child, &bs->children, next) {
if (!bdrv_is_inserted(child->bs)) {
return false;
}
}
return true;
}
/**
* If eject_flag is TRUE, eject the media. Otherwise, close the tray
*/
void bdrv_eject(BlockDriverState *bs, bool eject_flag)
{
BlockDriver *drv = bs->drv;
if (drv && drv->bdrv_eject) {
drv->bdrv_eject(bs, eject_flag);
}
}
/**
* Lock or unlock the media (if it is locked, the user won't be able
* to eject it manually).
*/
void bdrv_lock_medium(BlockDriverState *bs, bool locked)
{
BlockDriver *drv = bs->drv;
trace_bdrv_lock_medium(bs, locked);
if (drv && drv->bdrv_lock_medium) {
drv->bdrv_lock_medium(bs, locked);
}
}
/* Get a reference to bs */
void bdrv_ref(BlockDriverState *bs)
{
bs->refcnt++;
}
/* Release a previously grabbed reference to bs.
* If after releasing, reference count is zero, the BlockDriverState is
* deleted. */
void bdrv_unref(BlockDriverState *bs)
{
if (!bs) {
return;
}
assert(bs->refcnt > 0);
if (--bs->refcnt == 0) {
bdrv_delete(bs);
}
}
struct BdrvOpBlocker {
Error *reason;
QLIST_ENTRY(BdrvOpBlocker) list;
};
bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp)
{
BdrvOpBlocker *blocker;
assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
if (!QLIST_EMPTY(&bs->op_blockers[op])) {
blocker = QLIST_FIRST(&bs->op_blockers[op]);
error_propagate_prepend(errp, error_copy(blocker->reason),
"Node '%s' is busy: ",
bdrv_get_device_or_node_name(bs));
return true;
}
return false;
}
void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason)
{
BdrvOpBlocker *blocker;
assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
blocker = g_new0(BdrvOpBlocker, 1);
blocker->reason = reason;
QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list);
}
void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason)
{
BdrvOpBlocker *blocker, *next;
assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) {
if (blocker->reason == reason) {
QLIST_REMOVE(blocker, list);
g_free(blocker);
}
}
}
void bdrv_op_block_all(BlockDriverState *bs, Error *reason)
{
int i;
for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
bdrv_op_block(bs, i, reason);
}
}
void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason)
{
int i;
for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
bdrv_op_unblock(bs, i, reason);
}
}
bool bdrv_op_blocker_is_empty(BlockDriverState *bs)
{
int i;
for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
if (!QLIST_EMPTY(&bs->op_blockers[i])) {
return false;
}
}
return true;
}
void bdrv_img_create(const char *filename, const char *fmt,
const char *base_filename, const char *base_fmt,
char *options, uint64_t img_size, int flags, bool quiet,
Error **errp)
{
QemuOptsList *create_opts = NULL;
QemuOpts *opts = NULL;
const char *backing_fmt, *backing_file;
int64_t size;
BlockDriver *drv, *proto_drv;
Error *local_err = NULL;
int ret = 0;
/* Find driver and parse its options */
drv = bdrv_find_format(fmt);
if (!drv) {
error_setg(errp, "Unknown file format '%s'", fmt);
return;
}
proto_drv = bdrv_find_protocol(filename, true, errp);
if (!proto_drv) {
return;
}
if (!drv->create_opts) {
error_setg(errp, "Format driver '%s' does not support image creation",
drv->format_name);
return;
}
if (!proto_drv->create_opts) {
error_setg(errp, "Protocol driver '%s' does not support image creation",
proto_drv->format_name);
return;
}
create_opts = qemu_opts_append(create_opts, drv->create_opts);
create_opts = qemu_opts_append(create_opts, proto_drv->create_opts);
/* Create parameter list with default values */
opts = qemu_opts_create(create_opts, NULL, 0, &error_abort);
qemu_opt_set_number(opts, BLOCK_OPT_SIZE, img_size, &error_abort);
/* Parse -o options */
if (options) {
qemu_opts_do_parse(opts, options, NULL, &local_err);
if (local_err) {
goto out;
}
}
if (base_filename) {
qemu_opt_set(opts, BLOCK_OPT_BACKING_FILE, base_filename, &local_err);
if (local_err) {
error_setg(errp, "Backing file not supported for file format '%s'",
fmt);
goto out;
}
}
if (base_fmt) {
qemu_opt_set(opts, BLOCK_OPT_BACKING_FMT, base_fmt, &local_err);
if (local_err) {
error_setg(errp, "Backing file format not supported for file "
"format '%s'", fmt);
goto out;
}
}
backing_file = qemu_opt_get(opts, BLOCK_OPT_BACKING_FILE);
if (backing_file) {
if (!strcmp(filename, backing_file)) {
error_setg(errp, "Error: Trying to create an image with the "
"same filename as the backing file");
goto out;
}
}
backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT);
/* The size for the image must always be specified, unless we have a backing
* file and we have not been forbidden from opening it. */
size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, img_size);
if (backing_file && !(flags & BDRV_O_NO_BACKING)) {
BlockDriverState *bs;
char *full_backing;
int back_flags;
QDict *backing_options = NULL;
full_backing =
bdrv_get_full_backing_filename_from_filename(filename, backing_file,
&local_err);
if (local_err) {
goto out;
}
assert(full_backing);
/* backing files always opened read-only */
back_flags = flags;
back_flags &= ~(BDRV_O_RDWR | BDRV_O_SNAPSHOT | BDRV_O_NO_BACKING);
backing_options = qdict_new();
if (backing_fmt) {
qdict_put_str(backing_options, "driver", backing_fmt);
}
qdict_put_bool(backing_options, BDRV_OPT_FORCE_SHARE, true);
bs = bdrv_open(full_backing, NULL, backing_options, back_flags,
&local_err);
g_free(full_backing);
if (!bs && size != -1) {
/* Couldn't open BS, but we have a size, so it's nonfatal */
warn_reportf_err(local_err,
"Could not verify backing image. "
"This may become an error in future versions.\n");
local_err = NULL;
} else if (!bs) {
/* Couldn't open bs, do not have size */
error_append_hint(&local_err,
"Could not open backing image to determine size.\n");
goto out;
} else {
if (size == -1) {
/* Opened BS, have no size */
size = bdrv_getlength(bs);
if (size < 0) {
error_setg_errno(errp, -size, "Could not get size of '%s'",
backing_file);
bdrv_unref(bs);
goto out;
}
qemu_opt_set_number(opts, BLOCK_OPT_SIZE, size, &error_abort);
}
bdrv_unref(bs);
}
} /* (backing_file && !(flags & BDRV_O_NO_BACKING)) */
if (size == -1) {
error_setg(errp, "Image creation needs a size parameter");
goto out;
}
if (!quiet) {
printf("Formatting '%s', fmt=%s ", filename, fmt);
qemu_opts_print(opts, " ");
puts("");
}
ret = bdrv_create(drv, filename, opts, &local_err);
if (ret == -EFBIG) {
/* This is generally a better message than whatever the driver would
* deliver (especially because of the cluster_size_hint), since that
* is most probably not much different from "image too large". */
const char *cluster_size_hint = "";
if (qemu_opt_get_size(opts, BLOCK_OPT_CLUSTER_SIZE, 0)) {
cluster_size_hint = " (try using a larger cluster size)";
}
error_setg(errp, "The image size is too large for file format '%s'"
"%s", fmt, cluster_size_hint);
error_free(local_err);
local_err = NULL;
}
out:
qemu_opts_del(opts);
qemu_opts_free(create_opts);
error_propagate(errp, local_err);
}
AioContext *bdrv_get_aio_context(BlockDriverState *bs)
{
return bs ? bs->aio_context : qemu_get_aio_context();
}
void bdrv_coroutine_enter(BlockDriverState *bs, Coroutine *co)
{
aio_co_enter(bdrv_get_aio_context(bs), co);
}
static void bdrv_do_remove_aio_context_notifier(BdrvAioNotifier *ban)
{
QLIST_REMOVE(ban, list);
g_free(ban);
}
static void bdrv_detach_aio_context(BlockDriverState *bs)
{
BdrvAioNotifier *baf, *baf_tmp;
assert(!bs->walking_aio_notifiers);
bs->walking_aio_notifiers = true;
QLIST_FOREACH_SAFE(baf, &bs->aio_notifiers, list, baf_tmp) {
if (baf->deleted) {
bdrv_do_remove_aio_context_notifier(baf);
} else {
baf->detach_aio_context(baf->opaque);
}
}
/* Never mind iterating again to check for ->deleted. bdrv_close() will
* remove remaining aio notifiers if we aren't called again.
*/
bs->walking_aio_notifiers = false;
if (bs->drv && bs->drv->bdrv_detach_aio_context) {
bs->drv->bdrv_detach_aio_context(bs);
}
if (bs->quiesce_counter) {
aio_enable_external(bs->aio_context);
}
bs->aio_context = NULL;
}
static void bdrv_attach_aio_context(BlockDriverState *bs,
AioContext *new_context)
{
BdrvAioNotifier *ban, *ban_tmp;
if (bs->quiesce_counter) {
aio_disable_external(new_context);
}
bs->aio_context = new_context;
if (bs->drv && bs->drv->bdrv_attach_aio_context) {
bs->drv->bdrv_attach_aio_context(bs, new_context);
}
assert(!bs->walking_aio_notifiers);
bs->walking_aio_notifiers = true;
QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_tmp) {
if (ban->deleted) {
bdrv_do_remove_aio_context_notifier(ban);
} else {
ban->attached_aio_context(new_context, ban->opaque);
}
}
bs->walking_aio_notifiers = false;
}
/*
* Changes the AioContext used for fd handlers, timers, and BHs by this
* BlockDriverState and all its children and parents.
*
* The caller must own the AioContext lock for the old AioContext of bs, but it
* must not own the AioContext lock for new_context (unless new_context is the
* same as the current context of bs).
*
* @ignore will accumulate all visited BdrvChild object. The caller is
* responsible for freeing the list afterwards.
*/
void bdrv_set_aio_context_ignore(BlockDriverState *bs,
AioContext *new_context, GSList **ignore)
{
BdrvChild *child;
if (bdrv_get_aio_context(bs) == new_context) {
return;
}
bdrv_drained_begin(bs);
QLIST_FOREACH(child, &bs->children, next) {
if (g_slist_find(*ignore, child)) {
continue;
}
*ignore = g_slist_prepend(*ignore, child);
bdrv_set_aio_context_ignore(child->bs, new_context, ignore);
}
QLIST_FOREACH(child, &bs->parents, next_parent) {
if (g_slist_find(*ignore, child)) {
continue;
}
assert(child->role->set_aio_ctx);
*ignore = g_slist_prepend(*ignore, child);
child->role->set_aio_ctx(child, new_context, ignore);
}
bdrv_detach_aio_context(bs);
/* This function executes in the old AioContext so acquire the new one in
* case it runs in a different thread.
*/
aio_context_acquire(new_context);
bdrv_attach_aio_context(bs, new_context);
bdrv_drained_end(bs);
aio_context_release(new_context);
}
static bool bdrv_parent_can_set_aio_context(BdrvChild *c, AioContext *ctx,
GSList **ignore, Error **errp)
{
if (g_slist_find(*ignore, c)) {
return true;
}
*ignore = g_slist_prepend(*ignore, c);
/* A BdrvChildRole that doesn't handle AioContext changes cannot
* tolerate any AioContext changes */
if (!c->role->can_set_aio_ctx) {
char *user = bdrv_child_user_desc(c);
error_setg(errp, "Changing iothreads is not supported by %s", user);
g_free(user);
return false;
}
if (!c->role->can_set_aio_ctx(c, ctx, ignore, errp)) {
assert(!errp || *errp);
return false;
}
return true;
}
bool bdrv_child_can_set_aio_context(BdrvChild *c, AioContext *ctx,
GSList **ignore, Error **errp)
{
if (g_slist_find(*ignore, c)) {
return true;
}
*ignore = g_slist_prepend(*ignore, c);
return bdrv_can_set_aio_context(c->bs, ctx, ignore, errp);
}
/* @ignore will accumulate all visited BdrvChild object. The caller is
* responsible for freeing the list afterwards. */
bool bdrv_can_set_aio_context(BlockDriverState *bs, AioContext *ctx,
GSList **ignore, Error **errp)
{
BdrvChild *c;
if (bdrv_get_aio_context(bs) == ctx) {
return true;
}
QLIST_FOREACH(c, &bs->parents, next_parent) {
if (!bdrv_parent_can_set_aio_context(c, ctx, ignore, errp)) {
return false;
}
}
QLIST_FOREACH(c, &bs->children, next) {
if (!bdrv_child_can_set_aio_context(c, ctx, ignore, errp)) {
return false;
}
}
return true;
}
int bdrv_child_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
BdrvChild *ignore_child, Error **errp)
{
GSList *ignore;
bool ret;
ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL;
ret = bdrv_can_set_aio_context(bs, ctx, &ignore, errp);
g_slist_free(ignore);
if (!ret) {
return -EPERM;
}
ignore = ignore_child ? g_slist_prepend(NULL, ignore_child) : NULL;
bdrv_set_aio_context_ignore(bs, ctx, &ignore);
g_slist_free(ignore);
return 0;
}
int bdrv_try_set_aio_context(BlockDriverState *bs, AioContext *ctx,
Error **errp)
{
return bdrv_child_try_set_aio_context(bs, ctx, NULL, errp);
}
void bdrv_add_aio_context_notifier(BlockDriverState *bs,
void (*attached_aio_context)(AioContext *new_context, void *opaque),
void (*detach_aio_context)(void *opaque), void *opaque)
{
BdrvAioNotifier *ban = g_new(BdrvAioNotifier, 1);
*ban = (BdrvAioNotifier){
.attached_aio_context = attached_aio_context,
.detach_aio_context = detach_aio_context,
.opaque = opaque
};
QLIST_INSERT_HEAD(&bs->aio_notifiers, ban, list);
}
void bdrv_remove_aio_context_notifier(BlockDriverState *bs,
void (*attached_aio_context)(AioContext *,
void *),
void (*detach_aio_context)(void *),
void *opaque)
{
BdrvAioNotifier *ban, *ban_next;
QLIST_FOREACH_SAFE(ban, &bs->aio_notifiers, list, ban_next) {
if (ban->attached_aio_context == attached_aio_context &&
ban->detach_aio_context == detach_aio_context &&
ban->opaque == opaque &&
ban->deleted == false)
{
if (bs->walking_aio_notifiers) {
ban->deleted = true;
} else {
bdrv_do_remove_aio_context_notifier(ban);
}
return;
}
}
abort();
}
int bdrv_amend_options(BlockDriverState *bs, QemuOpts *opts,
BlockDriverAmendStatusCB *status_cb, void *cb_opaque,
Error **errp)
{
if (!bs->drv) {
error_setg(errp, "Node is ejected");
return -ENOMEDIUM;
}
if (!bs->drv->bdrv_amend_options) {
error_setg(errp, "Block driver '%s' does not support option amendment",
bs->drv->format_name);
return -ENOTSUP;
}
return bs->drv->bdrv_amend_options(bs, opts, status_cb, cb_opaque, errp);
}
/* This function will be called by the bdrv_recurse_is_first_non_filter method
* of block filter and by bdrv_is_first_non_filter.
* It is used to test if the given bs is the candidate or recurse more in the
* node graph.
*/
bool bdrv_recurse_is_first_non_filter(BlockDriverState *bs,
BlockDriverState *candidate)
{
/* return false if basic checks fails */
if (!bs || !bs->drv) {
return false;
}
/* the code reached a non block filter driver -> check if the bs is
* the same as the candidate. It's the recursion termination condition.
*/
if (!bs->drv->is_filter) {
return bs == candidate;
}
/* Down this path the driver is a block filter driver */
/* If the block filter recursion method is defined use it to recurse down
* the node graph.
*/
if (bs->drv->bdrv_recurse_is_first_non_filter) {
return bs->drv->bdrv_recurse_is_first_non_filter(bs, candidate);
}
/* the driver is a block filter but don't allow to recurse -> return false
*/
return false;
}
/* This function checks if the candidate is the first non filter bs down it's
* bs chain. Since we don't have pointers to parents it explore all bs chains
* from the top. Some filters can choose not to pass down the recursion.
*/
bool bdrv_is_first_non_filter(BlockDriverState *candidate)
{
BlockDriverState *bs;
BdrvNextIterator it;
/* walk down the bs forest recursively */
for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) {
bool perm;
/* try to recurse in this top level bs */
perm = bdrv_recurse_is_first_non_filter(bs, candidate);
/* candidate is the first non filter */
if (perm) {
bdrv_next_cleanup(&it);
return true;
}
}
return false;
}
BlockDriverState *check_to_replace_node(BlockDriverState *parent_bs,
const char *node_name, Error **errp)
{
BlockDriverState *to_replace_bs = bdrv_find_node(node_name);
AioContext *aio_context;
if (!to_replace_bs) {
error_setg(errp, "Node name '%s' not found", node_name);
return NULL;
}
aio_context = bdrv_get_aio_context(to_replace_bs);
aio_context_acquire(aio_context);
if (bdrv_op_is_blocked(to_replace_bs, BLOCK_OP_TYPE_REPLACE, errp)) {
to_replace_bs = NULL;
goto out;
}
/* We don't want arbitrary node of the BDS chain to be replaced only the top
* most non filter in order to prevent data corruption.
* Another benefit is that this tests exclude backing files which are
* blocked by the backing blockers.
*/
if (!bdrv_recurse_is_first_non_filter(parent_bs, to_replace_bs)) {
error_setg(errp, "Only top most non filter can be replaced");
to_replace_bs = NULL;
goto out;
}
out:
aio_context_release(aio_context);
return to_replace_bs;
}
/**
* Iterates through the list of runtime option keys that are said to
* be "strong" for a BDS. An option is called "strong" if it changes
* a BDS's data. For example, the null block driver's "size" and
* "read-zeroes" options are strong, but its "latency-ns" option is
* not.
*
* If a key returned by this function ends with a dot, all options
* starting with that prefix are strong.
*/
static const char *const *strong_options(BlockDriverState *bs,
const char *const *curopt)
{
static const char *const global_options[] = {
"driver", "filename", NULL
};
if (!curopt) {
return &global_options[0];
}
curopt++;
if (curopt == &global_options[ARRAY_SIZE(global_options) - 1] && bs->drv) {
curopt = bs->drv->strong_runtime_opts;
}
return (curopt && *curopt) ? curopt : NULL;
}
/**
* Copies all strong runtime options from bs->options to the given
* QDict. The set of strong option keys is determined by invoking
* strong_options().
*
* Returns true iff any strong option was present in bs->options (and
* thus copied to the target QDict) with the exception of "filename"
* and "driver". The caller is expected to use this value to decide
* whether the existence of strong options prevents the generation of
* a plain filename.
*/
static bool append_strong_runtime_options(QDict *d, BlockDriverState *bs)
{
bool found_any = false;
const char *const *option_name = NULL;
if (!bs->drv) {
return false;
}
while ((option_name = strong_options(bs, option_name))) {
bool option_given = false;
assert(strlen(*option_name) > 0);
if ((*option_name)[strlen(*option_name) - 1] != '.') {
QObject *entry = qdict_get(bs->options, *option_name);
if (!entry) {
continue;
}
qdict_put_obj(d, *option_name, qobject_ref(entry));
option_given = true;
} else {
const QDictEntry *entry;
for (entry = qdict_first(bs->options); entry;
entry = qdict_next(bs->options, entry))
{
if (strstart(qdict_entry_key(entry), *option_name, NULL)) {
qdict_put_obj(d, qdict_entry_key(entry),
qobject_ref(qdict_entry_value(entry)));
option_given = true;
}
}
}
/* While "driver" and "filename" need to be included in a JSON filename,
* their existence does not prohibit generation of a plain filename. */
if (!found_any && option_given &&
strcmp(*option_name, "driver") && strcmp(*option_name, "filename"))
{
found_any = true;
}
}
if (!qdict_haskey(d, "driver")) {
/* Drivers created with bdrv_new_open_driver() may not have a
* @driver option. Add it here. */
qdict_put_str(d, "driver", bs->drv->format_name);
}
return found_any;
}
/* Note: This function may return false positives; it may return true
* even if opening the backing file specified by bs's image header
* would result in exactly bs->backing. */
static bool bdrv_backing_overridden(BlockDriverState *bs)
{
if (bs->backing) {
return strcmp(bs->auto_backing_file,
bs->backing->bs->filename);
} else {
/* No backing BDS, so if the image header reports any backing
* file, it must have been suppressed */
return bs->auto_backing_file[0] != '\0';
}
}
/* Updates the following BDS fields:
* - exact_filename: A filename which may be used for opening a block device
* which (mostly) equals the given BDS (even without any
* other options; so reading and writing must return the same
* results, but caching etc. may be different)
* - full_open_options: Options which, when given when opening a block device
* (without a filename), result in a BDS (mostly)
* equalling the given one
* - filename: If exact_filename is set, it is copied here. Otherwise,
* full_open_options is converted to a JSON object, prefixed with
* "json:" (for use through the JSON pseudo protocol) and put here.
*/
void bdrv_refresh_filename(BlockDriverState *bs)
{
BlockDriver *drv = bs->drv;
BdrvChild *child;
QDict *opts;
bool backing_overridden;
bool generate_json_filename; /* Whether our default implementation should
fill exact_filename (false) or not (true) */
if (!drv) {
return;
}
/* This BDS's file name may depend on any of its children's file names, so
* refresh those first */
QLIST_FOREACH(child, &bs->children, next) {
bdrv_refresh_filename(child->bs);
}
if (bs->implicit) {
/* For implicit nodes, just copy everything from the single child */
child = QLIST_FIRST(&bs->children);
assert(QLIST_NEXT(child, next) == NULL);
pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
child->bs->exact_filename);
pstrcpy(bs->filename, sizeof(bs->filename), child->bs->filename);
bs->full_open_options = qobject_ref(child->bs->full_open_options);
return;
}
backing_overridden = bdrv_backing_overridden(bs);
if (bs->open_flags & BDRV_O_NO_IO) {
/* Without I/O, the backing file does not change anything.
* Therefore, in such a case (primarily qemu-img), we can
* pretend the backing file has not been overridden even if
* it technically has been. */
backing_overridden = false;
}
/* Gather the options QDict */
opts = qdict_new();
generate_json_filename = append_strong_runtime_options(opts, bs);
generate_json_filename |= backing_overridden;
if (drv->bdrv_gather_child_options) {
/* Some block drivers may not want to present all of their children's
* options, or name them differently from BdrvChild.name */
drv->bdrv_gather_child_options(bs, opts, backing_overridden);
} else {
QLIST_FOREACH(child, &bs->children, next) {
if (child->role == &child_backing && !backing_overridden) {
/* We can skip the backing BDS if it has not been overridden */
continue;
}
qdict_put(opts, child->name,
qobject_ref(child->bs->full_open_options));
}
if (backing_overridden && !bs->backing) {
/* Force no backing file */
qdict_put_null(opts, "backing");
}
}
qobject_unref(bs->full_open_options);
bs->full_open_options = opts;
if (drv->bdrv_refresh_filename) {
/* Obsolete information is of no use here, so drop the old file name
* information before refreshing it */
bs->exact_filename[0] = '\0';
drv->bdrv_refresh_filename(bs);
} else if (bs->file) {
/* Try to reconstruct valid information from the underlying file */
bs->exact_filename[0] = '\0';
/*
* We can use the underlying file's filename if:
* - it has a filename,
* - the file is a protocol BDS, and
* - opening that file (as this BDS's format) will automatically create
* the BDS tree we have right now, that is:
* - the user did not significantly change this BDS's behavior with
* some explicit (strong) options
* - no non-file child of this BDS has been overridden by the user
* Both of these conditions are represented by generate_json_filename.
*/
if (bs->file->bs->exact_filename[0] &&
bs->file->bs->drv->bdrv_file_open &&
!generate_json_filename)
{
strcpy(bs->exact_filename, bs->file->bs->exact_filename);
}
}
if (bs->exact_filename[0]) {
pstrcpy(bs->filename, sizeof(bs->filename), bs->exact_filename);
} else {
QString *json = qobject_to_json(QOBJECT(bs->full_open_options));
snprintf(bs->filename, sizeof(bs->filename), "json:%s",
qstring_get_str(json));
qobject_unref(json);
}
}
char *bdrv_dirname(BlockDriverState *bs, Error **errp)
{
BlockDriver *drv = bs->drv;
if (!drv) {
error_setg(errp, "Node '%s' is ejected", bs->node_name);
return NULL;
}
if (drv->bdrv_dirname) {
return drv->bdrv_dirname(bs, errp);
}
if (bs->file) {
return bdrv_dirname(bs->file->bs, errp);
}
bdrv_refresh_filename(bs);
if (bs->exact_filename[0] != '\0') {
return path_combine(bs->exact_filename, "");
}
error_setg(errp, "Cannot generate a base directory for %s nodes",
drv->format_name);
return NULL;
}
/*
* Hot add/remove a BDS's child. So the user can take a child offline when
* it is broken and take a new child online
*/
void bdrv_add_child(BlockDriverState *parent_bs, BlockDriverState *child_bs,
Error **errp)
{
if (!parent_bs->drv || !parent_bs->drv->bdrv_add_child) {
error_setg(errp, "The node %s does not support adding a child",
bdrv_get_device_or_node_name(parent_bs));
return;
}
if (!QLIST_EMPTY(&child_bs->parents)) {
error_setg(errp, "The node %s already has a parent",
child_bs->node_name);
return;
}
parent_bs->drv->bdrv_add_child(parent_bs, child_bs, errp);
}
void bdrv_del_child(BlockDriverState *parent_bs, BdrvChild *child, Error **errp)
{
BdrvChild *tmp;
if (!parent_bs->drv || !parent_bs->drv->bdrv_del_child) {
error_setg(errp, "The node %s does not support removing a child",
bdrv_get_device_or_node_name(parent_bs));
return;
}
QLIST_FOREACH(tmp, &parent_bs->children, next) {
if (tmp == child) {
break;
}
}
if (!tmp) {
error_setg(errp, "The node %s does not have a child named %s",
bdrv_get_device_or_node_name(parent_bs),
bdrv_get_device_or_node_name(child->bs));
return;
}
parent_bs->drv->bdrv_del_child(parent_bs, child, errp);
}
bool bdrv_can_store_new_dirty_bitmap(BlockDriverState *bs, const char *name,
uint32_t granularity, Error **errp)
{
BlockDriver *drv = bs->drv;
if (!drv) {
error_setg_errno(errp, ENOMEDIUM,
"Can't store persistent bitmaps to %s",
bdrv_get_device_or_node_name(bs));
return false;
}
if (!drv->bdrv_can_store_new_dirty_bitmap) {
error_setg_errno(errp, ENOTSUP,
"Can't store persistent bitmaps to %s",
bdrv_get_device_or_node_name(bs));
return false;
}
return drv->bdrv_can_store_new_dirty_bitmap(bs, name, granularity, errp);
}
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