qemu/block/raw-format.c
Max Reitz 228345bf5d block: Support BDRV_REQ_WRITE_UNCHANGED in filters
Update the rest of the filter drivers to support
BDRV_REQ_WRITE_UNCHANGED.  They already forward write request flags to
their children, so we just have to announce support for it.

This patch does not cover the replication driver because that currently
does not support flags at all, and because it just grabs the WRITE
permission for its children when it can, so we should be fine just
submitting the incoming WRITE_UNCHANGED requests as normal writes.

It also does not cover format drivers for similar reasons.  They all use
bdrv_format_default_perms() as their .bdrv_child_perm() implementation
so they just always grab the WRITE permission for their file children
whenever possible.  In addition, it often would be difficult to
ascertain whether incoming unchanging writes end up as unchanging writes
in their files.  So we just leave them as normal potentially changing
writes.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Message-id: 20180421132929.21610-7-mreitz@redhat.com
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2018-05-15 16:15:21 +02:00

523 lines
15 KiB
C

/* BlockDriver implementation for "raw" format driver
*
* Copyright (C) 2010-2016 Red Hat, Inc.
* Copyright (C) 2010, Blue Swirl <blauwirbel@gmail.com>
* Copyright (C) 2009, Anthony Liguori <aliguori@us.ibm.com>
*
* Author:
* Laszlo Ersek <lersek@redhat.com>
*
* 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/block_int.h"
#include "qapi/error.h"
#include "qemu/option.h"
typedef struct BDRVRawState {
uint64_t offset;
uint64_t size;
bool has_size;
} BDRVRawState;
static QemuOptsList raw_runtime_opts = {
.name = "raw",
.head = QTAILQ_HEAD_INITIALIZER(raw_runtime_opts.head),
.desc = {
{
.name = "offset",
.type = QEMU_OPT_SIZE,
.help = "offset in the disk where the image starts",
},
{
.name = "size",
.type = QEMU_OPT_SIZE,
.help = "virtual disk size",
},
{ /* end of list */ }
},
};
static QemuOptsList raw_create_opts = {
.name = "raw-create-opts",
.head = QTAILQ_HEAD_INITIALIZER(raw_create_opts.head),
.desc = {
{
.name = BLOCK_OPT_SIZE,
.type = QEMU_OPT_SIZE,
.help = "Virtual disk size"
},
{ /* end of list */ }
}
};
static int raw_read_options(QDict *options, BlockDriverState *bs,
BDRVRawState *s, Error **errp)
{
Error *local_err = NULL;
QemuOpts *opts = NULL;
int64_t real_size = 0;
int ret;
real_size = bdrv_getlength(bs->file->bs);
if (real_size < 0) {
error_setg_errno(errp, -real_size, "Could not get image size");
return real_size;
}
opts = qemu_opts_create(&raw_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 end;
}
s->offset = qemu_opt_get_size(opts, "offset", 0);
if (s->offset > real_size) {
error_setg(errp, "Offset (%" PRIu64 ") cannot be greater than "
"size of the containing file (%" PRId64 ")",
s->offset, real_size);
ret = -EINVAL;
goto end;
}
if (qemu_opt_find(opts, "size") != NULL) {
s->size = qemu_opt_get_size(opts, "size", 0);
s->has_size = true;
} else {
s->has_size = false;
s->size = real_size - s->offset;
}
/* Check size and offset */
if ((real_size - s->offset) < s->size) {
error_setg(errp, "The sum of offset (%" PRIu64 ") and size "
"(%" PRIu64 ") has to be smaller or equal to the "
" actual size of the containing file (%" PRId64 ")",
s->offset, s->size, real_size);
ret = -EINVAL;
goto end;
}
/* Make sure size is multiple of BDRV_SECTOR_SIZE to prevent rounding
* up and leaking out of the specified area. */
if (s->has_size && !QEMU_IS_ALIGNED(s->size, BDRV_SECTOR_SIZE)) {
error_setg(errp, "Specified size is not multiple of %llu",
BDRV_SECTOR_SIZE);
ret = -EINVAL;
goto end;
}
ret = 0;
end:
qemu_opts_del(opts);
return ret;
}
static int raw_reopen_prepare(BDRVReopenState *reopen_state,
BlockReopenQueue *queue, Error **errp)
{
assert(reopen_state != NULL);
assert(reopen_state->bs != NULL);
reopen_state->opaque = g_new0(BDRVRawState, 1);
return raw_read_options(
reopen_state->options,
reopen_state->bs,
reopen_state->opaque,
errp);
}
static void raw_reopen_commit(BDRVReopenState *state)
{
BDRVRawState *new_s = state->opaque;
BDRVRawState *s = state->bs->opaque;
memcpy(s, new_s, sizeof(BDRVRawState));
g_free(state->opaque);
state->opaque = NULL;
}
static void raw_reopen_abort(BDRVReopenState *state)
{
g_free(state->opaque);
state->opaque = NULL;
}
static int coroutine_fn raw_co_preadv(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov,
int flags)
{
BDRVRawState *s = bs->opaque;
if (offset > UINT64_MAX - s->offset) {
return -EINVAL;
}
offset += s->offset;
BLKDBG_EVENT(bs->file, BLKDBG_READ_AIO);
return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
}
static int coroutine_fn raw_co_pwritev(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, QEMUIOVector *qiov,
int flags)
{
BDRVRawState *s = bs->opaque;
void *buf = NULL;
BlockDriver *drv;
QEMUIOVector local_qiov;
int ret;
if (s->has_size && (offset > s->size || bytes > (s->size - offset))) {
/* There's not enough space for the data. Don't write anything and just
* fail to prevent leaking out of the size specified in options. */
return -ENOSPC;
}
if (offset > UINT64_MAX - s->offset) {
ret = -EINVAL;
goto fail;
}
if (bs->probed && offset < BLOCK_PROBE_BUF_SIZE && bytes) {
/* Handling partial writes would be a pain - so we just
* require that guests have 512-byte request alignment if
* probing occurred */
QEMU_BUILD_BUG_ON(BLOCK_PROBE_BUF_SIZE != 512);
QEMU_BUILD_BUG_ON(BDRV_SECTOR_SIZE != 512);
assert(offset == 0 && bytes >= BLOCK_PROBE_BUF_SIZE);
buf = qemu_try_blockalign(bs->file->bs, 512);
if (!buf) {
ret = -ENOMEM;
goto fail;
}
ret = qemu_iovec_to_buf(qiov, 0, buf, 512);
if (ret != 512) {
ret = -EINVAL;
goto fail;
}
drv = bdrv_probe_all(buf, 512, NULL);
if (drv != bs->drv) {
ret = -EPERM;
goto fail;
}
/* Use the checked buffer, a malicious guest might be overwriting its
* original buffer in the background. */
qemu_iovec_init(&local_qiov, qiov->niov + 1);
qemu_iovec_add(&local_qiov, buf, 512);
qemu_iovec_concat(&local_qiov, qiov, 512, qiov->size - 512);
qiov = &local_qiov;
}
offset += s->offset;
BLKDBG_EVENT(bs->file, BLKDBG_WRITE_AIO);
ret = bdrv_co_pwritev(bs->file, offset, bytes, qiov, flags);
fail:
if (qiov == &local_qiov) {
qemu_iovec_destroy(&local_qiov);
}
qemu_vfree(buf);
return ret;
}
static int coroutine_fn raw_co_block_status(BlockDriverState *bs,
bool want_zero, int64_t offset,
int64_t bytes, int64_t *pnum,
int64_t *map,
BlockDriverState **file)
{
BDRVRawState *s = bs->opaque;
*pnum = bytes;
*file = bs->file->bs;
*map = offset + s->offset;
return BDRV_BLOCK_RAW | BDRV_BLOCK_OFFSET_VALID;
}
static int coroutine_fn raw_co_pwrite_zeroes(BlockDriverState *bs,
int64_t offset, int bytes,
BdrvRequestFlags flags)
{
BDRVRawState *s = bs->opaque;
if (offset > UINT64_MAX - s->offset) {
return -EINVAL;
}
offset += s->offset;
return bdrv_co_pwrite_zeroes(bs->file, offset, bytes, flags);
}
static int coroutine_fn raw_co_pdiscard(BlockDriverState *bs,
int64_t offset, int bytes)
{
BDRVRawState *s = bs->opaque;
if (offset > UINT64_MAX - s->offset) {
return -EINVAL;
}
offset += s->offset;
return bdrv_co_pdiscard(bs->file->bs, offset, bytes);
}
static int64_t raw_getlength(BlockDriverState *bs)
{
int64_t len;
BDRVRawState *s = bs->opaque;
/* Update size. It should not change unless the file was externally
* modified. */
len = bdrv_getlength(bs->file->bs);
if (len < 0) {
return len;
}
if (len < s->offset) {
s->size = 0;
} else {
if (s->has_size) {
/* Try to honour the size */
s->size = MIN(s->size, len - s->offset);
} else {
s->size = len - s->offset;
}
}
return s->size;
}
static BlockMeasureInfo *raw_measure(QemuOpts *opts, BlockDriverState *in_bs,
Error **errp)
{
BlockMeasureInfo *info;
int64_t required;
if (in_bs) {
required = bdrv_getlength(in_bs);
if (required < 0) {
error_setg_errno(errp, -required, "Unable to get image size");
return NULL;
}
} else {
required = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
BDRV_SECTOR_SIZE);
}
info = g_new(BlockMeasureInfo, 1);
info->required = required;
/* Unallocated sectors count towards the file size in raw images */
info->fully_allocated = info->required;
return info;
}
static int raw_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
return bdrv_get_info(bs->file->bs, bdi);
}
static void raw_refresh_limits(BlockDriverState *bs, Error **errp)
{
if (bs->probed) {
/* To make it easier to protect the first sector, any probed
* image is restricted to read-modify-write on sub-sector
* operations. */
bs->bl.request_alignment = BDRV_SECTOR_SIZE;
}
}
static int raw_truncate(BlockDriverState *bs, int64_t offset,
PreallocMode prealloc, Error **errp)
{
BDRVRawState *s = bs->opaque;
if (s->has_size) {
error_setg(errp, "Cannot resize fixed-size raw disks");
return -ENOTSUP;
}
if (INT64_MAX - offset < s->offset) {
error_setg(errp, "Disk size too large for the chosen offset");
return -EINVAL;
}
s->size = offset;
offset += s->offset;
return bdrv_truncate(bs->file, offset, prealloc, errp);
}
static void raw_eject(BlockDriverState *bs, bool eject_flag)
{
bdrv_eject(bs->file->bs, eject_flag);
}
static void raw_lock_medium(BlockDriverState *bs, bool locked)
{
bdrv_lock_medium(bs->file->bs, locked);
}
static int raw_co_ioctl(BlockDriverState *bs, unsigned long int req, void *buf)
{
BDRVRawState *s = bs->opaque;
if (s->offset || s->has_size) {
return -ENOTSUP;
}
return bdrv_co_ioctl(bs->file->bs, req, buf);
}
static int raw_has_zero_init(BlockDriverState *bs)
{
return bdrv_has_zero_init(bs->file->bs);
}
static int coroutine_fn raw_co_create_opts(const char *filename, QemuOpts *opts,
Error **errp)
{
return bdrv_create_file(filename, opts, errp);
}
static int raw_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
BDRVRawState *s = bs->opaque;
int ret;
bs->file = bdrv_open_child(NULL, options, "file", bs, &child_file,
false, errp);
if (!bs->file) {
return -EINVAL;
}
bs->sg = bs->file->bs->sg;
bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |
(BDRV_REQ_FUA & bs->file->bs->supported_write_flags);
bs->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP) &
bs->file->bs->supported_zero_flags);
if (bs->probed && !bdrv_is_read_only(bs)) {
fprintf(stderr,
"WARNING: Image format was not specified for '%s' and probing "
"guessed raw.\n"
" Automatically detecting the format is dangerous for "
"raw images, write operations on block 0 will be restricted.\n"
" Specify the 'raw' format explicitly to remove the "
"restrictions.\n",
bs->file->bs->filename);
}
ret = raw_read_options(options, bs, s, errp);
if (ret < 0) {
return ret;
}
if (bs->sg && (s->offset || s->has_size)) {
error_setg(errp, "Cannot use offset/size with SCSI generic devices");
return -EINVAL;
}
return 0;
}
static void raw_close(BlockDriverState *bs)
{
}
static int raw_probe(const uint8_t *buf, int buf_size, const char *filename)
{
/* smallest possible positive score so that raw is used if and only if no
* other block driver works
*/
return 1;
}
static int raw_probe_blocksizes(BlockDriverState *bs, BlockSizes *bsz)
{
BDRVRawState *s = bs->opaque;
int ret;
ret = bdrv_probe_blocksizes(bs->file->bs, bsz);
if (ret < 0) {
return ret;
}
if (!QEMU_IS_ALIGNED(s->offset, MAX(bsz->log, bsz->phys))) {
return -ENOTSUP;
}
return 0;
}
static int raw_probe_geometry(BlockDriverState *bs, HDGeometry *geo)
{
BDRVRawState *s = bs->opaque;
if (s->offset || s->has_size) {
return -ENOTSUP;
}
return bdrv_probe_geometry(bs->file->bs, geo);
}
BlockDriver bdrv_raw = {
.format_name = "raw",
.instance_size = sizeof(BDRVRawState),
.bdrv_probe = &raw_probe,
.bdrv_reopen_prepare = &raw_reopen_prepare,
.bdrv_reopen_commit = &raw_reopen_commit,
.bdrv_reopen_abort = &raw_reopen_abort,
.bdrv_open = &raw_open,
.bdrv_close = &raw_close,
.bdrv_child_perm = bdrv_filter_default_perms,
.bdrv_co_create_opts = &raw_co_create_opts,
.bdrv_co_preadv = &raw_co_preadv,
.bdrv_co_pwritev = &raw_co_pwritev,
.bdrv_co_pwrite_zeroes = &raw_co_pwrite_zeroes,
.bdrv_co_pdiscard = &raw_co_pdiscard,
.bdrv_co_block_status = &raw_co_block_status,
.bdrv_truncate = &raw_truncate,
.bdrv_getlength = &raw_getlength,
.has_variable_length = true,
.bdrv_measure = &raw_measure,
.bdrv_get_info = &raw_get_info,
.bdrv_refresh_limits = &raw_refresh_limits,
.bdrv_probe_blocksizes = &raw_probe_blocksizes,
.bdrv_probe_geometry = &raw_probe_geometry,
.bdrv_eject = &raw_eject,
.bdrv_lock_medium = &raw_lock_medium,
.bdrv_co_ioctl = &raw_co_ioctl,
.create_opts = &raw_create_opts,
.bdrv_has_zero_init = &raw_has_zero_init
};
static void bdrv_raw_init(void)
{
bdrv_register(&bdrv_raw);
}
block_init(bdrv_raw_init);