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block: Connect BlockBackend to BlockDriverState

Browse source 
Convenience function blk_new_with_bs() creates a BlockBackend with its
BlockDriverState.  Callers have to unref both.  The commit after next
will relieve them of the need to unref the BlockDriverState.

Complication: due to the silly way drive_del works, we need a way to
hide a BlockBackend, just like bdrv_make_anon().  To emphasize its
"special" status, give the function a suitably off-putting name:
blk_hide_on_behalf_of_do_drive_del().  Unfortunately, hiding turns the
BlockBackend's name into the empty string.  Can't avoid that without
breaking the blk->bs->device_name equals blk->name invariant.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Markus Armbruster 2014-10-07 13:59:05 +02:00 committed by Kevin Wolf
parent 26f54e9a3c
commit 7e7d56d9e0
9 changed files with 159 additions and 97 deletions
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12
block.c
View file

@ -2025,6 +2025,8 @@ static void bdrv_move_feature_fields(BlockDriverState *bs_dest,
pstrcpy(bs_dest->device_name, sizeof(bs_dest->device_name),
bs_src->device_name);
bs_dest->device_list = bs_src->device_list;
bs_dest->blk = bs_src->blk;
memcpy(bs_dest->op_blockers, bs_src->op_blockers,
sizeof(bs_dest->op_blockers));
}
@ -2037,7 +2039,7 @@ static void bdrv_move_feature_fields(BlockDriverState *bs_dest,
* This will modify the BlockDriverState fields, and swap contents
* between bs_new and bs_old. Both bs_new and bs_old are modified.
*
* bs_new is required to be anonymous.
* bs_new must be nameless and not attached to a BlockBackend.
*
* This function does not create any image files.
*/
@ -2056,8 +2058,9 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
QTAILQ_REMOVE(&graph_bdrv_states, bs_old, node_list);
}
/* bs_new must be anonymous and shouldn't have anything fancy enabled */
/* bs_new must be nameless and shouldn't have anything fancy enabled */
assert(bs_new->device_name[0] == '\0');
assert(!bs_new->blk);
assert(QLIST_EMPTY(&bs_new->dirty_bitmaps));
assert(bs_new->job == NULL);
assert(bs_new->dev == NULL);
@ -2073,8 +2076,9 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
bdrv_move_feature_fields(bs_old, bs_new);
bdrv_move_feature_fields(bs_new, &tmp);
/* bs_new shouldn't be in bdrv_states even after the swap! */
/* bs_new must remain nameless and unattached */
assert(bs_new->device_name[0] == '\0');
assert(!bs_new->blk);
/* Check a few fields that should remain attached to the device */
assert(bs_new->dev == NULL);
@ -2101,7 +2105,7 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
* 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 is required to be anonymous.
* bs_new must be nameless and not attached to a BlockBackend.
*
* This function does not create any image files.
*/

71
block/block-backend.c
View file

@ -16,10 +16,11 @@
struct BlockBackend {
char *name;
int refcnt;
BlockDriverState *bs;
QTAILQ_ENTRY(BlockBackend) link; /* for blk_backends */
};
/* All the BlockBackends */
/* All the BlockBackends (except for hidden ones) */
static QTAILQ_HEAD(, BlockBackend) blk_backends =
QTAILQ_HEAD_INITIALIZER(blk_backends);
@ -47,10 +48,44 @@ BlockBackend *blk_new(const char *name, Error **errp)
return blk;
}
/*
* Create a new BlockBackend with a new BlockDriverState attached.
* Both have a reference count of one. Caller owns *both* references.
* TODO Let caller own only the BlockBackend reference
* Otherwise just like blk_new(), which see.
*/
BlockBackend *blk_new_with_bs(const char *name, Error **errp)
{
BlockBackend *blk;
BlockDriverState *bs;
blk = blk_new(name, errp);
if (!blk) {
return NULL;
}
bs = bdrv_new_root(name, errp);
if (!bs) {
blk_unref(blk);
return NULL;
}
blk->bs = bs;
bs->blk = blk;
return blk;
}
static void blk_delete(BlockBackend *blk)
{
assert(!blk->refcnt);
QTAILQ_REMOVE(&blk_backends, blk, link);
if (blk->bs) {
blk->bs->blk = NULL;
blk->bs = NULL;
}
/* Avoid double-remove after blk_hide_on_behalf_of_do_drive_del() */
if (blk->name[0]) {
QTAILQ_REMOVE(&blk_backends, blk, link);
}
g_free(blk->name);
g_free(blk);
}
@ -68,6 +103,8 @@ void blk_ref(BlockBackend *blk)
* Decrement @blk's reference count.
* If this drops it to zero, destroy @blk.
* For convenience, do nothing if @blk is null.
* Does *not* touch the attached BlockDriverState's reference count.
* TODO Decrement it!
*/
void blk_unref(BlockBackend *blk)
{
@ -95,7 +132,9 @@ BlockBackend *blk_next(BlockBackend *blk)
}
/*
* Return @blk's name, a non-null, non-empty string.
* Return @blk's name, a non-null string.
* Wart: the name is empty iff @blk has been hidden with
* blk_hide_on_behalf_of_do_drive_del().
*/
const char *blk_name(BlockBackend *blk)
{
@ -118,3 +157,29 @@ BlockBackend *blk_by_name(const char *name)
}
return NULL;
}
/*
* Return the BlockDriverState attached to @blk if any, else null.
*/
BlockDriverState *blk_bs(BlockBackend *blk)
{
return blk->bs;
}
/*
* Hide @blk.
* @blk must not have been hidden already.
* Make attached BlockDriverState, if any, anonymous.
* Once hidden, @blk is invisible to all functions that don't receive
* it as argument. For example, blk_by_name() won't return it.
* Strictly for use by do_drive_del().
* TODO get rid of it!
*/
void blk_hide_on_behalf_of_do_drive_del(BlockBackend *blk)
{
QTAILQ_REMOVE(&blk_backends, blk, link);
blk->name[0] = 0;
if (blk->bs) {
bdrv_make_anon(blk->bs);
}
}

19
blockdev.c
View file

@ -279,7 +279,7 @@ static void bdrv_format_print(void *opaque, const char *name)
void drive_del(DriveInfo *dinfo)
{
BlockBackend *blk = blk_by_name(dinfo->id);
BlockBackend *blk = dinfo->bdrv->blk;
bdrv_unref(dinfo->bdrv);
blk_unref(blk);
@ -528,14 +528,11 @@ static DriveInfo *blockdev_init(const char *file, QDict *bs_opts,
}
/* init */
blk = blk_new(qemu_opts_id(opts), errp);
blk = blk_new_with_bs(qemu_opts_id(opts), errp);
if (!blk) {
goto early_err;
}
bs = bdrv_new_root(qemu_opts_id(opts), errp);
if (!bs) {
goto bdrv_new_err;
}
bs = blk_bs(blk);
bs->open_flags = snapshot ? BDRV_O_SNAPSHOT : 0;
bs->read_only = ro;
bs->detect_zeroes = detect_zeroes;
@ -600,7 +597,6 @@ static DriveInfo *blockdev_init(const char *file, QDict *bs_opts,
err:
bdrv_unref(bs);
bdrv_new_err:
blk_unref(blk);
early_err:
qemu_opts_del(opts);
@ -1840,16 +1836,18 @@ void qmp_block_set_io_throttle(const char *device, int64_t bps, int64_t bps_rd,
int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data)
{
const char *id = qdict_get_str(qdict, "id");
BlockBackend *blk;
BlockDriverState *bs;
DriveInfo *dinfo;
AioContext *aio_context;
Error *local_err = NULL;
bs = bdrv_find(id);
if (!bs) {
blk = blk_by_name(id);
if (!blk) {
error_report("Device '%s' not found", id);
return -1;
}
bs = blk_bs(blk);
dinfo = drive_get_by_blockdev(bs);
if (dinfo && !dinfo->enable_auto_del) {
@ -1879,8 +1877,7 @@ int do_drive_del(Monitor *mon, const QDict *qdict, QObject **ret_data)
* then we can just get rid of the block driver state right here.
*/
if (bdrv_get_attached_dev(bs)) {
bdrv_make_anon(bs);
blk_hide_on_behalf_of_do_drive_del(blk);
/* Further I/O must not pause the guest */
bdrv_set_on_error(bs, BLOCKDEV_ON_ERROR_REPORT,
BLOCKDEV_ON_ERROR_REPORT);

8
hw/block/xen_disk.c
View file

@ -860,15 +860,11 @@ static int blk_connect(struct XenDevice *xendev)
/* setup via xenbus -> create new block driver instance */
xen_be_printf(&blkdev->xendev, 2, "create new bdrv (xenbus setup)\n");
blk = blk_new(blkdev->dev, NULL);
blk = blk_new_with_bs(blkdev->dev, NULL);
if (!blk) {
return -1;
}
blkdev->bs = bdrv_new_root(blkdev->dev, NULL);
if (!blkdev->bs) {
blk_unref(blk);
return -1;
}
blkdev->bs = blk_bs(blk);
drv = bdrv_find_whitelisted_format(blkdev->fileproto, readonly);
if (bdrv_open(&blkdev->bs, blkdev->filename, NULL, NULL, qflags,

2
include/block/block_int.h
View file

@ -324,6 +324,8 @@ struct BlockDriverState {
BlockDriver *drv; /* NULL means no media */
void *opaque;
BlockBackend *blk; /* owning backend, if any */
void *dev; /* attached device model, if any */
/* TODO change to DeviceState when all users are qdevified */
const BlockDevOps *dev_ops;

5
include/sysemu/block-backend.h
View file

@ -17,10 +17,15 @@
#include "qapi/error.h"
BlockBackend *blk_new(const char *name, Error **errp);
BlockBackend *blk_new_with_bs(const char *name, Error **errp);
void blk_ref(BlockBackend *blk);
void blk_unref(BlockBackend *blk);
const char *blk_name(BlockBackend *blk);
BlockBackend *blk_by_name(const char *name);
BlockBackend *blk_next(BlockBackend *blk);
BlockDriverState *blk_bs(BlockBackend *blk);
void blk_hide_on_behalf_of_do_drive_del(BlockBackend *blk);
#endif

131
qemu-img.c
View file

@ -284,20 +284,19 @@ static int print_block_option_help(const char *filename, const char *fmt)
return 0;
}
static BlockDriverState *bdrv_new_open(const char *id,
const char *filename,
const char *fmt,
int flags,
bool require_io,
bool quiet)
static BlockBackend *img_open(const char *id, const char *filename,
const char *fmt, int flags,
bool require_io, bool quiet)
{
BlockBackend *blk;
BlockDriverState *bs;
BlockDriver *drv;
char password[256];
Error *local_err = NULL;
int ret;
bs = bdrv_new_root(id, &error_abort);
blk = blk_new_with_bs(id, &error_abort);
bs = blk_bs(blk);
if (fmt) {
drv = bdrv_find_format(fmt);
@ -328,9 +327,10 @@ static BlockDriverState *bdrv_new_open(const char *id,
goto fail;
}
}
return bs;
return blk;
fail:
bdrv_unref(bs);
blk_unref(blk);
return NULL;
}
@ -580,7 +580,7 @@ static int img_check(int argc, char **argv)
BlockDriverState *bs;
int fix = 0;
int flags = BDRV_O_FLAGS | BDRV_O_CHECK;
ImageCheck *check = NULL;
ImageCheck *check;
bool quiet = false;
fmt = NULL;
@ -651,12 +651,11 @@ static int img_check(int argc, char **argv)
return 1;
}
blk = blk_new("image", &error_abort);
bs = bdrv_new_open("image", filename, fmt, flags, true, quiet);
if (!bs) {
ret = 1;
goto fail;
blk = img_open("image", filename, fmt, flags, true, quiet);
if (!blk) {
return 1;
}
bs = blk_bs(blk);
check = g_new0(ImageCheck, 1);
ret = collect_image_check(bs, check, filename, fmt, fix);
@ -762,12 +761,12 @@ static int img_commit(int argc, char **argv)
return 1;
}
blk = blk_new("image", &error_abort);
bs = bdrv_new_open("image", filename, fmt, flags, true, quiet);
if (!bs) {
ret = -1;
goto out;
blk = img_open("image", filename, fmt, flags, true, quiet);
if (!blk) {
return 1;
}
bs = blk_bs(blk);
ret = bdrv_commit(bs);
switch(ret) {
case 0:
@ -787,7 +786,6 @@ static int img_commit(int argc, char **argv)
break;
}
out:
bdrv_unref(bs);
blk_unref(blk);
if (ret) {
@ -1022,21 +1020,21 @@ static int img_compare(int argc, char **argv)
goto out3;
}
blk1 = blk_new("image_1", &error_abort);
bs1 = bdrv_new_open("image_1", filename1, fmt1, flags, true, quiet);
if (!bs1) {
blk1 = img_open("image_1", filename1, fmt1, flags, true, quiet);
if (!blk1) {
error_report("Can't open file %s", filename1);
ret = 2;
goto out3;
}
bs1 = blk_bs(blk1);
blk2 = img_open("image_2", filename2, fmt2, flags, true, quiet);
if (!blk2) {
error_report("Can't open file %s", filename2);
ret = 2;
goto out2;
}
blk2 = blk_new("image_2", &error_abort);
bs2 = bdrv_new_open("image_2", filename2, fmt2, flags, true, quiet);
if (!bs2) {
error_report("Can't open file %s", filename2);
ret = 2;
goto out1;
}
bs2 = blk_bs(blk2);
buf1 = qemu_blockalign(bs1, IO_BUF_SIZE);
buf2 = qemu_blockalign(bs2, IO_BUF_SIZE);
@ -1198,7 +1196,6 @@ static int img_compare(int argc, char **argv)
out:
qemu_vfree(buf1);
qemu_vfree(buf2);
out1:
bdrv_unref(bs2);
blk_unref(blk2);
out2:
@ -1379,15 +1376,15 @@ static int img_convert(int argc, char **argv)
for (bs_i = 0; bs_i < bs_n; bs_i++) {
char *id = bs_n > 1 ? g_strdup_printf("source_%d", bs_i)
: g_strdup("source");
blk[bs_i] = blk_new(id, &error_abort);
bs[bs_i] = bdrv_new_open(id, argv[optind + bs_i], fmt, src_flags,
true, quiet);
blk[bs_i] = img_open(id, argv[optind + bs_i], fmt, src_flags,
true, quiet);
g_free(id);
if (!bs[bs_i]) {
if (!blk[bs_i]) {
error_report("Could not open '%s'", argv[optind + bs_i]);
ret = -1;
goto out;
}
bs[bs_i] = blk_bs(blk[bs_i]);
bs_sectors[bs_i] = bdrv_nb_sectors(bs[bs_i]);
if (bs_sectors[bs_i] < 0) {
error_report("Could not get size of %s: %s",
@ -1505,12 +1502,12 @@ static int img_convert(int argc, char **argv)
goto out;
}
out_blk = blk_new("target", &error_abort);
out_bs = bdrv_new_open("target", out_filename, out_fmt, flags, true, quiet);
if (!out_bs) {
out_blk = img_open("target", out_filename, out_fmt, flags, true, quiet);
if (!out_blk) {
ret = -1;
goto out;
}
out_bs = blk_bs(out_blk);
bs_i = 0;
bs_offset = 0;
@ -1895,13 +1892,12 @@ static ImageInfoList *collect_image_info_list(const char *filename,
}
g_hash_table_insert(filenames, (gpointer)filename, NULL);
blk = blk_new("image", &error_abort);
bs = bdrv_new_open("image", filename, fmt,
BDRV_O_FLAGS | BDRV_O_NO_BACKING, false, false);
if (!bs) {
blk_unref(blk);
blk = img_open("image", filename, fmt,
BDRV_O_FLAGS | BDRV_O_NO_BACKING, false, false);
if (!blk) {
goto err;
}
bs = blk_bs(blk);
bdrv_query_image_info(bs, &info, &err);
if (err) {
@ -2161,12 +2157,11 @@ static int img_map(int argc, char **argv)
return 1;
}
blk = blk_new("image", &error_abort);
bs = bdrv_new_open("image", filename, fmt, BDRV_O_FLAGS, true, false);
if (!bs) {
ret = -1;
goto out;
blk = img_open("image", filename, fmt, BDRV_O_FLAGS, true, false);
if (!blk) {
return 1;
}
bs = blk_bs(blk);
if (output_format == OFORMAT_HUMAN) {
printf("%-16s%-16s%-16s%s\n", "Offset", "Length", "Mapped to", "File");
@ -2285,12 +2280,11 @@ static int img_snapshot(int argc, char **argv)
filename = argv[optind++];
/* Open the image */
blk = blk_new("image", &error_abort);
bs = bdrv_new_open("image", filename, NULL, bdrv_oflags, true, quiet);
if (!bs) {
ret = -1;
goto out;
blk = img_open("image", filename, NULL, bdrv_oflags, true, quiet);
if (!blk) {
return 1;
}
bs = blk_bs(blk);
/* Perform the requested action */
switch(action) {
@ -2333,7 +2327,6 @@ static int img_snapshot(int argc, char **argv)
}
/* Cleanup */
out:
bdrv_unref(bs);
blk_unref(blk);
if (ret) {
@ -2433,12 +2426,12 @@ static int img_rebase(int argc, char **argv)
* Ignore the old backing file for unsafe rebase in case we want to correct
* the reference to a renamed or moved backing file.
*/
blk = blk_new("image", &error_abort);
bs = bdrv_new_open("image", filename, fmt, flags, true, quiet);
if (!bs) {
blk = img_open("image", filename, fmt, flags, true, quiet);
if (!blk) {
ret = -1;
goto out;
}
bs = blk_bs(blk);
/* Find the right drivers for the backing files */
old_backing_drv = NULL;
@ -2466,8 +2459,8 @@ static int img_rebase(int argc, char **argv)
if (!unsafe) {
char backing_name[1024];
blk_old_backing = blk_new("old_backing", &error_abort);
bs_old_backing = bdrv_new_root("old_backing", &error_abort);
blk_old_backing = blk_new_with_bs("old_backing", &error_abort);
bs_old_backing = blk_bs(blk_old_backing);
bdrv_get_backing_filename(bs, backing_name, sizeof(backing_name));
ret = bdrv_open(&bs_old_backing, backing_name, NULL, NULL, src_flags,
old_backing_drv, &local_err);
@ -2478,8 +2471,8 @@ static int img_rebase(int argc, char **argv)
goto out;
}
if (out_baseimg[0]) {
blk_new_backing = blk_new("new_backing", &error_abort);
bs_new_backing = bdrv_new_root("new_backing", &error_abort);
blk_new_backing = blk_new_with_bs("new_backing", &error_abort);
bs_new_backing = blk_bs(blk_new_backing);
ret = bdrv_open(&bs_new_backing, out_baseimg, NULL, NULL, src_flags,
new_backing_drv, &local_err);
if (ret) {
@ -2755,13 +2748,13 @@ static int img_resize(int argc, char **argv)
n = qemu_opt_get_size(param, BLOCK_OPT_SIZE, 0);
qemu_opts_del(param);
blk = blk_new("image", &error_abort);
bs = bdrv_new_open("image", filename, fmt, BDRV_O_FLAGS | BDRV_O_RDWR,
true, quiet);
if (!bs) {
blk = img_open("image", filename, fmt, BDRV_O_FLAGS | BDRV_O_RDWR,
true, quiet);
if (!blk) {
ret = -1;
goto out;
}
bs = blk_bs(blk);
if (relative) {
total_size = bdrv_getlength(bs) + n * relative;
@ -2873,13 +2866,13 @@ static int img_amend(int argc, char **argv)
goto out;
}
blk = blk_new("image", &error_abort);
bs = bdrv_new_open("image", filename, fmt, flags, true, quiet);
if (!bs) {
blk = img_open("image", filename, fmt, flags, true, quiet);
if (!blk) {
error_report("Could not open image '%s'", filename);
ret = -1;
goto out;
}
bs = blk_bs(blk);
fmt = bs->drv->format_name;

4
qemu-io.c
View file

@ -62,8 +62,8 @@ static int openfile(char *name, int flags, int growable, QDict *opts)
return 1;
}
qemuio_blk = blk_new("hda", &error_abort);
qemuio_bs = bdrv_new_root("hda", &error_abort);
qemuio_blk = blk_new_with_bs("hda", &error_abort);
qemuio_bs = blk_bs(qemuio_blk);
if (growable) {
flags |= BDRV_O_PROTOCOL;

4
qemu-nbd.c
View file

@ -692,8 +692,8 @@ int main(int argc, char **argv)
drv = NULL;
}
blk = blk_new("hda", &error_abort);
bs = bdrv_new_root("hda", &error_abort);
blk = blk_new_with_bs("hda", &error_abort);
bs = blk_bs(blk);
srcpath = argv[optind];
ret = bdrv_open(&bs, srcpath, NULL, NULL, flags, drv, &local_err);