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block: Add backing_blocker in BlockDriverState

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This makes use of op_blocker and blocks all the operations except for
commit target, on each BlockDriverState->backing_hd.

The asserts for op_blocker in bdrv_swap are removed because with this
change, the target of block commit has at least the backing blocker of
its child, so the assertion is not true. Callers should do their check.

Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Fam Zheng 2014-05-23 21:29:47 +08:00 • committed by Stefan Hajnoczi
parent 920beae103
commit 826b6ca0b0
3 changed files with 23 additions and 5 deletions
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23
block.c
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@ -1097,14 +1097,30 @@ fail:
void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd)
{
if (bs->backing_hd) {
assert(bs->backing_blocker);
bdrv_op_unblock_all(bs->backing_hd, bs->backing_blocker);
} else if (backing_hd) {
error_setg(&bs->backing_blocker,
"device is used as backing hd of '%s'",
bs->device_name);
}
bs->backing_hd = backing_hd;
if (!backing_hd) {
error_free(bs->backing_blocker);
bs->backing_blocker = NULL;
goto out;
}
bs->open_flags &= ~BDRV_O_NO_BACKING;
pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_hd->filename);
pstrcpy(bs->backing_format, sizeof(bs->backing_format),
backing_hd->drv ? backing_hd->drv->format_name : "");
bdrv_op_block_all(bs->backing_hd, bs->backing_blocker);
/* Otherwise we won't be able to commit due to check in bdrv_commit */
bdrv_op_unblock(bs->backing_hd, BLOCK_OP_TYPE_COMMIT,
bs->backing_blocker);
out:
bdrv_refresh_limits(bs);
}
@ -1803,8 +1819,9 @@ void bdrv_close(BlockDriverState *bs)
if (bs->drv) {
if (bs->backing_hd) {
bdrv_unref(bs->backing_hd);
bs->backing_hd = NULL;
BlockDriverState *backing_hd = bs->backing_hd;
bdrv_set_backing_hd(bs, NULL);
bdrv_unref(backing_hd);
}
bs->drv->bdrv_close(bs);
g_free(bs->opaque);
@ -2006,7 +2023,6 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
assert(QLIST_EMPTY(&bs_new->dirty_bitmaps));
assert(bs_new->job == NULL);
assert(bs_new->dev == NULL);
assert(bdrv_op_blocker_is_empty(bs_new));
assert(bs_new->io_limits_enabled == false);
assert(!throttle_have_timer(&bs_new->throttle_state));
@ -2025,7 +2041,6 @@ void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old)
/* Check a few fields that should remain attached to the device */
assert(bs_new->dev == NULL);
assert(bs_new->job == NULL);
assert(bdrv_op_blocker_is_empty(bs_new));
assert(bs_new->io_limits_enabled == false);
assert(!throttle_have_timer(&bs_new->throttle_state));