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block: Flush all children in generic code 

If the driver does not support .bdrv_co_flush() so bdrv_co_flush()
itself has to flush the children of the given node, it should not flush
just bs->file->bs, but in fact all children that might have been written
to (judging from the permissions taken on them).

This is a bug fix for qcow2 images with an external data file, as they
so far did not flush that data_file node.

In any case, the BLKDBG_EVENT() should be emitted on the primary child,
because that is where a blkdebug node would be if there is any.

Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Andrey Shinkevich <andrey.shinkevich@virtuozzo.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Max Reitz 2019-06-12 18:18:05 +02:00 committed by Kevin Wolf
parent 1d42f48c3a
commit 883833e29c
1 changed files with 17 additions and 6 deletions
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23
block/io.c
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@ -2771,6 +2771,8 @@ static int coroutine_fn bdrv_flush_co_entry(void *opaque)
int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
{
BdrvChild *primary_child = bdrv_primary_child(bs);
BdrvChild *child;
int current_gen;
int ret = 0;
@ -2800,7 +2802,7 @@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
}
/* Write back cached data to the OS even with cache=unsafe */
BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_OS);
BLKDBG_EVENT(primary_child, BLKDBG_FLUSH_TO_OS);
if (bs->drv->bdrv_co_flush_to_os) {
ret = bs->drv->bdrv_co_flush_to_os(bs);
if (ret < 0) {
@ -2810,15 +2812,15 @@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
/* But don't actually force it to the disk with cache=unsafe */
if (bs->open_flags & BDRV_O_NO_FLUSH) {
goto flush_parent;
goto flush_children;
}
/* Check if we really need to flush anything */
if (bs->flushed_gen == current_gen) {
goto flush_parent;
goto flush_children;
}
BLKDBG_EVENT(bs->file, BLKDBG_FLUSH_TO_DISK);
BLKDBG_EVENT(primary_child, BLKDBG_FLUSH_TO_DISK);
if (!bs->drv) {
/* bs->drv->bdrv_co_flush() might have ejected the BDS
* (even in case of apparent success) */
@ -2862,8 +2864,17 @@ int coroutine_fn bdrv_co_flush(BlockDriverState *bs)
/* Now flush the underlying protocol. It will also have BDRV_O_NO_FLUSH
* in the case of cache=unsafe, so there are no useless flushes.
*/
flush_parent:
ret = bs->file ? bdrv_co_flush(bs->file->bs) : 0;
flush_children:
ret = 0;
QLIST_FOREACH(child, &bs->children, next) {
if (child->perm & (BLK_PERM_WRITE | BLK_PERM_WRITE_UNCHANGED)) {
int this_child_ret = bdrv_co_flush(child->bs);
if (!ret) {
ret = this_child_ret;
}
}
}
out:
/* Notify any pending flushes that we have completed */
if (ret == 0) {