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author | Kevin Wolf <kwolf@redhat.com> | 2018-03-22 14:35:58 +0100 |
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committer | Kevin Wolf <kwolf@redhat.com> | 2018-06-18 15:03:25 +0200 |
commit | d30b8e64b7b282da785307504ada59efa8096fb1 (patch) | |
tree | 90efda3f69182288751288ef62431b28c59e0988 /block | |
parent | 89bd030533e3592ca0a995450dcfc5d53e459e20 (diff) | |
download | qemu-d30b8e64b7b282da785307504ada59efa8096fb1.zip qemu-d30b8e64b7b282da785307504ada59efa8096fb1.tar.gz qemu-d30b8e64b7b282da785307504ada59efa8096fb1.tar.bz2 |
block: Remove bdrv_drain_recurse()
For bdrv_drain(), recursively waiting for child node requests is
pointless because we didn't quiesce their parents, so new requests could
come in anyway. Letting the function work only on a single node makes it
more consistent.
For subtree drains and drain_all, we already have the recursion in
bdrv_do_drained_begin(), so the extra recursion doesn't add anything
either.
Remove the useless code.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Diffstat (limited to 'block')
-rw-r--r-- | block/io.c | 36 |
1 files changed, 3 insertions, 33 deletions
@@ -219,38 +219,6 @@ static bool bdrv_drain_poll_top_level(BlockDriverState *bs, return bdrv_drain_poll(bs, ignore_parent); } -static bool bdrv_drain_recurse(BlockDriverState *bs, BdrvChild *parent) -{ - BdrvChild *child, *tmp; - bool waited; - - /* Wait for drained requests to finish */ - waited = BDRV_POLL_WHILE(bs, bdrv_drain_poll_top_level(bs, parent)); - - QLIST_FOREACH_SAFE(child, &bs->children, next, tmp) { - BlockDriverState *bs = child->bs; - bool in_main_loop = - qemu_get_current_aio_context() == qemu_get_aio_context(); - assert(bs->refcnt > 0); - if (in_main_loop) { - /* In case the recursive bdrv_drain_recurse processes a - * block_job_defer_to_main_loop BH and modifies the graph, - * let's hold a reference to bs until we are done. - * - * IOThread doesn't have such a BH, and it is not safe to call - * bdrv_unref without BQL, so skip doing it there. - */ - bdrv_ref(bs); - } - waited |= bdrv_drain_recurse(bs, child); - if (in_main_loop) { - bdrv_unref(bs); - } - } - - return waited; -} - static void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive, BdrvChild *parent); static void bdrv_do_drained_end(BlockDriverState *bs, bool recursive, @@ -318,7 +286,9 @@ void bdrv_do_drained_begin(BlockDriverState *bs, bool recursive, bdrv_parent_drained_begin(bs, parent); bdrv_drain_invoke(bs, true); - bdrv_drain_recurse(bs, parent); + + /* Wait for drained requests to finish */ + BDRV_POLL_WHILE(bs, bdrv_drain_poll_top_level(bs, parent)); if (recursive) { bs->recursive_quiesce_counter++; |