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authorMax Reitz <mreitz@redhat.com>2016-04-20 00:59:47 +0200
committerKevin Wolf <kwolf@redhat.com>2016-04-20 16:52:55 +0200
commit9c83625bdd3c1900d304058ece152040ef5d1ead (patch)
tree5e9e0b0ac950fd5c988096721ba1567cc752e38a
parent4113b0532da6c448f8e458b413ebde035234d0ea (diff)
downloadqemu-9c83625bdd3c1900d304058ece152040ef5d1ead.tar.gz
block/mirror: Revive dead yielding code
mirror_iteration() is supposed to wait if the current chunk is subject to a still in-flight mirroring operation. However, it mixed checking this conflict situation with checking the dirty status of a chunk. A simplification for the latter condition (the first chunk encountered is always dirty) led to neglecting the former: We just skip the first chunk and thus never test whether it conflicts with an in-flight operation. To fix this, pull out the code which waits for in-flight operations on the first chunk of the range to be mirrored to settle. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
-rw-r--r--block/mirror.c23
1 files changed, 12 insertions, 11 deletions
diff --git a/block/mirror.c b/block/mirror.c
index c2cfc1a5ef..2714a77d69 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -298,7 +298,7 @@ static void mirror_do_zero_or_discard(MirrorBlockJob *s,
static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
{
BlockDriverState *source = s->common.bs;
- int64_t sector_num;
+ int64_t sector_num, first_chunk;
uint64_t delay_ns = 0;
/* At least the first dirty chunk is mirrored in one iteration. */
int nb_chunks = 1;
@@ -313,6 +313,12 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
assert(sector_num >= 0);
}
+ first_chunk = sector_num / sectors_per_chunk;
+ while (test_bit(first_chunk, s->in_flight_bitmap)) {
+ trace_mirror_yield_in_flight(s, first_chunk, s->in_flight);
+ mirror_wait_for_io(s);
+ }
+
/* Find the number of consective dirty chunks following the first dirty
* one, and wait for in flight requests in them. */
while (nb_chunks * sectors_per_chunk < (s->buf_size >> BDRV_SECTOR_BITS)) {
@@ -324,17 +330,12 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
break;
}
if (test_bit(next_chunk, s->in_flight_bitmap)) {
- if (nb_chunks > 0) {
- break;
- }
- trace_mirror_yield_in_flight(s, next_sector, s->in_flight);
- mirror_wait_for_io(s);
- /* Now retry. */
- } else {
- hbitmap_next = hbitmap_iter_next(&s->hbi);
- assert(hbitmap_next == next_sector);
- nb_chunks++;
+ break;
}
+
+ hbitmap_next = hbitmap_iter_next(&s->hbi);
+ assert(hbitmap_next == next_sector);
+ nb_chunks++;
}
/* Clear dirty bits before querying the block status, because