In writeback mode, when we get a cache flush we need to make sure we
issue a flush to the backing device.
The code for sending down an extra flush was wrong - by cloning the bio
we were probably getting flags that didn't make sense for a bare flush,
and also the old code was firing for FUA bios, for which we don't need
to send a flush to the backing device.
This was causing data corruption somehow - the mechanism was never
determined, but this patch fixes it for the users that were seeing it.
Signed-off-by: Kent Overstreet <kmo@xxxxxxxxxxxxx>
Cc: linux-stable <stable@xxxxxxxxxxxxxxx> # >= v3.10
---
drivers/md/bcache/request.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 786a1a4..71eb233 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -997,14 +997,17 @@ static void request_write(struct cached_dev *dc, struct search *s)
} else {
bch_writeback_add(dc);
- if (s->op.flush_journal) {
+ if (bio->bi_rw & REQ_FLUSH) {
/* Also need to send a flush to the backing device */
- s->op.cache_bio = bio_clone_bioset(bio, GFP_NOIO,
- dc->disk.bio_split);
+ struct bio *flush = bio_alloc_bioset(0, GFP_NOIO,
+ dc->disk.bio_split);
- bio->bi_size = 0;
- bio->bi_vcnt = 0;
- closure_bio_submit(bio, cl, s->d);
+ flush->bi_rw = WRITE_FLUSH;
+ flush->bi_bdev = bio->bi_bdev;
+ flush->bi_end_io = request_endio;
+ flush->bi_private = cl;
+
+ closure_bio_submit(flush, cl, s->d);
} else {
s->op.cache_bio = bio;
}
--
1.8.4.rc3
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