bcache: Fix flushes in writeback mode
commit c0f04d88e46d14de51f4baebb6efafb7d59e9f96 upstream.
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@daterainc.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index afb9a99..2fe37fa 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -1056,14 +1056,17 @@
trace_bcache_writeback(s->orig_bio);
bch_writeback_add(dc, bio_sectors(bio));
- 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;
}