[ 11/52] bcache: Fix flushes in writeback mode

[Greg Kroah-Hartman]

3.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kent Overstreet <kmo@xxxxxxxxxxxxx>

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@xxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/md/bcache/request.c |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -1056,14 +1056,17 @@ static void request_write(struct cached_
 		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;
 		}


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/