[RFC PATCH] block: all callers should check blkdev_issue_flush's return

[Mike Snitzer <snitzer@redhat.com>]

It is concerning that a FLUSH may fail but the blkdev_issue_flush
callers assume it will always succeed.

Each blkdev_issue_flush caller should come to terms with the reality
that a FLUSH may fail -- the file_operations' .fsync methods in
particular.  nilfs2 is the only filesystem that checks
blkdev_issue_flush's return.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---
 include/linux/blkdev.h |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index ba43f40..76d6e48 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -968,7 +968,7 @@ static inline struct request *blk_map_queue_find_tag(struct blk_queue_tag *bqt,
 
 #define BLKDEV_DISCARD_SECURE  0x01    /* secure discard */
 
-extern int blkdev_issue_flush(struct block_device *, gfp_t, sector_t *);
+extern int __must_check blkdev_issue_flush(struct block_device *, gfp_t, sector_t *);
 extern int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp_mask, unsigned long flags);
 extern int blkdev_issue_zeroout(struct block_device *bdev, sector_t sector,
-- 
1.7.1