[PATCH] btrfs: don't report readahead errors and don't update statistics

[David Sterba <dsterba@suse.com>]

As readahead is an optimization, all errors are usually filtered out,
but still properly handled when the real read call is done. The commit
5e9d398240b2 added REQ_RAHEAD to readpages() because that's only used
for readahead (despite what one would expect from the callback name).

This causes a flood of messages and inflated read error stats, so skip
reporting in case it's readahead.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202403
Reported-by: LimeTech <tomm@lime-technology.com>
Fixes: 5e9d398240b2 ("btrfs: readpages() should submit IO as read-ahead")
CC: stable@vger.kernel.org # 4.19+
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/volumes.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 9024eee889b9..db934ceae9c1 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6407,7 +6407,7 @@ static void btrfs_end_bio(struct bio *bio)
 				if (bio_op(bio) == REQ_OP_WRITE)
 					btrfs_dev_stat_inc_and_print(dev,
 						BTRFS_DEV_STAT_WRITE_ERRS);
-				else
+				else if (!(bio->bi_opf & REQ_RAHEAD))
 					btrfs_dev_stat_inc_and_print(dev,
 						BTRFS_DEV_STAT_READ_ERRS);
 				if (bio->bi_opf & REQ_PREFLUSH)
-- 
2.20.1