[PATCH 4.19 047/134] btrfs: dont report readahead errors and dont update statistics

[Greg Kroah-Hartman]

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

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

From: David Sterba <dsterba@xxxxxxxx>

commit 0cc068e6ee59c1fffbfa977d8bf868b7551d80ac upstream.

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 ("btrfs: readpages() should submit IO as read-ahead") 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@xxxxxxxxxxxxxxxxxxx>
Fixes: 5e9d398240b2 ("btrfs: readpages() should submit IO as read-ahead")
CC: stable@xxxxxxxxxxxxxxx # 4.19+
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/btrfs/volumes.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6051,7 +6051,7 @@ static void btrfs_end_bio(struct bio *bi
 				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)