dm: fix REQ_RAHEAD handling

A few (but not all) dm targets use a special EWOULDBLOCK error code for
failing REQ_RAHEAD requests that fail due to a lack of available resources.
But no one else knows about this magic code, and lower level drivers also
don't generate it when failing read-ahead requests for similar reasons.

So remove this special casing and ignore all additional error handling for
REQ_RAHEAD - if this was a real underlying error we'd get a normal read
once the real read comes in.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <Bart.VanAssche@sandisk.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index a95cbb80fb34444144bad346b3e769c625e8c788..5e30b08b91d9e70d4fb6edf4928cca61e62ad64d 100644 (file)
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -1214,7 +1214,7 @@ static int mirror_map(struct dm_target *ti, struct bio *bio)
         */
        if (!r || (r == -EWOULDBLOCK)) {
                if (bio->bi_opf & REQ_RAHEAD)
-                       return -EWOULDBLOCK;
+                       return -EIO;
 
                queue_bio(ms, bio, rw);
                return DM_MAPIO_SUBMITTED;
@@ -1258,7 +1258,7 @@ static int mirror_end_io(struct dm_target *ti, struct bio *bio, int error)
        if (error == -EOPNOTSUPP)
                return error;
 
-       if ((error == -EWOULDBLOCK) && (bio->bi_opf & REQ_RAHEAD))
+       if (bio->bi_opf & REQ_RAHEAD)
                return error;
 
        if (unlikely(error)) {

diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 75152482f3ad068b71e17001129903c091a5628d..780e95889a7c425dcb20bf21947f408967b27ad0 100644 (file)
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -384,7 +384,7 @@ static int stripe_end_io(struct dm_target *ti, struct bio *bio, int error)
        if (!error)
                return 0; /* I/O complete */
 
-       if ((error == -EWOULDBLOCK) && (bio->bi_opf & REQ_RAHEAD))
+       if (bio->bi_opf & REQ_RAHEAD)
                return error;
 
        if (error == -EOPNOTSUPP)