dm: fix REQ_RAHEAD handling (9966afaf) · Commits · 戴 / test

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>

drivers/md/dm-raid1.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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)) {

drivers/md/dm-stripe.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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)

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