[ 083/104] MD: ignore discard request for hard disks of hybid raid1/raid10 array

[Greg Kroah-Hartman]

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

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

From: Shaohua Li <shli@xxxxxxxxxx>

commit 32f9f570d04461a41bdcd5c1d93b41ebc5ce182a upstream.

In SSD/hard disk hybid storage, discard request should be ignored for hard
disk. We used to be doing this way, but the unplug path forgets it.

This is suitable for stable tree since v3.6.

Reported-and-tested-by: Markus <M4rkusXXL@xxxxxx>
Signed-off-by: Shaohua Li <shli@xxxxxxxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/md/raid1.c  |    7 ++++++-
 drivers/md/raid10.c |    7 ++++++-
 2 files changed, 12 insertions(+), 2 deletions(-)

--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -981,7 +981,12 @@ static void raid1_unplug(struct blk_plug
 	while (bio) { /* submit pending writes */
 		struct bio *next = bio->bi_next;
 		bio->bi_next = NULL;
-		generic_make_request(bio);
+		if (unlikely((bio->bi_rw & REQ_DISCARD) &&
+		    !blk_queue_discard(bdev_get_queue(bio->bi_bdev))))
+			/* Just ignore it */
+			bio_endio(bio, 0);
+		else
+			generic_make_request(bio);
 		bio = next;
 	}
 	kfree(plug);
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1087,7 +1087,12 @@ static void raid10_unplug(struct blk_plu
 	while (bio) { /* submit pending writes */
 		struct bio *next = bio->bi_next;
 		bio->bi_next = NULL;
-		generic_make_request(bio);
+		if (unlikely((bio->bi_rw & REQ_DISCARD) &&
+		    !blk_queue_discard(bdev_get_queue(bio->bi_bdev))))
+			/* Just ignore it */
+			bio_endio(bio, 0);
+		else
+			generic_make_request(bio);
 		bio = next;
 	}
 	kfree(plug);


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