md: raid1/raid10: fix problem with merge_bvec_fn

The new merge_bvec_fn which calls the corresponding function
in subsidiary devices requires that mddev->merge_check_needed
be set if any child has a merge_bvec_fn.

However were were only setting that when a device was hot-added,
not when a device was present from the start.

This bug was introduced in 3.4 so patch is suitable for 3.4.y
kernels.  However that are conflicts in raid10.c so a separate
patch will be needed for 3.4.y.

Cc: stable@vger.kernel.org
Reported-by: Sebastian Riemer <sebastian.riemer@profitbricks.com>
Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 835de71..a9c7981 100644 (file)
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -2550,6 +2550,7 @@ static struct r1conf *setup_conf(struct mddev *mddev)
        err = -EINVAL;
        spin_lock_init(&conf->device_lock);
        rdev_for_each(rdev, mddev) {
+               struct request_queue *q;
                int disk_idx = rdev->raid_disk;
                if (disk_idx >= mddev->raid_disks
                    || disk_idx < 0)
@@ -2562,6 +2563,9 @@ static struct r1conf *setup_conf(struct mddev *mddev)
                if (disk->rdev)
                        goto abort;
                disk->rdev = rdev;
+               q = bdev_get_queue(rdev->bdev);
+               if (q->merge_bvec_fn)
+                       mddev->merge_check_needed = 1;
 
                disk->head_position = 0;
        }

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 987db37..99ae606 100644 (file)
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3475,6 +3475,7 @@ static int run(struct mddev *mddev)
 
        rdev_for_each(rdev, mddev) {
                long long diff;
+               struct request_queue *q;
 
                disk_idx = rdev->raid_disk;
                if (disk_idx < 0)
@@ -3493,6 +3494,9 @@ static int run(struct mddev *mddev)
                                goto out_free_conf;
                        disk->rdev = rdev;
                }
+               q = bdev_get_queue(rdev->bdev);
+               if (q->merge_bvec_fn)
+                       mddev->merge_check_needed = 1;
                diff = (rdev->new_data_offset - rdev->data_offset);
                if (!mddev->reshape_backwards)
                        diff = -diff;