md/raid0: update queue parameter in a safer location.

When a (e.g.) RAID5 array is reshaped to RAID0, the updating
of queue parameters (e.g. max number of sectors per bio) is
done in the wrong place.
It should be part of ->run, but it is actually part of ->takeover.
This means it happens before level_store() calls:

	blk_set_stacking_limits(&mddev->queue->limits);

and so it ineffective.  This can lead to errors from underlying
devices.

So move all the relevant settings out of create_stripe_zones()
and into raid0_run().

As this can lead to a bug-on it is suitable for any -stable
kernel which supports reshape to RAID0.  So 2.6.35 or later.
As the bug has been present for five years there is no urgency,
so no need to rush into -stable.

Fixes: 9af204cf720c ("md: Add support for Raid5->Raid0 and Raid10->Raid0 takeover")
Cc: stable@vger.kernel.org (v2.6.35+ - please delay until after -final release).
Reported-by: Yi Zhang <yizhan@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.com>

diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index efb654e..4a13c3c 100644 (file)
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -83,7 +83,7 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
        char b[BDEVNAME_SIZE];
        char b2[BDEVNAME_SIZE];
        struct r0conf *conf = kzalloc(sizeof(*conf), GFP_KERNEL);
-       bool discard_supported = false;
+       unsigned short blksize = 512;
 
        if (!conf)
                return -ENOMEM;
@@ -98,6 +98,9 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
                sector_div(sectors, mddev->chunk_sectors);
                rdev1->sectors = sectors * mddev->chunk_sectors;
 
+               blksize = max(blksize, queue_logical_block_size(
+                                     rdev1->bdev->bd_disk->queue));
+
                rdev_for_each(rdev2, mddev) {
                        pr_debug("md/raid0:%s:   comparing %s(%llu)"
                                 " with %s(%llu)\n",
@@ -134,6 +137,18 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
        }
        pr_debug("md/raid0:%s: FINAL %d zones\n",
                 mdname(mddev), conf->nr_strip_zones);
+       /*
+        * now since we have the hard sector sizes, we can make sure
+        * chunk size is a multiple of that sector size
+        */
+       if ((mddev->chunk_sectors << 9) % blksize) {
+               printk(KERN_ERR "md/raid0:%s: chunk_size of %d not multiple of block size %d\n",
+                      mdname(mddev),
+                      mddev->chunk_sectors << 9, blksize);
+               err = -EINVAL;
+               goto abort;
+       }
+
        err = -ENOMEM;
        conf->strip_zone = kzalloc(sizeof(struct strip_zone)*
                                conf->nr_strip_zones, GFP_KERNEL);
@@ -188,19 +203,12 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
                }
                dev[j] = rdev1;
 
-               if (mddev->queue)
-                       disk_stack_limits(mddev->gendisk, rdev1->bdev,
-                                         rdev1->data_offset << 9);
-
                if (rdev1->bdev->bd_disk->queue->merge_bvec_fn)
                        conf->has_merge_bvec = 1;
 
                if (!smallest || (rdev1->sectors < smallest->sectors))
                        smallest = rdev1;
                cnt++;
-
-               if (blk_queue_discard(bdev_get_queue(rdev1->bdev)))
-                       discard_supported = true;
        }
        if (cnt != mddev->raid_disks) {
                printk(KERN_ERR "md/raid0:%s: too few disks (%d of %d) - "
@@ -261,28 +269,6 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
                         (unsigned long long)smallest->sectors);
        }
 
-       /*
-        * now since we have the hard sector sizes, we can make sure
-        * chunk size is a multiple of that sector size
-        */
-       if ((mddev->chunk_sectors << 9) % queue_logical_block_size(mddev->queue)) {
-               printk(KERN_ERR "md/raid0:%s: chunk_size of %d not valid\n",
-                      mdname(mddev),
-                      mddev->chunk_sectors << 9);
-               goto abort;
-       }
-
-       if (mddev->queue) {
-               blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
-               blk_queue_io_opt(mddev->queue,
-                                (mddev->chunk_sectors << 9) * mddev->raid_disks);
-
-               if (!discard_supported)
-                       queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
-               else
-                       queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
-       }
-
        pr_debug("md/raid0:%s: done.\n", mdname(mddev));
        *private_conf = conf;
 
@@ -433,12 +419,6 @@ static int raid0_run(struct mddev *mddev)
        if (md_check_no_bitmap(mddev))
                return -EINVAL;
 
-       if (mddev->queue) {
-               blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
-               blk_queue_max_write_same_sectors(mddev->queue, mddev->chunk_sectors);
-               blk_queue_max_discard_sectors(mddev->queue, mddev->chunk_sectors);
-       }
-
        /* if private is not null, we are here after takeover */
        if (mddev->private == NULL) {
                ret = create_strip_zones(mddev, &conf);
@@ -447,6 +427,29 @@ static int raid0_run(struct mddev *mddev)
                mddev->private = conf;
        }
        conf = mddev->private;
+       if (mddev->queue) {
+               struct md_rdev *rdev;
+               bool discard_supported = false;
+
+               rdev_for_each(rdev, mddev) {
+                       disk_stack_limits(mddev->gendisk, rdev->bdev,
+                                         rdev->data_offset << 9);
+                       if (blk_queue_discard(bdev_get_queue(rdev->bdev)))
+                               discard_supported = true;
+               }
+               blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
+               blk_queue_max_write_same_sectors(mddev->queue, mddev->chunk_sectors);
+               blk_queue_max_discard_sectors(mddev->queue, mddev->chunk_sectors);
+
+               blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
+               blk_queue_io_opt(mddev->queue,
+                                (mddev->chunk_sectors << 9) * mddev->raid_disks);
+
+               if (!discard_supported)
+                       queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
+               else
+                       queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, mddev->queue);
+       }
 
        /* calculate array device size */
        md_set_array_sectors(mddev, raid0_size(mddev, 0, 0));