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

commit 199dc6ed5179251fa6158a461499c24bdd99c836 upstream.

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")
Reported-by: Yi Zhang <yizhan@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.com>
[bwh: Backported to 3.2:
 - md has no discard or write-same support
 - md is not used by dm-raid so mddev->queue is never null
 - Open-code rdev_for_each()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index d3e6f354f87837234c8d7a7756772aefa9815b7a..0abae394295f4cdb5e2137e157aa962503be9b6e 100644 (file)
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -88,6 +88,7 @@ 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);
+       unsigned short blksize = 512;
 
        if (!conf)
                return -ENOMEM;
@@ -102,6 +103,9 @@ 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));
+
                list_for_each_entry(rdev2, &mddev->disks, same_set) {
                        pr_debug("md/raid0:%s:   comparing %s(%llu)"
                                 " with %s(%llu)\n",
@@ -138,6 +142,18 @@ 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);
@@ -186,8 +202,6 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
                }
                dev[j] = rdev1;
 
-               disk_stack_limits(mddev->gendisk, rdev1->bdev,
-                                 rdev1->data_offset << 9);
                /* as we don't honour merge_bvec_fn, we must never risk
                 * violating it, so limit ->max_segments to 1, lying within
                 * a single page.
@@ -263,21 +277,6 @@ static int create_strip_zones(struct mddev *mddev, struct r0conf **private_conf)
        mddev->queue->backing_dev_info.congested_fn = raid0_congested;
        mddev->queue->backing_dev_info.congested_data = mddev;
 
-       /*
-        * 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;
-       }
-
-       blk_queue_io_min(mddev->queue, mddev->chunk_sectors << 9);
-       blk_queue_io_opt(mddev->queue,
-                        (mddev->chunk_sectors << 9) * mddev->raid_disks);
-
        pr_debug("md/raid0:%s: done.\n", mdname(mddev));
        *private_conf = conf;
 
@@ -340,6 +339,7 @@ static int raid0_run(struct mddev *mddev)
 {
        struct r0conf *conf;
        int ret;
+       struct md_rdev *rdev;
 
        if (mddev->chunk_sectors == 0) {
                printk(KERN_ERR "md/raid0:%s: chunk size must be set.\n",
@@ -348,7 +348,6 @@ static int raid0_run(struct mddev *mddev)
        }
        if (md_check_no_bitmap(mddev))
                return -EINVAL;
-       blk_queue_max_hw_sectors(mddev->queue, mddev->chunk_sectors);
 
        /* if private is not null, we are here after takeover */
        if (mddev->private == NULL) {
@@ -359,6 +358,16 @@ static int raid0_run(struct mddev *mddev)
        }
        conf = mddev->private;
 
+       list_for_each_entry(rdev, &mddev->disks, same_set) {
+               disk_stack_limits(mddev->gendisk, rdev->bdev,
+                                 rdev->data_offset << 9);
+       }
+       blk_queue_max_hw_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);
+
        /* calculate array device size */
        md_set_array_sectors(mddev, raid0_size(mddev, 0, 0));