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Subject[PATCH 3.16.y-ckt 117/126] md/raid0: update queue parameter in a safer location.
Date
3.16.7-ckt21 -stable review patch.  If anyone has any objections, please let me know.

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

From: NeilBrown <neilb@suse.com>

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>
[ luis: backported to 3.16:
- raid0 isn't accessed from dm-raid so no conditional mddev->queue accesses
(done with commit 753f2856cda2 "md raid0: access mddev->queue (request
queue member) conditionally because it is not set when accessed from
dm-raid")
- adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
drivers/md/raid0.c | 66 +++++++++++++++++++++++++++++-------------------------
1 file changed, 36 insertions(+), 30 deletions(-)

diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index 9afd00b45f83..3d6b97b6dc6f 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -88,7 +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);
- bool discard_supported = false;
+ unsigned short blksize = 512;

if (!conf)
return -ENOMEM;
@@ -103,6 +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));
+
rdev_for_each(rdev2, mddev) {
pr_debug("md/raid0:%s: comparing %s(%llu)"
" with %s(%llu)\n",
@@ -139,6 +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);
@@ -193,18 +208,12 @@ 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);
-
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) - "
@@ -267,26 +276,6 @@ 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);
-
- 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;

@@ -429,6 +418,8 @@ static int raid0_run(struct mddev *mddev)
{
struct r0conf *conf;
int ret;
+ struct md_rdev *rdev;
+ bool discard_supported = false;

if (mddev->chunk_sectors == 0) {
printk(KERN_ERR "md/raid0:%s: chunk size must be set.\n",
@@ -437,9 +428,6 @@ 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);
- 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) {
@@ -449,6 +437,24 @@ static int raid0_run(struct mddev *mddev)
mddev->private = conf;
}
conf = mddev->private;
+ 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));

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