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md/raid0: update queue parameter in a safer location.
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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: 9af204c ("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>
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NeilBrown committed Aug 3, 2015
1 parent 25eafe1 commit 199dc6e
Showing 1 changed file with 39 additions and 36 deletions.
75 changes: 39 additions & 36 deletions drivers/md/raid0.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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",
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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) - "
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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);
Expand All @@ -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));
Expand Down

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