md/linear: remove rcu protections in favour of suspend/resume
The use of 'rcu' to protect accesses to ->private_data so that
the ->private_data could be updated predates the introduction
of mddev_suspend/mddev_resume.
These are a cleaner mechanism for providing stability while
swapping in a new ->private data - it is used by level_store()
to support changing of raid levels.
So get rid of the RCU stuff and just use mddev_suspend, mddev_resume.
As these function call ->quiesce(), we add an empty function for
linear just like for raid0.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index 4c2a92c..b3e717a 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -34,7 +34,7 @@
lo = 0;
hi = mddev->raid_disks - 1;
- conf = rcu_dereference(mddev->private);
+ conf = mddev->private;
/*
* Binary Search
@@ -70,7 +70,6 @@
int maxbytes = biovec->bv_len;
struct request_queue *subq;
- rcu_read_lock();
dev0 = which_dev(mddev, sector);
maxsectors = dev0->end_sector - sector;
subq = bdev_get_queue(dev0->rdev->bdev);
@@ -80,7 +79,6 @@
maxbytes = min(maxbytes, subq->merge_bvec_fn(subq, bvm,
biovec));
}
- rcu_read_unlock();
if (maxsectors < bio_sectors)
maxsectors = 0;
@@ -101,15 +99,13 @@
struct linear_conf *conf;
int i, ret = 0;
- rcu_read_lock();
- conf = rcu_dereference(mddev->private);
+ conf = mddev->private;
for (i = 0; i < mddev->raid_disks && !ret ; i++) {
struct request_queue *q = bdev_get_queue(conf->disks[i].rdev->bdev);
ret |= bdi_congested(&q->backing_dev_info, bits);
}
- rcu_read_unlock();
return ret;
}
@@ -118,12 +114,10 @@
struct linear_conf *conf;
sector_t array_sectors;
- rcu_read_lock();
- conf = rcu_dereference(mddev->private);
+ conf = mddev->private;
WARN_ONCE(sectors || raid_disks,
"%s does not support generic reshape\n", __func__);
array_sectors = conf->array_sectors;
- rcu_read_unlock();
return array_sectors;
}
@@ -243,33 +237,22 @@
if (!newconf)
return -ENOMEM;
- oldconf = rcu_dereference_protected(mddev->private,
- lockdep_is_held(
- &mddev->reconfig_mutex));
+ mddev_suspend(mddev);
+ oldconf = mddev->private;
mddev->raid_disks++;
- rcu_assign_pointer(mddev->private, newconf);
+ mddev->private = newconf;
md_set_array_sectors(mddev, linear_size(mddev, 0, 0));
set_capacity(mddev->gendisk, mddev->array_sectors);
+ mddev_resume(mddev);
revalidate_disk(mddev->gendisk);
- kfree_rcu(oldconf, rcu);
+ kfree(oldconf);
return 0;
}
static int linear_stop (struct mddev *mddev)
{
- struct linear_conf *conf =
- rcu_dereference_protected(mddev->private,
- lockdep_is_held(
- &mddev->reconfig_mutex));
+ struct linear_conf *conf = mddev->private;
- /*
- * We do not require rcu protection here since
- * we hold reconfig_mutex for both linear_add and
- * linear_stop, so they cannot race.
- * We should make sure any old 'conf's are properly
- * freed though.
- */
- rcu_barrier();
blk_sync_queue(mddev->queue); /* the unplug fn references 'conf'*/
kfree(conf);
mddev->private = NULL;
@@ -290,16 +273,12 @@
}
do {
- rcu_read_lock();
-
tmp_dev = which_dev(mddev, bio->bi_iter.bi_sector);
start_sector = tmp_dev->end_sector - tmp_dev->rdev->sectors;
end_sector = tmp_dev->end_sector;
data_offset = tmp_dev->rdev->data_offset;
bio->bi_bdev = tmp_dev->rdev->bdev;
- rcu_read_unlock();
-
if (unlikely(bio->bi_iter.bi_sector >= end_sector ||
bio->bi_iter.bi_sector < start_sector))
goto out_of_bounds;
@@ -346,6 +325,10 @@
seq_printf(seq, " %dk rounding", mddev->chunk_sectors / 2);
}
+static void linear_quiesce(struct mddev *mddev, int state)
+{
+}
+
static struct md_personality linear_personality =
{
.name = "linear",
@@ -357,6 +340,7 @@
.status = linear_status,
.hot_add_disk = linear_add,
.size = linear_size,
+ .quiesce = linear_quiesce,
.congested = linear_congested,
.mergeable_bvec = linear_mergeable_bvec,
};