Commit 36d091f4 authored by NeilBrown's avatar NeilBrown
Browse files

md: protect ->pers changes with mddev->lock 



->pers is already protected by ->reconfig_mutex, and
cannot possibly change when there are threads running or
outstanding IO.

However there are some places where we access ->pers
not in a thread or IO context, and where ->reconfig_mutex
is unnecessarily heavy-weight:  level_show and md_seq_show().

So protect all changes, and those accesses, with ->lock.
This is a step toward taking those accesses out from under
reconfig_mutex.

[Fixed missing "mddev->pers" -> "pers" conversion, thanks to
 Dan Carpenter <dan.carpenter@oracle.com>]

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent db721d32

drivers/md/md.c

+34 −21
Original line number Diff line number Diff line
@@ -3264,15 +3264,20 @@ __ATTR(safe_mode_delay, S_IRUGO|S_IWUSR,safe_delay_show, safe_delay_store); 
static ssize_t

level_show(struct mddev *mddev, char *page)

{

	struct md_personality *p = mddev->pers;

	struct md_personality *p;

	int ret;

	spin_lock(&mddev->lock);

	p = mddev->pers;

	if (p)

		return sprintf(page, "%s\n", p->name);

		ret = sprintf(page, "%s\n", p->name);

	else if (mddev->clevel[0])

		return sprintf(page, "%s\n", mddev->clevel);

		ret = sprintf(page, "%s\n", mddev->clevel);

	else if (mddev->level != LEVEL_NONE)

		return sprintf(page, "%d\n", mddev->level);

		ret = sprintf(page, "%d\n", mddev->level);

	else

		return 0;

		ret = 0;

	spin_unlock(&mddev->lock);

	return ret;

}



static ssize_t
@@ -3374,6 +3379,8 @@ level_store(struct mddev *mddev, const char *buf, size_t len) 
	/* Looks like we have a winner */

	mddev_suspend(mddev);

	mddev_detach(mddev);



	spin_lock(&mddev->lock);

	oldpers = mddev->pers;

	oldpriv = mddev->private;

	mddev->pers = pers;
@@ -3385,6 +3392,7 @@ level_store(struct mddev *mddev, const char *buf, size_t len) 
	mddev->delta_disks = 0;

	mddev->reshape_backwards = 0;

	mddev->degraded = 0;

	spin_unlock(&mddev->lock);



	if (oldpers->sync_request == NULL &&

	    mddev->external) {
@@ -4866,7 +4874,6 @@ int md_run(struct mddev *mddev) 
			       mddev->clevel);

		return -EINVAL;

	}

	mddev->pers = pers;

	spin_unlock(&pers_lock);

	if (mddev->level != pers->level) {

		mddev->level = pers->level;
@@ -4877,7 +4884,6 @@ int md_run(struct mddev *mddev) 
	if (mddev->reshape_position != MaxSector &&

	    pers->start_reshape == NULL) {

		/* This personality cannot handle reshaping... */

		mddev->pers = NULL;

		module_put(pers->owner);

		return -EINVAL;

	}
@@ -4921,19 +4927,19 @@ int md_run(struct mddev *mddev) 
	if (start_readonly && mddev->ro == 0)

		mddev->ro = 2; /* read-only, but switch on first write */



	err = mddev->pers->run(mddev);

	err = pers->run(mddev);

	if (err)

		printk(KERN_ERR "md: pers->run() failed ...\n");

	else if (mddev->pers->size(mddev, 0, 0) < mddev->array_sectors) {

	else if (pers->size(mddev, 0, 0) < mddev->array_sectors) {

		WARN_ONCE(!mddev->external_size, "%s: default size too small,"

			  " but 'external_size' not in effect?\n", __func__);

		printk(KERN_ERR

		       "md: invalid array_size %llu > default size %llu\n",

		       (unsigned long long)mddev->array_sectors / 2,

		       (unsigned long long)mddev->pers->size(mddev, 0, 0) / 2);

		       (unsigned long long)pers->size(mddev, 0, 0) / 2);

		err = -EINVAL;

	}

	if (err == 0 && mddev->pers->sync_request &&

	if (err == 0 && pers->sync_request &&

	    (mddev->bitmap_info.file || mddev->bitmap_info.offset)) {

		err = bitmap_create(mddev);

		if (err)
@@ -4942,9 +4948,8 @@ int md_run(struct mddev *mddev) 
	}

	if (err) {

		mddev_detach(mddev);

		mddev->pers->free(mddev, mddev->private);

		module_put(mddev->pers->owner);

		mddev->pers = NULL;

		pers->free(mddev, mddev->private);

		module_put(pers->owner);

		bitmap_destroy(mddev);

		return err;

	}
@@ -4953,7 +4958,7 @@ int md_run(struct mddev *mddev) 
		mddev->queue->backing_dev_info.congested_fn = md_congested;

		blk_queue_merge_bvec(mddev->queue, md_mergeable_bvec);

	}

	if (mddev->pers->sync_request) {

	if (pers->sync_request) {

		if (mddev->kobj.sd &&

		    sysfs_create_group(&mddev->kobj, &md_redundancy_group))

			printk(KERN_WARNING
@@ -4972,7 +4977,10 @@ int md_run(struct mddev *mddev) 
	mddev->safemode_delay = (200 * HZ)/1000 +1; /* 200 msec delay */

	mddev->in_sync = 1;

	smp_wmb();

	spin_lock(&mddev->lock);

	mddev->pers = pers;

	mddev->ready = 1;

	spin_unlock(&mddev->lock);

	rdev_for_each(rdev, mddev)

		if (rdev->raid_disk >= 0)

			if (sysfs_link_rdev(mddev, rdev))
@@ -5126,7 +5134,7 @@ static void mddev_detach(struct mddev *mddev) 
		wait_event(bitmap->behind_wait,

			   atomic_read(&bitmap->behind_writes) == 0);

	}

	if (mddev->pers->quiesce) {

	if (mddev->pers && mddev->pers->quiesce) {

		mddev->pers->quiesce(mddev, 1);

		mddev->pers->quiesce(mddev, 0);

	}
@@ -5137,13 +5145,16 @@ static void mddev_detach(struct mddev *mddev) 


static void __md_stop(struct mddev *mddev)

{

	mddev->ready = 0;

	struct md_personality *pers = mddev->pers;

	mddev_detach(mddev);

	mddev->pers->free(mddev, mddev->private);

	if (mddev->pers->sync_request && mddev->to_remove == NULL)

		mddev->to_remove = &md_redundancy_group;

	module_put(mddev->pers->owner);

	spin_lock(&mddev->lock);

	mddev->ready = 0;

	mddev->pers = NULL;

	spin_unlock(&mddev->lock);

	pers->free(mddev, mddev->private);

	if (pers->sync_request && mddev->to_remove == NULL)

		mddev->to_remove = &md_redundancy_group;

	module_put(pers->owner);

	clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);

}
@@ -6942,6 +6953,7 @@ static int md_seq_show(struct seq_file *seq, void *v) 
	if (mddev_lock(mddev) < 0)

		return -EINTR;



	spin_lock(&mddev->lock);

	if (mddev->pers || mddev->raid_disks || !list_empty(&mddev->disks)) {

		seq_printf(seq, "%s : %sactive", mdname(mddev),

						mddev->pers ? "" : "in");
@@ -7012,6 +7024,7 @@ static int md_seq_show(struct seq_file *seq, void *v) 


		seq_printf(seq, "\n");

	}

	spin_unlock(&mddev->lock);

	mddev_unlock(mddev);



	return 0;

drivers/md/md.h

+1 −0
Original line number Diff line number Diff line
@@ -391,6 +391,7 @@ struct mddev { 
	 *   rdev superblocks, events

	 *   clearing MD_CHANGE_*

	 *   in_sync - and related safemode and MD_CHANGE changes

	 *   pers (also protected by reconfig_mutex and pending IO).

	 */

	spinlock_t			lock;

	wait_queue_head_t		sb_wait;	/* for waiting on superblock updates */

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