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

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->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: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2014-12-15 12:56:58 +11:00
parent db721d32b7
commit 36d091f475
2 changed files with 35 additions and 21 deletions
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55
drivers/md/md.c
View file

@ -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;

1
drivers/md/md.h
View file

@ -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 */