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md: only count actual openers as access which prevent a 'stop' 

Open isn't the only thing that increments ->active.  e.g. reading
/proc/mdstat will increment it briefly.  So to avoid false positives
in testing for concurrent access, introduce a new counter that counts
just the number of times the md device it open.

Signed-off-by: NeilBrown <neilb@suse.de>
This commit is contained in:
NeilBrown 2008-07-21 17:05:25 +10:00
parent d6e2215052
commit f2ea68cf42
2 changed files with 8 additions and 4 deletions
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9
drivers/md/md.c
View File

@ -273,6 +273,7 @@ static mddev_t * mddev_find(dev_t unit)
INIT_LIST_HEAD(&new->all_mddevs);
init_timer(&new->safemode_timer);
atomic_set(&new->active, 1);
atomic_set(&new->openers, 0);
spin_lock_init(&new->write_lock);
init_waitqueue_head(&new->sb_wait);
init_waitqueue_head(&new->recovery_wait);
@ -2695,14 +2696,14 @@ array_state_store(mddev_t *mddev, const char *buf, size_t len)
break;
case clear:
/* stopping an active array */
if (atomic_read(&mddev->active) > 1)
if (atomic_read(&mddev->openers) > 0)
return -EBUSY;
err = do_md_stop(mddev, 0, 0);
break;
case inactive:
/* stopping an active array */
if (mddev->pers) {
if (atomic_read(&mddev->active) > 1)
if (atomic_read(&mddev->openers) > 0)
return -EBUSY;
err = do_md_stop(mddev, 2, 0);
} else
@ -3816,7 +3817,7 @@ static int do_md_stop(mddev_t * mddev, int mode, int is_open)
int err = 0;
struct gendisk *disk = mddev->gendisk;
if (atomic_read(&mddev->active) > 1 + is_open) {
if (atomic_read(&mddev->openers) > is_open) {
printk("md: %s still in use.\n",mdname(mddev));
return -EBUSY;
}
@ -5014,6 +5015,7 @@ static int md_open(struct inode *inode, struct file *file)
err = 0;
mddev_get(mddev);
atomic_inc(&mddev->openers);
mddev_unlock(mddev);
check_disk_change(inode->i_bdev);
@ -5026,6 +5028,7 @@ static int md_release(struct inode *inode, struct file * file)
mddev_t *mddev = inode->i_bdev->bd_disk->private_data;
BUG_ON(!mddev);
atomic_dec(&mddev->openers);
mddev_put(mddev);
return 0;

3
include/linux/raid/md_k.h
View File

@ -215,7 +215,8 @@ struct mddev_s
int in_sync; /* know to not need resync */
struct mutex reconfig_mutex;
atomic_t active;
atomic_t active; /* general refcount */
atomic_t openers; /* number of active opens */
int changed; /* true if we might need to reread partition info */
int degraded; /* whether md should consider