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o Use count should be an atomic_t

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This commit is contained in:
Steven Whitehouse 2001-09-17 09:01:23 +00:00
parent de37c802d7
commit dea83b3f4c
1 changed files with 10 additions and 6 deletions
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16
driver/device-mapper/dm-blkdev.c
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@ -22,12 +22,13 @@
#include <linux/config.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <asm/atomic.h>
#include "dm.h"
struct dm_bdev {
struct list_head list;
struct block_device *bdev;
int use;
atomic_t use;
};
#define DMB_HASH_SHIFT 8
@ -69,7 +70,7 @@ static struct dm_bdev *__dm_get_device(struct block_device *bdev, unsigned hash)
b = list_entry(tmp, struct dm_bdev, list);
if (b->bdev != bdev)
continue;
b->use++;
atomic_inc(&b->use);
return b;
}
@ -94,7 +95,7 @@ static struct block_device *dm_get_device(struct block_device *bdev)
return ERR_PTR(-ENOMEM);
n->bdev = bdev;
n->use = 1;
atomic_set(&n->use, 1);
down(&bdev_sem);
read_lock(&bdev_lock);
@ -151,7 +152,7 @@ static void dm_blkdev_drop(struct dm_bdev *d)
{
down(&bdev_sem);
write_lock(&bdev_lock);
if (d->use == 0) {
if (atomic_read(&d->use) == 0) {
list_del(&d->list);
} else {
d = NULL;
@ -173,8 +174,11 @@ int dm_blkdev_put(struct block_device *bdev)
read_lock(&bdev_lock);
d = __dm_get_device(bdev, hash);
if (d) {
--d->use; /* Drop count from __dm_get_device */
if (--d->use == 0)
/*
* One for ref that we want to drop,
* one for ref from __dm_get_device()
*/
if (atomic_sub_and_test(2, &d->use))
do_drop = 1;
}
read_unlock(&bdev_lock);