dm: fix a race condition in retrieve_deps

[linux-2.6-microblaze.git] / drivers / md / dm-table.c

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 7d208b2..37b48f6 100644 (file)
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -135,6 +135,7 @@ int dm_table_create(struct dm_table **result, blk_mode_t mode,
                return -ENOMEM;
 
        INIT_LIST_HEAD(&t->devices);
+       init_rwsem(&t->devices_lock);
 
        if (!num_targets)
                num_targets = KEYS_PER_NODE;
@@ -359,16 +360,20 @@ int __ref dm_get_device(struct dm_target *ti, const char *path, blk_mode_t mode,
        if (dev == disk_devt(t->md->disk))
                return -EINVAL;
 
+       down_write(&t->devices_lock);
+
        dd = find_device(&t->devices, dev);
        if (!dd) {
                dd = kmalloc(sizeof(*dd), GFP_KERNEL);
-               if (!dd)
-                       return -ENOMEM;
+               if (!dd) {
+                       r = -ENOMEM;
+                       goto unlock_ret_r;
+               }
 
                r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev);
                if (r) {
                        kfree(dd);
-                       return r;
+                       goto unlock_ret_r;
                }
 
                refcount_set(&dd->count, 1);
@@ -378,12 +383,17 @@ int __ref dm_get_device(struct dm_target *ti, const char *path, blk_mode_t mode,
        } else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) {
                r = upgrade_mode(dd, mode, t->md);
                if (r)
-                       return r;
+                       goto unlock_ret_r;
        }
        refcount_inc(&dd->count);
 out:
+       up_write(&t->devices_lock);
        *result = dd->dm_dev;
        return 0;
+
+unlock_ret_r:
+       up_write(&t->devices_lock);
+       return r;
 }
 EXPORT_SYMBOL(dm_get_device);
 
@@ -419,9 +429,12 @@ static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
 void dm_put_device(struct dm_target *ti, struct dm_dev *d)
 {
        int found = 0;
-       struct list_head *devices = &ti->table->devices;
+       struct dm_table *t = ti->table;
+       struct list_head *devices = &t->devices;
        struct dm_dev_internal *dd;
 
+       down_write(&t->devices_lock);
+
        list_for_each_entry(dd, devices, list) {
                if (dd->dm_dev == d) {
                        found = 1;
@@ -430,14 +443,17 @@ void dm_put_device(struct dm_target *ti, struct dm_dev *d)
        }
        if (!found) {
                DMERR("%s: device %s not in table devices list",
-                     dm_device_name(ti->table->md), d->name);
-               return;
+                     dm_device_name(t->md), d->name);
+               goto unlock_ret;
        }
        if (refcount_dec_and_test(&dd->count)) {
-               dm_put_table_device(ti->table->md, d);
+               dm_put_table_device(t->md, d);
                list_del(&dd->list);
                kfree(dd);
        }
+
+unlock_ret:
+       up_write(&t->devices_lock);
 }
 EXPORT_SYMBOL(dm_put_device);