Merge branch 'devel-stable' of master.kernel.org:/home/rmk/linux-2.6-arm

[pandora-kernel.git] / fs / block_dev.c

diff --git a/fs/block_dev.c b/fs/block_dev.c
index fe3f59c..333a7bb 100644 (file)
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -432,6 +432,9 @@ static void init_once(void *foo)
        mutex_init(&bdev->bd_mutex);
        INIT_LIST_HEAD(&bdev->bd_inodes);
        INIT_LIST_HEAD(&bdev->bd_list);
+#ifdef CONFIG_SYSFS
+       INIT_LIST_HEAD(&bdev->bd_holder_disks);
+#endif
        inode_init_once(&ei->vfs_inode);
        /* Initialize mutex for freeze. */
        mutex_init(&bdev->bd_fsfreeze_mutex);
@@ -779,6 +782,23 @@ static struct block_device *bd_start_claiming(struct block_device *bdev,
 }
 
 #ifdef CONFIG_SYSFS
+struct bd_holder_disk {
+       struct list_head        list;
+       struct gendisk          *disk;
+       int                     refcnt;
+};
+
+static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
+                                                 struct gendisk *disk)
+{
+       struct bd_holder_disk *holder;
+
+       list_for_each_entry(holder, &bdev->bd_holder_disks, list)
+               if (holder->disk == disk)
+                       return holder;
+       return NULL;
+}
+
 static int add_symlink(struct kobject *from, struct kobject *to)
 {
        return sysfs_create_link(from, to, kobject_name(to));
@@ -794,6 +814,8 @@ static void del_symlink(struct kobject *from, struct kobject *to)
  * @bdev: the claimed slave bdev
  * @disk: the holding disk
  *
+ * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
+ *
  * This functions creates the following sysfs symlinks.
  *
  * - from "slaves" directory of the holder @disk to the claimed @bdev
@@ -817,47 +839,83 @@ static void del_symlink(struct kobject *from, struct kobject *to)
  */
 int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
 {
+       struct bd_holder_disk *holder;
        int ret = 0;
 
        mutex_lock(&bdev->bd_mutex);
 
-       WARN_ON_ONCE(!bdev->bd_holder || bdev->bd_holder_disk);
+       WARN_ON_ONCE(!bdev->bd_holder);
 
        /* FIXME: remove the following once add_disk() handles errors */
        if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
                goto out_unlock;
 
-       ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
-       if (ret)
+       holder = bd_find_holder_disk(bdev, disk);
+       if (holder) {
+               holder->refcnt++;
                goto out_unlock;
+       }
 
-       ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
-       if (ret) {
-               del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
+       holder = kzalloc(sizeof(*holder), GFP_KERNEL);
+       if (!holder) {
+               ret = -ENOMEM;
                goto out_unlock;
        }
 
-       bdev->bd_holder_disk = disk;
+       INIT_LIST_HEAD(&holder->list);
+       holder->disk = disk;
+       holder->refcnt = 1;
+
+       ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
+       if (ret)
+               goto out_free;
+
+       ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
+       if (ret)
+               goto out_del;
+
+       list_add(&holder->list, &bdev->bd_holder_disks);
+       goto out_unlock;
+
+out_del:
+       del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
+out_free:
+       kfree(holder);
 out_unlock:
        mutex_unlock(&bdev->bd_mutex);
        return ret;
 }
 EXPORT_SYMBOL_GPL(bd_link_disk_holder);
 
-static void bd_unlink_disk_holder(struct block_device *bdev)
+/**
+ * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
+ * @bdev: the calimed slave bdev
+ * @disk: the holding disk
+ *
+ * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
+ *
+ * CONTEXT:
+ * Might sleep.
+ */
+void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
 {
-       struct gendisk *disk = bdev->bd_holder_disk;
+       struct bd_holder_disk *holder;
 
-       bdev->bd_holder_disk = NULL;
-       if (!disk)
-               return;
+       mutex_lock(&bdev->bd_mutex);
 
-       del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
-       del_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
+       holder = bd_find_holder_disk(bdev, disk);
+
+       if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
+               del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
+               del_symlink(bdev->bd_part->holder_dir,
+                           &disk_to_dev(disk)->kobj);
+               list_del_init(&holder->list);
+               kfree(holder);
+       }
+
+       mutex_unlock(&bdev->bd_mutex);
 }
-#else
-static inline void bd_unlink_disk_holder(struct block_device *bdev)
-{ }
+EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
 #endif
 
 /**
@@ -1380,7 +1438,6 @@ int blkdev_put(struct block_device *bdev, fmode_t mode)
                 * unblock evpoll if it was a write holder.
                 */
                if (bdev_free) {
-                       bd_unlink_disk_holder(bdev);
                        if (bdev->bd_write_holder) {
                                disk_unblock_events(bdev->bd_disk);
                                bdev->bd_write_holder = false;