btrfs: make use of btrfs_scratch_superblocks() in btrfs_rm_device()

With the previous patches now the btrfs_scratch_superblocks() is ready to
be used in btrfs_rm_device() so use it.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
[ use GFP_KERNEL ]
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index d742605..8264b06 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1752,13 +1752,11 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
 {
        struct btrfs_device *device;
        struct btrfs_device *next_device;
-       struct block_device *bdev = NULL;
-       struct buffer_head *bh = NULL;
-       struct btrfs_super_block *disk_super = NULL;
        struct btrfs_fs_devices *cur_devices;
        u64 num_devices;
        int ret = 0;
        bool clear_super = false;
+       char *dev_name = NULL;
 
        mutex_lock(&uuid_mutex);
 
@@ -1786,6 +1784,11 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
                list_del_init(&device->dev_alloc_list);
                device->fs_devices->rw_devices--;
                unlock_chunks(root);
+               dev_name = kstrdup(device->name->str, GFP_KERNEL);
+               if (!dev_name) {
+                       ret = -ENOMEM;
+                       goto error_undo;
+               }
                clear_super = true;
        }
 
@@ -1869,73 +1872,19 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path)
         * remove it from the devices list and zero out the old super
         */
        if (clear_super) {
-               u64 bytenr;
-               int i;
-
-               if (!disk_super) {
-                       ret = btrfs_get_bdev_and_sb(device_path,
-                                       FMODE_WRITE | FMODE_EXCL,
-                                       root->fs_info->bdev_holder, 0,
-                                       &bdev, &bh);
-                       if (ret) {
-                               /*
-                                * It could be a failed device ok for clear_super
-                                * to fail. So return success
-                                */
-                               ret = 0;
-                               goto out;
-                       }
-
-                       disk_super = (struct btrfs_super_block *)bh->b_data;
-               }
-               /* make sure this device isn't detected as part of
-                * the FS anymore
-                */
-               memset(&disk_super->magic, 0, sizeof(disk_super->magic));
-               set_buffer_dirty(bh);
-               sync_dirty_buffer(bh);
-               brelse(bh);
-
-               /* clear the mirror copies of super block on the disk
-                * being removed, 0th copy is been taken care above and
-                * the below would take of the rest
-                */
-               for (i = 1; i < BTRFS_SUPER_MIRROR_MAX; i++) {
-                       bytenr = btrfs_sb_offset(i);
-                       if (bytenr + BTRFS_SUPER_INFO_SIZE >=
-                                       i_size_read(bdev->bd_inode))
-                               break;
-
-                       bh = __bread(bdev, bytenr / 4096,
-                                       BTRFS_SUPER_INFO_SIZE);
-                       if (!bh)
-                               continue;
+               struct block_device *bdev;
 
-                       disk_super = (struct btrfs_super_block *)bh->b_data;
-
-                       if (btrfs_super_bytenr(disk_super) != bytenr ||
-                               btrfs_super_magic(disk_super) != BTRFS_MAGIC) {
-                               brelse(bh);
-                               continue;
-                       }
-                       memset(&disk_super->magic, 0,
-                                               sizeof(disk_super->magic));
-                       set_buffer_dirty(bh);
-                       sync_dirty_buffer(bh);
-                       brelse(bh);
-               }
-
-               if (bdev) {
-                       /* Notify udev that device has changed */
-                       btrfs_kobject_uevent(bdev, KOBJ_CHANGE);
-
-                       /* Update ctime/mtime for device path for libblkid */
-                       update_dev_time(device_path);
+               bdev = blkdev_get_by_path(dev_name, FMODE_READ | FMODE_EXCL,
+                                               root->fs_info->bdev_holder);
+               if (!IS_ERR(bdev)) {
+                       btrfs_scratch_superblocks(bdev, dev_name);
                        blkdev_put(bdev, FMODE_READ | FMODE_EXCL);
                }
        }
 
 out:
+       kfree(dev_name);
+
        mutex_unlock(&uuid_mutex);
        return ret;