btrfs: remove fsid argument from btrfs_sysfs_update_sprout_fsid

It can be accessed from 'fs_devices' as it's identical to
fs_info->fs_devices. Also add a comment about why we are calling the
function. No semantic changes.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/sysfs.c

@@ -1328,16 +1328,16 @@ void btrfs_kobject_uevent(struct block_device *bdev, enum kobject_action action)
 			&disk_to_dev(bdev->bd_disk)->kobj);
 }
 
-void btrfs_sysfs_update_sprout_fsid(struct btrfs_fs_devices *fs_devices,
-				    const u8 *fsid)
+void btrfs_sysfs_update_sprout_fsid(struct btrfs_fs_devices *fs_devices)
+
 {
 	char fsid_buf[BTRFS_UUID_UNPARSED_SIZE];
 
 	/*
 	 * Sprouting changes fsid of the mounted filesystem, rename the fsid
 	 * directory
 	 */
-	snprintf(fsid_buf, BTRFS_UUID_UNPARSED_SIZE, "%pU", fsid);
+	snprintf(fsid_buf, BTRFS_UUID_UNPARSED_SIZE, "%pU", fs_devices->fsid);
 	if (kobject_rename(&fs_devices->fsid_kobj, fsid_buf))
 		btrfs_warn(fs_devices->fs_info,
 				"sysfs: failed to create fsid for sprout");

fs/btrfs/sysfs.h

@@ -20,8 +20,7 @@ int btrfs_sysfs_remove_devices_dir(struct btrfs_fs_devices *fs_devices,
                 struct btrfs_device *one_device);
 int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs);
 void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs);
-void btrfs_sysfs_update_sprout_fsid(struct btrfs_fs_devices *fs_devices,
-				    const u8 *fsid);
+void btrfs_sysfs_update_sprout_fsid(struct btrfs_fs_devices *fs_devices);
 void btrfs_sysfs_feature_update(struct btrfs_fs_info *fs_info,
 		u64 bit, enum btrfs_feature_set set);
 void btrfs_kobject_uevent(struct block_device *bdev, enum kobject_action action);

fs/btrfs/volumes.c

@@ -2645,8 +2645,11 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
 			goto error_sysfs;
 		}
 
-		btrfs_sysfs_update_sprout_fsid(fs_devices,
-				fs_info->fs_devices->fsid);
+		/*
+		 * fs_devices now represents the newly sprouted filesystem and
+		 * its fsid has been changed by btrfs_prepare_sprout
+		 */
+		btrfs_sysfs_update_sprout_fsid(fs_devices);
 	}
 
 	ret = btrfs_commit_transaction(trans);