btrfs: don't pass a holder for non-exclusive blkdev_get_by_path

Passing a holder to blkdev_get_by_path when FMODE_EXCL isn't set doesn't
make sense, so pass NULL instead and remove the holder argument from the
call chains the only end up in non-FMODE_EXCL blkdev_get_by_path calls.

Exclusive mode for device scanning is not used since commit 50d281f
("btrfs: scan device in non-exclusive mode")".

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: David Sterba <dsterba@suse.com>
Link: https://lore.kernel.org/r/20230608110258.189493-15-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/btrfs/super.c

@@ -849,8 +849,7 @@ int btrfs_parse_options(struct btrfs_fs_info *info, char *options,
  * All other options will be parsed on much later in the mount process and
  * only when we need to allocate a new super block.
  */
-static int btrfs_parse_device_options(const char *options, fmode_t flags,
-				      void *holder)
+static int btrfs_parse_device_options(const char *options, fmode_t flags)
 {
 	substring_t args[MAX_OPT_ARGS];
 	char *device_name, *opts, *orig, *p;
@@ -884,8 +883,7 @@ static int btrfs_parse_device_options(const char *options, fmode_t flags,
 				error = -ENOMEM;
 				goto out;
 			}
-			device = btrfs_scan_one_device(device_name, flags,
-					holder);
+			device = btrfs_scan_one_device(device_name, flags);
 			kfree(device_name);
 			if (IS_ERR(device)) {
 				error = PTR_ERR(device);
@@ -1477,13 +1475,13 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
 	}
 
 	mutex_lock(&uuid_mutex);
-	error = btrfs_parse_device_options(data, mode, fs_type);
+	error = btrfs_parse_device_options(data, mode);
 	if (error) {
 		mutex_unlock(&uuid_mutex);
 		goto error_fs_info;
 	}
 
-	device = btrfs_scan_one_device(device_name, mode, fs_type);
+	device = btrfs_scan_one_device(device_name, mode);
 	if (IS_ERR(device)) {
 		mutex_unlock(&uuid_mutex);
 		error = PTR_ERR(device);
@@ -2190,8 +2188,7 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
 	switch (cmd) {
 	case BTRFS_IOC_SCAN_DEV:
 		mutex_lock(&uuid_mutex);
-		device = btrfs_scan_one_device(vol->name, FMODE_READ,
-					       &btrfs_root_fs_type);
+		device = btrfs_scan_one_device(vol->name, FMODE_READ);
 		ret = PTR_ERR_OR_ZERO(device);
 		mutex_unlock(&uuid_mutex);
 		break;
@@ -2205,8 +2202,7 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
 		break;
 	case BTRFS_IOC_DEVICES_READY:
 		mutex_lock(&uuid_mutex);
-		device = btrfs_scan_one_device(vol->name, FMODE_READ,
-					       &btrfs_root_fs_type);
+		device = btrfs_scan_one_device(vol->name, FMODE_READ);
 		if (IS_ERR(device)) {
 			mutex_unlock(&uuid_mutex);
 			ret = PTR_ERR(device);

fs/btrfs/volumes.c

@@ -1348,8 +1348,7 @@ int btrfs_forget_devices(dev_t devt)
  * and we are not allowed to call set_blocksize during the scan. The superblock
  * is read via pagecache
  */
-struct btrfs_device *btrfs_scan_one_device(const char *path, fmode_t flags,
-					   void *holder)
+struct btrfs_device *btrfs_scan_one_device(const char *path, fmode_t flags)
 {
 	struct btrfs_super_block *disk_super;
 	bool new_device_added = false;
@@ -1368,16 +1367,16 @@ struct btrfs_device *btrfs_scan_one_device(const char *path, fmode_t flags,
 	 */
 
 	/*
-	 * Avoid using flag |= FMODE_EXCL here, as the systemd-udev may
-	 * initiate the device scan which may race with the user's mount
-	 * or mkfs command, resulting in failure.
-	 * Since the device scan is solely for reading purposes, there is
-	 * no need for FMODE_EXCL. Additionally, the devices are read again
+	 * Avoid an exclusive open here, as the systemd-udev may initiate the
+	 * device scan which may race with the user's mount or mkfs command,
+	 * resulting in failure.
+	 * Since the device scan is solely for reading purposes, there is no
+	 * need for an exclusive open. Additionally, the devices are read again
 	 * during the mount process. It is ok to get some inconsistent
 	 * values temporarily, as the device paths of the fsid are the only
 	 * required information for assembling the volume.
 	 */
-	bdev = blkdev_get_by_path(path, flags, holder, NULL);
+	bdev = blkdev_get_by_path(path, flags, NULL, NULL);
 	if (IS_ERR(bdev))
 		return ERR_CAST(bdev);
 
@@ -2381,7 +2380,7 @@ int btrfs_get_dev_args_from_path(struct btrfs_fs_info *fs_info,
 		return -ENOMEM;
 	}
 
-	ret = btrfs_get_bdev_and_sb(path, FMODE_READ, fs_info->bdev_holder, 0,
+	ret = btrfs_get_bdev_and_sb(path, FMODE_READ, NULL, 0,
 				    &bdev, &disk_super);
 	if (ret) {
 		btrfs_put_dev_args_from_path(args);

fs/btrfs/volumes.h

@@ -600,8 +600,7 @@ struct btrfs_block_group *btrfs_create_chunk(struct btrfs_trans_handle *trans,
 void btrfs_mapping_tree_free(struct extent_map_tree *tree);
 int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
 		       fmode_t flags, void *holder);
-struct btrfs_device *btrfs_scan_one_device(const char *path,
-					   fmode_t flags, void *holder);
+struct btrfs_device *btrfs_scan_one_device(const char *path, fmode_t flags);
 int btrfs_forget_devices(dev_t devt);
 void btrfs_close_devices(struct btrfs_fs_devices *fs_devices);
 void btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices);