Commit ae818824 authored by Christoph Hellwig's avatar Christoph Hellwig Committed by David Sterba
Browse files

btrfs: always open the device read-only in btrfs_scan_one_device() 



btrfs_scan_one_device() opens the block device only to read the super
block.  Instead of passing a blk_mode_t argument to sometimes open
it for writing, just hard code BLK_OPEN_READ as it will never write
to the device or hand the block_device out to someone else.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent ea124ec3

fs/btrfs/super.c

+4 −5
Original line number Diff line number Diff line
@@ -364,10 +364,9 @@ static int btrfs_parse_param(struct fs_context *fc, struct fs_parameter *param) 
		break;

	case Opt_device: {

		struct btrfs_device *device;

		blk_mode_t mode = btrfs_open_mode(fc);



		mutex_lock(&uuid_mutex);

		device = btrfs_scan_one_device(param->string, mode, false);

		device = btrfs_scan_one_device(param->string, false);

		mutex_unlock(&uuid_mutex);

		if (IS_ERR(device))

			return PTR_ERR(device);
@@ -1855,7 +1854,7 @@ static int btrfs_get_tree_super(struct fs_context *fc) 
	 * With 'true' passed to btrfs_scan_one_device() (mount time) we expect

	 * either a valid device or an error.

	 */

	device = btrfs_scan_one_device(fc->source, mode, true);

	device = btrfs_scan_one_device(fc->source, true);

	ASSERT(device != NULL);

	if (IS_ERR(device)) {

		mutex_unlock(&uuid_mutex);
@@ -2233,7 +2232,7 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd, 
		 * Scanning outside of mount can return NULL which would turn

		 * into 0 error code.

		 */

		device = btrfs_scan_one_device(vol->name, BLK_OPEN_READ, false);

		device = btrfs_scan_one_device(vol->name, false);

		ret = PTR_ERR_OR_ZERO(device);

		mutex_unlock(&uuid_mutex);

		break;
@@ -2251,7 +2250,7 @@ static long btrfs_control_ioctl(struct file *file, unsigned int cmd, 
		 * Scanning outside of mount can return NULL which would turn

		 * into 0 error code.

		 */

		device = btrfs_scan_one_device(vol->name, BLK_OPEN_READ, false);

		device = btrfs_scan_one_device(vol->name, false);

		if (IS_ERR_OR_NULL(device)) {

			mutex_unlock(&uuid_mutex);

			if (IS_ERR(device))

fs/btrfs/volumes.c

+2 −2
Original line number Diff line number Diff line
@@ -1439,7 +1439,7 @@ static bool btrfs_skip_registration(struct btrfs_super_block *disk_super, 
 * the device or return an error. Multi-device and seeding devices are registered

 * in both cases.

 */

struct btrfs_device *btrfs_scan_one_device(const char *path, blk_mode_t flags,

struct btrfs_device *btrfs_scan_one_device(const char *path,

					   bool mount_arg_dev)

{

	struct btrfs_super_block *disk_super;
@@ -1460,7 +1460,7 @@ struct btrfs_device *btrfs_scan_one_device(const char *path, blk_mode_t flags, 
	 * values temporarily, as the device paths of the fsid are the only

	 * required information for assembling the volume.

	 */

	bdev_file = bdev_file_open_by_path(path, flags, NULL, NULL);

	bdev_file = bdev_file_open_by_path(path, BLK_OPEN_READ, NULL, NULL);

	if (IS_ERR(bdev_file))

		return ERR_CAST(bdev_file);

fs/btrfs/volumes.h

+1 −2
Original line number Diff line number Diff line
@@ -719,8 +719,7 @@ struct btrfs_block_group *btrfs_create_chunk(struct btrfs_trans_handle *trans, 
void btrfs_mapping_tree_free(struct btrfs_fs_info *fs_info);

int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,

		       blk_mode_t flags, void *holder);

struct btrfs_device *btrfs_scan_one_device(const char *path, blk_mode_t flags,

					   bool mount_arg_dev);

struct btrfs_device *btrfs_scan_one_device(const char *path, bool mount_arg_dev);

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);