Re: [PATCH 06/12] fs: use the super_block as holder when mounting file systems

Jan Kara
2023-08-03T11:51:39Z

On Wed 02-08-23 17:41:25, Christoph Hellwig wrote:
> The file system type is not a very useful holder as it doesn't allow us
> to go back to the actual file system instance. Pass the super_block instead
> which is useful when passed back to the file system driver.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Nice, this is what I also wanted to eventually do :). Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza

> ---
> fs/btrfs/super.c | 7 ++-----
> fs/f2fs/super.c | 7 +++----
> fs/super.c | 8 ++++----
> 3 files changed, 9 insertions(+), 13 deletions(-)
>
> diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
> index 5980b5dcc6b163..8a47c7f2690880 100644
> --- a/fs/btrfs/super.c
> +++ b/fs/btrfs/super.c
> @@ -69,8 +69,6 @@ static const struct super_operations btrfs_super_ops;
> * requested by subvol=/path. That way the callchain is straightforward and we
> * don't have to play tricks with the mount options and recursive calls to
> * btrfs_mount.
> - *
> - * The new btrfs_root_fs_type also servers as a tag for the bdev_holder.
> */
> static struct file_system_type btrfs_fs_type;
> static struct file_system_type btrfs_root_fs_type;
> @@ -1498,8 +1496,7 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
> } else {
> struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
>
> - error = btrfs_open_devices(fs_devices, sb_open_mode(flags),
> - fs_type);
> + error = btrfs_open_devices(fs_devices, sb_open_mode(flags), s);
> if (error)
> goto out_deactivate;
>
> @@ -1513,7 +1510,7 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
> fs_devices->latest_dev->bdev);
> shrinker_debugfs_rename(&s->s_shrink, "sb-%s:%s", fs_type->name,
> s->s_id);
> - btrfs_sb(s)->bdev_holder = fs_type;
> + fs_info->bdev_holder = s;
> error = btrfs_fill_super(s, fs_devices, data);
> }
> if (!error)
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index ca31163da00a55..05c90fdb7a6cca 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -1561,7 +1561,7 @@ static void destroy_device_list(struct f2fs_sb_info *sbi)
> int i;
>
> for (i = 0; i < sbi->s_ndevs; i++) {
> - blkdev_put(FDEV(i).bdev, sbi->sb->s_type);
> + blkdev_put(FDEV(i).bdev, sbi->sb);
> #ifdef CONFIG_BLK_DEV_ZONED
> kvfree(FDEV(i).blkz_seq);
> #endif
> @@ -4198,7 +4198,7 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
> /* Single zoned block device mount */
> FDEV(0).bdev =
> blkdev_get_by_dev(sbi->sb->s_bdev->bd_dev, mode,
> - sbi->sb->s_type, NULL);
> + sbi->sb, NULL);
> } else {
> /* Multi-device mount */
> memcpy(FDEV(i).path, RDEV(i).path, MAX_PATH_LEN);
> @@ -4217,8 +4217,7 @@ static int f2fs_scan_devices(struct f2fs_sb_info *sbi)
> sbi->log_blocks_per_seg) - 1;
> }
> FDEV(i).bdev = blkdev_get_by_path(FDEV(i).path, mode,
> - sbi->sb->s_type,
> - NULL);
> + sbi->sb, NULL);
> }
> if (IS_ERR(FDEV(i).bdev))
> return PTR_ERR(FDEV(i).bdev);
> diff --git a/fs/super.c b/fs/super.c
> index 6aaa275fa8630d..09b65ee1a8b737 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -1249,7 +1249,7 @@ int setup_bdev_super(struct super_block *sb, int sb_flags,
> blk_mode_t mode = sb_open_mode(sb_flags);
> struct block_device *bdev;
>
> - bdev = blkdev_get_by_dev(sb->s_dev, mode, sb->s_type, &fs_holder_ops);
> + bdev = blkdev_get_by_dev(sb->s_dev, mode, sb, &fs_holder_ops);
> if (IS_ERR(bdev)) {
> if (fc)
> errorf(fc, "%s: Can't open blockdev", fc->source);
> @@ -1262,7 +1262,7 @@ int setup_bdev_super(struct super_block *sb, int sb_flags,
> * writable from userspace even for a read-only block device.
> */
> if ((mode & BLK_OPEN_WRITE) && bdev_read_only(bdev)) {
> - blkdev_put(bdev, sb->s_type);
> + blkdev_put(bdev, sb);
> return -EACCES;
> }
>
> @@ -1278,7 +1278,7 @@ int setup_bdev_super(struct super_block *sb, int sb_flags,
> mutex_unlock(&bdev->bd_fsfreeze_mutex);
> if (fc)
> warnf(fc, "%pg: Can't mount, blockdev is frozen", bdev);
> - blkdev_put(bdev, sb->s_type);
> + blkdev_put(bdev, sb);
> return -EBUSY;
> }
> spin_lock(&sb_lock);
> @@ -1418,7 +1418,7 @@ void kill_block_super(struct super_block *sb)
> if (bdev) {
> bdev->bd_super = NULL;
> sync_blockdev(bdev);
> - blkdev_put(bdev, sb->s_type);
> + blkdev_put(bdev, sb);
> }
> }
>
> --
> 2.39.2
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR