Older kernels would generally be able to still mount the filesystem with the default subvolume set, but it would result in a different volume being mounted, which could be an even more unpleasant suprise for users. So if you set your default subvolume, you can't go back to older kernels. Thanks,
Signed-off-by: Josef Bacik <[email protected]> --- fs/btrfs/ctree.h | 4 +++- fs/btrfs/ioctl.c | 8 ++++++++ 2 files changed, 11 insertions(+), 1 deletions(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 917211b..8c57180 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -370,11 +370,13 @@ struct btrfs_super_block { * ones specified below then we will fail to mount */ #define BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF (1ULL << 0) +#define BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL (2ULL << 0) #define BTRFS_FEATURE_COMPAT_SUPP 0ULL #define BTRFS_FEATURE_COMPAT_RO_SUPP 0ULL #define BTRFS_FEATURE_INCOMPAT_SUPP \ - BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF + (BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF | \ + BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL) /* * A leaf is full of items. offset and size tell us where to find diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 81d8378..9070b86 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -1563,6 +1563,8 @@ static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp) struct btrfs_path *path; struct btrfs_key location; struct btrfs_disk_key disk_key; + struct btrfs_super_block *disk_super; + u64 features; u64 objectid = 0; u64 dir_id; @@ -1610,6 +1612,12 @@ static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp) btrfs_mark_buffer_dirty(path->nodes[0]); btrfs_free_path(path); + disk_super = &root->fs_info->super_copy; + features = btrfs_super_incompat_flags(disk_super); + if (!(features & BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL)) { + features |= BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL; + btrfs_set_super_incompat_flags(disk_super, features); + } btrfs_end_transaction(trans, root); return 0; -- 1.5.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
