This allows us to set a snapshot or a subvolume readonly or writable on the fly.
Usage: Set BTRFS_SUBVOL_RDONLY of btrfs_ioctl_vol_arg_v2->flags, and then call ioctl(BTRFS_IOCTL_SUBVOL_SETFLAGS); Changelog for v2: - Add _GETFLAGS ioctl. - Check if the passed fd is the root of a subvolume. - Change the name from _SNAP_SETFLAGS to _SUBVOL_SETFLAGS. Signed-off-by: Li Zefan <l...@cn.fujitsu.com> --- fs/btrfs/ioctl.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ fs/btrfs/ioctl.h | 4 ++ 2 files changed, 96 insertions(+), 0 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index db2b231..29304c7 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -1010,6 +1010,94 @@ out: return ret; } +static noinline int btrfs_ioctl_subvol_getflags(struct file *file, + void __user *arg) +{ + struct inode *inode = fdentry(file)->d_inode; + struct btrfs_root *root = BTRFS_I(inode)->root; + struct btrfs_ioctl_vol_args_v2 *vol_args; + int ret = 0; + u64 flags = 0; + + if (inode->i_ino != BTRFS_FIRST_FREE_OBJECTID) + return -EINVAL; + + vol_args = memdup_user(arg, sizeof(*vol_args)); + if (IS_ERR(vol_args)) + return PTR_ERR(vol_args); + + down_read(&root->fs_info->subvol_sem); + if (root->readonly) + flags |= BTRFS_SUBVOL_RDONLY; + up_read(&root->fs_info->subvol_sem); + + if (copy_to_user(arg + offsetof(struct btrfs_ioctl_vol_args_v2, flags), + &flags, sizeof(flags))) + ret = -EFAULT; + + kfree(vol_args); + return ret; +} + +static noinline int btrfs_ioctl_subvol_setflags(struct file *file, + void __user *arg) +{ + struct inode *inode = fdentry(file)->d_inode; + struct btrfs_root *root = BTRFS_I(inode)->root; + struct btrfs_trans_handle *trans; + struct btrfs_ioctl_vol_args_v2 *vol_args; + u64 root_flags; + u64 flags; + int ret = 0; + + if (root->fs_info->sb->s_flags & MS_RDONLY) + return -EROFS; + + if (inode->i_ino != BTRFS_FIRST_FREE_OBJECTID) + return -EINVAL; + + vol_args = memdup_user(arg, sizeof(*vol_args)); + if (IS_ERR(vol_args)) + return PTR_ERR(vol_args); + flags = vol_args->flags; + + if (flags & ~BTRFS_SUBVOL_RDONLY) { + ret = -EINVAL; + goto out; + } + + down_write(&root->fs_info->subvol_sem); + + /* nothing to do */ + if (!!(flags & BTRFS_SUBVOL_RDONLY) == root->readonly) + goto out_unlock; + + root_flags = btrfs_root_flags(&root->root_item); + if (flags & BTRFS_SUBVOL_RDONLY) + btrfs_set_root_flags(&root->root_item, + root_flags | BTRFS_ROOT_SNAP_RDONLY); + else + btrfs_set_root_flags(&root->root_item, + root_flags & ~BTRFS_ROOT_SNAP_RDONLY); + root->readonly = !root->readonly; + + trans = btrfs_start_transaction(root, 1); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + goto out_unlock; + } + + ret = btrfs_update_root(trans, root, + &root->root_key, &root->root_item); + + btrfs_commit_transaction(trans, root); +out_unlock: + up_write(&root->fs_info->subvol_sem); +out: + kfree(vol_args); + return ret; +} + /* * helper to check if the subvolume references other subvolumes */ @@ -2283,6 +2371,10 @@ long btrfs_ioctl(struct file *file, unsigned int return btrfs_ioctl_snap_create(file, argp, 1); case BTRFS_IOC_SNAP_DESTROY: return btrfs_ioctl_snap_destroy(file, argp); + case BTRFS_IOC_SUBVOL_GETFLAGS: + return btrfs_ioctl_subvol_getflags(file, argp); + case BTRFS_IOC_SUBVOL_SETFLAGS: + return btrfs_ioctl_subvol_setflags(file, argp); case BTRFS_IOC_DEFAULT_SUBVOL: return btrfs_ioctl_default_subvol(file, argp); case BTRFS_IOC_DEFRAG: diff --git a/fs/btrfs/ioctl.h b/fs/btrfs/ioctl.h index 192fa99..19f7259 100644 --- a/fs/btrfs/ioctl.h +++ b/fs/btrfs/ioctl.h @@ -194,4 +194,8 @@ struct btrfs_ioctl_space_args { #define BTRFS_IOC_WAIT_SYNC _IOW(BTRFS_IOCTL_MAGIC, 22, __u64) #define BTRFS_IOC_SNAP_CREATE_V2 _IOW(BTRFS_IOCTL_MAGIC, 23, \ struct btrfs_ioctl_vol_args_v2) +#define BTRFS_IOC_SUBVOL_GETFLAGS _IOW(BTRFS_IOCTL_MAGIC, 25, \ + struct btrfs_ioctl_vol_args_v2) +#define BTRFS_IOC_SUBVOL_SETFLAGS _IOW(BTRFS_IOCTL_MAGIC, 26, \ + struct btrfs_ioctl_vol_args_v2) #endif -- 1.6.3 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html