From b83cc9693f39689490970c19f6c5b866f6719a70 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Mon, 20 Dec 2010 16:04:08 +0800 Subject: Btrfs: Add readonly snapshots support Usage: Set BTRFS_SUBVOL_RDONLY of btrfs_ioctl_vol_arg_v2->flags, and call ioctl(BTRFS_I0CTL_SNAP_CREATE_V2). Implementation: - Set readonly bit of btrfs_root_item->flags. - Add readonly checks in btrfs_permission (inode_permission), btrfs_setattr, btrfs_set/remove_xattr and some ioctls. Changelog for v3: - Eliminate btrfs_root->readonly, but check btrfs_root->root_item.flags. - Rename BTRFS_ROOT_SNAP_RDONLY to BTRFS_ROOT_SUBVOL_RDONLY. Signed-off-by: Li Zefan --- fs/btrfs/ioctl.c | 42 ++++++++++++++++++++++++++++++++---------- 1 file changed, 32 insertions(+), 10 deletions(-) (limited to 'fs/btrfs/ioctl.c') diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 02554e1..f066ccb 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -147,6 +147,9 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg) unsigned int flags, oldflags; int ret; + if (btrfs_root_readonly(root)) + return -EROFS; + if (copy_from_user(&flags, arg, sizeof(flags))) return -EFAULT; @@ -360,7 +363,8 @@ fail: } static int create_snapshot(struct btrfs_root *root, struct dentry *dentry, - char *name, int namelen, u64 *async_transid) + char *name, int namelen, u64 *async_transid, + bool readonly) { struct inode *inode; struct dentry *parent; @@ -378,6 +382,7 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry, btrfs_init_block_rsv(&pending_snapshot->block_rsv); pending_snapshot->dentry = dentry; pending_snapshot->root = root; + pending_snapshot->readonly = readonly; trans = btrfs_start_transaction(root->fs_info->extent_root, 5); if (IS_ERR(trans)) { @@ -509,7 +514,7 @@ static inline int btrfs_may_create(struct inode *dir, struct dentry *child) static noinline int btrfs_mksubvol(struct path *parent, char *name, int namelen, struct btrfs_root *snap_src, - u64 *async_transid) + u64 *async_transid, bool readonly) { struct inode *dir = parent->dentry->d_inode; struct dentry *dentry; @@ -541,7 +546,7 @@ static noinline int btrfs_mksubvol(struct path *parent, if (snap_src) { error = create_snapshot(snap_src, dentry, - name, namelen, async_transid); + name, namelen, async_transid, readonly); } else { error = create_subvol(BTRFS_I(dir)->root, dentry, name, namelen, async_transid); @@ -901,7 +906,8 @@ static noinline int btrfs_ioctl_snap_create_transid(struct file *file, char *name, unsigned long fd, int subvol, - u64 *transid) + u64 *transid, + bool readonly) { struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root; struct file *src_file; @@ -919,7 +925,7 @@ static noinline int btrfs_ioctl_snap_create_transid(struct file *file, if (subvol) { ret = btrfs_mksubvol(&file->f_path, name, namelen, - NULL, transid); + NULL, transid, readonly); } else { struct inode *src_inode; src_file = fget(fd); @@ -938,7 +944,7 @@ static noinline int btrfs_ioctl_snap_create_transid(struct file *file, } ret = btrfs_mksubvol(&file->f_path, name, namelen, BTRFS_I(src_inode)->root, - transid); + transid, readonly); fput(src_file); } out: @@ -957,7 +963,8 @@ static noinline int btrfs_ioctl_snap_create(struct file *file, vol_args->name[BTRFS_PATH_NAME_MAX] = '\0'; ret = btrfs_ioctl_snap_create_transid(file, vol_args->name, - vol_args->fd, subvol, NULL); + vol_args->fd, subvol, + NULL, false); kfree(vol_args); return ret; @@ -970,22 +977,27 @@ static noinline int btrfs_ioctl_snap_create_v2(struct file *file, int ret; u64 transid = 0; u64 *ptr = NULL; + bool readonly = false; vol_args = memdup_user(arg, sizeof(*vol_args)); if (IS_ERR(vol_args)) return PTR_ERR(vol_args); vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0'; - if (vol_args->flags & ~BTRFS_SUBVOL_CREATE_ASYNC) { - ret = -EINVAL; + if (vol_args->flags & + ~(BTRFS_SUBVOL_CREATE_ASYNC | BTRFS_SUBVOL_RDONLY)) { + ret = -EOPNOTSUPP; goto out; } if (vol_args->flags & BTRFS_SUBVOL_CREATE_ASYNC) ptr = &transid; + if (vol_args->flags & BTRFS_SUBVOL_RDONLY) + readonly = true; ret = btrfs_ioctl_snap_create_transid(file, vol_args->name, - vol_args->fd, subvol, ptr); + vol_args->fd, subvol, + ptr, readonly); if (ret == 0 && ptr && copy_to_user(arg + @@ -1505,6 +1517,9 @@ static int btrfs_ioctl_defrag(struct file *file, void __user *argp) struct btrfs_ioctl_defrag_range_args *range; int ret; + if (btrfs_root_readonly(root)) + return -EROFS; + ret = mnt_want_write(file->f_path.mnt); if (ret) return ret; @@ -1633,6 +1648,9 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd, if (!(file->f_mode & FMODE_WRITE) || (file->f_flags & O_APPEND)) return -EINVAL; + if (btrfs_root_readonly(root)) + return -EROFS; + ret = mnt_want_write(file->f_path.mnt); if (ret) return ret; @@ -1954,6 +1972,10 @@ static long btrfs_ioctl_trans_start(struct file *file) if (file->private_data) goto out; + ret = -EROFS; + if (btrfs_root_readonly(root)) + goto out; + ret = mnt_want_write(file->f_path.mnt); if (ret) goto out; -- cgit v1.1