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 <lizf@cn.fujitsu.com>
This commit is contained in:
Li Zefan
parent
fa0d2b9bd7
commit
b83cc9693f
@ -597,6 +597,8 @@ struct btrfs_dir_item {
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u8 type;
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} __attribute__ ((__packed__));
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#define BTRFS_ROOT_SUBVOL_RDONLY (1ULL << 0)
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struct btrfs_root_item {
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struct btrfs_inode_item inode;
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__le64 generation;
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@ -1893,6 +1895,11 @@ BTRFS_SETGET_STACK_FUNCS(root_limit, struct btrfs_root_item, byte_limit, 64);
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BTRFS_SETGET_STACK_FUNCS(root_last_snapshot, struct btrfs_root_item,
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last_snapshot, 64);
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static inline bool btrfs_root_readonly(struct btrfs_root *root)
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{
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return root->root_item.flags & BTRFS_ROOT_SUBVOL_RDONLY;
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}
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/* struct btrfs_super_block */
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BTRFS_SETGET_STACK_FUNCS(super_bytenr, struct btrfs_super_block, bytenr, 64);
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@ -3671,8 +3671,12 @@ static int btrfs_setattr_size(struct inode *inode, struct iattr *attr)
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static int btrfs_setattr(struct dentry *dentry, struct iattr *attr)
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{
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struct inode *inode = dentry->d_inode;
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struct btrfs_root *root = BTRFS_I(inode)->root;
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int err;
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if (btrfs_root_readonly(root))
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return -EROFS;
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err = inode_change_ok(inode, attr);
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if (err)
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return err;
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@ -7206,6 +7210,10 @@ static int btrfs_set_page_dirty(struct page *page)
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static int btrfs_permission(struct inode *inode, int mask)
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{
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struct btrfs_root *root = BTRFS_I(inode)->root;
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if (btrfs_root_readonly(root) && (mask & MAY_WRITE))
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return -EROFS;
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if ((BTRFS_I(inode)->flags & BTRFS_INODE_READONLY) && (mask & MAY_WRITE))
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return -EACCES;
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return generic_permission(inode, mask, btrfs_check_acl);
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@ -147,6 +147,9 @@ static int btrfs_ioctl_setflags(struct file *file, void __user *arg)
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unsigned int flags, oldflags;
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int ret;
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if (btrfs_root_readonly(root))
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return -EROFS;
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if (copy_from_user(&flags, arg, sizeof(flags)))
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return -EFAULT;
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@ -360,7 +363,8 @@ fail:
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}
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static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
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char *name, int namelen, u64 *async_transid)
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char *name, int namelen, u64 *async_transid,
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bool readonly)
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{
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struct inode *inode;
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struct dentry *parent;
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@ -378,6 +382,7 @@ static int create_snapshot(struct btrfs_root *root, struct dentry *dentry,
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btrfs_init_block_rsv(&pending_snapshot->block_rsv);
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pending_snapshot->dentry = dentry;
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pending_snapshot->root = root;
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pending_snapshot->readonly = readonly;
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trans = btrfs_start_transaction(root->fs_info->extent_root, 5);
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if (IS_ERR(trans)) {
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@ -509,7 +514,7 @@ static inline int btrfs_may_create(struct inode *dir, struct dentry *child)
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static noinline int btrfs_mksubvol(struct path *parent,
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char *name, int namelen,
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struct btrfs_root *snap_src,
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u64 *async_transid)
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u64 *async_transid, bool readonly)
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{
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struct inode *dir = parent->dentry->d_inode;
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struct dentry *dentry;
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@ -541,7 +546,7 @@ static noinline int btrfs_mksubvol(struct path *parent,
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if (snap_src) {
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error = create_snapshot(snap_src, dentry,
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name, namelen, async_transid);
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name, namelen, async_transid, readonly);
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} else {
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error = create_subvol(BTRFS_I(dir)->root, dentry,
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name, namelen, async_transid);
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@ -901,7 +906,8 @@ static noinline int btrfs_ioctl_snap_create_transid(struct file *file,
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char *name,
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unsigned long fd,
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int subvol,
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u64 *transid)
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u64 *transid,
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bool readonly)
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{
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struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
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struct file *src_file;
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@ -919,7 +925,7 @@ static noinline int btrfs_ioctl_snap_create_transid(struct file *file,
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if (subvol) {
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ret = btrfs_mksubvol(&file->f_path, name, namelen,
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NULL, transid);
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NULL, transid, readonly);
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} else {
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struct inode *src_inode;
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src_file = fget(fd);
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@ -938,7 +944,7 @@ static noinline int btrfs_ioctl_snap_create_transid(struct file *file,
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}
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ret = btrfs_mksubvol(&file->f_path, name, namelen,
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BTRFS_I(src_inode)->root,
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transid);
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transid, readonly);
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fput(src_file);
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}
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out:
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@ -957,7 +963,8 @@ static noinline int btrfs_ioctl_snap_create(struct file *file,
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vol_args->name[BTRFS_PATH_NAME_MAX] = '\0';
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ret = btrfs_ioctl_snap_create_transid(file, vol_args->name,
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vol_args->fd, subvol, NULL);
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vol_args->fd, subvol,
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NULL, false);
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kfree(vol_args);
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return ret;
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@ -970,22 +977,27 @@ static noinline int btrfs_ioctl_snap_create_v2(struct file *file,
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int ret;
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u64 transid = 0;
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u64 *ptr = NULL;
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bool readonly = false;
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vol_args = memdup_user(arg, sizeof(*vol_args));
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if (IS_ERR(vol_args))
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return PTR_ERR(vol_args);
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vol_args->name[BTRFS_SUBVOL_NAME_MAX] = '\0';
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if (vol_args->flags & ~BTRFS_SUBVOL_CREATE_ASYNC) {
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ret = -EINVAL;
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if (vol_args->flags &
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~(BTRFS_SUBVOL_CREATE_ASYNC | BTRFS_SUBVOL_RDONLY)) {
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ret = -EOPNOTSUPP;
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goto out;
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}
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if (vol_args->flags & BTRFS_SUBVOL_CREATE_ASYNC)
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ptr = &transid;
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if (vol_args->flags & BTRFS_SUBVOL_RDONLY)
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readonly = true;
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ret = btrfs_ioctl_snap_create_transid(file, vol_args->name,
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vol_args->fd, subvol, ptr);
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vol_args->fd, subvol,
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ptr, readonly);
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if (ret == 0 && ptr &&
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copy_to_user(arg +
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@ -1505,6 +1517,9 @@ static int btrfs_ioctl_defrag(struct file *file, void __user *argp)
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struct btrfs_ioctl_defrag_range_args *range;
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int ret;
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if (btrfs_root_readonly(root))
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return -EROFS;
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ret = mnt_want_write(file->f_path.mnt);
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if (ret)
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return ret;
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@ -1633,6 +1648,9 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
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if (!(file->f_mode & FMODE_WRITE) || (file->f_flags & O_APPEND))
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return -EINVAL;
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if (btrfs_root_readonly(root))
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return -EROFS;
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ret = mnt_want_write(file->f_path.mnt);
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if (ret)
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return ret;
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@ -1954,6 +1972,10 @@ static long btrfs_ioctl_trans_start(struct file *file)
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if (file->private_data)
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goto out;
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ret = -EROFS;
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if (btrfs_root_readonly(root))
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goto out;
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ret = mnt_want_write(file->f_path.mnt);
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if (ret)
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goto out;
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@ -31,6 +31,7 @@ struct btrfs_ioctl_vol_args {
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};
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#define BTRFS_SUBVOL_CREATE_ASYNC (1ULL << 0)
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#define BTRFS_SUBVOL_RDONLY (1ULL << 1)
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#define BTRFS_SUBVOL_NAME_MAX 4039
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struct btrfs_ioctl_vol_args_v2 {
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@ -910,6 +910,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
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u64 to_reserve = 0;
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u64 index = 0;
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u64 objectid;
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u64 root_flags;
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new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
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if (!new_root_item) {
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@ -967,6 +968,13 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
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btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
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memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
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root_flags = btrfs_root_flags(new_root_item);
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if (pending->readonly)
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root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
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else
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root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
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btrfs_set_root_flags(new_root_item, root_flags);
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old = btrfs_lock_root_node(root);
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btrfs_cow_block(trans, root, old, NULL, 0, &old);
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btrfs_set_lock_blocking(old);
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@ -62,6 +62,7 @@ struct btrfs_pending_snapshot {
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struct btrfs_block_rsv block_rsv;
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/* extra metadata reseration for relocation */
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int error;
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bool readonly;
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struct list_head list;
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};
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@ -316,6 +316,15 @@ ssize_t btrfs_getxattr(struct dentry *dentry, const char *name,
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int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
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size_t size, int flags)
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{
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struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;
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/*
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* The permission on security.* and system.* is not checked
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* in permission().
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*/
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if (btrfs_root_readonly(root))
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return -EROFS;
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/*
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* If this is a request for a synthetic attribute in the system.*
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* namespace use the generic infrastructure to resolve a handler
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@ -336,6 +345,15 @@ int btrfs_setxattr(struct dentry *dentry, const char *name, const void *value,
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int btrfs_removexattr(struct dentry *dentry, const char *name)
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{
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struct btrfs_root *root = BTRFS_I(dentry->d_inode)->root;
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/*
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* The permission on security.* and system.* is not checked
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* in permission().
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*/
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if (btrfs_root_readonly(root))
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return -EROFS;
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/*
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* If this is a request for a synthetic attribute in the system.*
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* namespace use the generic infrastructure to resolve a handler
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