btrfs: add support for RENAME_EXCHANGE and RENAME_WHITEOUT
Two new flags, RENAME_EXCHANGE and RENAME_WHITEOUT, provide for new
behavior in the renameat2() syscall. This behavior is primarily used by
overlayfs. This patch adds support for these flags to btrfs, enabling it to
be used as a fully functional upper layer for overlayfs.
RENAME_EXCHANGE support was written by Davide Italiano
<dccitaliano@gmail.com>, originally submitted on 2 April 2015.
Signed-off-by: Dan Fuhry <dfuhry@datto.com>
@@ -9220,8 +9220,246 @@ static int btrfs_getattr(struct vfsmount *mnt,
return 0;
}
+static int btrfs_rename_exchange(struct inode *old_dir,
+ struct dentry *old_dentry,
+ struct inode *new_dir,
+ struct dentry *new_dentry)
+{
+ struct btrfs_trans_handle *trans;
+ struct btrfs_root *root = BTRFS_I(old_dir)->root;
+ struct btrfs_root *dest = BTRFS_I(new_dir)->root;
+ struct inode *new_inode = new_dentry->d_inode;
+ struct inode *old_inode = old_dentry->d_inode;
+ struct timespec ctime = CURRENT_TIME;
+ struct dentry *parent;
+ u64 old_ino = btrfs_ino(old_inode);
+ u64 new_ino = btrfs_ino(new_inode);
+ u64 old_idx = 0;
+ u64 new_idx = 0;
+ u64 root_objectid;
+ int ret;
+
+ /* we only allow rename subvolume link between subvolumes */
+ if (old_ino != BTRFS_FIRST_FREE_OBJECTID && root != dest)
+ return -EXDEV;
+
+ /* close the racy window with snapshot create/destroy ioctl */
+ if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
+ down_read(&root->fs_info->subvol_sem);
+ if (new_ino == BTRFS_FIRST_FREE_OBJECTID)
+ down_read(&dest->fs_info->subvol_sem);
+
+ /*
+ * We want to reserve the absolute worst case amount of items. So if
+ * both inodes are subvols and we need to unlink them then that would
+ * require 4 item modifications, but if they are both normal inodes it
+ * would require 5 item modifications, so we'll assume their normal
+ * inodes. So 5 * 2 is 10, plus 2 for the new links, so 12 total items
+ * should cover the worst case number of items we'll modify.
+ */
+ trans = btrfs_start_transaction(root, 12);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ goto out_notrans;
+ }
+
+ /*
+ * We need to find a free sequence number both in the source and
+ * in the destination directory for the exchange.
+ */
+ ret = btrfs_set_inode_index(new_dir, &old_idx);
+ if (ret)
+ goto out_fail;
+ ret = btrfs_set_inode_index(old_dir, &new_idx);
+ if (ret)
+ goto out_fail;
+
+ BTRFS_I(old_inode)->dir_index = 0ULL;
+ BTRFS_I(new_inode)->dir_index = 0ULL;
+
+ /* Reference for the source. */
+ if (unlikely(old_ino == BTRFS_FIRST_FREE_OBJECTID)) {
+ /* force full log commit if subvolume involved. */
+ btrfs_set_log_full_commit(root->fs_info, trans);
+ } else {
+ ret = btrfs_insert_inode_ref(trans, dest,
+ new_dentry->d_name.name,
+ new_dentry->d_name.len,
+ old_ino,
+ btrfs_ino(new_dir), old_idx);
+ if (ret)
+ goto out_fail;
+ btrfs_pin_log_trans(root);
+ }
+
+ /* And now for the dest. */
+ if (unlikely(new_ino == BTRFS_FIRST_FREE_OBJECTID)) {
+ /* force full log commit if subvolume involved. */
+ btrfs_set_log_full_commit(dest->fs_info, trans);
+ } else {
+ ret = btrfs_insert_inode_ref(trans, root,
+ old_dentry->d_name.name,
+ old_dentry->d_name.len,
+ new_ino,
+ btrfs_ino(old_dir), new_idx);
+ if (ret)
+ goto out_fail;
+ btrfs_pin_log_trans(dest);
+ }
+
+ /*
+ * Update i-node version and ctime/mtime.
+ */
+ inode_inc_iversion(old_dir);
+ inode_inc_iversion(new_dir);
+ inode_inc_iversion(old_inode);
+ inode_inc_iversion(new_inode);
+ old_dir->i_ctime = old_dir->i_mtime = ctime;
+ new_dir->i_ctime = new_dir->i_mtime = ctime;
+ old_inode->i_ctime = ctime;
+ new_inode->i_ctime = ctime;
+
+ if (old_dentry->d_parent != new_dentry->d_parent) {
+ btrfs_record_unlink_dir(trans, old_dir, old_inode, 1);
+ btrfs_record_unlink_dir(trans, new_dir, new_inode, 1);
+ }
+
+ /* src is a subvolume */
+ if (unlikely(old_ino == BTRFS_FIRST_FREE_OBJECTID)) {
+ root_objectid = BTRFS_I(old_inode)->root->root_key.objectid;
+ ret = btrfs_unlink_subvol(trans, root, old_dir,
+ root_objectid,
+ old_dentry->d_name.name,
+ old_dentry->d_name.len);
+ } else { /* src is a inode */
+ ret = __btrfs_unlink_inode(trans, root, old_dir,
+ old_dentry->d_inode,
+ old_dentry->d_name.name,
+ old_dentry->d_name.len);
+ if (!ret)
+ ret = btrfs_update_inode(trans, root, old_inode);
+ }
+ if (ret) {
+ btrfs_abort_transaction(trans, root, ret);
+ goto out_fail;
+ }
+
+ /* dest is a subvolume */
+ if (unlikely(new_ino == BTRFS_FIRST_FREE_OBJECTID)) {
+ root_objectid = BTRFS_I(new_inode)->root->root_key.objectid;
+ ret = btrfs_unlink_subvol(trans, dest, new_dir,
+ root_objectid,
+ new_dentry->d_name.name,
+ new_dentry->d_name.len);
+ } else { /* dest is an inode */
+ ret = __btrfs_unlink_inode(trans, dest, new_dir,
+ new_dentry->d_inode,
+ new_dentry->d_name.name,
+ new_dentry->d_name.len);
+ if (!ret)
+ ret = btrfs_update_inode(trans, dest, new_inode);
+ }
+ if (ret) {
+ btrfs_abort_transaction(trans, root, ret);
+ goto out_fail;
+ }
+
+ ret = btrfs_add_link(trans, new_dir, old_inode,
+ new_dentry->d_name.name,
+ new_dentry->d_name.len, 0, old_idx);
+ if (ret) {
+ btrfs_abort_transaction(trans, root, ret);
+ goto out_fail;
+ }
+
+ ret = btrfs_add_link(trans, old_dir, new_inode,
+ old_dentry->d_name.name,
+ old_dentry->d_name.len, 0, new_idx);
+ if (ret) {
+ btrfs_abort_transaction(trans, root, ret);
+ goto out_fail;
+ }
+
+ if (old_inode->i_nlink == 1)
+ BTRFS_I(old_inode)->dir_index = old_idx;
+ if (new_inode->i_nlink == 1)
+ BTRFS_I(new_inode)->dir_index = new_idx;
+
+ if (old_ino != BTRFS_FIRST_FREE_OBJECTID) {
+ parent = new_dentry->d_parent;
+ btrfs_log_new_name(trans, old_inode, old_dir, parent);
+ btrfs_end_log_trans(root);
+ }
+ if (new_ino != BTRFS_FIRST_FREE_OBJECTID) {
+ parent = old_dentry->d_parent;
+ btrfs_log_new_name(trans, new_inode, new_dir, parent);
+ btrfs_end_log_trans(dest);
+ }
+out_fail:
+ ret = btrfs_end_transaction(trans, root);
+out_notrans:
+ if (new_ino == BTRFS_FIRST_FREE_OBJECTID)
+ up_read(&dest->fs_info->subvol_sem);
+ if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
+ up_read(&root->fs_info->subvol_sem);
+
+ return ret;
+}
+
+static int btrfs_whiteout_for_rename(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root,
+ struct inode *dir,
+ struct dentry *dentry)
+{
+ int ret;
+ struct inode *inode;
+ u64 objectid;
+ u64 index;
+
+ ret = btrfs_find_free_ino(root, &objectid);
+ if (ret)
+ return ret;
+
+ inode = btrfs_new_inode(trans, root, dir,
+ dentry->d_name.name,
+ dentry->d_name.len,
+ btrfs_ino(dir),
+ objectid,
+ S_IFCHR | WHITEOUT_MODE,
+ &index);
+
+ if (IS_ERR(inode)) {
+ ret = PTR_ERR(inode);
+ return ret;
+ }
+
+ inode->i_op = &btrfs_special_inode_operations;
+ init_special_inode(inode, inode->i_mode,
+ WHITEOUT_DEV);
+
+ ret = btrfs_init_inode_security(trans, inode, dir,
+ &dentry->d_name);
+ if (ret)
+ return ret;
+
+ ret = btrfs_add_nondir(trans, dir, dentry,
+ inode, 0, index);
+ if (ret)
+ return ret;
+
+ ret = btrfs_update_inode(trans, root, inode);
+ if (ret)
+ return ret;
+
+ unlock_new_inode(inode);
+ iput(inode);
+
+ return 0;
+}
+
static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
- struct inode *new_dir, struct dentry *new_dentry)
+ struct inode *new_dir, struct dentry *new_dentry,
+ unsigned int flags)
{
struct btrfs_trans_handle *trans;
struct btrfs_root *root = BTRFS_I(old_dir)->root;
@@ -9283,15 +9521,15 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
* We want to reserve the absolute worst case amount of items. So if
* both inodes are subvols and we need to unlink them then that would
* require 4 item modifications, but if they are both normal inodes it
- * would require 5 item modifications, so we'll assume their normal
+ * would require 5 item modifications, so we'll assume they are normal
* inodes. So 5 * 2 is 10, plus 1 for the new link, so 11 total items
* should cover the worst case number of items we'll modify.
*/
trans = btrfs_start_transaction(root, 11);
if (IS_ERR(trans)) {
- ret = PTR_ERR(trans);
- goto out_notrans;
- }
+ ret = PTR_ERR(trans);
+ goto out_notrans;
+ }
if (dest != root)
btrfs_record_root_in_trans(trans, dest);
@@ -9391,6 +9629,16 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
btrfs_log_new_name(trans, old_inode, old_dir, parent);
btrfs_end_log_trans(root);
}
+
+ if (flags & RENAME_WHITEOUT) {
+ ret = btrfs_whiteout_for_rename(trans, root, old_dir,
+ old_dentry);
+
+ if (ret) {
+ btrfs_abort_transaction(trans, root, ret);
+ goto out_fail;
+ }
+ }
out_fail:
btrfs_end_transaction(trans, root);
out_notrans:
@@ -9404,10 +9652,14 @@ static int btrfs_rename2(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry,
unsigned int flags)
{
- if (flags & ~RENAME_NOREPLACE)
+ if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
return -EINVAL;
- return btrfs_rename(old_dir, old_dentry, new_dir, new_dentry);
+ if (flags & RENAME_EXCHANGE)
+ return btrfs_rename_exchange(old_dir, old_dentry, new_dir,
+ new_dentry);
+
+ return btrfs_rename(old_dir, old_dentry, new_dir, new_dentry, flags);
}
static void btrfs_run_delalloc_work(struct btrfs_work *work)