forked from Minki/linux
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 originally submitted on 2 April 2015. Signed-off-by: Davide Italiano <dccitaliano@gmail.com> Signed-off-by: Dan Fuhry <dfuhry@datto.com> [ remove unlikely ] Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Filipe Manana <fdmanana@suse.com>
This commit is contained in:
Dan Fuhry
Filipe Manana
parent
c4aba95454
commit
cdd1fedf82
264
fs/btrfs/inode.c
264
fs/btrfs/inode.c
@ -9394,8 +9394,244 @@ static int btrfs_getattr(struct vfsmount *mnt,
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return 0;
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}
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static int btrfs_rename_exchange(struct inode *old_dir,
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struct dentry *old_dentry,
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struct inode *new_dir,
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struct dentry *new_dentry)
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{
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struct btrfs_trans_handle *trans;
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struct btrfs_root *root = BTRFS_I(old_dir)->root;
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struct btrfs_root *dest = BTRFS_I(new_dir)->root;
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struct inode *new_inode = new_dentry->d_inode;
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struct inode *old_inode = old_dentry->d_inode;
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struct timespec ctime = CURRENT_TIME;
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struct dentry *parent;
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u64 old_ino = btrfs_ino(old_inode);
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u64 new_ino = btrfs_ino(new_inode);
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u64 old_idx = 0;
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u64 new_idx = 0;
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u64 root_objectid;
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int ret;
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/* we only allow rename subvolume link between subvolumes */
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if (old_ino != BTRFS_FIRST_FREE_OBJECTID && root != dest)
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return -EXDEV;
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/* close the race window with snapshot create/destroy ioctl */
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if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
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down_read(&root->fs_info->subvol_sem);
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if (new_ino == BTRFS_FIRST_FREE_OBJECTID)
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down_read(&dest->fs_info->subvol_sem);
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/*
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* We want to reserve the absolute worst case amount of items. So if
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* both inodes are subvols and we need to unlink them then that would
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* require 4 item modifications, but if they are both normal inodes it
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* would require 5 item modifications, so we'll assume their normal
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* inodes. So 5 * 2 is 10, plus 2 for the new links, so 12 total items
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* should cover the worst case number of items we'll modify.
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*/
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trans = btrfs_start_transaction(root, 12);
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if (IS_ERR(trans)) {
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ret = PTR_ERR(trans);
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goto out_notrans;
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}
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/*
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* We need to find a free sequence number both in the source and
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* in the destination directory for the exchange.
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*/
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ret = btrfs_set_inode_index(new_dir, &old_idx);
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if (ret)
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goto out_fail;
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ret = btrfs_set_inode_index(old_dir, &new_idx);
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if (ret)
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goto out_fail;
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BTRFS_I(old_inode)->dir_index = 0ULL;
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BTRFS_I(new_inode)->dir_index = 0ULL;
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/* Reference for the source. */
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if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
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/* force full log commit if subvolume involved. */
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btrfs_set_log_full_commit(root->fs_info, trans);
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} else {
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ret = btrfs_insert_inode_ref(trans, dest,
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new_dentry->d_name.name,
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new_dentry->d_name.len,
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old_ino,
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btrfs_ino(new_dir), old_idx);
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if (ret)
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goto out_fail;
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btrfs_pin_log_trans(root);
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}
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/* And now for the dest. */
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if (new_ino == BTRFS_FIRST_FREE_OBJECTID) {
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/* force full log commit if subvolume involved. */
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btrfs_set_log_full_commit(dest->fs_info, trans);
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} else {
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ret = btrfs_insert_inode_ref(trans, root,
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old_dentry->d_name.name,
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old_dentry->d_name.len,
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new_ino,
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btrfs_ino(old_dir), new_idx);
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if (ret)
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goto out_fail;
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btrfs_pin_log_trans(dest);
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}
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/* Update inode version and ctime/mtime. */
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inode_inc_iversion(old_dir);
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inode_inc_iversion(new_dir);
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inode_inc_iversion(old_inode);
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inode_inc_iversion(new_inode);
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old_dir->i_ctime = old_dir->i_mtime = ctime;
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new_dir->i_ctime = new_dir->i_mtime = ctime;
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old_inode->i_ctime = ctime;
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new_inode->i_ctime = ctime;
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if (old_dentry->d_parent != new_dentry->d_parent) {
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btrfs_record_unlink_dir(trans, old_dir, old_inode, 1);
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btrfs_record_unlink_dir(trans, new_dir, new_inode, 1);
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}
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/* src is a subvolume */
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if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
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root_objectid = BTRFS_I(old_inode)->root->root_key.objectid;
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ret = btrfs_unlink_subvol(trans, root, old_dir,
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root_objectid,
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old_dentry->d_name.name,
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old_dentry->d_name.len);
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} else { /* src is an inode */
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ret = __btrfs_unlink_inode(trans, root, old_dir,
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old_dentry->d_inode,
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old_dentry->d_name.name,
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old_dentry->d_name.len);
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if (!ret)
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ret = btrfs_update_inode(trans, root, old_inode);
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}
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if (ret) {
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btrfs_abort_transaction(trans, root, ret);
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goto out_fail;
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}
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/* dest is a subvolume */
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if (new_ino == BTRFS_FIRST_FREE_OBJECTID) {
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root_objectid = BTRFS_I(new_inode)->root->root_key.objectid;
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ret = btrfs_unlink_subvol(trans, dest, new_dir,
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root_objectid,
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new_dentry->d_name.name,
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new_dentry->d_name.len);
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} else { /* dest is an inode */
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ret = __btrfs_unlink_inode(trans, dest, new_dir,
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new_dentry->d_inode,
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new_dentry->d_name.name,
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new_dentry->d_name.len);
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if (!ret)
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ret = btrfs_update_inode(trans, dest, new_inode);
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}
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if (ret) {
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btrfs_abort_transaction(trans, root, ret);
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goto out_fail;
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}
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ret = btrfs_add_link(trans, new_dir, old_inode,
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new_dentry->d_name.name,
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new_dentry->d_name.len, 0, old_idx);
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if (ret) {
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btrfs_abort_transaction(trans, root, ret);
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goto out_fail;
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}
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ret = btrfs_add_link(trans, old_dir, new_inode,
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old_dentry->d_name.name,
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old_dentry->d_name.len, 0, new_idx);
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if (ret) {
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btrfs_abort_transaction(trans, root, ret);
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goto out_fail;
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}
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if (old_inode->i_nlink == 1)
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BTRFS_I(old_inode)->dir_index = old_idx;
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if (new_inode->i_nlink == 1)
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BTRFS_I(new_inode)->dir_index = new_idx;
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if (old_ino != BTRFS_FIRST_FREE_OBJECTID) {
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parent = new_dentry->d_parent;
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btrfs_log_new_name(trans, old_inode, old_dir, parent);
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btrfs_end_log_trans(root);
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}
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if (new_ino != BTRFS_FIRST_FREE_OBJECTID) {
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parent = old_dentry->d_parent;
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btrfs_log_new_name(trans, new_inode, new_dir, parent);
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btrfs_end_log_trans(dest);
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}
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out_fail:
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ret = btrfs_end_transaction(trans, root);
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out_notrans:
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if (new_ino == BTRFS_FIRST_FREE_OBJECTID)
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up_read(&dest->fs_info->subvol_sem);
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if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
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up_read(&root->fs_info->subvol_sem);
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return ret;
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}
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static int btrfs_whiteout_for_rename(struct btrfs_trans_handle *trans,
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struct btrfs_root *root,
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struct inode *dir,
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struct dentry *dentry)
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{
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int ret;
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struct inode *inode;
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u64 objectid;
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u64 index;
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ret = btrfs_find_free_ino(root, &objectid);
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if (ret)
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return ret;
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inode = btrfs_new_inode(trans, root, dir,
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dentry->d_name.name,
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dentry->d_name.len,
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btrfs_ino(dir),
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objectid,
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S_IFCHR | WHITEOUT_MODE,
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&index);
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if (IS_ERR(inode)) {
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ret = PTR_ERR(inode);
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return ret;
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}
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inode->i_op = &btrfs_special_inode_operations;
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init_special_inode(inode, inode->i_mode,
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WHITEOUT_DEV);
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ret = btrfs_init_inode_security(trans, inode, dir,
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&dentry->d_name);
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if (ret)
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return ret;
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ret = btrfs_add_nondir(trans, dir, dentry,
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inode, 0, index);
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if (ret)
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return ret;
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ret = btrfs_update_inode(trans, root, inode);
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if (ret)
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return ret;
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unlock_new_inode(inode);
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iput(inode);
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return 0;
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}
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static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
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struct inode *new_dir, struct dentry *new_dentry)
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struct inode *new_dir, struct dentry *new_dentry,
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unsigned int flags)
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{
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struct btrfs_trans_handle *trans;
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struct btrfs_root *root = BTRFS_I(old_dir)->root;
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@ -9457,15 +9693,15 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
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* We want to reserve the absolute worst case amount of items. So if
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* both inodes are subvols and we need to unlink them then that would
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* require 4 item modifications, but if they are both normal inodes it
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* would require 5 item modifications, so we'll assume their normal
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* would require 5 item modifications, so we'll assume they are normal
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* inodes. So 5 * 2 is 10, plus 1 for the new link, so 11 total items
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* should cover the worst case number of items we'll modify.
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*/
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trans = btrfs_start_transaction(root, 11);
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if (IS_ERR(trans)) {
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ret = PTR_ERR(trans);
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goto out_notrans;
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}
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ret = PTR_ERR(trans);
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goto out_notrans;
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}
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if (dest != root)
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btrfs_record_root_in_trans(trans, dest);
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@ -9561,6 +9797,16 @@ static int btrfs_rename(struct inode *old_dir, struct dentry *old_dentry,
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btrfs_end_log_trans(root);
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log_pinned = false;
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}
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if (flags & RENAME_WHITEOUT) {
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ret = btrfs_whiteout_for_rename(trans, root, old_dir,
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old_dentry);
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if (ret) {
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btrfs_abort_transaction(trans, root, ret);
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goto out_fail;
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}
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}
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out_fail:
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/*
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* If we have pinned the log and an error happened, we unpin tasks
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@ -9596,10 +9842,14 @@ static int btrfs_rename2(struct inode *old_dir, struct dentry *old_dentry,
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struct inode *new_dir, struct dentry *new_dentry,
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unsigned int flags)
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{
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if (flags & ~RENAME_NOREPLACE)
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if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
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return -EINVAL;
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return btrfs_rename(old_dir, old_dentry, new_dir, new_dentry);
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if (flags & RENAME_EXCHANGE)
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return btrfs_rename_exchange(old_dir, old_dentry, new_dir,
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new_dentry);
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return btrfs_rename(old_dir, old_dentry, new_dir, new_dentry, flags);
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}
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static void btrfs_run_delalloc_work(struct btrfs_work *work)
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