int nfs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
	       struct dentry *old_dentry, struct inode *new_dir,
	       struct dentry *new_dentry, unsigned int flags)
{
	struct inode *old_inode = d_inode(old_dentry);
	struct inode *new_inode = d_inode(new_dentry);
	struct dentry *dentry = NULL, *rehash = NULL;
	struct rpc_task *task;
	int error = -EBUSY;

	if (flags)
		return -EINVAL;

	dfprintk(VFS, "NFS: rename(%pd2 -> %pd2, ct=%d)\n",
		 old_dentry, new_dentry,
		 d_count(new_dentry));

	trace_nfs_rename_enter(old_dir, old_dentry, new_dir, new_dentry);
	/*
	 * For non-directories, check whether the target is busy and if so,
	 * make a copy of the dentry and then do a silly-rename. If the
	 * silly-rename succeeds, the copied dentry is hashed and becomes
	 * the new target.
	 */
	if (new_inode && !S_ISDIR(new_inode->i_mode)) {
		/*
		 * To prevent any new references to the target during the
		 * rename, we unhash the dentry in advance.
		 */
		if (!d_unhashed(new_dentry)) {
			d_drop(new_dentry);
			rehash = new_dentry;
		}

		if (d_count(new_dentry) > 2) {
			int err;

			/* copy the target dentry's name */
			dentry = d_alloc(new_dentry->d_parent,
					 &new_dentry->d_name);
			if (!dentry)
				goto out;

			/* silly-rename the existing target ... */
			err = nfs_sillyrename(new_dir, new_dentry);
			if (err)
				goto out;

			new_dentry = dentry;
			rehash = NULL;
			new_inode = NULL;
		}
	}

	if (S_ISREG(old_inode->i_mode))
		nfs_sync_inode(old_inode);
	task = nfs_async_rename(old_dir, new_dir, old_dentry, new_dentry, NULL);
	if (IS_ERR(task)) {
		error = PTR_ERR(task);
		goto out;
	}

	error = rpc_wait_for_completion_task(task);
	if (error != 0) {
		((struct nfs_renamedata *)task->tk_calldata)->cancelled = 1;
		/* Paired with the atomic_dec_and_test() barrier in rpc_do_put_task() */
		smp_wmb();
	} else
		error = task->tk_status;
	rpc_put_task(task);
	/* Ensure the inode attributes are revalidated */
	if (error == 0) {
		spin_lock(&old_inode->i_lock);
		NFS_I(old_inode)->attr_gencount = nfs_inc_attr_generation_counter();
		nfs_set_cache_invalid(old_inode, NFS_INO_INVALID_CHANGE |
							 NFS_INO_INVALID_CTIME |
							 NFS_INO_REVAL_FORCED);
		spin_unlock(&old_inode->i_lock);
	}
out:
	if (rehash)
		d_rehash(rehash);
	trace_nfs_rename_exit(old_dir, old_dentry,
			new_dir, new_dentry, error);
	if (!error) {
		if (new_inode != NULL)
			nfs_drop_nlink(new_inode);
		/*
		 * The d_move() should be here instead of in an async RPC completion
		 * handler because we need the proper locks to move the dentry.  If
		 * we're interrupted by a signal, the async RPC completion handler
		 * should mark the directories for revalidation.
		 */
		d_move(old_dentry, new_dentry);
		nfs_set_verifier(old_dentry,
					nfs_save_change_attribute(new_dir));
	} else if (error == -ENOENT)
		nfs_dentry_handle_enoent(old_dentry);

	/* new dentry created? */
	if (dentry)
		dput(dentry);
	return error;
}
Unknown