Re: [PATCH v3 05/38] vfs: allow rmdir to wait for delegation break on parent

[Jeff Layton <jlayton@kernel.org>]

On Wed, 2025-09-24 at 14:05 -0400, Jeff Layton wrote:
> In order to add directory delegation support, we need to break
> delegations on the parent whenever there is going to be a change in the
> directory.
> 
> Rename vfs_rmdir as __vfs_rmdir, make it static and add a new
> delegated_inode parameter. Add a vfs_rmdir wrapper that passes in a NULL
> pointer for it. Add the necessary try_break_deleg calls to
> __vfs_rmdir(). Convert do_rmdir to use __vfs_rmdir and wait for the
> delegation break to complete before proceeding.
> 

I've fixed this patch along the lines of the vfs_mkdir() patch
(eliminating the wrapper and just adding the extra parameter). The
updated patch is in my dir-deleg branch.

> Signed-off-by: Jeff Layton <jlayton@kernel.org>
> ---
>  fs/namei.c | 51 ++++++++++++++++++++++++++++++++++-----------------
>  1 file changed, 34 insertions(+), 17 deletions(-)
> 
> diff --git a/fs/namei.c b/fs/namei.c
> index c939a58f16f9c4edded424475aff52f2c423d301..4e058b00208c1663ba828c6f8ed1f82c26a4f136 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -4433,22 +4433,8 @@ SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode)
>  	return do_mkdirat(AT_FDCWD, getname(pathname), mode);
>  }
>  
> -/**
> - * vfs_rmdir - remove directory
> - * @idmap:	idmap of the mount the inode was found from
> - * @dir:	inode of the parent directory
> - * @dentry:	dentry of the child directory
> - *
> - * Remove a directory.
> - *
> - * If the inode has been found through an idmapped mount the idmap of
> - * the vfsmount must be passed through @idmap. This function will then take
> - * care to map the inode according to @idmap before checking permissions.
> - * On non-idmapped mounts or if permission checking is to be performed on the
> - * raw inode simply pass @nop_mnt_idmap.
> - */
> -int vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir,
> -		     struct dentry *dentry)
> +static int __vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir,
> +		       struct dentry *dentry, struct inode **delegated_inode)
>  {
>  	int error = may_delete(idmap, dir, dentry, 1);
>  
> @@ -4470,6 +4456,10 @@ int vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir,
>  	if (error)
>  		goto out;
>  
> +	error = try_break_deleg(dir, delegated_inode);
> +	if (error)
> +		goto out;
> +
>  	error = dir->i_op->rmdir(dir, dentry);
>  	if (error)
>  		goto out;
> @@ -4486,6 +4476,26 @@ int vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir,
>  		d_delete_notify(dir, dentry);
>  	return error;
>  }
> +
> +/**
> + * vfs_rmdir - remove directory
> + * @idmap:	idmap of the mount the inode was found from
> + * @dir:	inode of the parent directory
> + * @dentry:	dentry of the child directory
> + *
> + * Remove a directory.
> + *
> + * If the inode has been found through an idmapped mount the idmap of
> + * the vfsmount must be passed through @idmap. This function will then take
> + * care to map the inode according to @idmap before checking permissions.
> + * On non-idmapped mounts or if permission checking is to be performed on the
> + * raw inode simply pass @nop_mnt_idmap.
> + */
> +int vfs_rmdir(struct mnt_idmap *idmap, struct inode *dir,
> +		     struct dentry *dentry)
> +{
> +	return __vfs_rmdir(idmap, dir, dentry, NULL);
> +}
>  EXPORT_SYMBOL(vfs_rmdir);
>  
>  int do_rmdir(int dfd, struct filename *name)
> @@ -4496,6 +4506,7 @@ int do_rmdir(int dfd, struct filename *name)
>  	struct qstr last;
>  	int type;
>  	unsigned int lookup_flags = 0;
> +	struct inode *delegated_inode = NULL;
>  retry:
>  	error = filename_parentat(dfd, name, lookup_flags, &path, &last, &type);
>  	if (error)
> @@ -4525,7 +4536,8 @@ int do_rmdir(int dfd, struct filename *name)
>  	error = security_path_rmdir(&path, dentry);
>  	if (error)
>  		goto exit4;
> -	error = vfs_rmdir(mnt_idmap(path.mnt), path.dentry->d_inode, dentry);
> +	error = __vfs_rmdir(mnt_idmap(path.mnt), path.dentry->d_inode,
> +			    dentry, &delegated_inode);
>  exit4:
>  	dput(dentry);
>  exit3:
> @@ -4533,6 +4545,11 @@ int do_rmdir(int dfd, struct filename *name)
>  	mnt_drop_write(path.mnt);
>  exit2:
>  	path_put(&path);
> +	if (delegated_inode) {
> +		error = break_deleg_wait(&delegated_inode);
> +		if (!error)
> +			goto retry;
> +	}
>  	if (retry_estale(error, lookup_flags)) {
>  		lookup_flags |= LOOKUP_REVAL;
>  		goto retry;

-- 
Jeff Layton <jlayton@kernel.org>