Re: [PATCH v5 14/14] VFS: introduce end_creating_keep()

Jeff Layton
2025-11-12T19:46:44Z

On Thu, 2025-11-06 at 11:50 +1100, NeilBrown wrote:
> From: NeilBrown <neil@brown.name>
>
> Occasionally the caller of end_creating() wants to keep using the dentry.
> Rather then requiring them to dget() the dentry (when not an error)
> before calling end_creating(), provide end_creating_keep() which does
> this.
>
> cachefiles and overlayfs make use of this.
>
> Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> Signed-off-by: NeilBrown <neil@brown.name>
> ---
> fs/cachefiles/namei.c | 3 +--
> fs/overlayfs/dir.c | 8 ++------
> fs/overlayfs/super.c | 11 +++--------
> include/linux/namei.h | 22 ++++++++++++++++++++++
> 4 files changed, 28 insertions(+), 16 deletions(-)
>
> diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
> index 59327618ac42..ef22ac19545b 100644
> --- a/fs/cachefiles/namei.c
> +++ b/fs/cachefiles/namei.c
> @@ -155,8 +155,7 @@ struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
>
> /* Tell rmdir() it's not allowed to delete the subdir */
> inode_lock(d_inode(subdir));
> - dget(subdir);
> - end_creating(subdir);
> + end_creating_keep(subdir);
>
> if (!__cachefiles_mark_inode_in_use(NULL, d_inode(subdir))) {
> pr_notice("cachefiles: Inode already in use: %pd (B=%lx)\n",
> diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
> index a4a0dc261310..50717ff8cac7 100644
> --- a/fs/overlayfs/dir.c
> +++ b/fs/overlayfs/dir.c
> @@ -252,10 +252,7 @@ struct dentry *ovl_create_temp(struct ovl_fs *ofs, struct dentry *workdir,
> if (IS_ERR(ret))
> return ret;
> ret = ovl_create_real(ofs, workdir, ret, attr);
> - if (!IS_ERR(ret))
> - dget(ret);
> - end_creating(ret);
> - return ret;
> + return end_creating_keep(ret);
> }
>
> static int ovl_set_opaque_xerr(struct dentry *dentry, struct dentry *upper,
> @@ -365,8 +362,7 @@ static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
> if (IS_ERR(newdentry))
> return PTR_ERR(newdentry);
>
> - dget(newdentry);
> - end_creating(newdentry);
> + end_creating_keep(newdentry);
>
> if (ovl_type_merge(dentry->d_parent) && d_is_dir(newdentry) &&
> !ovl_allow_offline_changes(ofs)) {
> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
> index 3acda985c8a3..7b8fc1cab6eb 100644
> --- a/fs/overlayfs/super.c
> +++ b/fs/overlayfs/super.c
> @@ -319,8 +319,7 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
> };
>
> if (work->d_inode) {
> - dget(work);
> - end_creating(work);
> + end_creating_keep(work);
> if (persist)
> return work;
> err = -EEXIST;
> @@ -336,9 +335,7 @@ static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
> }
>
> work = ovl_do_mkdir(ofs, dir, work, attr.ia_mode);
> - if (!IS_ERR(work))
> - dget(work);
> - end_creating(work);
> + end_creating_keep(work);
> err = PTR_ERR(work);
> if (IS_ERR(work))
> goto out_err;
> @@ -630,9 +627,7 @@ static struct dentry *ovl_lookup_or_create(struct ovl_fs *ofs,
> if (!child->d_inode)
> child = ovl_create_real(ofs, parent, child,
> OVL_CATTR(mode));
> - if (!IS_ERR(child))
> - dget(child);
> - end_creating(child);
> + end_creating_keep(child);
> }
> dput(parent);
>
> diff --git a/include/linux/namei.h b/include/linux/namei.h
> index b4d95b79b5a8..58600cf234bc 100644
> --- a/include/linux/namei.h
> +++ b/include/linux/namei.h
> @@ -126,6 +126,28 @@ static inline void end_creating(struct dentry *child)
> end_dirop(child);
> }
>
> +/* end_creating_keep - finish action started with start_creating() and return result
> + * @child: dentry returned by start_creating() or vfs_mkdir()
> + *
> + * Unlock and return the child. This can be called after
> + * start_creating() whether that function succeeded or not,
> + * but it is not needed on failure.
> + *
> + * If vfs_mkdir() was called then the value returned from that function
> + * should be given for @child rather than the original dentry, as vfs_mkdir()
> + * may have provided a new dentry.
> + *
> + * Returns: @child, which may be a dentry or an error.
> + *
> + */
> +static inline struct dentry *end_creating_keep(struct dentry *child)
> +{
> + if (!IS_ERR(child))
> + dget(child);
> + end_dirop(child);
> + return child;
> +}
> +
> /**
> * end_removing - finish action started with start_removing
> * @child: dentry returned by start_removing()

Reviewed-by: Jeff Layton <jlayton@kernel.org>