On Tue, 25 Feb 2025, Al Viro wrote:
> Convert the last user (d_alloc_pseudo()) and be done with that.
> Any out-of-tree filesystem using it should switch to d_splice_alias_ops()
> or, better yet, check whether it really needs to have ->d_op vary among
> its dentries.
>
> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> ---
> Documentation/filesystems/porting.rst | 11 +++++++++++
> fs/dcache.c | 5 ++---
> include/linux/dcache.h | 1 -
> 3 files changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst
> index 004cd69617a2..61b5771dde53 100644
> --- a/Documentation/filesystems/porting.rst
> +++ b/Documentation/filesystems/porting.rst
> @@ -1164,3 +1164,14 @@ magic.
>
> If your filesystem sets the default dentry_operations, use set_default_d_op()
> rather than manually setting sb->s_d_op.
> +
> +---
> +
> +**mandatory**
> +
> +d_set_d_op() is no longer exported (or public, for that matter); _if_
> +your filesystem really needed that, make use of d_splice_alias_ops()
> +to have them set. Better yet, think hard whether you need different
> +->d_op for different dentries - if not, just use set_default_d_op()
> +at mount time and be done with that. Currently procfs is the only
> +thing that really needs ->d_op varying between dentries.
> diff --git a/fs/dcache.c b/fs/dcache.c
> index a4795617c3db..29db27228d97 100644
> --- a/fs/dcache.c
> +++ b/fs/dcache.c
> @@ -1796,7 +1796,7 @@ struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
> if (likely(dentry)) {
> dentry->d_flags |= DCACHE_NORCU;
> if (!dentry->d_op)
> - d_set_d_op(dentry, &anon_ops);
> + dentry->d_op = &anon_ops;
This is safe because d_op_flags(anon_ops) is zero so there is no need to
update dentry->d_flags. I wonder if that deserves a comment.
Thanks,
NeilBrown
> }
> return dentry;
> }
> @@ -1837,7 +1837,7 @@ static unsigned int d_op_flags(const struct dentry_operations *op)
> return flags;
> }
>
> -void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
> +static void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
> {
> unsigned int flags = d_op_flags(op);
> WARN_ON_ONCE(dentry->d_op);
> @@ -1846,7 +1846,6 @@ void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op)
> if (flags)
> dentry->d_flags |= flags;
> }
> -EXPORT_SYMBOL(d_set_d_op);
>
> void set_default_d_op(struct super_block *s, const struct dentry_operations *ops)
> {
> diff --git a/include/linux/dcache.h b/include/linux/dcache.h
> index e8cf1d0fdd08..5a03e85f92a4 100644
> --- a/include/linux/dcache.h
> +++ b/include/linux/dcache.h
> @@ -242,7 +242,6 @@ extern void d_instantiate_new(struct dentry *, struct inode *);
> extern void __d_drop(struct dentry *dentry);
> extern void d_drop(struct dentry *dentry);
> extern void d_delete(struct dentry *);
> -extern void d_set_d_op(struct dentry *dentry, const struct dentry_operations *op);
>
> /* allocate/de-allocate */
> extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
> --
> 2.39.5
>
>
