On Mon, Feb 24, 2025 at 09:20:38PM +0000, Al Viro wrote:
> No need to mess with ->d_op at all. Note that ->d_delete that always
> returns 1 is equivalent to having DCACHE_DONTCACHE in ->d_flags.
> Later the same thing will be placed into ->s_d_flags of the filesystems
> where we want that behaviour for all dentries; then the check in
> simple_lookup() will at least get unlikely() slapped on it.
>
> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> ---
Reviewed-by: Christian Brauner <brauner@xxxxxxxxxx>
> fs/libfs.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/fs/libfs.c b/fs/libfs.c
> index 929bef0fecbd..b15a2148714e 100644
> --- a/fs/libfs.c
> +++ b/fs/libfs.c
> @@ -75,9 +75,11 @@ struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned
> {
> if (dentry->d_name.len > NAME_MAX)
> return ERR_PTR(-ENAMETOOLONG);
> - if (!dentry->d_op)
> - d_set_d_op(dentry, &simple_dentry_operations);
> -
> + if (!(dentry->d_flags & DCACHE_DONTCACHE)) {
> + spin_lock(&dentry->d_lock);
> + dentry->d_flags |= DCACHE_DONTCACHE;
> + spin_unlock(&dentry->d_lock);
> + }
> if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
> return NULL;
>
> --
> 2.39.5
>
