Re: [PATCH RFC 08/24] vfs: make vfs_mknod break delegations on parent directory

Christian Brauner
2024-03-20T13:42:53Z

> int vfs_mknod(struct mnt_idmap *, struct inode *, struct dentry *,
> - umode_t, dev_t);
> + umode_t, dev_t, struct inode **);

So we will have at least the following helpers with an additional
delegated inode argument.

vfs_unlink()
vfs_link()
notify_change()
vfs_create()
vfs_mknod()
vfs_mkdir()
vfs_rmdir()

From looking at callers all these helpers will be called with non-NULL
delegated inode argument in vfs only. Unless it is generally conceivable
that other callers will want to pass a non-NULL inode argument over time
it might make more sense to add vfs_<operation>_delegated() or
__vfs_<operation>() and make vfs_mknod() and friends exported wrappers
around it.

I mean it's a matter of preference ultimately but this seems cleaner to
me. So at least for the new ones we should consider it. Would also make
the patch smaller.

> int vfs_symlink(struct mnt_idmap *, struct inode *,
> struct dentry *, const char *);
> int vfs_link(struct dentry *, struct mnt_idmap *, struct inode *,
> @@ -1879,7 +1879,7 @@ static inline int vfs_whiteout(struct mnt_idmap *idmap,
> struct inode *dir, struct dentry *dentry)
> {
> return vfs_mknod(idmap, dir, dentry, S_IFCHR | WHITEOUT_MODE,
> - WHITEOUT_DEV);
> + WHITEOUT_DEV, NULL);
> }
>
> struct file *kernel_tmpfile_open(struct mnt_idmap *idmap,
> diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
> index 0748e7ea5210..34fbcc90c984 100644
> --- a/net/unix/af_unix.c
> +++ b/net/unix/af_unix.c
> @@ -1227,7 +1227,7 @@ static int unix_bind_bsd(struct sock *sk, struct sockaddr_un *sunaddr,
> idmap = mnt_idmap(parent.mnt);
> err = security_path_mknod(&parent, dentry, mode, 0);
> if (!err)
> - err = vfs_mknod(idmap, d_inode(parent.dentry), dentry, mode, 0);
> + err = vfs_mknod(idmap, d_inode(parent.dentry), dentry, mode, 0, NULL);
> if (err)
> goto out_path;
> err = mutex_lock_interruptible(&u->bindlock);
>
> --
> 2.44.0
>