[PATCH 5.15.y 3/6] procfs: kill ->proc_dops

[Sasha Levin <sashal@kernel.org>]

From: Al Viro <viro@zeniv.linux.org.uk>

[ Upstream commit 5943c611c47c9444e834555c867dec744158b7ad ]

It has two possible values - one for "forced lookup" entries, another
for the normal ones.  We'd be better off with that as an explicit
flag anyway and in addition to that it opens some fun possibilities
with ->d_op and ->d_flags handling.

[moved PROC_ENTRY_FORCE_LOOKUP to include/linux/proc_fs.h, switched it
to an unused bit - there was a conflict]

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Stable-dep-of: eeecea75ece2 ("proc: don't let an entry below /proc/<pid>/net be a mountpoint")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/proc/generic.c       | 8 +++++---
 fs/proc/internal.h      | 3 +--
 include/linux/proc_fs.h | 2 ++
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 81756fd46c4ca..4a438f1f318d1 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -256,7 +256,10 @@ struct dentry *proc_lookup_de(struct inode *dir, struct dentry *dentry,
 		inode = proc_get_inode(dir->i_sb, de);
 		if (!inode)
 			return ERR_PTR(-ENOMEM);
-		d_set_d_op(dentry, de->proc_dops);
+		if (de->flags & PROC_ENTRY_FORCE_LOOKUP)
+			d_set_d_op(dentry, &proc_net_dentry_ops);
+		else
+			d_set_d_op(dentry, &proc_misc_dentry_ops);
 		return d_splice_alias(inode, dentry);
 	}
 	read_unlock(&proc_subdir_lock);
@@ -448,9 +451,8 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
 	INIT_LIST_HEAD(&ent->pde_openers);
 	proc_set_user(ent, (*parent)->uid, (*parent)->gid);
 
-	ent->proc_dops = &proc_misc_dentry_ops;
 	/* Revalidate everything under /proc/${pid}/net */
-	if ((*parent)->proc_dops == &proc_net_dentry_ops)
+	if ((*parent)->flags & PROC_ENTRY_FORCE_LOOKUP)
 		pde_force_lookup(ent);
 
 out:
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 2c652681172b8..a51ff1a60e804 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -43,7 +43,6 @@ struct proc_dir_entry {
 		const struct proc_ops *proc_ops;
 		const struct file_operations *proc_dir_ops;
 	};
-	const struct dentry_operations *proc_dops;
 	union {
 		const struct seq_operations *seq_ops;
 		int (*single_show)(struct seq_file *, void *);
@@ -330,7 +329,7 @@ extern const struct dentry_operations proc_net_dentry_ops;
 static inline void pde_force_lookup(struct proc_dir_entry *pde)
 {
 	/* /proc/net/ entries can be changed under us by setns(CLONE_NEWNET) */
-	pde->proc_dops = &proc_net_dentry_ops;
+	pde->flags |= PROC_ENTRY_FORCE_LOOKUP;
 }
 
 /*
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 4789761707463..2d4c7e5801dee 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -27,6 +27,8 @@ enum {
 
 	PROC_ENTRY_proc_read_iter	= 1U << 1,
 	PROC_ENTRY_proc_compat_ioctl	= 1U << 2,
+
+	PROC_ENTRY_FORCE_LOOKUP		= 1U << 7,
 };
 
 struct proc_ops {
-- 
2.53.0