[PATCH 5.10.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 3651bc8245227..ab9f499fc749f 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -261,7 +261,10 @@ 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);
@@ -453,9 +456,8 @@ 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 e35e28415dd8e..56fc4197d92b8 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 *);
@@ -329,7 +328,7 @@ 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 9f8e0072b30fe..cd320ccb60bf6 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