linux-kernel - [PATCH 2/5] procfs: factor out inode revalidation work from pid

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Date:   Mon, 23 Apr 2018 22:21:03 -0400
From:   jeffm@...e.com
To:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Oleg Nesterov <oleg@...hat.com>, Jeff Mahoney <jeffm@...e.com>
Subject: [PATCH 2/5] procfs: factor out inode revalidation work from pid_revalidation

From: Jeff Mahoney <jeffm@...e.com>

Subsequent patches will introduce their own d_revalidate callbacks and we
won't want to get the task multiple times.

Signed-off-by: Jeff Mahoney <jeffm@...e.com>
---
 fs/proc/base.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index e9876a89a5ad..e7ca45504a5f 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1802,14 +1802,24 @@ int pid_getattr(const struct path *path, struct kstat *stat,
 
 /* dentry stuff */
 
+
+/*
+ * Rewrite the inode's ownerships here because the owning task may have
+ * performed a setuid(), etc.
+ */
+static void pid_revalidate_inode(struct inode *inode, struct task_struct *task)
+{
+	task_dump_owner(task, inode->i_mode, &inode->i_uid, &inode->i_gid);
+
+	inode->i_mode &= ~(S_ISUID | S_ISGID);
+	security_task_to_inode(task, inode);
+}
+
 /*
  *	Exceptional case: normally we are not allowed to unhash a busy
  * directory. In this case, however, we can do it - no aliasing problems
  * due to the way we treat inodes.
  *
- * Rewrite the inode's ownerships here because the owning task may have
- * performed a setuid(), etc.
- *
  */
 int pid_revalidate(struct dentry *dentry, unsigned int flags)
 {
@@ -1823,10 +1833,7 @@ int pid_revalidate(struct dentry *dentry, unsigned int flags)
 	task = get_proc_task(inode);
 
 	if (task) {
-		task_dump_owner(task, inode->i_mode, &inode->i_uid, &inode->i_gid);
-
-		inode->i_mode &= ~(S_ISUID | S_ISGID);
-		security_task_to_inode(task, inode);
+		pid_revalidate_inode(inode, task);
 		put_task_struct(task);
 		return 1;
 	}
-- 
2.12.3