fs: provide rcu-walk aware permission i_ops

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index dc5b2fcadc3b..b953d41d9abf 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2114,11 +2114,13 @@ static const struct file_operations proc_fd_operations = {
  * /proc/pid/fd needs a special permission handler so that a process can still
  * access /proc/self/fd after it has executed a setuid().
  */
-static int proc_fd_permission(struct inode *inode, int mask)
+static int proc_fd_permission(struct inode *inode, int mask, unsigned int flags)
 {
         int rv;
 
-        rv = generic_permission(inode, mask, NULL);
+        if (flags & IPERM_FLAG_RCU)
+                return -ECHILD;
+        rv = generic_permission(inode, mask, flags, NULL);
         if (rv == 0)
                 return 0;
         if (task_pid(current) == proc_pid(inode))