proc: introduce a proc_pid_ns helper

Factor out retrieving the per-sb pid namespaces from the sb private data
into an easier to understand helper.

Suggested-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index 928ef9e4d912..4edcde510631 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -83,4 +83,10 @@ struct ns_common;
 int open_related_ns(struct ns_common *ns,
                    struct ns_common *(*get_ns)(struct ns_common *ns));
 
+/* get the associated pid namespace for a file in procfs */
+static inline struct pid_namespace *proc_pid_ns(struct inode *inode)
+{
+        return inode->i_sb->s_fs_info;
+}
+
 #endif /* _LINUX_PROC_FS_H */