5 files changed, 19 insertions, 20 deletions

diff --git a/fs/proc/array.c b/fs/proc/array.c
index ae2c807fd719..911f66924d81 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -677,12 +677,7 @@ out:
 
 static int children_seq_show(struct seq_file *seq, void *v)
 {
-        struct inode *inode = seq->private;
-        pid_t pid;
-
-        pid = pid_nr_ns(v, inode->i_sb->s_fs_info);
-        seq_printf(seq, "%d ", pid);
-
+        seq_printf(seq, "%d ", pid_nr_ns(v, proc_pid_ns(seq->private)));
         return 0;
 }
 
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 1b2ede6abcdf..29237cad19fd 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -698,7 +698,7 @@ static bool has_pid_permissions(struct pid_namespace *pid,
 
 static int proc_pid_permission(struct inode *inode, int mask)
 {
-        struct pid_namespace *pid = inode->i_sb->s_fs_info;
+        struct pid_namespace *pid = proc_pid_ns(inode);
         struct task_struct *task;
         bool has_perms;
 
@@ -733,13 +733,11 @@ static const struct inode_operations proc_def_inode_operations = {
 static int proc_single_show(struct seq_file *m, void *v)
 {
         struct inode *inode = m->private;
-        struct pid_namespace *ns;
-        struct pid *pid;
+        struct pid_namespace *ns = proc_pid_ns(inode);
+        struct pid *pid = proc_pid(inode);
         struct task_struct *task;
         int ret;
 
-        ns = inode->i_sb->s_fs_info;
-        pid = proc_pid(inode);
         task = get_pid_task(pid, PIDTYPE_PID);
         if (!task)
                 return -ESRCH;
@@ -1410,7 +1408,7 @@ static const struct file_operations proc_fail_nth_operations = {
 static int sched_show(struct seq_file *m, void *v)
 {
         struct inode *inode = m->private;
-        struct pid_namespace *ns = inode->i_sb->s_fs_info;
+        struct pid_namespace *ns = proc_pid_ns(inode);
         struct task_struct *p;
 
         p = get_proc_task(inode);
@@ -1782,8 +1780,8 @@ int pid_getattr(const struct path *path, struct kstat *stat,
                 u32 request_mask, unsigned int query_flags)
 {
         struct inode *inode = d_inode(path->dentry);
+        struct pid_namespace *pid = proc_pid_ns(inode);
         struct task_struct *task;
-        struct pid_namespace *pid = path->dentry->d_sb->s_fs_info;
 
         generic_fillattr(inode, stat);
 
@@ -2337,7 +2335,7 @@ static int proc_timers_open(struct inode *inode, struct file *file)
                 return -ENOMEM;
 
         tp->pid = proc_pid(inode);
-        tp->ns = inode->i_sb->s_fs_info;
+        tp->ns = proc_pid_ns(inode);
         return 0;
 }
 
@@ -3239,7 +3237,7 @@ retry:
 int proc_pid_readdir(struct file *file, struct dir_context *ctx)
 {
         struct tgid_iter iter;
-        struct pid_namespace *ns = file_inode(file)->i_sb->s_fs_info;
+        struct pid_namespace *ns = proc_pid_ns(file_inode(file));
         loff_t pos = ctx->pos;
 
         if (pos >= PID_MAX_LIMIT + TGID_OFFSET)
@@ -3588,7 +3586,7 @@ static int proc_task_readdir(struct file *file, struct dir_context *ctx)
         /* f_version caches the tgid value that the last readdir call couldn't
          * return. lseek aka telldir automagically resets f_version to 0.
          */
-        ns = inode->i_sb->s_fs_info;
+        ns = proc_pid_ns(inode);
         tid = (int)file->f_version;
         file->f_version = 0;
         for (task = first_tid(proc_pid(inode), tid, ctx->pos - 2, ns);
diff --git a/fs/proc/self.c b/fs/proc/self.c
index 4d7d061696b3..127265e5c55f 100644
--- a/fs/proc/self.c
+++ b/fs/proc/self.c
@@ -12,7 +12,7 @@ static const char *proc_self_get_link(struct dentry *dentry,
                                       struct inode *inode,
                                       struct delayed_call *done)
 {
-        struct pid_namespace *ns = inode->i_sb->s_fs_info;
+        struct pid_namespace *ns = proc_pid_ns(inode);
         pid_t tgid = task_tgid_nr_ns(current, ns);
         char *name;
 
@@ -36,7 +36,7 @@ static unsigned self_inum __ro_after_init;
 int proc_setup_self(struct super_block *s)
 {
         struct inode *root_inode = d_inode(s->s_root);
-        struct pid_namespace *ns = s->s_fs_info;
+        struct pid_namespace *ns = proc_pid_ns(root_inode);
         struct dentry *self;
         
         inode_lock(root_inode);
diff --git a/fs/proc/thread_self.c b/fs/proc/thread_self.c
index 9d2efaca499f..b905010ca9eb 100644
--- a/fs/proc/thread_self.c
+++ b/fs/proc/thread_self.c
@@ -12,7 +12,7 @@ static const char *proc_thread_self_get_link(struct dentry *dentry,
                                              struct inode *inode,
                                              struct delayed_call *done)
 {
-        struct pid_namespace *ns = inode->i_sb->s_fs_info;
+        struct pid_namespace *ns = proc_pid_ns(inode);
         pid_t tgid = task_tgid_nr_ns(current, ns);
         pid_t pid = task_pid_nr_ns(current, ns);
         char *name;
@@ -36,7 +36,7 @@ static unsigned thread_self_inum __ro_after_init;
 int proc_setup_thread_self(struct super_block *s)
 {
         struct inode *root_inode = d_inode(s->s_root);
-        struct pid_namespace *ns = s->s_fs_info;
+        struct pid_namespace *ns = proc_pid_ns(root_inode);
         struct dentry *thread_self;
 
         inode_lock(root_inode);
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 */