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, 8 insertions, 10 deletions

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);