get rid of magic in proc_namespace.c

don't rely on proc_mounts->m being the first field; container_of()
is there for purpose.  No need to bother with ->private, while
we are at it - the same container_of will do nicely.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 9 insertions, 8 deletions

diff --git a/fs/mount.h b/fs/mount.h
index 05a2a1185efc..4f291f9de641 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -74,10 +74,12 @@ static inline void get_mnt_ns(struct mnt_namespace *ns)
 }
 
 struct proc_mounts {
-        struct seq_file m; /* must be the first element */
+        struct seq_file m;
         struct mnt_namespace *ns;
         struct path root;
         int (*show)(struct seq_file *, struct vfsmount *);
 };
 
+#define proc_mounts(p) (container_of((p), struct proc_mounts, m))
+
 extern const struct seq_operations mounts_op;
diff --git a/fs/namespace.c b/fs/namespace.c
index a524ea4dbd80..8f412abcb67f 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -923,7 +923,7 @@ EXPORT_SYMBOL(replace_mount_options);
 /* iterator; we want it to have access to namespace_sem, thus here... */
 static void *m_start(struct seq_file *m, loff_t *pos)
 {
-        struct proc_mounts *p = container_of(m, struct proc_mounts, m);
+        struct proc_mounts *p = proc_mounts(m);
 
         down_read(&namespace_sem);
         return seq_list_start(&p->ns->list, *pos);
@@ -931,7 +931,7 @@ static void *m_start(struct seq_file *m, loff_t *pos)
 
 static void *m_next(struct seq_file *m, void *v, loff_t *pos)
 {
-        struct proc_mounts *p = container_of(m, struct proc_mounts, m);
+        struct proc_mounts *p = proc_mounts(m);
 
         return seq_list_next(v, &p->ns->list, pos);
 }
@@ -943,7 +943,7 @@ static void m_stop(struct seq_file *m, void *v)
 
 static int m_show(struct seq_file *m, void *v)
 {
-        struct proc_mounts *p = container_of(m, struct proc_mounts, m);
+        struct proc_mounts *p = proc_mounts(m);
         struct mount *r = list_entry(v, struct mount, mnt_list);
         return p->show(m, &r->mnt);
 }
diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c
index 5e289a7cbad1..5fe34c355e85 100644
--- a/fs/proc_namespace.c
+++ b/fs/proc_namespace.c
@@ -17,7 +17,7 @@
 
 static unsigned mounts_poll(struct file *file, poll_table *wait)
 {
-        struct proc_mounts *p = file->private_data;
+        struct proc_mounts *p = proc_mounts(file->private_data);
         struct mnt_namespace *ns = p->ns;
         unsigned res = POLLIN | POLLRDNORM;
 
@@ -121,7 +121,7 @@ out:
 
 static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt)
 {
-        struct proc_mounts *p = m->private;
+        struct proc_mounts *p = proc_mounts(m);
         struct mount *r = real_mount(mnt);
         struct super_block *sb = mnt->mnt_sb;
         struct path mnt_path = { .dentry = mnt->mnt_root, .mnt = mnt };
@@ -268,7 +268,6 @@ static int mounts_open_common(struct inode *inode, struct file *file,
         if (ret)
                 goto err_free;
 
-        p->m.private = p;
         p->ns = ns;
         p->root = root;
         p->m.poll_event = ns->event;
@@ -288,7 +287,7 @@ static int mounts_open_common(struct inode *inode, struct file *file,
 
 static int mounts_release(struct inode *inode, struct file *file)
 {
-        struct proc_mounts *p = file->private_data;
+        struct proc_mounts *p = proc_mounts(file->private_data);
         path_put(&p->root);
         put_mnt_ns(p->ns);
         return seq_release(inode, file);