VFS: Comment mount following code

Add comments describing what the directions "up" and "down" mean and ref count handling to the VFS mount following family of functions. Signed-off-by: Valerie Aurora <vaurora@redhat.com> (Original author) Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

VFS: Comment mount following code
Add comments describing what the directions "up" and "down" mean and ref count handling to the VFS mount following family of functions. Signed-off-by: Valerie Aurora <vaurora@redhat.com> (Original author) Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
David Howells · Al Viro
1 parent be34d1a3bc
Showing 2 changed files with 24 additions and 2 deletions Side-by-side Diff
fs/namei.c
fs/namespace.c
@@ -672,6 +672,16 @@
 	return 1;
 }
  
+/*
+ * follow_up - Find the mountpoint of path's vfsmount
+ *
+ * Given a path, find the mountpoint of its source file system.
+ * Replace @path with the path of the mountpoint in the parent mount.
+ * Up is towards /.
+ *
+ * Return 1 if we went up a level and 0 if we were already at the
+ * root.
+ */
 int follow_up(struct path *path)
 {
 	struct mount *mnt = real_mount(path->mnt);
@@ -515,8 +515,20 @@
 }
  
 /*
- * lookup_mnt increments the ref count before returning
- * the vfsmount struct.
+ * lookup_mnt - Return the first child mount mounted at path
+ *
+ * "First" means first mounted chronologically.  If you create the
+ * following mounts:
+ *
+ * mount /dev/sda1 /mnt
+ * mount /dev/sda2 /mnt
+ * mount /dev/sda3 /mnt
+ *
+ * Then lookup_mnt() on the base /mnt dentry in the root mount will
+ * return successively the root dentry and vfsmount of /dev/sda1, then
+ * /dev/sda2, then /dev/sda3, then NULL.
+ *
+ * lookup_mnt takes a reference to the found vfsmount.
  */
 struct vfsmount *lookup_mnt(struct path *path)
 {
...	...	@@ -672,6 +672,16 @@
672	672	return 1;
673	673	}
674	674
	675	+/*
	676	+ * follow_up - Find the mountpoint of path's vfsmount
	677	+ *
	678	+ * Given a path, find the mountpoint of its source file system.
	679	+ * Replace @path with the path of the mountpoint in the parent mount.
	680	+ * Up is towards /.
	681	+ *
	682	+ * Return 1 if we went up a level and 0 if we were already at the
	683	+ * root.
	684	+ */
675	685	int follow_up(struct path *path)
676	686	{
677	687	struct mount *mnt = real_mount(path->mnt);
...	...	@@ -515,8 +515,20 @@
515	515	}
516	516
517	517	/*
518		- * lookup_mnt increments the ref count before returning
519		- * the vfsmount struct.
	518	+ * lookup_mnt - Return the first child mount mounted at path
	519	+ *
	520	+ * "First" means first mounted chronologically. If you create the
	521	+ * following mounts:
	522	+ *
	523	+ * mount /dev/sda1 /mnt
	524	+ * mount /dev/sda2 /mnt
	525	+ * mount /dev/sda3 /mnt
	526	+ *
	527	+ * Then lookup_mnt() on the base /mnt dentry in the root mount will
	528	+ * return successively the root dentry and vfsmount of /dev/sda1, then
	529	+ * /dev/sda2, then /dev/sda3, then NULL.
	530	+ *
	531	+ * lookup_mnt takes a reference to the found vfsmount.
520	532	*/
521	533	struct vfsmount lookup_mnt(struct path path)
522	534	{