proc: Allow creating permanently empty directories that serve as mount points
Add a new function proc_create_mount_point that when used to creates a
directory that can not be added to.
Add a new function is_empty_pde to test if a function is a mount
point.
Update the code to use make_empty_dir_inode when reporting
a permanently empty directory to the vfs.
Update the code to not allow adding to permanently empty directories.
Update /proc/openprom and /proc/fs/nfsd to be permanently empty directories.
Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 8272aab..e3eb552 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -423,6 +423,10 @@
inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
PROC_I(inode)->pde = de;
+ if (is_empty_pde(de)) {
+ make_empty_dir_inode(inode);
+ return inode;
+ }
if (de->mode) {
inode->i_mode = de->mode;
inode->i_uid = de->uid;