[PATCH] autofs4: fix false negative return from expire

Fix the case where an expire returns busy on a tree mount when it is in fact
not busy.  This case was overlooked when the patch to prevent the expiring
away of "scaffolding" directories for tree mounts was applied.

The problem arises when a tree of mounts is a member of a map with other keys.
 The current logic will not expire the tree if any other mount in the map is
busy.  The solution is to maintain a "minimum" use count for each autofs
dentry and compare this to the actual dentry usage count during expire.

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 11 insertions, 1 deletions

diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c
index 1ad98d48e550..2335b1d6490f 100644
--- a/fs/autofs4/inode.c
+++ b/fs/autofs4/inode.c
@@ -46,6 +46,7 @@ struct autofs_info *autofs4_init_ino(struct autofs_info *ino,
         ino->size = 0;
 
         ino->last_used = jiffies;
+        atomic_set(&ino->count, 0);
 
         ino->sbi = sbi;
 
@@ -64,10 +65,19 @@ struct autofs_info *autofs4_init_ino(struct autofs_info *ino,
 
 void autofs4_free_ino(struct autofs_info *ino)
 {
+        struct autofs_info *p_ino;
+
         if (ino->dentry) {
                 ino->dentry->d_fsdata = NULL;
-                if (ino->dentry->d_inode)
+                if (ino->dentry->d_inode) {
+                        struct dentry *parent = ino->dentry->d_parent;
+                        if (atomic_dec_and_test(&ino->count)) {
+                                p_ino = autofs4_dentry_ino(parent);
+                                if (p_ino && parent != ino->dentry)
+                                        atomic_dec(&p_ino->count);
+                        }
                         dput(ino->dentry);
+                }
                 ino->dentry = NULL;
         }
         if (ino->free)