[PATCH] autofs4: fix infamous "Busy inodes after umount ..." message

[linux-2.6-omap-h63xx.git] / fs / autofs4 / inode.c

diff --git a/fs/autofs4/inode.c b/fs/autofs4/inode.c
index 4bb14cc680407eb808d4b2a9876a54708b639224..0a3c05d101679ea0dd24d2794a9a66f64ab5ba10 100644 (file)
--- a/fs/autofs4/inode.c
+++ b/fs/autofs4/inode.c
@@ -16,6 +16,7 @@
 #include <linux/pagemap.h>
 #include <linux/parser.h>
 #include <linux/bitops.h>
+#include <linux/smp_lock.h>
 #include "autofs_i.h"
 #include <linux/module.h>
 
@@ -76,6 +77,66 @@ void autofs4_free_ino(struct autofs_info *ino)
        kfree(ino);
 }
 
+/*
+ * Deal with the infamous "Busy inodes after umount ..." message.
+ *
+ * Clean up the dentry tree. This happens with autofs if the user
+ * space program goes away due to a SIGKILL, SIGSEGV etc.
+ */
+static void autofs4_force_release(struct autofs_sb_info *sbi)
+{
+       struct dentry *this_parent = sbi->root;
+       struct list_head *next;
+
+       spin_lock(&dcache_lock);
+repeat:
+       next = this_parent->d_subdirs.next;
+resume:
+       while (next != &this_parent->d_subdirs) {
+               struct dentry *dentry = list_entry(next, struct dentry, d_child);
+
+               /* Negative dentry - don`t care */
+               if (!simple_positive(dentry)) {
+                       next = next->next;
+                       continue;
+               }
+
+               if (!list_empty(&dentry->d_subdirs)) {
+                       this_parent = dentry;
+                       goto repeat;
+               }
+
+               next = next->next;
+               spin_unlock(&dcache_lock);
+
+               DPRINTK("dentry %p %.*s",
+                       dentry, (int)dentry->d_name.len, dentry->d_name.name);
+
+               dput(dentry);
+               spin_lock(&dcache_lock);
+       }
+
+       if (this_parent != sbi->root) {
+               struct dentry *dentry = this_parent;
+
+               next = this_parent->d_child.next;
+               this_parent = this_parent->d_parent;
+               spin_unlock(&dcache_lock);
+               DPRINTK("parent dentry %p %.*s",
+                       dentry, (int)dentry->d_name.len, dentry->d_name.name);
+               dput(dentry);
+               spin_lock(&dcache_lock);
+               goto resume;
+       }
+       spin_unlock(&dcache_lock);
+
+       dput(sbi->root);
+       sbi->root = NULL;
+       shrink_dcache_sb(sbi->sb);
+
+       return;
+}
+
 static void autofs4_put_super(struct super_block *sb)
 {
        struct autofs_sb_info *sbi = autofs4_sbi(sb);
@@ -85,6 +146,10 @@ static void autofs4_put_super(struct super_block *sb)
        if ( !sbi->catatonic )
                autofs4_catatonic_mode(sbi); /* Free wait queues, close pipe */
 
+       /* Clean up and release dangling references */
+       if (sbi)
+               autofs4_force_release(sbi);
+
        kfree(sbi);
 
        DPRINTK("shutting down");
@@ -199,6 +264,7 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent)
 
        s->s_fs_info = sbi;
        sbi->magic = AUTOFS_SBI_MAGIC;
+       sbi->root = NULL;
        sbi->catatonic = 0;
        sbi->exp_timeout = 0;
        sbi->oz_pgrp = process_group(current);
@@ -266,6 +332,13 @@ int autofs4_fill_super(struct super_block *s, void *data, int silent)
                goto fail_fput;
        sbi->pipe = pipe;
 
+       /*
+        * Take a reference to the root dentry so we get a chance to
+        * clean up the dentry tree on umount.
+        * See autofs4_force_release.
+        */
+       sbi->root = dget(root);
+
        /*
         * Success! Install the root dentry now to indicate completion.
         */