[PATCH] autofs4: add v5 expire logic

This patch adds expire logic for autofs direct mounts.

Signed-off-by: Ian Kent <raven@themaw.net>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 87 insertions, 9 deletions

diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index 02a218fbde5f..8fd92eaf936d 100644
--- a/fs/autofs4/expire.c
+++ b/fs/autofs4/expire.c
@@ -4,7 +4,7 @@
  *
  *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
  *  Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
- *  Copyright 2001-2003 Ian Kent <raven@themaw.net>
+ *  Copyright 2001-2006 Ian Kent <raven@themaw.net>
  *
  * This file is part of the Linux kernel and is made available under
  * the terms of the GNU General Public License, version 2, or at your
@@ -99,6 +99,39 @@ static struct dentry *next_dentry(struct dentry *p, struct dentry *root)
         return list_entry(next, struct dentry, d_u.d_child);
 }
 
+/*
+ * Check a direct mount point for busyness.
+ * Direct mounts have similar expiry semantics to tree mounts.
+ * The tree is not busy iff no mountpoints are busy and there are no
+ * autofs submounts.
+ */
+static int autofs4_direct_busy(struct vfsmount *mnt,
+                                struct dentry *top,
+                                unsigned long timeout,
+                                int do_now)
+{
+        DPRINTK("top %p %.*s",
+                top, (int) top->d_name.len, top->d_name.name);
+
+        /* Not a mountpoint - give up */
+        if (!d_mountpoint(top))
+                return 1;
+
+        /* If it's busy update the expiry counters */
+        if (!may_umount_tree(mnt)) {
+                struct autofs_info *ino = autofs4_dentry_ino(top);
+                if (ino)
+                        ino->last_used = jiffies;
+                return 1;
+        }
+
+        /* Timeout of a direct mount is determined by its top dentry */
+        if (!autofs4_can_expire(top, timeout, do_now))
+                return 1;
+
+        return 0;
+}
+
 /* Check a directory tree of mount points for busyness
  * The tree is not busy iff no mountpoints are busy
  */
@@ -208,16 +241,48 @@ cont:
         return NULL;
 }
 
+/* Check if we can expire a direct mount (possibly a tree) */
+static struct dentry *autofs4_expire_direct(struct super_block *sb,
+                                            struct vfsmount *mnt,
+                                            struct autofs_sb_info *sbi,
+                                            int how)
+{
+        unsigned long timeout;
+        struct dentry *root = dget(sb->s_root);
+        int do_now = how & AUTOFS_EXP_IMMEDIATE;
+
+        if (!sbi->exp_timeout || !root)
+                return NULL;
+
+        now = jiffies;
+        timeout = sbi->exp_timeout;
+
+        /* Lock the tree as we must expire as a whole */
+        spin_lock(&sbi->fs_lock);
+        if (!autofs4_direct_busy(mnt, root, timeout, do_now)) {
+                struct autofs_info *ino = autofs4_dentry_ino(root);
+
+                /* Set this flag early to catch sys_chdir and the like */
+                ino->flags |= AUTOFS_INF_EXPIRING;
+                spin_unlock(&sbi->fs_lock);
+                return root;
+        }
+        spin_unlock(&sbi->fs_lock);
+        dput(root);
+
+        return NULL;
+}
+
 /*
  * Find an eligible tree to time-out
  * A tree is eligible if :-
  *  - it is unused by any user process
  *  - it has been unused for exp_timeout time
  */
-static struct dentry *autofs4_expire(struct super_block *sb,
-                                     struct vfsmount *mnt,
-                                     struct autofs_sb_info *sbi,
-                                     int how)
+static struct dentry *autofs4_expire_indirect(struct super_block *sb,
+                                              struct vfsmount *mnt,
+                                              struct autofs_sb_info *sbi,
+                                              int how)
 {
         unsigned long timeout;
         struct dentry *root = sb->s_root;
@@ -249,7 +314,12 @@ static struct dentry *autofs4_expire(struct super_block *sb,
                 dentry = dget(dentry);
                 spin_unlock(&dcache_lock);
 
-                /* Case 1: indirect mount or top level direct mount */
+                /*
+                 * Case 1: (i) indirect mount or top level pseudo direct mount
+                 *         (autofs-4.1).
+                 *         (ii) indirect mount with offset mount, check the "/"
+                 *         offset (autofs-5.0+).
+                 */
                 if (d_mountpoint(dentry)) {
                         DPRINTK("checking mountpoint %p %.*s",
                                 dentry, (int)dentry->d_name.len, dentry->d_name.name);
@@ -283,7 +353,10 @@ static struct dentry *autofs4_expire(struct super_block *sb,
                                 break;
                         }
                         spin_unlock(&sbi->fs_lock);
-                /* Case 3: direct mount, expire individual leaves */
+                /*
+                 * Case 3: pseudo direct mount, expire individual leaves
+                 *         (autofs-4.1).
+                 */
                 } else {
                         expired = autofs4_check_leaves(mnt, dentry, timeout, do_now);
                         if (expired) {
@@ -325,7 +398,7 @@ int autofs4_expire_run(struct super_block *sb,
         pkt.hdr.proto_version = sbi->version;
         pkt.hdr.type = autofs_ptype_expire;
 
-        if ((dentry = autofs4_expire(sb, mnt, sbi, 0)) == NULL)
+        if ((dentry = autofs4_expire_indirect(sb, mnt, sbi, 0)) == NULL)
                 return -EAGAIN;
 
         pkt.len = dentry->d_name.len;
@@ -351,7 +424,12 @@ int autofs4_expire_multi(struct super_block *sb, struct vfsmount *mnt,
         if (arg && get_user(do_now, arg))
                 return -EFAULT;
 
-        if ((dentry = autofs4_expire(sb, mnt, sbi, do_now)) != NULL) {
+        if (sbi->type & AUTOFS_TYP_DIRECT)
+                dentry = autofs4_expire_direct(sb, mnt, sbi, do_now);
+        else
+                dentry = autofs4_expire_indirect(sb, mnt, sbi, do_now);
+
+        if (dentry) {
                 struct autofs_info *ino = autofs4_dentry_ino(dentry);
 
                 /* This is synchronous because it makes the daemon a