Merge with /pub/scm/linux/kernel/git/torvalds/linux-2.6.git

Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 183 insertions, 109 deletions

diff --git a/fs/autofs4/expire.c b/fs/autofs4/expire.c
index dc39589df16..b8ce02607d6 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
@@ -16,7 +16,7 @@
 
 static unsigned long now;
 
-/* Check if a dentry can be expired return 1 if it can else return 0 */
+/* Check if a dentry can be expired */
 static inline int autofs4_can_expire(struct dentry *dentry,
 					unsigned long timeout, int do_now)
 {
@@ -41,14 +41,14 @@ static inline int autofs4_can_expire(struct dentry *dentry,
 		     attempts if expire fails the first time */
 		ino->last_used = now;
 	}
-
 	return 1;
 }
 
-/* Check a mount point for busyness return 1 if not busy, otherwise */
-static int autofs4_check_mount(struct vfsmount *mnt, struct dentry *dentry)
+/* Check a mount point for busyness */
+static int autofs4_mount_busy(struct vfsmount *mnt, struct dentry *dentry)
 {
-	int status = 0;
+	struct dentry *top = dentry;
+	int status = 1;
 
 	DPRINTK("dentry %p %.*s",
 		dentry, (int)dentry->d_name.len, dentry->d_name.name);
@@ -63,9 +63,14 @@ static int autofs4_check_mount(struct vfsmount *mnt, struct dentry *dentry)
 	if (is_autofs4_dentry(dentry))
 		goto done;
 
-	/* The big question */
-	if (may_umount_tree(mnt) == 0)
-		status = 1;
+	/* Update the expiry counter if fs is busy */
+	if (!may_umount_tree(mnt)) {
+		struct autofs_info *ino = autofs4_dentry_ino(top);
+		ino->last_used = jiffies;
+		goto done;
+	}
+
+	status = 0;
 done:
 	DPRINTK("returning = %d", status);
 	mntput(mnt);
@@ -73,78 +78,124 @@ done:
 	return status;
 }
 
+/*
+ * Calculate next entry in top down tree traversal.
+ * From next_mnt in namespace.c - elegant.
+ */
+static struct dentry *next_dentry(struct dentry *p, struct dentry *root)
+{
+	struct list_head *next = p->d_subdirs.next;
+
+	if (next == &p->d_subdirs) {
+		while (1) {
+			if (p == root)
+				return NULL;
+			next = p->d_u.d_child.next;
+			if (next != &p->d_parent->d_subdirs)
+				break;
+			p = p->d_parent;
+		}
+	}
+	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);
+
+	/* 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
- * Return 1 if the tree is busy or 0 otherwise
  */
-static int autofs4_check_tree(struct vfsmount *mnt,
-	       		      struct dentry *top,
-			      unsigned long timeout,
-			      int do_now)
+static int autofs4_tree_busy(struct vfsmount *mnt,
+	       		     struct dentry *top,
+			     unsigned long timeout,
+			     int do_now)
 {
-	struct dentry *this_parent = top;
-	struct list_head *next;
+	struct autofs_info *top_ino = autofs4_dentry_ino(top);
+	struct dentry *p;
 
-	DPRINTK("parent %p %.*s",
+	DPRINTK("top %p %.*s",
 		top, (int)top->d_name.len, top->d_name.name);
 
 	/* Negative dentry - give up */
 	if (!simple_positive(top))
-		return 0;
-
-	/* Timeout of a tree mount is determined by its top dentry */
-	if (!autofs4_can_expire(top, timeout, do_now))
-		return 0;
-
-	/* Is someone visiting anywhere in the tree ? */
-	if (may_umount_tree(mnt))
-		return 0;
+		return 1;
 
 	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_u.d_child);
-
+	for (p = top; p; p = next_dentry(p, top)) {
 		/* Negative dentry - give up */
-		if (!simple_positive(dentry)) {
-			next = next->next;
+		if (!simple_positive(p))
 			continue;
-		}
 
 		DPRINTK("dentry %p %.*s",
-			dentry, (int)dentry->d_name.len, dentry->d_name.name);
-
-		if (!simple_empty_nolock(dentry)) {
-			this_parent = dentry;
-			goto repeat;
-		}
+			p, (int) p->d_name.len, p->d_name.name);
 
-		dentry = dget(dentry);
+		p = dget(p);
 		spin_unlock(&dcache_lock);
 
-		if (d_mountpoint(dentry)) {
-			/* First busy => tree busy */
-			if (!autofs4_check_mount(mnt, dentry)) {
-				dput(dentry);
-				return 0;
+		/*
+		 * Is someone visiting anywhere in the subtree ?
+		 * If there's no mount we need to check the usage
+		 * count for the autofs dentry.
+		 * If the fs is busy update the expiry counter.
+		 */
+		if (d_mountpoint(p)) {
+			if (autofs4_mount_busy(mnt, p)) {
+				top_ino->last_used = jiffies;
+				dput(p);
+				return 1;
+			}
+		} else {
+			struct autofs_info *ino = autofs4_dentry_ino(p);
+			unsigned int ino_count = atomic_read(&ino->count);
+
+			/* allow for dget above and top is already dgot */
+			if (p == top)
+				ino_count += 2;
+			else
+				ino_count++;
+
+			if (atomic_read(&p->d_count) > ino_count) {
+				top_ino->last_used = jiffies;
+				dput(p);
+				return 1;
 			}
 		}
-
-		dput(dentry);
+		dput(p);
 		spin_lock(&dcache_lock);
-		next = next->next;
-	}
-
-	if (this_parent != top) {
-		next = this_parent->d_u.d_child.next;
-		this_parent = this_parent->d_parent;
-		goto resume;
 	}
 	spin_unlock(&dcache_lock);
 
-	return 1;
+	/* Timeout of a tree mount is ultimately determined by its top dentry */
+	if (!autofs4_can_expire(top, timeout, do_now))
+		return 1;
+
+	return 0;
 }
 
 static struct dentry *autofs4_check_leaves(struct vfsmount *mnt,
@@ -152,58 +203,68 @@ static struct dentry *autofs4_check_leaves(struct vfsmount *mnt,
 					   unsigned long timeout,
 					   int do_now)
 {
-	struct dentry *this_parent = parent;
-	struct list_head *next;
+	struct dentry *p;
 
 	DPRINTK("parent %p %.*s",
 		parent, (int)parent->d_name.len, parent->d_name.name);
 
 	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_u.d_child);
-
+	for (p = parent; p; p = next_dentry(p, parent)) {
 		/* Negative dentry - give up */
-		if (!simple_positive(dentry)) {
-			next = next->next;
+		if (!simple_positive(p))
 			continue;
-		}
 
 		DPRINTK("dentry %p %.*s",
-			dentry, (int)dentry->d_name.len, dentry->d_name.name);
-
-		if (!list_empty(&dentry->d_subdirs)) {
-			this_parent = dentry;
-			goto repeat;
-		}
+			p, (int) p->d_name.len, p->d_name.name);
 
-		dentry = dget(dentry);
+		p = dget(p);
 		spin_unlock(&dcache_lock);
 
-		if (d_mountpoint(dentry)) {
-			/* Can we expire this guy */
-			if (!autofs4_can_expire(dentry, timeout, do_now))
-				goto cont;
-
+		if (d_mountpoint(p)) {
 			/* Can we umount this guy */
-			if (autofs4_check_mount(mnt, dentry))
-				return dentry;
+			if (autofs4_mount_busy(mnt, p))
+				goto cont;
 
+			/* Can we expire this guy */
+			if (autofs4_can_expire(p, timeout, do_now))
+				return p;
 		}
 cont:
-		dput(dentry);
+		dput(p);
 		spin_lock(&dcache_lock);
-		next = next->next;
 	}
+	spin_unlock(&dcache_lock);
+	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);
 
-	if (this_parent != parent) {
-		next = this_parent->d_u.d_child.next;
-		this_parent = this_parent->d_parent;
-		goto resume;
+		/* 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(&dcache_lock);
+	spin_unlock(&sbi->fs_lock);
+	dput(root);
 
 	return NULL;
 }
@@ -214,10 +275,10 @@ cont:
  *  - 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;
@@ -241,7 +302,7 @@ static struct dentry *autofs4_expire(struct super_block *sb,
 		struct dentry *dentry = list_entry(next, struct dentry, d_u.d_child);
 
 		/* Negative dentry - give up */
-		if ( !simple_positive(dentry) ) {
+		if (!simple_positive(dentry)) {
 			next = next->next;
 			continue;
 		}
@@ -249,31 +310,36 @@ 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);
 
-			/* Can we expire this guy */
-			if (!autofs4_can_expire(dentry, timeout, do_now))
+			/* Can we umount this guy */
+			if (autofs4_mount_busy(mnt, dentry))
 				goto next;
 
-			/* Can we umount this guy */
-			if (autofs4_check_mount(mnt, dentry)) {
+			/* Can we expire this guy */
+			if (autofs4_can_expire(dentry, timeout, do_now)) {
 				expired = dentry;
 				break;
 			}
 			goto next;
 		}
 
-		if ( simple_empty(dentry) )
+		if (simple_empty(dentry))
 			goto next;
 
 		/* Case 2: tree mount, expire iff entire tree is not busy */
 		if (!exp_leaves) {
 			/* Lock the tree as we must expire as a whole */
 			spin_lock(&sbi->fs_lock);
-			if (autofs4_check_tree(mnt, dentry, timeout, do_now)) {
+			if (!autofs4_tree_busy(mnt, dentry, timeout, do_now)) {
 				struct autofs_info *inf = autofs4_dentry_ino(dentry);
 
 				/* Set this flag early to catch sys_chdir and the like */
@@ -283,7 +349,10 @@ 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) {
@@ -297,7 +366,7 @@ next:
 		next = next->next;
 	}
 
-	if ( expired ) {
+	if (expired) {
 		DPRINTK("returning %p %.*s",
 			expired, (int)expired->d_name.len, expired->d_name.name);
 		spin_lock(&dcache_lock);
@@ -325,7 +394,7 @@ 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;
@@ -351,17 +420,22 @@ 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) {
-		struct autofs_info *de_info = autofs4_dentry_ino(dentry);
+	if (sbi->type & AUTOFS_TYPE_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
                    little easier */
-		de_info->flags |= AUTOFS_INF_EXPIRING;
+		ino->flags |= AUTOFS_INF_EXPIRING;
 		ret = autofs4_wait(sbi, dentry, NFY_EXPIRE);
-		de_info->flags &= ~AUTOFS_INF_EXPIRING;
+		ino->flags &= ~AUTOFS_INF_EXPIRING;
 		dput(dentry);
 	}
-		
+
 	return ret;
 }