1 files changed, 114 insertions, 43 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index c13072a5f1e..6ede3a539ed 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -8,16 +8,17 @@
  * Heavily rewritten.
  */
 
-#include <linux/config.h>
 #include <linux/syscalls.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/smp_lock.h>
 #include <linux/init.h>
+#include <linux/kernel.h>
 #include <linux/quotaops.h>
 #include <linux/acct.h>
 #include <linux/capability.h>
 #include <linux/module.h>
+#include <linux/sysfs.h>
 #include <linux/seq_file.h>
 #include <linux/namespace.h>
 #include <linux/namei.h>
@@ -29,15 +30,6 @@
 
 extern int __init init_rootfs(void);
 
-#ifdef CONFIG_SYSFS
-extern int __init sysfs_init(void);
-#else
-static inline int sysfs_init(void)
-{
-	return 0;
-}
-#endif
-
 /* spinlock for vfsmount related operations, inplace of dcache_lock */
 __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock);
 
@@ -526,10 +518,8 @@ void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill)
 {
 	struct vfsmount *p;
 
-	for (p = mnt; p; p = next_mnt(p, mnt)) {
-		list_del(&p->mnt_hash);
-		list_add(&p->mnt_hash, kill);
-	}
+	for (p = mnt; p; p = next_mnt(p, mnt))
+		list_move(&p->mnt_hash, kill);
 
 	if (propagate)
 		propagate_umount(kill);
@@ -585,8 +575,8 @@ static int do_umount(struct vfsmount *mnt, int flags)
 	 */
 
 	lock_kernel();
-	if ((flags & MNT_FORCE) && sb->s_op->umount_begin)
-		sb->s_op->umount_begin(sb);
+	if (sb->s_op->umount_begin)
+		sb->s_op->umount_begin(mnt, flags);
 	unlock_kernel();
 
 	/*
@@ -1172,13 +1162,46 @@ static void expire_mount(struct vfsmount *mnt, struct list_head *mounts,
 }
 
 /*
+ * go through the vfsmounts we've just consigned to the graveyard to
+ * - check that they're still dead
+ * - delete the vfsmount from the appropriate namespace under lock
+ * - dispose of the corpse
+ */
+static void expire_mount_list(struct list_head *graveyard, struct list_head *mounts)
+{
+	struct namespace *namespace;
+	struct vfsmount *mnt;
+
+	while (!list_empty(graveyard)) {
+		LIST_HEAD(umounts);
+		mnt = list_entry(graveyard->next, struct vfsmount, mnt_expire);
+		list_del_init(&mnt->mnt_expire);
+
+		/* don't do anything if the namespace is dead - all the
+		 * vfsmounts from it are going away anyway */
+		namespace = mnt->mnt_namespace;
+		if (!namespace || !namespace->root)
+			continue;
+		get_namespace(namespace);
+
+		spin_unlock(&vfsmount_lock);
+		down_write(&namespace_sem);
+		expire_mount(mnt, mounts, &umounts);
+		up_write(&namespace_sem);
+		release_mounts(&umounts);
+		mntput(mnt);
+		put_namespace(namespace);
+		spin_lock(&vfsmount_lock);
+	}
+}
+
+/*
  * process a list of expirable mountpoints with the intent of discarding any
  * mountpoints that aren't in use and haven't been touched since last we came
  * here
  */
 void mark_mounts_for_expiry(struct list_head *mounts)
 {
-	struct namespace *namespace;
 	struct vfsmount *mnt, *next;
 	LIST_HEAD(graveyard);
 
@@ -1202,38 +1225,79 @@ void mark_mounts_for_expiry(struct list_head *mounts)
 		list_move(&mnt->mnt_expire, &graveyard);
 	}
 
-	/*
-	 * go through the vfsmounts we've just consigned to the graveyard to
-	 * - check that they're still dead
-	 * - delete the vfsmount from the appropriate namespace under lock
-	 * - dispose of the corpse
-	 */
-	while (!list_empty(&graveyard)) {
-		LIST_HEAD(umounts);
-		mnt = list_entry(graveyard.next, struct vfsmount, mnt_expire);
-		list_del_init(&mnt->mnt_expire);
+	expire_mount_list(&graveyard, mounts);
 
-		/* don't do anything if the namespace is dead - all the
-		 * vfsmounts from it are going away anyway */
-		namespace = mnt->mnt_namespace;
-		if (!namespace || !namespace->root)
+	spin_unlock(&vfsmount_lock);
+}
+
+EXPORT_SYMBOL_GPL(mark_mounts_for_expiry);
+
+/*
+ * Ripoff of 'select_parent()'
+ *
+ * search the list of submounts for a given mountpoint, and move any
+ * shrinkable submounts to the 'graveyard' list.
+ */
+static int select_submounts(struct vfsmount *parent, struct list_head *graveyard)
+{
+	struct vfsmount *this_parent = parent;
+	struct list_head *next;
+	int found = 0;
+
+repeat:
+	next = this_parent->mnt_mounts.next;
+resume:
+	while (next != &this_parent->mnt_mounts) {
+		struct list_head *tmp = next;
+		struct vfsmount *mnt = list_entry(tmp, struct vfsmount, mnt_child);
+
+		next = tmp->next;
+		if (!(mnt->mnt_flags & MNT_SHRINKABLE))
 			continue;
-		get_namespace(namespace);
+		/*
+		 * Descend a level if the d_mounts list is non-empty.
+		 */
+		if (!list_empty(&mnt->mnt_mounts)) {
+			this_parent = mnt;
+			goto repeat;
+		}
 
-		spin_unlock(&vfsmount_lock);
-		down_write(&namespace_sem);
-		expire_mount(mnt, mounts, &umounts);
-		up_write(&namespace_sem);
-		release_mounts(&umounts);
-		mntput(mnt);
-		put_namespace(namespace);
-		spin_lock(&vfsmount_lock);
+		if (!propagate_mount_busy(mnt, 1)) {
+			mntget(mnt);
+			list_move_tail(&mnt->mnt_expire, graveyard);
+			found++;
+		}
+	}
+	/*
+	 * All done at this level ... ascend and resume the search
+	 */
+	if (this_parent != parent) {
+		next = this_parent->mnt_child.next;
+		this_parent = this_parent->mnt_parent;
+		goto resume;
 	}
+	return found;
+}
+
+/*
+ * process a list of expirable mountpoints with the intent of discarding any
+ * submounts of a specific parent mountpoint
+ */
+void shrink_submounts(struct vfsmount *mountpoint, struct list_head *mounts)
+{
+	LIST_HEAD(graveyard);
+	int found;
+
+	spin_lock(&vfsmount_lock);
+
+	/* extract submounts of 'mountpoint' from the expiration list */
+	while ((found = select_submounts(mountpoint, &graveyard)) != 0)
+		expire_mount_list(&graveyard, mounts);
 
 	spin_unlock(&vfsmount_lock);
 }
 
-EXPORT_SYMBOL_GPL(mark_mounts_for_expiry);
+EXPORT_SYMBOL_GPL(shrink_submounts);
 
 /*
  * Some copy_from_user() implementations do not return the exact number of
@@ -1750,6 +1814,7 @@ void __init mnt_init(unsigned long mempages)
 	struct list_head *d;
 	unsigned int nr_hash;
 	int i;
+	int err;
 
 	init_rwsem(&namespace_sem);
 
@@ -1790,8 +1855,14 @@ void __init mnt_init(unsigned long mempages)
 		d++;
 		i--;
 	} while (i);
-	sysfs_init();
-	subsystem_register(&fs_subsys);
+	err = sysfs_init();
+	if (err)
+		printk(KERN_WARNING "%s: sysfs_init error: %d\n",
+			__FUNCTION__, err);
+	err = subsystem_register(&fs_subsys);
+	if (err)
+		printk(KERN_WARNING "%s: subsystem_register error: %d\n",
+			__FUNCTION__, err);
 	init_rootfs();
 	init_mount_tree();
 }