X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=fs%2Fnamespace.c;h=8192e0eefbed4a1ed3fe0e1604abfa6ffa0a95c5;hb=16cf0ec7408f389279d413869e94c1a351392f97;hp=e1f8b7318194453680b881eb0df563c42fd67eaf;hpb=6a77f38946aaee1cd85eeec6cf4229b204c15071;p=linux-2.6.git

diff --git a/fs/namespace.c b/fs/namespace.c
index e1f8b7318..8192e0eef 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -24,7 +24,6 @@
 #include <linux/mount.h>
 #include <linux/vserver/namespace.h>
 #include <linux/vserver/xid.h>
-
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
 
@@ -225,8 +224,6 @@ static int mnt_is_reachable(struct vfsmount *mnt)
 	struct dentry *root, *point;
 	int ret;
 
-	if (!mnt)
-		return 1;
 	if (mnt == mnt->mnt_namespace->root)
 		return 1;
 
@@ -1344,10 +1341,19 @@ static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd)
 }
 
 /*
- * Moves the current root to put_root, and sets root/cwd of all processes
- * which had them on the old root to new_root.
+ * pivot_root Semantics:
+ * Moves the root file system of the current process to the directory put_old,
+ * makes new_root as the new root file system of the current process, and sets
+ * root/cwd of all processes which had them on the current root to new_root.
+ *
+ * Restrictions:
+ * The new_root and put_old must be directories, and  must not be on the
+ * same file  system as the current process root. The put_old  must  be
+ * underneath new_root,  i.e. adding a non-zero number of /.. to the string
+ * pointed to by put_old must yield the same directory as new_root. No other
+ * file system may be mounted on put_old. After all, new_root is a mountpoint.
  *
- * Note:
+ * Notes:
  *  - we don't move root/cwd if they are not at the root (reason: if something
  *    cared enough to change them, it's probably wrong to force them elsewhere)
  *  - it's okay to pick a root that isn't the root of a file system, e.g.
@@ -1402,10 +1408,10 @@ asmlinkage long sys_pivot_root(const char __user *new_root, const char __user *p
 		goto out2;
 	error = -EBUSY;
 	if (new_nd.mnt == user_nd.mnt || old_nd.mnt == user_nd.mnt)
-		goto out2; /* loop */
+		goto out2; /* loop, on the same file system  */
 	error = -EINVAL;
 	if (user_nd.mnt->mnt_root != user_nd.dentry)
-		goto out2;
+		goto out2; /* not a mountpoint */
 	if (new_nd.mnt->mnt_root != new_nd.dentry)
 		goto out2; /* not a mountpoint */
 	tmp = old_nd.mnt; /* make sure we can reach put_old from new_root */
@@ -1413,7 +1419,7 @@ asmlinkage long sys_pivot_root(const char __user *new_root, const char __user *p
 	if (tmp != new_nd.mnt) {
 		for (;;) {
 			if (tmp->mnt_parent == tmp)
-				goto out3;
+				goto out3; /* already mounted on put_old */
 			if (tmp->mnt_parent == new_nd.mnt)
 				break;
 			tmp = tmp->mnt_parent;
@@ -1424,8 +1430,8 @@ asmlinkage long sys_pivot_root(const char __user *new_root, const char __user *p
 		goto out3;
 	detach_mnt(new_nd.mnt, &parent_nd);
 	detach_mnt(user_nd.mnt, &root_parent);
-	attach_mnt(user_nd.mnt, &old_nd);
-	attach_mnt(new_nd.mnt, &root_parent);
+	attach_mnt(user_nd.mnt, &old_nd);     /* mount old root on put_old */
+	attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */
 	spin_unlock(&vfsmount_lock);
 	chroot_fs_refs(&user_nd, &new_nd);
 	security_sb_post_pivotroot(&user_nd, &new_nd);
@@ -1481,16 +1487,14 @@ static void __init init_mount_tree(void)
 void __init mnt_init(unsigned long mempages)
 {
 	struct list_head *d;
-	unsigned long order;
 	unsigned int nr_hash;
 	int i;
 
 	mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct vfsmount),
 			0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
 
-	order = 0; 
 	mount_hashtable = (struct list_head *)
-		__get_free_pages(GFP_ATOMIC, order);
+		__get_free_page(GFP_ATOMIC);
 
 	if (!mount_hashtable)
 		panic("Failed to allocate mount hash table\n");
@@ -1500,7 +1504,7 @@ void __init mnt_init(unsigned long mempages)
 	 * We don't guarantee that "sizeof(struct list_head)" is necessarily
 	 * a power-of-two.
 	 */
-	nr_hash = (1UL << order) * PAGE_SIZE / sizeof(struct list_head);
+	nr_hash = PAGE_SIZE / sizeof(struct list_head);
 	hash_bits = 0;
 	do {
 		hash_bits++;
@@ -1514,8 +1518,7 @@ void __init mnt_init(unsigned long mempages)
 	nr_hash = 1UL << hash_bits;
 	hash_mask = nr_hash-1;
 
-	printk("Mount-cache hash table entries: %d (order: %ld, %ld bytes)\n",
-			nr_hash, order, (PAGE_SIZE << order));
+	printk("Mount-cache hash table entries: %d\n", nr_hash);
 
 	/* And initialize the newly allocated array */
 	d = mount_hashtable;