X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=fs%2Fsuper.c;h=998fc473e1579ee9e1bb99d063ec047655524aac;hb=c7b5ebbddf7bcd3651947760f423e3783bbe6573;hp=8d9bff178bcac6ea625e79b2aa7a95d78153bba0;hpb=9213980e6a70d8473e0ffd4b39ab5b6caaba9ff5;p=linux-2.6.git

diff --git a/fs/super.c b/fs/super.c
index 8d9bff178..998fc473e 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -35,6 +35,8 @@
 #include <linux/vfs.h>
 #include <linux/writeback.h>		/* for the emergency remount stuff */
 #include <linux/idr.h>
+#include <linux/devpts_fs.h>
+#include <linux/proc_fs.h>
 #include <asm/uaccess.h>
 
 
@@ -116,6 +118,27 @@ int __put_super(struct super_block *sb)
 	return ret;
 }
 
+/*
+ * Drop a superblock's refcount.
+ * Returns non-zero if the superblock is about to be destroyed and
+ * at least is already removed from super_blocks list, so if we are
+ * making a loop through super blocks then we need to restart.
+ * The caller must hold sb_lock.
+ */
+int __put_super_and_need_restart(struct super_block *sb)
+{
+	/* check for race with generic_shutdown_super() */
+	if (list_empty(&sb->s_list)) {
+		/* super block is removed, need to restart... */
+		__put_super(sb);
+		return 1;
+	}
+	/* can't be the last, since s_list is still in use */
+	sb->s_count--;
+	BUG_ON(sb->s_count == 0);
+	return 0;
+}
+
 /**
  *	put_super	-	drop a temporary reference to superblock
  *	@s: superblock in question
@@ -229,7 +252,8 @@ void generic_shutdown_super(struct super_block *sb)
 		unlock_super(sb);
 	}
 	spin_lock(&sb_lock);
-	list_del(&sb->s_list);
+	/* should be initialized for __put_super_and_need_restart() */
+	list_del_init(&sb->s_list);
 	list_del(&sb->s_instances);
 	spin_unlock(&sb_lock);
 	up_write(&sb->s_umount);
@@ -282,7 +306,7 @@ retry:
 	}
 	s->s_type = type;
 	strlcpy(s->s_id, type->name, sizeof(s->s_id));
-	list_add(&s->s_list, super_blocks.prev);
+	list_add_tail(&s->s_list, &super_blocks);
 	list_add(&s->s_instances, &type->fs_supers);
 	spin_unlock(&sb_lock);
 	get_filesystem(type);
@@ -569,14 +593,19 @@ static spinlock_t unnamed_dev_lock = SPIN_LOCK_UNLOCKED;/* protects the above */
 int set_anon_super(struct super_block *s, void *data)
 {
 	int dev;
+	int error;
 
-	spin_lock(&unnamed_dev_lock);
-	if (idr_pre_get(&unnamed_dev_idr, GFP_ATOMIC) == 0) {
-		spin_unlock(&unnamed_dev_lock);
+ retry:
+	if (idr_pre_get(&unnamed_dev_idr, GFP_ATOMIC) == 0)
 		return -ENOMEM;
-	}
-	dev = idr_get_new(&unnamed_dev_idr, NULL);
+	spin_lock(&unnamed_dev_lock);
+	error = idr_get_new(&unnamed_dev_idr, NULL, &dev);
 	spin_unlock(&unnamed_dev_lock);
+	if (error == -EAGAIN)
+		/* We raced and lost with another CPU. */
+		goto retry;
+	else if (error)
+		return -EAGAIN;
 
 	if ((dev & MAX_ID_MASK) == (1 << MINORBITS)) {
 		spin_lock(&unnamed_dev_lock);
@@ -781,6 +810,13 @@ do_kern_mount(const char *fstype, int flags, const char *name, void *data)
 	sb = type->get_sb(type, flags, name, data);
 	if (IS_ERR(sb))
 		goto out_free_secdata;
+
+	error = -EPERM;
+	if (!capable(CAP_SYS_ADMIN) && !sb->s_bdev &&
+		(sb->s_magic != PROC_SUPER_MAGIC) &&
+		(sb->s_magic != DEVPTS_SUPER_MAGIC))
+		goto out_sb;
+
  	error = security_sb_kern_mount(sb, secdata);
  	if (error)
  		goto out_sb;
@@ -788,6 +824,7 @@ do_kern_mount(const char *fstype, int flags, const char *name, void *data)
 	mnt->mnt_root = dget(sb->s_root);
 	mnt->mnt_mountpoint = sb->s_root;
 	mnt->mnt_parent = mnt;
+	mnt->mnt_namespace = current->namespace;
 	up_write(&sb->s_umount);
 	put_filesystem(type);
 	return mnt;
@@ -804,6 +841,8 @@ out:
 	return (struct vfsmount *)sb;
 }
 
+EXPORT_SYMBOL_GPL(do_kern_mount);
+
 struct vfsmount *kern_mount(struct file_system_type *type)
 {
 	return do_kern_mount(type->name, 0, type->name, NULL);