mkfs.btrfs on 24 disks in parallel crashes kernel

Commit Message

Ian Kent Nov. 9, 2010, 4:10 a.m. UTC

None

Patch

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 718b10d..9b463b9 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -565,6 +565,8 @@  static int btrfs_test_super(struct super_block *s, void *data)
 	struct btrfs_fs_devices *test_fs_devices = data;
 	struct btrfs_root *root = btrfs_sb(s);
 
+	if (!root)
+		return 0;
 	return root->fs_info->fs_devices == test_fs_devices;
 }
 
@@ -585,6 +587,7 @@  static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
 	char *subvol_name = NULL;
 	u64 subvol_objectid = 0;
 	int error = 0;
+	DEFINE_MUTEX(super_mutex);
 
 	if (!(flags & MS_RDONLY))
 		mode |= FMODE_WRITE;
@@ -613,8 +616,10 @@  static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
 	if (IS_ERR(s))
 		goto error_s;
 
+	mutex_lock(&super_mutex);
 	if (s->s_root) {
 		if ((flags ^ s->s_flags) & MS_RDONLY) {
+			mutex_unlock(&super_mutex);
 			deactivate_locked_super(s);
 			error = -EBUSY;
 			goto error_close_devices;
@@ -629,6 +634,7 @@  static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
 		error = btrfs_fill_super(s, fs_devices, data,
 					 flags & MS_SILENT ? 1 : 0);
 		if (error) {
+			mutex_unlock(&super_mutex);
 			deactivate_locked_super(s);
 			goto error_free_subvol_name;
 		}
@@ -636,6 +642,7 @@  static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
 		btrfs_sb(s)->fs_info->bdev_holder = fs_type;
 		s->s_flags |= MS_ACTIVE;
 	}
+	mutex_unlock(&super_mutex);
 
 	root = get_default_root(s, subvol_objectid);
 	if (IS_ERR(root)) {