Btrfs: prevent loops in the directory tree when creating snapshots

For a directory tree:

/mnt/subvolA/subvolB

btrfsctl -s /mnt/subvolA/subvolB /mnt

Will create a directory loop with subvolA under subvolB.  This
commit uses the forward refs for each subvol and snapshot to error out
before creating the loop.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 8d7866b733d6..e18250a6fd2d 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1129,7 +1129,7 @@ struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
                 kfree(root);
                 return ERR_PTR(ret);
         }
-
+#if 0
         ret = btrfs_sysfs_add_root(root);
         if (ret) {
                 free_extent_buffer(root->node);
@@ -1137,6 +1137,7 @@ struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info,
                 kfree(root);
                 return ERR_PTR(ret);
         }
+#endif
         root->in_sysfs = 1;
         return root;
 }
@@ -1963,8 +1964,10 @@ int btrfs_free_fs_root(struct btrfs_fs_info *fs_info, struct btrfs_root *root)
                 down_write(&root->anon_super.s_umount);
                 kill_anon_super(&root->anon_super);
         }
+#if 0
         if (root->in_sysfs)
                 btrfs_sysfs_del_root(root);
+#endif
         if (root->node)
                 free_extent_buffer(root->node);
         if (root->commit_root)