btrfs: hold a ref on the root in search_ioctl

We lookup a arbitrary fs root, we need to hold a ref on that root.  If
we're using our own inodes root then grab a ref on that as well to make
the cleanup easier.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 0e524f3..b173bb6 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2180,7 +2180,7 @@ static noinline int search_ioctl(struct inode *inode,
 
        if (sk->tree_id == 0) {
                /* search the root of the inode that was passed */
-               root = BTRFS_I(inode)->root;
+               root = btrfs_grab_fs_root(BTRFS_I(inode)->root);
        } else {
                key.objectid = sk->tree_id;
                key.type = BTRFS_ROOT_ITEM_KEY;
@@ -2190,6 +2190,10 @@ static noinline int search_ioctl(struct inode *inode,
                        btrfs_free_path(path);
                        return PTR_ERR(root);
                }
+               if (!btrfs_grab_fs_root(root)) {
+                       btrfs_free_path(path);
+                       return -ENOENT;
+               }
        }
 
        key.objectid = sk->min_objectid;
@@ -2214,6 +2218,7 @@ static noinline int search_ioctl(struct inode *inode,
                ret = 0;
 err:
        sk->nr_items = num_found;
+       btrfs_put_fs_root(root);
        btrfs_free_path(path);
        return ret;
 }