btrfs: merge unlocking to common exit block in btrfs_commit_transaction

The tree_log_mutex and reloc_mutex locks are properly nested so we can
simplify error handling and add labels for them. This reduces line count
of the function.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index fdfdfc42653952ae376ae220377d37a84a714a63..702e0f2b8307de56d94a1220ffc66a566bbd9a0f 100644 (file)
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -2194,10 +2194,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
         * core function of the snapshot creation.
         */
        ret = create_pending_snapshots(trans);
-       if (ret) {
-               mutex_unlock(&fs_info->reloc_mutex);
-               goto scrub_continue;
-       }
+       if (ret)
+               goto unlock_reloc;
 
        /*
         * We insert the dir indexes of the snapshots and update the inode
@@ -2210,16 +2208,12 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
         * the nodes and leaves.
         */
        ret = btrfs_run_delayed_items(trans);
-       if (ret) {
-               mutex_unlock(&fs_info->reloc_mutex);
-               goto scrub_continue;
-       }
+       if (ret)
+               goto unlock_reloc;
 
        ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
-       if (ret) {
-               mutex_unlock(&fs_info->reloc_mutex);
-               goto scrub_continue;
-       }
+       if (ret)
+               goto unlock_reloc;
 
        /*
         * make sure none of the code above managed to slip in a
@@ -2245,11 +2239,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
        mutex_lock(&fs_info->tree_log_mutex);
 
        ret = commit_fs_roots(trans);
-       if (ret) {
-               mutex_unlock(&fs_info->tree_log_mutex);
-               mutex_unlock(&fs_info->reloc_mutex);
-               goto scrub_continue;
-       }
+       if (ret)
+               goto unlock_tree_log;
 
        /*
         * Since the transaction is done, we can apply the pending changes
@@ -2267,29 +2258,20 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
         * new delayed refs. Must handle them or qgroup can be wrong.
         */
        ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
-       if (ret) {
-               mutex_unlock(&fs_info->tree_log_mutex);
-               mutex_unlock(&fs_info->reloc_mutex);
-               goto scrub_continue;
-       }
+       if (ret)
+               goto unlock_tree_log;
 
        /*
         * Since fs roots are all committed, we can get a quite accurate
         * new_roots. So let's do quota accounting.
         */
        ret = btrfs_qgroup_account_extents(trans);
-       if (ret < 0) {
-               mutex_unlock(&fs_info->tree_log_mutex);
-               mutex_unlock(&fs_info->reloc_mutex);
-               goto scrub_continue;
-       }
+       if (ret < 0)
+               goto unlock_tree_log;
 
        ret = commit_cowonly_roots(trans);
-       if (ret) {
-               mutex_unlock(&fs_info->tree_log_mutex);
-               mutex_unlock(&fs_info->reloc_mutex);
-               goto scrub_continue;
-       }
+       if (ret)
+               goto unlock_tree_log;
 
        /*
         * The tasks which save the space cache and inode cache may also
@@ -2297,9 +2279,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
         */
        if (TRANS_ABORTED(cur_trans)) {
                ret = cur_trans->aborted;
-               mutex_unlock(&fs_info->tree_log_mutex);
-               mutex_unlock(&fs_info->reloc_mutex);
-               goto scrub_continue;
+               goto unlock_tree_log;
        }
 
        btrfs_prepare_extent_commit(fs_info);
@@ -2346,6 +2326,10 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
        if (ret) {
                btrfs_handle_fs_error(fs_info, ret,
                                      "Error while writing out transaction");
+               /*
+                * reloc_mutex has been unlocked, tree_log_mutex is still held
+                * but we can't jump to unlock_tree_log causing double unlock
+                */
                mutex_unlock(&fs_info->tree_log_mutex);
                goto scrub_continue;
        }
@@ -2394,6 +2378,10 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
 
        return ret;
 
+unlock_tree_log:
+       mutex_unlock(&fs_info->tree_log_mutex);
+unlock_reloc:
+       mutex_unlock(&fs_info->reloc_mutex);
 scrub_continue:
        btrfs_scrub_continue(fs_info);
 cleanup_transaction: