ocfs2: extend transaction for ocfs2_remove_rightmost_path() and ocfs2_update_edge_lengths() before to avoid inconsistency between inode and et

I found that jbd2_journal_restart() is called in some places without
keeping things consistently before.  However, jbd2_journal_restart() may
commit the handle's transaction and restart another one.  If the first
transaction is committed successfully while another not, it may cause
filesystem inconsistency or read only.  This is an effort to fix this
kind of problems.

This patch (of 3):

The following functions will be called while truncating an extent:
ocfs2_remove_btree_range
  -> ocfs2_start_trans
  -> ocfs2_remove_extent
     -> ocfs2_truncate_rec
       -> ocfs2_extend_rotate_transaction
         -> jbd2_journal_restart if jbd2_journal_extend fail
       -> ocfs2_rotate_tree_left
         -> ocfs2_remove_rightmost_path
             -> ocfs2_extend_rotate_transaction
               -> ocfs2_unlink_subtree
                -> ocfs2_update_edge_lengths
                  -> ocfs2_extend_trans
                    -> jbd2_journal_restart if jbd2_journal_extend fail
  -> ocfs2_et_update_clusters
  -> ocfs2_commit_trans

jbd2_journal_restart() may be called and it may happened that the buffers
dirtied in ocfs2_truncate_rec() are committed while buffers dirtied in
ocfs2_et_update_clusters() are not, the total clusters on extent tree and
i_clusters in ocfs2_dinode is inconsistency.  So the clusters got from
ocfs2_dinode is incorrect, and it also cause read-only problem when call
ocfs2_commit_truncate() with the error message: "Inode %llu has empty
extent block at %llu".

We should extend enough credits for function ocfs2_remove_rightmost_path
and ocfs2_update_edge_lengths to avoid this inconsistency.

Signed-off-by: joyce.xue <xuejiufei@huawei.com>
Acked-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ocfs2/alloc.c

@@ -2516,21 +2516,6 @@ static int ocfs2_update_edge_lengths(handle_t *handle,
 	struct ocfs2_extent_block *eb;
 	u32 range;
 
-	/*
-	 * In normal tree rotation process, we will never touch the
-	 * tree branch above subtree_index and ocfs2_extend_rotate_transaction
-	 * doesn't reserve the credits for them either.
-	 *
-	 * But we do have a special case here which will update the rightmost
-	 * records for all the bh in the path.
-	 * So we have to allocate extra credits and access them.
-	 */
-	ret = ocfs2_extend_trans(handle, subtree_index);
-	if (ret) {
-		mlog_errno(ret);
-		goto out;
-	}
-
 	ret = ocfs2_journal_access_path(et->et_ci, handle, path);
 	if (ret) {
 		mlog_errno(ret);
@@ -2956,7 +2941,7 @@ static int __ocfs2_rotate_tree_left(handle_t *handle,
 		     right_path->p_node[subtree_root].bh->b_blocknr,
 		     right_path->p_tree_depth);
 
-		ret = ocfs2_extend_rotate_transaction(handle, subtree_root,
+		ret = ocfs2_extend_rotate_transaction(handle, 0,
 						      orig_credits, left_path);
 		if (ret) {
 			mlog_errno(ret);
@@ -3029,21 +3014,9 @@ static int ocfs2_remove_rightmost_path(handle_t *handle,
 	struct ocfs2_extent_block *eb;
 	struct ocfs2_extent_list *el;
 
-
 	ret = ocfs2_et_sanity_check(et);
 	if (ret)
 		goto out;
-	/*
-	 * There's two ways we handle this depending on
-	 * whether path is the only existing one.
-	 */
-	ret = ocfs2_extend_rotate_transaction(handle, 0,
-					      handle->h_buffer_credits,
-					      path);
-	if (ret) {
-		mlog_errno(ret);
-		goto out;
-	}
 
 	ret = ocfs2_journal_access_path(et->et_ci, handle, path);
 	if (ret) {
@@ -3641,6 +3614,14 @@ static int ocfs2_merge_rec_left(struct ocfs2_path *right_path,
 		 */
 		if (le16_to_cpu(right_rec->e_leaf_clusters) == 0 &&
 		    le16_to_cpu(el->l_next_free_rec) == 1) {
+			/* extend credit for ocfs2_remove_rightmost_path */
+			ret = ocfs2_extend_rotate_transaction(handle, 0,
+					handle->h_buffer_credits,
+					right_path);
+			if (ret) {
+				mlog_errno(ret);
+				goto out;
+			}
 
 			ret = ocfs2_remove_rightmost_path(handle, et,
 							  right_path,
@@ -3679,6 +3660,14 @@ static int ocfs2_try_to_merge_extent(handle_t *handle,
 	BUG_ON(ctxt->c_contig_type == CONTIG_NONE);
 
 	if (ctxt->c_split_covers_rec && ctxt->c_has_empty_extent) {
+		/* extend credit for ocfs2_remove_rightmost_path */
+		ret = ocfs2_extend_rotate_transaction(handle, 0,
+				handle->h_buffer_credits,
+				path);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
 		/*
 		 * The merge code will need to create an empty
 		 * extent to take the place of the newly
@@ -3727,6 +3716,15 @@ static int ocfs2_try_to_merge_extent(handle_t *handle,
 		 */
 		BUG_ON(!ocfs2_is_empty_extent(&el->l_recs[0]));
 
+		/* extend credit for ocfs2_remove_rightmost_path */
+		ret = ocfs2_extend_rotate_transaction(handle, 0,
+					handle->h_buffer_credits,
+					path);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
 		/* The merge left us with an empty extent, remove it. */
 		ret = ocfs2_rotate_tree_left(handle, et, path, dealloc);
 		if (ret) {
@@ -3748,6 +3746,15 @@ static int ocfs2_try_to_merge_extent(handle_t *handle,
 			goto out;
 		}
 
+		/* extend credit for ocfs2_remove_rightmost_path */
+		ret = ocfs2_extend_rotate_transaction(handle, 0,
+				handle->h_buffer_credits,
+				path);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
 		ret = ocfs2_rotate_tree_left(handle, et, path, dealloc);
 		/*
 		 * Error from this last rotate is not critical, so
@@ -3783,6 +3790,16 @@ static int ocfs2_try_to_merge_extent(handle_t *handle,
 		}
 
 		if (ctxt->c_split_covers_rec) {
+			/* extend credit for ocfs2_remove_rightmost_path */
+			ret = ocfs2_extend_rotate_transaction(handle, 0,
+					handle->h_buffer_credits,
+					path);
+			if (ret) {
+				mlog_errno(ret);
+				ret = 0;
+				goto out;
+			}
+
 			/*
 			 * The merge may have left an empty extent in
 			 * our leaf. Try to rotate it away.
@@ -5342,6 +5359,15 @@ static int ocfs2_truncate_rec(handle_t *handle,
 	struct ocfs2_extent_block *eb;
 
 	if (ocfs2_is_empty_extent(&el->l_recs[0]) && index > 0) {
+		/* extend credit for ocfs2_remove_rightmost_path */
+		ret = ocfs2_extend_rotate_transaction(handle, 0,
+				handle->h_buffer_credits,
+				path);
+		if (ret) {
+			mlog_errno(ret);
+			goto out;
+		}
+
 		ret = ocfs2_rotate_tree_left(handle, et, path, dealloc);
 		if (ret) {
 			mlog_errno(ret);