ext4: Fix s_dirty_blocks_counter if block allocation failed with nodelalloc

With nodelalloc option we need to update the dirty block counter on
block allocation failure. This is needed because we increment the
dirty block counter early in the block allocation phase. Without
the patch s_dirty_blocks_counter goes wrong so that filesystem's
free blocks decreases incorrectly.

Tested-by: Akira Fujita <a-fujita@rs.jp.nec.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@kernel.org

fs/ext4/mballoc.c

@@ -4541,7 +4541,7 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
 	}
 	if (ar->len == 0) {
 		*errp = -EDQUOT;
-		return 0;
+		goto out3;
 	}
 	inquota = ar->len;
 
@@ -4614,6 +4614,13 @@ out2:
 out1:
 	if (ar->len < inquota)
 		DQUOT_FREE_BLOCK(ar->inode, inquota - ar->len);
+out3:
+	if (!ar->len) {
+		if (!EXT4_I(ar->inode)->i_delalloc_reserved_flag)
+			/* release all the reserved blocks if non delalloc */
+			percpu_counter_sub(&sbi->s_dirtyblocks_counter,
+						reserv_blks);
+	}
 
 	return block;
 }