Re: [PATCH v2] ext4: add WARN_ON to check the length of allocated blocks

[Theodore Ts'o <tytso@mit.edu>]

The patch didn't apply as-is so I had to adjust it a bit.  I also
reworded the commit description.

					- Ted

>From 44fb851dfb2f8e3462617e19a7b3b9025db9d919 Mon Sep 17 00:00:00 2001
From: Zheng Liu <wenqing.lz@taobao.com>
Date: Mon, 29 Jul 2013 12:51:42 -0400
Subject: [PATCH] ext4: add WARN_ON to check the length of allocated blocks

In commit 921f266b: ext4: add self-testing infrastructure to do a
sanity check, some sanity checks were added in map_blocks to make sure
'retval == map->m_len'.

Enable these checks by default and report any assertion failures using
ext4_warning() and WARN_ON() since they can help us to figure out some
bugs that are otherwise hard to hit.

Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
 fs/ext4/inode.c | 39 ++++++++++++++++++---------------------
 1 file changed, 18 insertions(+), 21 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index ba33c67..dd32a2e 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -555,14 +555,13 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
 		int ret;
 		unsigned long long status;
 
-#ifdef ES_AGGRESSIVE_TEST
-		if (retval != map->m_len) {
-			printk("ES len assertion failed for inode: %lu "
-			       "retval %d != map->m_len %d "
-			       "in %s (lookup)\n", inode->i_ino, retval,
-			       map->m_len, __func__);
+		if (unlikely(retval != map->m_len)) {
+			ext4_warning(inode->i_sb,
+				     "ES len assertion failed for inode "
+				     "%lu: retval %d != map->m_len %d",
+				     inode->i_ino, retval, map->m_len);
+			WARN_ON(1);
 		}
-#endif
 
 		status = map->m_flags & EXT4_MAP_UNWRITTEN ?
 				EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
@@ -656,14 +655,13 @@ found:
 		int ret;
 		unsigned long long status;
 
-#ifdef ES_AGGRESSIVE_TEST
-		if (retval != map->m_len) {
-			printk("ES len assertion failed for inode: %lu "
-			       "retval %d != map->m_len %d "
-			       "in %s (allocation)\n", inode->i_ino, retval,
-			       map->m_len, __func__);
+		if (unlikely(retval != map->m_len)) {
+			ext4_warning(inode->i_sb,
+				     "ES len assertion failed for inode "
+				     "%lu: retval %d != map->m_len %d",
+				     inode->i_ino, retval, map->m_len);
+			WARN_ON(1);
 		}
-#endif
 
 		/*
 		 * If the extent has been zeroed out, we don't need to update
@@ -1637,14 +1635,13 @@ add_delayed:
 		int ret;
 		unsigned long long status;
 
-#ifdef ES_AGGRESSIVE_TEST
-		if (retval != map->m_len) {
-			printk("ES len assertion failed for inode: %lu "
-			       "retval %d != map->m_len %d "
-			       "in %s (lookup)\n", inode->i_ino, retval,
-			       map->m_len, __func__);
+		if (unlikely(retval != map->m_len)) {
+			ext4_warning(inode->i_sb,
+				     "ES len assertion failed for inode "
+				     "%lu: retval %d != map->m_len %d",
+				     inode->i_ino, retval, map->m_len);
+			WARN_ON(1);
 		}
-#endif
 
 		status = map->m_flags & EXT4_MAP_UNWRITTEN ?
 				EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
-- 
1.7.12.rc0.22.gcdd159b