2007-10-19 13:46:31

by Adrian Bunk

Subject: ext4/balloc.c:read_block_bitmap(): inconsequent NULL checking

Commit 7c9e69faa28027913ee059c285a5ea8382e24b5d results in the following
inconsequent NULL checking in fs/ext4/balloc.c:

<-- snip -->

...
struct buffer_head *
read_block_bitmap(struct super_block *sb, unsigned int block_group)
{
...
if (!bh)
ext4_error (sb, __FUNCTION__,
"Cannot read block bitmap - "
"block_group = %d, block_bitmap = %llu",
block_group, bitmap_blk);

/* check whether block bitmap block number is set */
if (!block_in_use(bitmap_blk, sb, bh->b_data)) {
... ^^^^^^^^^^

<-- snip -->

Spotted by the Coverity checker.

cu
Adrian

--

"Is there not promise of rain?" Ling Tan asked suddenly out
of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
Pearl S. Buck - Dragon Seed

2007-10-19 14:46:42

by Aneesh Kumar K.V

Subject: Re: ext4/balloc.c:read_block_bitmap(): inconsequent NULL checking

I checked rest of the ext4 sources to make sure we return properly after ext4_error.
I guess i have taken care of all the places.

-aneesh

Adrian Bunk wrote:
> Commit 7c9e69faa28027913ee059c285a5ea8382e24b5d results in the following
> inconsequent NULL checking in fs/ext4/balloc.c:
>
> <-- snip -->
>
> ...
> struct buffer_head *
> read_block_bitmap(struct super_block *sb, unsigned int block_group)
> {
> ...
> if (!bh)
> ext4_error (sb, __FUNCTION__,
> "Cannot read block bitmap - "
> "block_group = %d, block_bitmap = %llu",
> block_group, bitmap_blk);
>
> /* check whether block bitmap block number is set */
> if (!block_in_use(bitmap_blk, sb, bh->b_data)) {
> ... ^^^^^^^^^^
>
> <-- snip -->
>
> Spotted by the Coverity checker.
>
>



>From 5c04ec0d8e43ef582cec2856f262b575376233ba Mon Sep 17 00:00:00 2001
From: Aneesh Kumar K.V <[email protected]>
Date: Fri, 19 Oct 2007 20:10:17 +0530
Subject: [PATCH] ext4: Return after ext4_error in case of failures

This fix some instances where we were continuing
after marking the file system errors.
Even though ext4_error mark the file system read only
and panic depending on mount option it is good
to handle the return properly.

Reported by:
Adrian Bunk <[email protected]>

Signed-off-by: Aneesh Kumar K.V <[email protected]>
---
fs/ext4/balloc.c | 12 +++++++++---
1 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
index e906b65..8517dd7 100644
--- a/fs/ext4/balloc.c
+++ b/fs/ext4/balloc.c
@@ -234,11 +234,13 @@ read_block_bitmap(struct super_block *sb, unsigned int block_group)
} else {
bh = sb_bread(sb, bitmap_blk);
}
- if (!bh)
+ if (!bh) {
ext4_error (sb, __FUNCTION__,
"Cannot read block bitmap - "
"block_group = %d, block_bitmap = %llu",
block_group, bitmap_blk);
+ return NULL;
+ }

/* check whether block bitmap block number is set */
if (!block_in_use(bitmap_blk, sb, bh->b_data)) {
@@ -628,11 +630,13 @@ do_more:
in_range(ext4_inode_bitmap(sb, desc), block, count) ||
in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
in_range(block + count - 1, ext4_inode_table(sb, desc),
- sbi->s_itb_per_group))
+ sbi->s_itb_per_group)) {
ext4_error (sb, "ext4_free_blocks",
"Freeing blocks in system zones - "
"Block = %llu, count = %lu",
block, count);
+ goto error_return;
+ }

/*
* We are about to start releasing blocks in the bitmap,
@@ -1733,11 +1737,13 @@ allocated:
in_range(ret_block, ext4_inode_table(sb, gdp),
EXT4_SB(sb)->s_itb_per_group) ||
in_range(ret_block + num - 1, ext4_inode_table(sb, gdp),
- EXT4_SB(sb)->s_itb_per_group))
+ EXT4_SB(sb)->s_itb_per_group)) {
ext4_error(sb, "ext4_new_block",
"Allocating block in system zone - "
"blocks from %llu, length %lu",
ret_block, num);
+ goto out;
+ }

performed_allocation = 1;

--
1.5.3.4.206.g58ba4-dirty