linux-ext4 - [PATCH] e2fsck: Let end_blk to be the maximum value of u32.

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Date:	Wed, 16 May 2012 16:50:25 +0800
From:	Tao Ma <tm@....ma>
To:	linux-ext4@...r.kernel.org
Cc:	Theodore Ts'o <tytso@....edu>
Subject: [PATCH] e2fsck: Let end_blk to be the maximum value of u32.

From: Tao Ma <boyu.mt@...bao.com>

Now we can use fallocate to create a large file while keep the size
to be small. It will cause the e2fsck complain about it. The test
script is simple and I have pasted it here.

DEVICE=/dev/sdb1
mount -t ext4 $DEVICE /mnt/ext4
for((i=0;i<10;i++))do fallocate -n -o $[$i*8192] -l 4096 /mnt/ext4/a;done
umount $DEVICE
e2fsck -fn $DEVICE

The error message will be like this:
e2fsck 1.42.3 (14-May-2012)
Pass 1: Checking inodes, blocks, and sizes
Inode 12 has zero length extent
	(invalid logical block 0, physical block 32775)
Clear? no

Inode 12, i_blocks is 88, should be 0.  Fix? no

Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Block bitmap differences:  -(8231--8232) -(32770--32778)
Fix? no

Now actually the end_blk can be any value which is less than
u32, so make end_blk be the maximum value of u32.

Cc: Theodore Ts'o <tytso@....edu>
Signed-off-by: Tao Ma <boyu.mt@...bao.com>
---
 lib/ext2fs/extent.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/lib/ext2fs/extent.c b/lib/ext2fs/extent.c
index eb096d6..e2815c2 100644
--- a/lib/ext2fs/extent.c
+++ b/lib/ext2fs/extent.c
@@ -253,9 +253,7 @@ extern errcode_t ext2fs_extent_open2(ext2_filsys fs, ext2_ino_t ino,
 		ext2fs_le16_to_cpu(eh->eh_entries);
 	handle->path[0].max_entries = ext2fs_le16_to_cpu(eh->eh_max);
 	handle->path[0].curr = 0;
-	handle->path[0].end_blk =
-		(EXT2_I_SIZE(handle->inode) + fs->blocksize - 1) >>
-		 EXT2_BLOCK_SIZE_BITS(fs->super);
+	handle->path[0].end_blk = ((((unsigned long long) 1) << 32) - 1);
 	handle->path[0].visit_num = 1;
 	handle->level = 0;
 	handle->magic = EXT2_ET_MAGIC_EXTENT_HANDLE;
-- 
1.7.1

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