[PATCH 24/49] ext4: fix for fiemap last-block test

Theodore Ts'o
2009-06-08T19:32:46Z

From: Eric Sandeen <sandeen@redhat.com>

Carl Henrik Lunde reported and debugged this; the test for the
last allocated block was comparing bytes to blocks in this test:

if (logical + length - 1 == EXT_MAX_BLOCK ||
ext4_ext_next_allocated_block(path) == EXT_MAX_BLOCK)
flags |= FIEMAP_EXTENT_LAST;

so any extent which ended right at 4G was stopping the extent
walk. Just replacing these values with the extent block &
length should fix it.

Also give blksize_bits a saner type, and reverse the order
of the tests to make the more likely case tested first.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reported-by: Carl Henrik Lunde <chlunde@ping.uio.no>
Tested-by: Carl Henrik Lunde <chlunde@ping.uio.no>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
fs/ext4/extents.c | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index ea5c476..5f72952 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3196,7 +3196,7 @@ static int ext4_ext_fiemap_cb(struct inode *inode, struct ext4_ext_path *path,
void *data)
{
struct fiemap_extent_info *fieinfo = data;
- unsigned long blksize_bits = inode->i_sb->s_blocksize_bits;
+ unsigned char blksize_bits = inode->i_sb->s_blocksize_bits;
__u64 logical;
__u64 physical;
__u64 length;
@@ -3243,8 +3243,8 @@ static int ext4_ext_fiemap_cb(struct inode *inode, struct ext4_ext_path *path,
*
* XXX this might miss a single-block extent at EXT_MAX_BLOCK
*/
- if (logical + length - 1 == EXT_MAX_BLOCK ||
- ext4_ext_next_allocated_block(path) == EXT_MAX_BLOCK)
+ if (ext4_ext_next_allocated_block(path) == EXT_MAX_BLOCK ||
+ newex->ec_block + newex->ec_len - 1 == EXT_MAX_BLOCK)
flags |= FIEMAP_EXTENT_LAST;

error = fiemap_fill_next_extent(fieinfo, logical, physical,
--
1.6.3.2.1.gb9f7d.dirty