ext4: fix for fiemap last-block test

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>

1 files changed, 3 insertions, 3 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index ea5c47608cea..5f7295287de1 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,