[ 3.8.y.z extended stable ] Patch "ocfs2: fix the end cluster offset of FIEMAP" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    ocfs2: fix the end cluster offset of FIEMAP

to the linux-3.8.y-queue branch of the 3.8.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.10.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From e0139f41da52327e8ffcff958b8ca5155a49d22f Mon Sep 17 00:00:00 2001
From: Jie Liu <jeff.liu at oracle.com>
Date: Wed, 11 Sep 2013 14:20:05 -0700
Subject: ocfs2: fix the end cluster offset of FIEMAP

commit 28e8be31803b19d0d8f76216cb11b480b8a98bec upstream.

Call fiemap ioctl(2) with given start offset as well as an desired mapping
range should show extents if possible.  However, we somehow figure out the
end offset of mapping via 'mapping_end -= cpos' before iterating the
extent records which would cause problems if the given fiemap length is
too small to a cluster size, e.g,

Cluster size 4096:
debugfs.ocfs2 1.6.3
        Block Size Bits: 12   Cluster Size Bits: 12

The extended fiemap test utility From David:
https://gist.github.com/anonymous/6172331

# dd if=/dev/urandom of=/ocfs2/test_file bs=1M count=1000
# ./fiemap /ocfs2/test_file 4096 10
start: 4096, length: 10
File /ocfs2/test_file has 0 extents:
#	Logical          Physical         Length           Flags
	^^^^^ <-- No extent is shown

In this case, at ocfs2_fiemap(): cpos == mapping_end == 1. Hence the
loop of searching extent records was not executed at all.

This patch remove the in question 'mapping_end -= cpos', and loops
until the cpos is larger than the mapping_end as usual.

# ./fiemap /ocfs2/test_file 4096 10
start: 4096, length: 10
File /ocfs2/test_file has 1 extents:
#	Logical          Physical         Length           Flags
0:	0000000000000000 0000000056a01000 0000000006a00000 0000

Signed-off-by: Jie Liu <jeff.liu at oracle.com>
Reported-by: David Weber <wb at munzinger.de>
Tested-by: David Weber <wb at munzinger.de>
Cc: Sunil Mushran <sunil.mushran at gmail.com>
Cc: Mark Fashen <mfasheh at suse.de>
Cc: Joel Becker <jlbec at evilplan.org>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 fs/ocfs2/extent_map.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c
index c5bfb4c..a1822f8 100644
--- a/fs/ocfs2/extent_map.c
+++ b/fs/ocfs2/extent_map.c
@@ -782,7 +782,6 @@ int ocfs2_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 	cpos = map_start >> osb->s_clustersize_bits;
 	mapping_end = ocfs2_clusters_for_bytes(inode->i_sb,
 					       map_start + map_len);
-	mapping_end -= cpos;
 	is_last = 0;
 	while (cpos < mapping_end && !is_last) {
 		u32 fe_flags;
--
1.8.1.2