[PATCH 090/104] ocfs2: fix the end cluster offset of FIEMAP

Luis Henriques luis.henriques at canonical.com
Mon Sep 30 10:11:07 UTC 2013


3.5.7.22 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jie Liu <jeff.liu at oracle.com>

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: Luis Henriques <luis.henriques 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 4dd0239..5083b75 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;
-- 
1.8.3.2





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