The position calculation in iomap_bmap() shifts bno the wrong way,
so we don't progress properly and end up re-mapping block zero
over and over, yielding an unchanging physical block range as the
logical block advances:
# filefrag -Be file
ext: logical_offset: physical_offset: length: expected: flags:
0: 0.. 0: 21.. 21: 1: merged
1: 1.. 1: 21.. 21: 1: 22: merged
Discontinuity: Block 1 is at 21 (was 22)
2: 2.. 2: 21.. 21: 1: 22: merged
Discontinuity: Block 2 is at 21 (was 22)
3: 3.. 3: 21.. 21: 1: 22: merged
This breaks the FIBMAP interface for anyone using it (XFS), which
in turn breaks LILO, zipl, etc.
Bug-actually-spotted-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Fixes: 89eb1906a953 ("iomap: add an iomap-based bmap implementation")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---
diff --git a/fs/iomap.c b/fs/iomap.c
index 77397b5a96ef..0d0bd8845586 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -1443,7 +1443,7 @@ iomap_bmap(struct address_space *mapping, sector_t bno,
const struct iomap_ops *ops)
{
struct inode *inode = mapping->host;
- loff_t pos = bno >> inode->i_blkbits;
+ loff_t pos = bno << inode->i_blkbits;
unsigned blocksize = i_blocksize(inode);
if (filemap_write_and_wait(mapping))
