From 79b3dbe4adb3420e74cf755b4beb5d2b43d5928d Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Thu, 2 Aug 2018 13:09:27 -0700 Subject: [PATCH] fs: fix iomap_bmap position calculation 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 Fixes: 89eb1906a953 ("iomap: add an iomap-based bmap implementation") Cc: stable@vger.kernel.org Signed-off-by: Eric Sandeen Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/iomap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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)) -- 2.39.5