From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:47662 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726984AbeHBV4b (ORCPT ); Thu, 2 Aug 2018 17:56:31 -0400 From: Eric Sandeen Subject: [PATCH] fs: fix iomap_bmap position calculation Message-ID: <78937e83-5665-11bf-14a6-7815221bf4d8@redhat.com> Date: Thu, 2 Aug 2018 15:03:51 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: linux-xfs , fsdevel Cc: Christoph Hellwig 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 --- 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))