From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:50653 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932957AbdELQXt (ORCPT ); Fri, 12 May 2017 12:23:49 -0400 Date: Fri, 12 May 2017 09:23:43 -0700 From: "Darrick J. Wong" Subject: Re: [PATCH 1/2] xfs: Fix missed holes in SEEK_HOLE implementation Message-ID: <20170512162343.GH4519@birch.djwong.org> References: <20170511165023.29887-1-jack@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170511165023.29887-1-jack@suse.cz> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Jan Kara Cc: linux-xfs@vger.kernel.org, stable@vger.kernel.org On Thu, May 11, 2017 at 06:50:22PM +0200, Jan Kara wrote: > XFS SEEK_HOLE implementation could miss a hole in an unwritten extent as > can be seen by the following command: > > xfs_io -c "falloc 0 256k" -c "pwrite 0 56k" -c "pwrite 128k 8k" > -c "seek -h 0" file > wrote 57344/57344 bytes at offset 0 > 56 KiB, 14 ops; 0.0000 sec (49.312 MiB/sec and 12623.9856 ops/sec) > wrote 8192/8192 bytes at offset 131072 > 8 KiB, 2 ops; 0.0000 sec (70.383 MiB/sec and 18018.0180 ops/sec) > Whence Result > HOLE 139264 > > Where we can see that hole at offset 56k was just ignored by SEEK_HOLE > implementation. The bug is in xfs_find_get_desired_pgoff() which does > not properly detect the case when a first page in the pagevec has larger > index than expected (and even if the condition was right, we would fail > to update the returned offset). > > Fix the problem by properly detecting when found page has larger offset > than expected. > > CC: stable@vger.kernel.org > Fixes: d126d43f631f996daeee5006714fed914be32368 > Signed-off-by: Jan Kara Looks ok, will test... Reviewed-by: Darrick J. Wong --D > --- > fs/xfs/xfs_file.c | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index 35703a801372..df51c025adfe 100644 > --- a/fs/xfs/xfs_file.c > +++ b/fs/xfs/xfs_file.c > @@ -1077,13 +1077,12 @@ xfs_find_get_desired_pgoff( > } > > /* > - * At lease we found one page. If this is the first time we > - * step into the loop, and if the first page index offset is > - * greater than the given search offset, a hole was found. > + * At least we found one page. If the current offset is smaller > + * than the first page offset, a hole was found. > */ > - if (type == HOLE_OFF && lastoff == startoff && > - lastoff < page_offset(pvec.pages[0])) { > + if (type == HOLE_OFF && lastoff < page_offset(pvec.pages[0])) { > found = true; > + *offset = lastoff; > break; > } > > -- > 2.12.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html