From: Jan Kara Subject: Re: [Ocfs2-devel] [PATCH 1/3] ext3/ext4: Factor out disk addressability check Date: Mon, 16 Aug 2010 21:21:00 +0200 Message-ID: <20100816192100.GD3708@quack.suse.cz> References: <20100812201534.GA22777@mail.oracle.com> <209AEA97-E284-4ADB-8774-50C2630606B9@dilger.ca> <20100812222949.GC22777@mail.oracle.com> <20100813163006.GB4329@quack.suse.cz> <4C6821A8.5080805@redhat.com> <20100816025436.GA9061@mail.oracle.com> <4C68B244.6080406@redhat.com> <20100816092114.GB9061@mail.oracle.com> <4C694ED3.5070500@redhat.com> <20100816191319.GC5786@mail.oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Eric Sandeen , Jan Kara , Andreas Dilger , Ted Ts'o , ocfs2-devel@oss.oracle.com, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, "linux-kernel@vger.kernel.org Patrick J. LoPresti" To: Joel Becker Return-path: Received: from cantor2.suse.de ([195.135.220.15]:59954 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755979Ab0HPTVp (ORCPT ); Mon, 16 Aug 2010 15:21:45 -0400 Content-Disposition: inline In-Reply-To: <20100816191319.GC5786@mail.oracle.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Mon 16-08-10 12:13:19, Joel Becker wrote: > On Mon, Aug 16, 2010 at 09:44:35AM -0500, Eric Sandeen wrote: > > Joel Becker wrote: > > > How about: > > > > > > u64 last_fs_page = last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits); > > > > > > ... || > > > (last_fs_page > (pgoff_t)(~0ULL))) { > > > > > > Is that more readable? > > > > To me, yes. Maybe do similar for last_fs_sector. > > last_fs_sector would be shifting up, which could wrap a really > large last_fs_blocks. So I'm going to keep the sector_t check as-is. > How's this: > > >From 8de5cb9164cdc179ba84a07b282a895d0eb794b0 Mon Sep 17 00:00:00 2001 > >From: Joel Becker > Date: Mon, 16 Aug 2010 12:10:17 -0700 > Subject: [PATCH] libfs: Fix shift bug in generic_check_addressable() > > generic_check_addressable() erroneously shifts pages down by a block > factor when it should be shifting up. To prevent overflow, we shift > blocks down to pages. > > Signed-off-by: Joel Becker Looks good. Reviewed-by: Jan Kara Honza > --- > fs/libfs.c | 8 ++++---- > 1 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/fs/libfs.c b/fs/libfs.c > index 8debe7b..62baa03 100644 > --- a/fs/libfs.c > +++ b/fs/libfs.c > @@ -925,6 +925,8 @@ EXPORT_SYMBOL(generic_file_fsync); > int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) > { > u64 last_fs_block = num_blocks - 1; > + u64 last_fs_page = > + last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits); > > if (unlikely(num_blocks == 0)) > return 0; > @@ -932,10 +934,8 @@ int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) > if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT)) > return -EINVAL; > > - if ((last_fs_block > > - (sector_t)(~0ULL) >> (blocksize_bits - 9)) || > - (last_fs_block > > - (pgoff_t)(~0ULL) >> (PAGE_CACHE_SHIFT - blocksize_bits))) { > + if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) || > + (last_fs_page > (pgoff_t)(~0ULL))) { > return -EFBIG; > } > return 0; > -- > 1.7.1 > > -- > > Life's Little Instruction Book #267 > > "Lie on your back and look at the stars." > > Joel Becker > Consulting Software Developer > Oracle > E-mail: joel.becker@oracle.com > Phone: (650) 506-8127 -- Jan Kara SUSE Labs, CR