Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-vc0-f174.google.com ([209.85.220.174]:65507 "EHLO mail-vc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756107AbaISSjL (ORCPT ); Fri, 19 Sep 2014 14:39:11 -0400 Received: by mail-vc0-f174.google.com with SMTP id hy10so2322209vcb.19 for ; Fri, 19 Sep 2014 11:39:10 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20140919133046.7d5ad943@gandalf.local.home> References: <20140919133046.7d5ad943@gandalf.local.home> Date: Fri, 19 Sep 2014 14:39:10 -0400 Message-ID: Subject: Re: [PATCH][linux-next] pnfs/blocklayout: Use do_div for 64 bit divide operations From: Trond Myklebust To: Steven Rostedt Cc: LKML , Linux NFS Mailing List , Christoph Hellwig Content-Type: text/plain; charset=UTF-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: Hi Steven, On Fri, Sep 19, 2014 at 1:30 PM, Steven Rostedt wrote: > > Commit 5c83746a0cf2 "pnfs/blocklayout: in-kernel GETDEVICEINFO XDR parsing" > added some open coded 64 bit divisions which caused the following > error on 32 bit builds: > > fs/built-in.o: In function `bl_map_stripe': > fs/nfs/blocklayout/dev.c:153: undefined reference to `__udivdi3' > fs/nfs/blocklayout/dev.c:154: undefined reference to `__umoddi3' > fs/nfs/blocklayout/dev.c:168: undefined reference to `__udivdi3' > > Signed-off-by: Steven Rostedt > --- > fs/nfs/blocklayout/dev.c | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > diff --git a/fs/nfs/blocklayout/dev.c b/fs/nfs/blocklayout/dev.c > index 00f159da06ee..05d32e2175db 100644 > --- a/fs/nfs/blocklayout/dev.c > +++ b/fs/nfs/blocklayout/dev.c > @@ -150,10 +150,18 @@ static bool bl_map_stripe(struct pnfs_block_dev *dev, u64 offset, > struct pnfs_block_dev_map *map) > { > struct pnfs_block_dev *child; > - u64 chunk = (offset / dev->chunk_size); > - int chunk_idx = chunk % dev->nr_children; > + u64 chunk; > + u64 chunk_tmp; > + int chunk_idx; > u64 disk_offset; > > + chunk = offset; > + /* chunk = offset / dev->chunk_size */ > + do_div(chunk, dev->chunk_size); > + chunk_tmp = chunk; > + /* chunk_idx = chunk % dev->nr_children) */ > + chunk_idx = do_div(chunk_tmp, dev->nr_children); > + > if (chunk_idx > dev->nr_children) { > dprintk("%s: invalid chunk idx %d (%lld/%lld)\n", > __func__, chunk_idx, offset, dev->chunk_size); > @@ -165,7 +173,9 @@ static bool bl_map_stripe(struct pnfs_block_dev *dev, u64 offset, > offset = chunk * dev->chunk_size; > > /* disk offset of the stripe */ > - disk_offset = offset / dev->nr_children; > + disk_offset = offset; > + /* disk_offset = offset / dev->nr_children */ > + do_div(disk_offset, dev->nr_children); > > child = &dev->children[chunk_idx]; > child->map(child, disk_offset, map); > -- > 1.8.1.4 > Thanks. I posted a similar bugfix on the linux-nfs mailing list yesterday. That hasn't been pushed to linux-next yet because Christoph wanted to run it through some QA tests first. Cheers Trond -- Trond Myklebust Linux NFS client maintainer, PrimaryData trond.myklebust@primarydata.com