From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756039Ab0EGJcz (ORCPT ); Fri, 7 May 2010 05:32:55 -0400 Received: from crca.org.au ([74.207.252.120]:42623 "EHLO crca.org.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755751Ab0EGJcv (ORCPT ); Fri, 7 May 2010 05:32:51 -0400 X-Bogosity: Ham, spamicity=0.000000 Message-ID: <4BE3DE3C.1090707@crca.org.au> Date: Fri, 07 May 2010 19:32:44 +1000 From: Nigel Cunningham User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.9) Gecko/20100423 Thunderbird/3.0.4 MIME-Version: 1.0 To: Nitin Gupta CC: Greg KH , Linus Torvalds , Pekka Enberg , Hugh Dickins , Cyp , Minchan Kim , Al Viro , Christoph Hellwig , Jens Axboe , Andi Kleen , Andrew Morton , driverdev , linux-kernel Subject: Re: [PATCH 1/3] Add flag to identify block swap devices References: <1273217107-2023-1-git-send-email-ngupta@vflare.org> <1273217107-2023-2-git-send-email-ngupta@vflare.org> In-Reply-To: <1273217107-2023-2-git-send-email-ngupta@vflare.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi again. On 07/05/10 17:25, Nitin Gupta wrote: > Added SWP_BLKDEV flag to distinguish block and regular file backed > swap devices. We could also check if a swap is entire block device, > rather than a file, by: > S_ISBLK(swap_info_struct->swap_file->f_mapping->host->i_mode) > but, I think, simply checking this flag is more convenient. > > Signed-off-by: Nitin Gupta > --- > include/linux/swap.h | 1 + > mm/swapfile.c | 1 + > 2 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/include/linux/swap.h b/include/linux/swap.h > index 1f59d93..ec2b7a4 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -146,6 +146,7 @@ enum { > SWP_DISCARDING = (1<< 3), /* now discarding a free cluster */ > SWP_SOLIDSTATE = (1<< 4), /* blkdev seeks are cheap */ > SWP_CONTINUED = (1<< 5), /* swap_map has count continuation */ > + SWP_BLKDEV = (1<< 6), /* its a block device */ > /* add others here before... */ > SWP_SCANNING = (1<< 8), /* refcount in scan_swap_map */ > }; > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 6cd0a8f..ecb069e 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -1884,6 +1884,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) > if (error< 0) > goto bad_swap; > p->bdev = bdev; > + p->flags |= SWP_BLKDEV; > } else if (S_ISREG(inode->i_mode)) { > p->bdev = inode->i_sb->s_bdev; > mutex_lock(&inode->i_mutex); The more I read your patches, the more I think either I'm seriously confused (entirely possible!) or you are. Don't you want to distinguish RAM backed swap from swap that's either a partition or a file? If that's the case, you should also be setting SWP_BLKDEV in the S_ISREG part that follows iff the p->bdev is a regular file. Regards, Nigel