From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zheng Liu Subject: Re: [PATCH v2 1/8] vfs: Add a new flag and related functions in buffer to count io types Date: Fri, 11 Nov 2011 23:36:29 +0800 Message-ID: <20111111153629.GB6826@gmail.com> References: <1320921294-30321-1-git-send-email-wenqing.lz@taobao.com> <1320921294-30321-2-git-send-email-wenqing.lz@taobao.com> <1321008513.2710.33.camel@menhir> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, Zheng Liu , Wang Shaoyan To: Steven Whitehouse Return-path: Received: from mail-iy0-f174.google.com ([209.85.210.174]:33382 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757929Ab1KKPe4 (ORCPT ); Fri, 11 Nov 2011 10:34:56 -0500 Content-Disposition: inline In-Reply-To: <1321008513.2710.33.camel@menhir> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Fri, Nov 11, 2011 at 10:48:33AM +0000, Steven Whitehouse wrote: > Hi, > > On Thu, 2011-11-10 at 18:34 +0800, Zheng Liu wrote: > > From: Zheng Liu > > > > 'Issue' flag is added into buffer_head to indicate that a request is issued > > to the disk. When an io doesn't hit page cache, 'Issue' flag will be set in > > submit_bh(). Filesystem can understand request is sent to the disk according > > to whether or not this flag is set. This flag will be cleared after filesystem > > tests it. If filesystem doesn't want to count the io type, it can ignore this > > flag. > > > > Signed-off-by: Zheng Liu > > Signed-off-by: Wang Shaoyan > > --- > > fs/buffer.c | 3 +++ > > include/linux/buffer_head.h | 5 +++++ > > 2 files changed, 8 insertions(+), 0 deletions(-) > > > > diff --git a/fs/buffer.c b/fs/buffer.c > > index 70a1974..f681caa 100644 > > --- a/fs/buffer.c > > +++ b/fs/buffer.c > > @@ -2920,6 +2920,9 @@ int submit_bh(int rw, struct buffer_head * bh) > > BUG_ON(buffer_delay(bh)); > > BUG_ON(buffer_unwritten(bh)); > > > > + /* set issue flag for indicating a request is issued to the disk */ > > + set_buffer_issue(bh); > > + > > /* > > * Only clear out a write error when rewriting > > */ > > diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h > > index 458f497..2bccdb4 100644 > > --- a/include/linux/buffer_head.h > > +++ b/include/linux/buffer_head.h > > @@ -38,6 +38,10 @@ enum bh_state_bits { > > BH_PrivateStart,/* not a state bit, but the first bit available > > * for private allocation by other entities > > */ > > + > > + BH_Issue, /* Issue a request to the disk when this request > > + * doesn't hit cache > > + */ > > }; > This looks like it will collide with any fs using more than one private > flag, for example, ext4. I will put this flag on the top of BH_PrivateStart. Regards, Zheng > > > Steve. > > > > > > > #define MAX_BUF_PER_PAGE (PAGE_CACHE_SIZE / 512) > > @@ -124,6 +128,7 @@ BUFFER_FNS(Delay, delay) > > BUFFER_FNS(Boundary, boundary) > > BUFFER_FNS(Write_EIO, write_io_error) > > BUFFER_FNS(Unwritten, unwritten) > > +BUFFER_FNS(Issue, issue) > > > > #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK) > > #define touch_buffer(bh) mark_page_accessed(bh->b_page) > >