From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Whitehouse 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 10:48:33 +0000 Message-ID: <1321008513.2710.33.camel@menhir> References: <1320921294-30321-1-git-send-email-wenqing.lz@taobao.com> <1320921294-30321-2-git-send-email-wenqing.lz@taobao.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, Zheng Liu , Wang Shaoyan To: Zheng Liu Return-path: In-Reply-To: <1320921294-30321-2-git-send-email-wenqing.lz@taobao.com> Sender: linux-ext4-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org 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. 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)