From: Namhyung Kim Subject: Re: [PATCH 1/2] block: add BH_Meta flag Date: Mon, 14 May 2012 10:42:49 +0900 Message-ID: <87wr4f1qsm.fsf@sejong.aot.lge.com> References: <1336748577-9258-1-git-send-email-saugata.das@stericsson.com> Mime-Version: 1.0 Content-Type: text/plain Cc: , , , , , , , Saugata Das To: Saugata Das Return-path: Received: from LGEMRELSE7Q.lge.com ([156.147.1.151]:64601 "EHLO LGEMRELSE7Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753498Ab2ENBol (ORCPT ); Sun, 13 May 2012 21:44:41 -0400 In-Reply-To: <1336748577-9258-1-git-send-email-saugata.das@stericsson.com> (Saugata Das's message of "Fri, 11 May 2012 20:32:56 +0530") Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi, On Fri, 11 May 2012 20:32:56 +0530, Saugata Das wrote: > From: Saugata Das > > Today, storage devices like eMMC has special features like data tagging > (introduced in MMC-4.5 version) in order to improve performance of some > specific writes. On MMC stack, data tagging is used for all writes which > has REQ_META flag set. This patch adds the capability to add REQ_META flag > during meta data write. > AFAIK, the REQ_META is only for marking a bio/req to be recognized when using blktrace or something. You can use REQ_PRIO for the purpose but it applies only if your ioscheduler is CFQ. But I'm not aware how the MMC stack works, so I might be missing something. Thanks, Namhyung > Signed-off-by: Saugata Das > --- > fs/buffer.c | 10 ++++++++-- > include/linux/buffer_head.h | 2 ++ > 2 files changed, 10 insertions(+), 2 deletions(-) > > diff --git a/fs/buffer.c b/fs/buffer.c > index 36d6665..688b38b 100644 > --- a/fs/buffer.c > +++ b/fs/buffer.c > @@ -1685,7 +1685,10 @@ static int __block_write_full_page(struct inode *inode, struct page *page, > do { > struct buffer_head *next = bh->b_this_page; > if (buffer_async_write(bh)) { > - submit_bh(write_op, bh); > + if (buffer_meta(bh)) > + submit_bh(write_op | REQ_META, bh); > + else > + submit_bh(write_op, bh); > nr_underway++; > } > bh = next; > @@ -1739,7 +1742,10 @@ recover: > struct buffer_head *next = bh->b_this_page; > if (buffer_async_write(bh)) { > clear_buffer_dirty(bh); > - submit_bh(write_op, bh); > + if (buffer_meta(bh)) > + submit_bh(write_op | REQ_META, bh); > + else > + submit_bh(write_op, bh); > nr_underway++; > } > bh = next; > diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h > index ef26043..0776564 100644 > --- a/include/linux/buffer_head.h > +++ b/include/linux/buffer_head.h > @@ -34,6 +34,7 @@ enum bh_state_bits { > BH_Write_EIO, /* I/O error on write */ > BH_Unwritten, /* Buffer is allocated on disk but not written */ > BH_Quiet, /* Buffer Error Prinks to be quiet */ > + BH_Meta, /* Is meta */ > > BH_PrivateStart,/* not a state bit, but the first bit available > * for private allocation by other entities > @@ -126,6 +127,7 @@ BUFFER_FNS(Delay, delay) > BUFFER_FNS(Boundary, boundary) > BUFFER_FNS(Write_EIO, write_io_error) > BUFFER_FNS(Unwritten, unwritten) > +BUFFER_FNS(Meta, meta) > > #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK) > #define touch_buffer(bh) mark_page_accessed(bh->b_page)