linux-ext4 - Re: [PATCH 1/2] block: add BH

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Date:	Wed, 16 May 2012 17:27:29 +0530
From:	Saugata Das <saugata.das@...aro.org>
To:	tytso@....edu, hch@...radead.org
Cc:	adilger@...mcloud.com, arnd.bergmann@...aro.org, venkat@...aro.org,
	Deepak Saxena <dsaxena@...aro.org>,
	Saugata Das PURKAYASTHA <saugata.das@...ricsson.com>,
	linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 1/2] block: add BH_Meta flag

Hi Ted, Christoph

Will you please comment on the following patch set,
[PATCH 1/2] block: add BH_Meta flag
[PATCH 2/2] ext4: annotate all meta data requests

If there is no remark, then will you please merge them to the next version.


Thanks,
Saugata


On 11 May 2012 20:32, Saugata Das <saugata.das@...ricsson.com> wrote:
> From: Saugata Das <saugata.das@...aro.org>
>
> 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.
>
> Signed-off-by: Saugata Das <saugata.das@...aro.org>
> ---
>  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)
> --
> 1.7.4.3
>
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