On 16 May 2012 18:02, Boaz Harrosh <bharrosh@xxxxxxxxxxx> wrote:
> On 05/11/2012 06:02 PM, Saugata Das wrote:
>
>> From: Saugata Das <saugata.das@xxxxxxxxxx>
>>
>> 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@xxxxxxxxxx>
>> ---
>> 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);
>
>
> Its not nice to duplicate a call site for the parameter difference
> it's better to change the parameter and call the function in one
> place. (an assembler call site can get big)
>
> You can do:
> + submit_bh(write_op | (buffer_meta(bh) << __REQ_META), bh);
>
> And also avoid a conditional inside a loop.
>
Thanks for your comments. I will take care of this in the next version.
>
>> 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);
>
>
> Here too
>
> Boaz
>
>> 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)
>
>
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