[7/7] sd: use ZERO_PAGE for WRITE_SAME payloads

Submitted by Christoph Hellwig on March 20, 2017, 8:43 p.m.

Details

Message ID 20170320204319.12628-8-hch@lst.de
State Not Applicable
Delegated to: David Miller
Headers show

Commit Message

Christoph Hellwig March 20, 2017, 8:43 p.m.
We're never touching the contents of the page, so save a memory
allocation for these cases.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 drivers/scsi/sd.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

Comments

Bart Van Assche March 27, 2017, 11:40 p.m.
On Mon, 2017-03-20 at 16:43 -0400, Christoph Hellwig wrote:
> We're never touching the contents of the page, so save a memory
> allocation for these cases.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  drivers/scsi/sd.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index c18fe9ff1f8f..af632e350ab4 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -756,7 +756,7 @@ static int sd_setup_write_same16_cmnd(struct scsi_cmnd *cmd)
>  	u32 nr_sectors = blk_rq_sectors(rq) >> (ilog2(sdp->sector_size) - 9);
>  	u32 data_len = sdp->sector_size;
>  
> -	rq->special_vec.bv_page = alloc_page(GFP_ATOMIC | __GFP_ZERO);
> +	rq->special_vec.bv_page = ZERO_PAGE(0);
>  	if (!rq->special_vec.bv_page)
>  		return BLKPREP_DEFER;
>  	rq->special_vec.bv_offset = 0;
> @@ -785,7 +785,7 @@ static int sd_setup_write_same10_cmnd(struct scsi_cmnd *cmd, bool unmap)
>  	u32 nr_sectors = blk_rq_sectors(rq) >> (ilog2(sdp->sector_size) - 9);
>  	u32 data_len = sdp->sector_size;
>  
> -	rq->special_vec.bv_page = alloc_page(GFP_ATOMIC | __GFP_ZERO);
> +	rq->special_vec.bv_page = ZERO_PAGE(0);
>  	if (!rq->special_vec.bv_page)
>  		return BLKPREP_DEFER;
>  	rq->special_vec.bv_offset = 0;
> @@ -1256,7 +1256,8 @@ static void sd_uninit_command(struct scsi_cmnd *SCpnt)
>  {
>  	struct request *rq = SCpnt->request;
>  
> -	if (rq->rq_flags & RQF_SPECIAL_PAYLOAD)
> +	if ((rq->rq_flags & RQF_SPECIAL_PAYLOAD) &&
> +	    rq->special_vec.bv_page != ZERO_PAGE(0))
>  		__free_page(rq->special_vec.bv_page);
>  
>  	if (SCpnt->cmnd != scsi_req(rq)->cmd) {

Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>


--
To unsubscribe from this list: send the line "unsubscribe linux-ide" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch hide | download patch | download mbox

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index c18fe9ff1f8f..af632e350ab4 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -756,7 +756,7 @@  static int sd_setup_write_same16_cmnd(struct scsi_cmnd *cmd)
 	u32 nr_sectors = blk_rq_sectors(rq) >> (ilog2(sdp->sector_size) - 9);
 	u32 data_len = sdp->sector_size;
 
-	rq->special_vec.bv_page = alloc_page(GFP_ATOMIC | __GFP_ZERO);
+	rq->special_vec.bv_page = ZERO_PAGE(0);
 	if (!rq->special_vec.bv_page)
 		return BLKPREP_DEFER;
 	rq->special_vec.bv_offset = 0;
@@ -785,7 +785,7 @@  static int sd_setup_write_same10_cmnd(struct scsi_cmnd *cmd, bool unmap)
 	u32 nr_sectors = blk_rq_sectors(rq) >> (ilog2(sdp->sector_size) - 9);
 	u32 data_len = sdp->sector_size;
 
-	rq->special_vec.bv_page = alloc_page(GFP_ATOMIC | __GFP_ZERO);
+	rq->special_vec.bv_page = ZERO_PAGE(0);
 	if (!rq->special_vec.bv_page)
 		return BLKPREP_DEFER;
 	rq->special_vec.bv_offset = 0;
@@ -1256,7 +1256,8 @@  static void sd_uninit_command(struct scsi_cmnd *SCpnt)
 {
 	struct request *rq = SCpnt->request;
 
-	if (rq->rq_flags & RQF_SPECIAL_PAYLOAD)
+	if ((rq->rq_flags & RQF_SPECIAL_PAYLOAD) &&
+	    rq->special_vec.bv_page != ZERO_PAGE(0))
 		__free_page(rq->special_vec.bv_page);
 
 	if (SCpnt->cmnd != scsi_req(rq)->cmd) {