[PATCH 7/7] sd: use ZERO_PAGE for WRITE_SAME payloads
From: Christoph Hellwig <hch@lst.de>
Date: 2017-03-20 20:43:19
Also in:
linux-ide, linux-scsi
Subsystem:
scsi subsystem, the rest · Maintainers:
"James E.J. Bottomley", "Martin K. Petersen", Linus Torvalds
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) {
--
2.11.0