[PATCH 1/2] scsi: fix write_same16 and write_same10 for sector size > PAGE_SIZE

[sw.prabhu6@gmail.com]

From: Swarna Prabhu <sw.prabhu6@gmail.com>

The WRITE SAME(16) and WRITE SAME(10) scsi commands uses
a page from a dedicated mempool('sd_page_pool') for its
payload. This pool was initialized to allocate single
pages, which was sufficient as long as the device sector
size did not exceed the PAGE_SIZE.

Given that block layer now supports block size upto
64K ie beyond PAGE_SIZE, adapt sd_set_special_bvec()
to accommodate that.

Signed-off-by: Swarna Prabhu <s.prabhu@samsung.com>
Co-developed-by: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
---
Note: We are allocating pages of order aligned to 
BLK_MAX_BLOCK_SIZE for the mempool page allocator 
'sd_page_pool' all the time. This is because we only
know that a bigger sector size device is attached at 
sd_probe and it might be too late to reallocate mempool
with order > 0.

 drivers/scsi/sd.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 0252d3f6bed1..c3502fcba1bb 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -895,11 +895,20 @@ static void sd_config_discard(struct scsi_disk *sdkp, struct queue_limits *lim,
 static void *sd_set_special_bvec(struct request *rq, unsigned int data_len)
 {
 	struct page *page;
+	struct scsi_device *sdp = scsi_disk(rq->q->disk)->device;
+	unsigned sector_size = sdp->sector_size;
+	unsigned int nr_pages = DIV_ROUND_UP(sector_size, PAGE_SIZE);
+	int n = 0;
 
 	page = mempool_alloc(sd_page_pool, GFP_ATOMIC);
 	if (!page)
 		return NULL;
-	clear_highpage(page);
+
+	do {
+		clear_highpage(page + n);
+		n++;
+	} while (n < nr_pages);
+
 	bvec_set_page(&rq->special_vec, page, data_len, 0);
 	rq->rq_flags |= RQF_SPECIAL_PAYLOAD;
 	return bvec_virt(&rq->special_vec);
@@ -4368,7 +4377,7 @@ static int __init init_sd(void)
 	if (err)
 		goto err_out;
 
-	sd_page_pool = mempool_create_page_pool(SD_MEMPOOL_SIZE, 0);
+	sd_page_pool = mempool_create_page_pool(SD_MEMPOOL_SIZE, get_order(BLK_MAX_BLOCK_SIZE));
 	if (!sd_page_pool) {
 		printk(KERN_ERR "sd: can't init discard page pool\n");
 		err = -ENOMEM;
-- 
2.51.0