linux-kernel - [RFC v2 1/2] scsi: sd: fix write_same16 and write_same10 for sector size > PAGE

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Message-ID: <20251203230546.1275683-2-sw.prabhu6@gmail.com>
Date: Wed,  3 Dec 2025 23:05:46 +0000
From: sw.prabhu6@...il.com
To: James.Bottomley@...senPartnership.com,
	martin.petersen@...cle.com,
	linux-scsi@...r.kernel.org,
	bvanassche@....org
Cc: linux-kernel@...r.kernel.org,
	mcgrof@...nel.org,
	kernel@...kajraghav.com,
	Swarna Prabhu <sw.prabhu6@...il.com>,
	Swarna Prabhu <s.prabhu@...sung.com>,
	Pankaj Raghav <p.raghav@...sung.com>
Subject: [RFC v2 1/2] scsi: sd: fix write_same16 and write_same10 for sector size > PAGE_SIZE

From: Swarna Prabhu <sw.prabhu6@...il.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.

With the above fix, enable sector sizes > PAGE_SIZE in
scsi sd driver.

Signed-off-by: Swarna Prabhu <s.prabhu@...sung.com>
Co-developed-by: Pankaj Raghav <p.raghav@...sung.com>
Signed-off-by: Pankaj Raghav <p.raghav@...sung.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 device is attached at sd_probe
and it might be too late to re allocate mempool with 
order > 0. 
 
drivers/scsi/sd.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 0252d3f6bed1..f2eac79d7263 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);
@@ -2880,10 +2889,8 @@ sd_read_capacity(struct scsi_disk *sdkp, struct queue_limits *lim,
 			  "assuming 512.\n");
 	}
 
-	if (sector_size != 512 &&
-	    sector_size != 1024 &&
-	    sector_size != 2048 &&
-	    sector_size != 4096) {
+	if (sector_size < 512 || sector_size > BLK_MAX_BLOCK_SIZE ||
+	    !is_power_of_2(sector_size)) {
 		sd_printk(KERN_NOTICE, sdkp, "Unsupported sector size %d.\n",
 			  sector_size);
 		/*
@@ -4368,7 +4375,7 @@ 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