[RFC v2 1/2] scsi: sd: fix write_same16 and write_same10 for sector size > PAGE_SIZE

[RFC v2 1/2] scsi: sd: fix write_same16 and write_same10 for sector size > PAGE_SIZE

[sw.prabhu6]

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.

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

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 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

[RFC v2 2/2] scsi: scsi_debug: enable sdebug_sector_size > PAGE_SIZE

[sw.prabhu6]

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

Now that block layer can support block size > PAGE_SIZE
and the issue with WRITE SAME(16) and WRITE SAME(10) are
fixed for sector sizes > PAGE_SIZE, enable sdebug_sector_size
> PAGE_SIZE in scsi_debug.

Signed-off-by: Swarna Prabhu <s.prabhu@samsung.com>
---
 drivers/scsi/scsi_debug.c | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index b2ab97be5db3..b5839e62d3bb 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -8459,13 +8459,8 @@ static int __init scsi_debug_init(void)
 	} else if (sdebug_ndelay > 0)
 		sdebug_jdelay = JDELAY_OVERRIDDEN;
 
-	switch (sdebug_sector_size) {
-	case  512:
-	case 1024:
-	case 2048:
-	case 4096:
-		break;
-	default:
+	if (sdebug_sector_size < 512 || sdebug_sector_size > BLK_MAX_BLOCK_SIZE ||
+	    !is_power_of_2(sdebug_sector_size)) {
 		pr_err("invalid sector_size %d\n", sdebug_sector_size);
 		return -EINVAL;
 	}
-- 
2.51.0

Re: [RFC v2 1/2] scsi: sd: fix write_same16 and write_same10 for sector size > PAGE_SIZE

[Luis Chamberlain]

On Wed, Dec 03, 2025 at 11:05:46PM +0000, sw.prabhu6@gmail.com wrote:
> 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.
> 
> With the above fix, enable sector sizes > PAGE_SIZE in
> scsi sd driver.
> 
> 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>

Just missing the Cc stable # v6.15 tag. Other than that:

Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>

  Luis

Re: [RFC v2 2/2] scsi: scsi_debug: enable sdebug_sector_size > PAGE_SIZE

[Luis Chamberlain]

On Wed, Dec 03, 2025 at 11:05:47PM +0000, sw.prabhu6@gmail.com wrote:
> From: Swarna Prabhu <sw.prabhu6@gmail.com>
> 
> Now that block layer can support block size > PAGE_SIZE
> and the issue with WRITE SAME(16) and WRITE SAME(10) are
> fixed for sector sizes > PAGE_SIZE, enable sdebug_sector_size
> > PAGE_SIZE in scsi_debug.
> 
> Signed-off-by: Swarna Prabhu <s.prabhu@samsung.com>

Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>

  Luis

Re: [RFC v2 1/2] scsi: sd: fix write_same16 and write_same10 for sector size > PAGE_SIZE

[Bart Van Assche]

On 12/3/25 1:05 PM, sw.prabhu6@gmail.com wrote:
>   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;

Instead of using this cumbersome approach to obtain the SCSI device
pointer, I recommend to change the 'struct request *rq' argument into
'struct scsi_cmnd *cmd' and to obtain the SCSI device pointer as
follows:

	struct scsi_device *sdp = cmd->device;

Otherwise this patch looks good to me.

Thanks,

Bart.

Re: [RFC v2 2/2] scsi: scsi_debug: enable sdebug_sector_size > PAGE_SIZE

[Bart Van Assche]

On 12/3/25 1:05 PM, sw.prabhu6@gmail.com wrote:
> diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> index b2ab97be5db3..b5839e62d3bb 100644
> --- a/drivers/scsi/scsi_debug.c
> +++ b/drivers/scsi/scsi_debug.c
> @@ -8459,13 +8459,8 @@ static int __init scsi_debug_init(void)
>   	} else if (sdebug_ndelay > 0)
>   		sdebug_jdelay = JDELAY_OVERRIDDEN;
>   
> -	switch (sdebug_sector_size) {
> -	case  512:
> -	case 1024:
> -	case 2048:
> -	case 4096:
> -		break;
> -	default:
> +	if (sdebug_sector_size < 512 || sdebug_sector_size > BLK_MAX_BLOCK_SIZE ||
> +	    !is_power_of_2(sdebug_sector_size)) {
>   		pr_err("invalid sector_size %d\n", sdebug_sector_size);
>   		return -EINVAL;
>   	}

Please use blk_validate_block_size() instead of open-coding it.

Thanks,

Bart.

Re: [RFC v2 1/2] scsi: sd: fix write_same16 and write_same10 for sector size > PAGE_SIZE

[Bart Van Assche]

On 12/3/25 1:05 PM, sw.prabhu6@gmail.com wrote:
> -	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);
>   		/*

Please use blk_validate_block_size() instead of open-coding it.

Thanks,

Bart.