[PATCH] scsi: sd: Optimal I/O size should be a multiple of physical block size

[PATCH] scsi: sd: Optimal I/O size should be a multiple of physical block size

[Martin K. Petersen]

It was reported that some devices report an OPTIMAL TRANSFER LENGTH of
0xFFFF blocks. That looks bogus, especially for a device with a
4096-byte physical block size.

Ignore OPTIMAL TRANSFER LENGTH if it is not a multiple of the device's
reported physical block size.

Cc: <stable@vger.kernel.org>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199759
Reported-by: Christoph Anton Mitterer <calestyo@scientia.net>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

---

Before:

NAME ALIGNMENT MIN-IO   OPT-IO PHY-SEC LOG-SEC ROTA SCHED      RQ-SIZE  RA WSAME
sda          0   4096 33553920    4096     512    0 mq-deadline    256 128   32M

After:

NAME ALIGNMENT MIN-IO OPT-IO PHY-SEC LOG-SEC ROTA SCHED       RQ-SIZE   RA WSAME
sda          0   4096      0    4096     512    0 mq-deadline     256 4096   32M
---
 drivers/scsi/sd.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 9aa409b38765..d5ede5d65838 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3060,7 +3060,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
 	struct request_queue *q = sdkp->disk->queue;
 	sector_t old_capacity = sdkp->capacity;
 	unsigned char *buffer;
-	unsigned int dev_max, rw_max;
+	unsigned int dev_max, rw_max, opt_xfer_bytes;
 
 	SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp,
 				      "sd_revalidate_disk\n"));
@@ -3119,13 +3119,16 @@ static int sd_revalidate_disk(struct gendisk *disk)
 
 	/*
 	 * Determine the device's preferred I/O size for reads and writes
-	 * unless the reported value is unreasonably small, large, or
-	 * garbage.
+	 * unless the reported value is unreasonably small, large, not a
+	 * multiple of the physical block size, or simply garbage.
 	 */
+	opt_xfer_bytes = logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
+
 	if (sdkp->opt_xfer_blocks &&
 	    sdkp->opt_xfer_blocks <= dev_max &&
 	    sdkp->opt_xfer_blocks <= SD_DEF_XFER_BLOCKS &&
-	    logical_to_bytes(sdp, sdkp->opt_xfer_blocks) >= PAGE_SIZE) {
+	    opt_xfer_bytes >= PAGE_SIZE &&
+	    (opt_xfer_bytes & (sdkp->physical_block_size - 1)) != 0) {
 		q->limits.io_opt = logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
 		rw_max = logical_to_sectors(sdp, sdkp->opt_xfer_blocks);
 	} else
-- 
2.19.2

Re: [PATCH] scsi: sd: Optimal I/O size should be a multiple of physical block size

[Christoph Hellwig]

On Fri, Feb 08, 2019 at 06:41:47PM -0500, Martin K. Petersen wrote:
> It was reported that some devices report an OPTIMAL TRANSFER LENGTH of
> 0xFFFF blocks. That looks bogus, especially for a device with a
> 4096-byte physical block size.
> 
> Ignore OPTIMAL TRANSFER LENGTH if it is not a multiple of the device's
> reported physical block size.

Looks generally fine, but should we log a warning in case of a bogus
OPTIMAL TRANSFER LENGTH?

[PATCH v2] scsi: sd: Optimal I/O size should be a multiple of physical block size

[Martin K. Petersen]

It was reported that some devices report an OPTIMAL TRANSFER LENGTH of
0xFFFF blocks. That looks bogus, especially for a device with a
4096-byte physical block size.

Ignore OPTIMAL TRANSFER LENGTH if it is not a multiple of the device's
reported physical block size.

To make the sanity checking conditionals more readable--and to
facilitate printing warnings--relocate the checking to a helper
function. No functional change aside from the printks.

Cc: <stable@vger.kernel.org>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199759
Reported-by: Christoph Anton Mitterer <calestyo@scientia.net>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

---

v2:
	- Added warnings as requested by hch
	- Moved the checks to a helper function

Before:

NAME ALIGNMENT MIN-IO   OPT-IO PHY-SEC LOG-SEC ROTA SCHED      RQ-SIZE  RA WSAME
sda          0   4096 33553920    4096     512    0 mq-deadline    256 128   32M

After:

NAME ALIGNMENT MIN-IO OPT-IO PHY-SEC LOG-SEC ROTA SCHED       RQ-SIZE   RA WSAME
sda          0   4096      0    4096     512    0 mq-deadline     256 4096   32M
---
 drivers/scsi/sd.c | 59 +++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 50 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 9aa409b38765..5dfe37b08d3b 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3048,6 +3048,55 @@ static void sd_read_security(struct scsi_disk *sdkp, unsigned char *buffer)
 		sdkp->security = 1;
 }
 
+/*
+ * Determine the device's preferred I/O size for reads and writes
+ * unless the reported value is unreasonably small, large, not a
+ * multiple of the physical block size, or simply garbage.
+ */
+static bool sd_validate_opt_xfer_size(struct scsi_disk *sdkp,
+				      unsigned int dev_max)
+{
+	struct scsi_device *sdp = sdkp->device;
+	unsigned int opt_xfer_bytes =
+		logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
+
+	if (sdkp->opt_xfer_blocks > dev_max) {
+		sd_first_printk(KERN_WARNING, sdkp,
+				"Optimal transfer size %u logical blocks " \
+				"> dev_max (%u logical blocks)\n",
+				sdkp->opt_xfer_blocks, dev_max);
+		return false;
+	}
+
+	if (sdkp->opt_xfer_blocks > SD_DEF_XFER_BLOCKS) {
+		sd_first_printk(KERN_WARNING, sdkp,
+				"Optimal transfer size %u logical blocks " \
+				"> sd driver limit (%u logical blocks)\n",
+				sdkp->opt_xfer_blocks, SD_DEF_XFER_BLOCKS);
+		return false;
+	}
+
+	if (opt_xfer_bytes < PAGE_SIZE) {
+		sd_first_printk(KERN_WARNING, sdkp,
+				"Optimal transfer size %u bytes < " \
+				"PAGE_SIZE (%u bytes)\n",
+				opt_xfer_bytes, (unsigned int)PAGE_SIZE);
+		return false;
+	}
+
+	if (opt_xfer_bytes & (sdkp->physical_block_size - 1)) {
+		sd_first_printk(KERN_WARNING, sdkp,
+				"Optimal transfer size %u bytes not a " \
+				"multiple of physical block size (%u bytes)\n",
+				opt_xfer_bytes, sdkp->physical_block_size);
+		return false;
+	}
+
+	sd_first_printk(KERN_INFO, sdkp, "Optimal transfer size %u bytes\n",
+			opt_xfer_bytes);
+	return true;
+}
+
 /**
  *	sd_revalidate_disk - called the first time a new disk is seen,
  *	performs disk spin up, read_capacity, etc.
@@ -3117,15 +3166,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
 	dev_max = min_not_zero(dev_max, sdkp->max_xfer_blocks);
 	q->limits.max_dev_sectors = logical_to_sectors(sdp, dev_max);
 
-	/*
-	 * Determine the device's preferred I/O size for reads and writes
-	 * unless the reported value is unreasonably small, large, or
-	 * garbage.
-	 */
-	if (sdkp->opt_xfer_blocks &&
-	    sdkp->opt_xfer_blocks <= dev_max &&
-	    sdkp->opt_xfer_blocks <= SD_DEF_XFER_BLOCKS &&
-	    logical_to_bytes(sdp, sdkp->opt_xfer_blocks) >= PAGE_SIZE) {
+	if (sd_validate_opt_xfer_size(sdkp, dev_max)) {
 		q->limits.io_opt = logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
 		rw_max = logical_to_sectors(sdp, sdkp->opt_xfer_blocks);
 	} else
-- 
2.19.2

Re: [PATCH v2] scsi: sd: Optimal I/O size should be a multiple of physical block size

[Martin K. Petersen]

Christoph?

> It was reported that some devices report an OPTIMAL TRANSFER LENGTH of
> 0xFFFF blocks. That looks bogus, especially for a device with a
> 4096-byte physical block size.
>
> Ignore OPTIMAL TRANSFER LENGTH if it is not a multiple of the device's
> reported physical block size.
>
> To make the sanity checking conditionals more readable--and to
> facilitate printing warnings--relocate the checking to a helper
> function. No functional change aside from the printks.
>
> Cc: <stable@vger.kernel.org>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199759
> Reported-by: Christoph Anton Mitterer <calestyo@scientia.net>
> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
>
> ---
>
> v2:
> 	- Added warnings as requested by hch
> 	- Moved the checks to a helper function
>
> Before:
>
> NAME ALIGNMENT MIN-IO   OPT-IO PHY-SEC LOG-SEC ROTA SCHED      RQ-SIZE  RA WSAME
> sda          0   4096 33553920    4096     512    0 mq-deadline    256 128   32M
>
> After:
>
> NAME ALIGNMENT MIN-IO OPT-IO PHY-SEC LOG-SEC ROTA SCHED       RQ-SIZE   RA WSAME
> sda          0   4096      0    4096     512    0 mq-deadline     256 4096   32M
> ---
>  drivers/scsi/sd.c | 59 +++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 50 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
> index 9aa409b38765..5dfe37b08d3b 100644
> --- a/drivers/scsi/sd.c
> +++ b/drivers/scsi/sd.c
> @@ -3048,6 +3048,55 @@ static void sd_read_security(struct scsi_disk *sdkp, unsigned char *buffer)
>  		sdkp->security = 1;
>  }
>  
> +/*
> + * Determine the device's preferred I/O size for reads and writes
> + * unless the reported value is unreasonably small, large, not a
> + * multiple of the physical block size, or simply garbage.
> + */
> +static bool sd_validate_opt_xfer_size(struct scsi_disk *sdkp,
> +				      unsigned int dev_max)
> +{
> +	struct scsi_device *sdp = sdkp->device;
> +	unsigned int opt_xfer_bytes =
> +		logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
> +
> +	if (sdkp->opt_xfer_blocks > dev_max) {
> +		sd_first_printk(KERN_WARNING, sdkp,
> +				"Optimal transfer size %u logical blocks " \
> +				"> dev_max (%u logical blocks)\n",
> +				sdkp->opt_xfer_blocks, dev_max);
> +		return false;
> +	}
> +
> +	if (sdkp->opt_xfer_blocks > SD_DEF_XFER_BLOCKS) {
> +		sd_first_printk(KERN_WARNING, sdkp,
> +				"Optimal transfer size %u logical blocks " \
> +				"> sd driver limit (%u logical blocks)\n",
> +				sdkp->opt_xfer_blocks, SD_DEF_XFER_BLOCKS);
> +		return false;
> +	}
> +
> +	if (opt_xfer_bytes < PAGE_SIZE) {
> +		sd_first_printk(KERN_WARNING, sdkp,
> +				"Optimal transfer size %u bytes < " \
> +				"PAGE_SIZE (%u bytes)\n",
> +				opt_xfer_bytes, (unsigned int)PAGE_SIZE);
> +		return false;
> +	}
> +
> +	if (opt_xfer_bytes & (sdkp->physical_block_size - 1)) {
> +		sd_first_printk(KERN_WARNING, sdkp,
> +				"Optimal transfer size %u bytes not a " \
> +				"multiple of physical block size (%u bytes)\n",
> +				opt_xfer_bytes, sdkp->physical_block_size);
> +		return false;
> +	}
> +
> +	sd_first_printk(KERN_INFO, sdkp, "Optimal transfer size %u bytes\n",
> +			opt_xfer_bytes);
> +	return true;
> +}
> +
>  /**
>   *	sd_revalidate_disk - called the first time a new disk is seen,
>   *	performs disk spin up, read_capacity, etc.
> @@ -3117,15 +3166,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
>  	dev_max = min_not_zero(dev_max, sdkp->max_xfer_blocks);
>  	q->limits.max_dev_sectors = logical_to_sectors(sdp, dev_max);
>  
> -	/*
> -	 * Determine the device's preferred I/O size for reads and writes
> -	 * unless the reported value is unreasonably small, large, or
> -	 * garbage.
> -	 */
> -	if (sdkp->opt_xfer_blocks &&
> -	    sdkp->opt_xfer_blocks <= dev_max &&
> -	    sdkp->opt_xfer_blocks <= SD_DEF_XFER_BLOCKS &&
> -	    logical_to_bytes(sdp, sdkp->opt_xfer_blocks) >= PAGE_SIZE) {
> +	if (sd_validate_opt_xfer_size(sdkp, dev_max)) {
>  		q->limits.io_opt = logical_to_bytes(sdp, sdkp->opt_xfer_blocks);
>  		rw_max = logical_to_sectors(sdp, sdkp->opt_xfer_blocks);
>  	} else

-- 
Martin K. Petersen	Oracle Linux Engineering

Re: [PATCH v2] scsi: sd: Optimal I/O size should be a multiple of physical block size

[Christoph Hellwig]

On Tue, Feb 12, 2019 at 04:21:05PM -0500, Martin K. Petersen wrote:
> It was reported that some devices report an OPTIMAL TRANSFER LENGTH of
> 0xFFFF blocks. That looks bogus, especially for a device with a
> 4096-byte physical block size.
> 
> Ignore OPTIMAL TRANSFER LENGTH if it is not a multiple of the device's
> reported physical block size.
> 
> To make the sanity checking conditionals more readable--and to
> facilitate printing warnings--relocate the checking to a helper
> function. No functional change aside from the printks.
> 
> Cc: <stable@vger.kernel.org>
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199759
> Reported-by: Christoph Anton Mitterer <calestyo@scientia.net>
> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>