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Subject[PATCH 5.0 081/238] scsi: sd: Optimal I/O size should be a multiple of physical block size
Date
5.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Martin K. Petersen <martin.petersen@oracle.com>

commit a83da8a4509d3ebfe03bb7fffce022e4d5d4764f upstream.

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>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/scsi/sd.c | 59 +++++++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 50 insertions(+), 9 deletions(-)

--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -3047,6 +3047,55 @@ static void sd_read_security(struct scsi
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.
@@ -3125,15 +3174,7 @@ static int sd_revalidate_disk(struct gen
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

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