usb-storage: Add a limitation for blk_queue_max_hw_sectors()

This patch fixes an issue that the following error happens on
swiotlb environment:

	xhci-hcd ee000000.usb: swiotlb buffer is full (sz: 524288 bytes), total 32768 (slots), used 1338 (slots)

On the kernel v5.1, block settings of a usb-storage with SuperSpeed
were the following so that the block layer will allocate buffers
up to 64 KiB, and then the issue didn't happen.

	max_segment_size = 65536
	max_hw_sectors_kb = 1024

After the commit 09324d32d2a0 ("block: force an unlimited segment
size on queues with a virt boundary") is applied, the block settings
are the following. So, the block layer will allocate buffers up to
1024 KiB, and then the issue happens:

	max_segment_size = 4294967295
	max_hw_sectors_kb = 1024

To fix the issue, the usb-storage driver checks the maximum size of
a mapping for the device and then adjusts the max_hw_sectors_kb
if required. After this patch is applied, the block settings will
be the following, and then the issue doesn't happen.

	max_segment_size = 4294967295
	max_hw_sectors_kb = 256

Fixes: 09324d32d2a0 ("block: force an unlimited segment size on queues with a virt boundary")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/1563793105-20597-1-git-send-email-yoshihiro.shimoda.uh@renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index 3079024..05b8021 100644 (file)
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -28,6 +28,8 @@
  * status of a command.
  */
 
+#include <linux/blkdev.h>
+#include <linux/dma-mapping.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 
@@ -99,6 +101,7 @@ static int slave_alloc (struct scsi_device *sdev)
 static int slave_configure(struct scsi_device *sdev)
 {
        struct us_data *us = host_to_us(sdev->host);
+       struct device *dev = us->pusb_dev->bus->sysdev;
 
        /*
         * Many devices have trouble transferring more than 32KB at a time,
@@ -128,6 +131,14 @@ static int slave_configure(struct scsi_device *sdev)
                blk_queue_max_hw_sectors(sdev->request_queue, 2048);
        }
 
+       /*
+        * The max_hw_sectors should be up to maximum size of a mapping for
+        * the device. Otherwise, a DMA API might fail on swiotlb environment.
+        */
+       blk_queue_max_hw_sectors(sdev->request_queue,
+               min_t(size_t, queue_max_hw_sectors(sdev->request_queue),
+                     dma_max_mapping_size(dev) >> SECTOR_SHIFT));
+
        /*
         * Some USB host controllers can't do DMA; they have to use PIO.
         * They indicate this by setting their dma_mask to NULL.  For