block/sd: Fix device-imposed transfer length limits

Orabug: 23615929

(commit ca369d51b3e1649be4a72addd6d6a168cfb3f537 of upstream)
Commit 4f258a46346c ("sd: Fix maximum I/O size for BLOCK_PC requests")
had the unfortunate side-effect of removing an implicit clamp to
BLK_DEF_MAX_SECTORS for REQ_TYPE_FS requests in the block layer
code. This caused problems for some SMR drives.

Debugging this issue revealed a few problems with the existing
infrastructure since the block layer didn't know how to deal with
device-imposed limits, only limits set by the I/O controller.

 - Introduce a new queue limit, max_dev_sectors, which is used by the
   ULD to signal the maximum sectors for a REQ_TYPE_FS request.

 - Ensure that max_dev_sectors is correctly stacked and taken into
   account when overriding max_sectors through sysfs.

 - Rework sd_read_block_limits() so it saves the max_xfer and opt_xfer
   values for later processing.

 - In sd_revalidate() set the queue's max_dev_sectors based on the
   MAXIMUM TRANSFER LENGTH value in the Block Limits VPD. If this value
   is not reported, fall back to a cap based on the CDB TRANSFER LENGTH
   field size.

 - In sd_revalidate(), use OPTIMAL TRANSFER LENGTH from the Block Limits
   VPD--if reported and sane--to signal the preferred device transfer
   size for FS requests. Otherwise use BLK_DEF_MAX_SECTORS.

 - blk_limits_max_hw_sectors() is no longer used and can be removed.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=93581
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: sweeneygj@gmx.com
Tested-by: Arzeets <anatol.pomozov@gmail.com>
Tested-by: David Eisner <david.eisner@oriel.oxon.org>
Tested-by: Mario Kicherer <dev@kicherer.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Joe Jin <joe.jin@oracle.com>
Conflicts:
  drivers/scsi/sd.h
  include/linux/blkdev.h
    Adding opt_xfer_blocks and max_dev_sectors breaks kABI.
    They will be added using by UEK_KABI_USE2() in a fix-up commit.
Signed-off-by: Chuck Anderson <chuck.anderson@oracle.com>

diff --git a/block/blk-settings.c b/block/blk-settings.c
index e0057d035200c4dd5e42d191f0395a7769489905..dc2e66e32b6618b0b5cf90c7e454c0bfefa2de46 100644 (file)
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -112,7 +112,8 @@ void blk_set_default_limits(struct queue_limits *lim)
        lim->max_integrity_segments = 0;
        lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
        lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
-       lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
+       lim->max_sectors = lim->max_dev_sectors = lim->max_hw_sectors =
+               BLK_SAFE_MAX_SECTORS;
        lim->chunk_sectors = 0;
        lim->max_write_same_sectors = 0;
        lim->max_discard_sectors = 0;
@@ -147,6 +148,7 @@ void blk_set_stacking_limits(struct queue_limits *lim)
        lim->max_hw_sectors = UINT_MAX;
        lim->max_segment_size = UINT_MAX;
        lim->max_sectors = UINT_MAX;
+       lim->max_dev_sectors = UINT_MAX;
        lim->max_write_same_sectors = UINT_MAX;
 }
 EXPORT_SYMBOL(blk_set_stacking_limits);
@@ -232,7 +234,6 @@ void blk_queue_bounce_limit(struct request_queue *q, u64 max_addr)
        }
 }
 EXPORT_SYMBOL(blk_queue_bounce_limit);
-
 /**
  * blk_limits_max_hw_sectors - set hard and soft limit of max sectors for request
  * @limits: the queue limits
@@ -267,11 +268,34 @@ EXPORT_SYMBOL(blk_limits_max_hw_sectors);
  * @max_hw_sectors:  max hardware sectors in the usual 512b unit
  *
  * Description:
- *    See description for blk_limits_max_hw_sectors().
+ *    Enables a low level driver to set a hard upper limit,
+ *    max_hw_sectors, on the size of requests.  max_hw_sectors is set by
+ *    the device driver based upon the capabilities of the I/O
+ *    controller.
+ *
+ *    max_dev_sectors is a hard limit imposed by the storage device for
+ *    READ/WRITE requests. It is set by the disk driver.
+ *
+ *    max_sectors is a soft limit imposed by the block layer for
+ *    filesystem type requests.  This value can be overridden on a
+ *    per-device basis in /sys/block/<device>/queue/max_sectors_kb.
+ *    The soft limit can not exceed max_hw_sectors.
  **/
 void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_sectors)
 {
-       blk_limits_max_hw_sectors(&q->limits, max_hw_sectors);
+       struct queue_limits *limits = &q->limits;
+       unsigned int max_sectors;
+
+       if ((max_hw_sectors << 9) < PAGE_CACHE_SIZE) {
+               max_hw_sectors = 1 << (PAGE_CACHE_SHIFT - 9);
+               printk(KERN_INFO "%s: set to minimum %d\n",
+                      __func__, max_hw_sectors);
+       }
+
+       limits->max_hw_sectors = max_hw_sectors;
+       max_sectors = min_not_zero(max_hw_sectors, limits->max_dev_sectors);
+       max_sectors = min_t(unsigned int, max_sectors, BLK_DEF_MAX_SECTORS);
+       limits->max_sectors = max_sectors;
 }
 EXPORT_SYMBOL(blk_queue_max_hw_sectors);
 
@@ -544,6 +568,7 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
 
        t->max_sectors = min_not_zero(t->max_sectors, b->max_sectors);
        t->max_hw_sectors = min_not_zero(t->max_hw_sectors, b->max_hw_sectors);
+       t->max_dev_sectors = min_not_zero(t->max_dev_sectors, b->max_dev_sectors);
        t->max_write_same_sectors = min(t->max_write_same_sectors,
                                        b->max_write_same_sectors);
        t->bounce_pfn = min_not_zero(t->bounce_pfn, b->bounce_pfn);

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 2b8fd302f677a967d87994f8a7532aab8dfe6569..1b0a8afc1b3fdaef0ebc651493f7d4ef85bdfc75 100644 (file)
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -173,6 +173,9 @@ queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
        if (ret < 0)
                return ret;
 
+       max_hw_sectors_kb = min_not_zero(max_hw_sectors_kb, (unsigned long)
+                                        q->limits.max_dev_sectors >> 1);
+
        if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
                return -EINVAL;
 

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 11ea52b2c36b3c1e6a38da80ea95080feea7e3e7..4cd30d95ac310cff327a42ab523fc1313bfde161 100644 (file)
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2224,11 +2224,8 @@ got_data:
                }
        }
 
-       if (sdkp->capacity > 0xffffffff) {
+       if (sdkp->capacity > 0xffffffff)
                sdp->use_16_for_rw = 1;
-               sdkp->max_xfer_blocks = SD_MAX_XFER_BLOCKS;
-       } else
-               sdkp->max_xfer_blocks = SD_DEF_XFER_BLOCKS;
 
        /* Rescale capacity to 512-byte units */
        if (sector_size == 4096)
@@ -2545,7 +2542,6 @@ static void sd_read_block_limits(struct scsi_disk *sdkp)
 {
        unsigned int sector_sz = sdkp->device->sector_size;
        const int vpd_len = 64;
-       u32 max_xfer_length;
        unsigned char *buffer = kmalloc(vpd_len, GFP_KERNEL);
 
        if (!buffer ||
@@ -2553,14 +2549,11 @@ static void sd_read_block_limits(struct scsi_disk *sdkp)
            scsi_get_vpd_page(sdkp->device, 0xb0, buffer, vpd_len))
                goto out;
 
-       max_xfer_length = get_unaligned_be32(&buffer[8]);
-       if (max_xfer_length)
-               sdkp->max_xfer_blocks = max_xfer_length;
-
        blk_queue_io_min(sdkp->disk->queue,
                         get_unaligned_be16(&buffer[6]) * sector_sz);
-       blk_queue_io_opt(sdkp->disk->queue,
-                        get_unaligned_be32(&buffer[12]) * sector_sz);
+
+       sdkp->max_xfer_blocks = get_unaligned_be32(&buffer[8]);
+       sdkp->opt_xfer_blocks = get_unaligned_be32(&buffer[12]);
 
        if (buffer[3] == 0x3c) {
                unsigned int lba_count, desc_count;
@@ -2709,6 +2702,11 @@ static int sd_try_extended_inquiry(struct scsi_device *sdp)
        return 0;
 }
 
+static inline u32 logical_to_sectors(struct scsi_device *sdev, u32 blocks)
+{
+       return blocks << (ilog2(sdev->sector_size) - 9);
+}
+
 /**
  *     sd_revalidate_disk - called the first time a new disk is seen,
  *     performs disk spin up, read_capacity, etc.
@@ -2718,8 +2716,9 @@ static int sd_revalidate_disk(struct gendisk *disk)
 {
        struct scsi_disk *sdkp = scsi_disk(disk);
        struct scsi_device *sdp = sdkp->device;
+       struct request_queue *q = sdkp->disk->queue;
        unsigned char *buffer;
-       unsigned int max_xfer;
+       unsigned int dev_max, rw_max;
 
        SCSI_LOG_HLQUEUE(3, sd_printk(KERN_INFO, sdkp,
                                      "sd_revalidate_disk\n"));
@@ -2767,11 +2766,26 @@ static int sd_revalidate_disk(struct gendisk *disk)
         */
        sd_set_flush_flag(sdkp);
 
-       max_xfer = sdkp->max_xfer_blocks;
-       max_xfer <<= ilog2(sdp->sector_size) - 9;
+       /* Initial block count limit based on CDB TRANSFER LENGTH field size. */
+       dev_max = sdp->use_16_for_rw ? SD_MAX_XFER_BLOCKS : SD_DEF_XFER_BLOCKS;
+
+       /* Some devices report a maximum block count for READ/WRITE requests. */
+       dev_max = min_not_zero(dev_max, sdkp->max_xfer_blocks);
+       q->limits.max_dev_sectors = logical_to_sectors(sdp, dev_max);
+
+       /*
+        * Use the device's preferred I/O size for reads and writes
+        * unless the reported value is unreasonably large (or garbage).
+        */
+       if (sdkp->opt_xfer_blocks && sdkp->opt_xfer_blocks <= dev_max &&
+           sdkp->opt_xfer_blocks <= SD_DEF_XFER_BLOCKS)
+               rw_max = q->limits.io_opt =
+                       logical_to_sectors(sdp, sdkp->opt_xfer_blocks);
+       else
+               rw_max = BLK_DEF_MAX_SECTORS;
 
-       sdkp->disk->queue->limits.max_sectors =
-               min_not_zero(queue_max_hw_sectors(sdkp->disk->queue), max_xfer);
+       /* Combine with controller limits */
+       q->limits.max_sectors = min(rw_max, queue_max_hw_sectors(q));
 
        set_capacity(disk, sdkp->capacity);
        sd_config_write_same(sdkp);