block/sd: Fix device-imposed transfer length limits
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>
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 7d8f129..dd49735 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -91,7 +91,8 @@
lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
lim->virt_boundary_mask = 0;
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;
@@ -127,6 +128,7 @@
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);
@@ -214,8 +216,8 @@
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
+ * blk_queue_max_hw_sectors - set max sectors for a request for this queue
+ * @q: the request queue for the device
* @max_hw_sectors: max hardware sectors in the usual 512b unit
*
* Description:
@@ -224,13 +226,19 @@
* 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_limits_max_hw_sectors(struct queue_limits *limits, unsigned int max_hw_sectors)
+void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int 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",
@@ -238,22 +246,9 @@
}
limits->max_hw_sectors = max_hw_sectors;
- limits->max_sectors = min_t(unsigned int, max_hw_sectors,
- BLK_DEF_MAX_SECTORS);
-}
-EXPORT_SYMBOL(blk_limits_max_hw_sectors);
-
-/**
- * blk_queue_max_hw_sectors - set max sectors for a request for this queue
- * @q: the request queue for the device
- * @max_hw_sectors: max hardware sectors in the usual 512b unit
- *
- * Description:
- * See description for blk_limits_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);
+ 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);
@@ -527,6 +522,7 @@
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 3e44a9d..55c637b 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -205,6 +205,9 @@
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 e868d39..7af47ed 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -2238,11 +2238,8 @@
}
}
- 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)
@@ -2559,7 +2556,6 @@
{
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 ||
@@ -2567,14 +2563,11 @@
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;
@@ -2723,6 +2716,11 @@
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.
@@ -2732,8 +2730,9 @@
{
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"));
@@ -2781,11 +2780,26 @@
*/
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;
- sdkp->disk->queue->limits.max_sectors =
- min_not_zero(queue_max_hw_sectors(sdkp->disk->queue), max_xfer);
+ /* 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;
+
+ /* 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);
diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 63ba5ca..5f2a84a 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -67,6 +67,7 @@
atomic_t openers;
sector_t capacity; /* size in 512-byte sectors */
u32 max_xfer_blocks;
+ u32 opt_xfer_blocks;
u32 max_ws_blocks;
u32 max_unmap_blocks;
u32 unmap_granularity;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 38a5ff7..9dacb74 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -253,6 +253,7 @@
unsigned long virt_boundary_mask;
unsigned int max_hw_sectors;
+ unsigned int max_dev_sectors;
unsigned int chunk_sectors;
unsigned int max_sectors;
unsigned int max_segment_size;
@@ -948,7 +949,6 @@
extern void blk_cleanup_queue(struct request_queue *);
extern void blk_queue_make_request(struct request_queue *, make_request_fn *);
extern void blk_queue_bounce_limit(struct request_queue *, u64);
-extern void blk_limits_max_hw_sectors(struct queue_limits *, unsigned int);
extern void blk_queue_max_hw_sectors(struct request_queue *, unsigned int);
extern void blk_queue_chunk_sectors(struct request_queue *, unsigned int);
extern void blk_queue_max_segments(struct request_queue *, unsigned short);