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.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=93581
Signed-off-by: Martin K. Petersen
---
block/blk-settings.c | 36
block/blk-sysfs.c | 3 +++
drivers/scsi/sd.c | 46 ++
drivers/scsi/sd.h | 1 +
include/linux/blkdev.h | 2 +-
5 files changed, 51 insertions(+), 37 deletions(-)
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 7d8f129a1516..dd4973583978 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -91,7 +91,8 @@ void blk_set_default_limits(struct queue_limits *lim)
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 @@ 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);
@@ -214,8 +216,8 @@ 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
+ * 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 @@ EXPORT_SYMBOL(blk_queue_bounce_limit);
*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//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 @@ void blk_limits_max_hw_sectors(struct queue_limits
*limits, unsigned int max_hw_
}
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_
