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block/sd: Fix device-imposed transfer length limits

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Commit 4f258a4634 ("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>
This commit is contained in:
Martin K. Petersen 2015-11-13 16:46:48 -05:00
parent f7f9f26b13
commit ca369d51b3
5 changed files with 51 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
block/blk-settings.c
View File

@ -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/<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 @@ 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_sectors, BLK_DEF_MAX_SECTORS);
limits->max_sectors = max_sectors;
}
EXPORT_SYMBOL(blk_queue_max_hw_sectors);
@ -527,6 +522,7 @@ 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);

3
block/blk-sysfs.c
View File

@ -205,6 +205,9 @@ 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;

46
drivers/scsi/sd.c
View File

@ -2238,11 +2238,8 @@ sd_read_capacity(struct scsi_disk *sdkp, unsigned char *buffer)
}
}
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 @@ 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 ||
@ -2567,14 +2563,11 @@ 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;
@ -2723,6 +2716,11 @@ 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.
@ -2732,8 +2730,9 @@ 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"));
@ -2781,11 +2780,26 @@ 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;
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);

1
drivers/scsi/sd.h
View File

@ -67,6 +67,7 @@ struct scsi_disk {
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;

2
include/linux/blkdev.h
View File

@ -253,6 +253,7 @@ struct queue_limits {
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 struct request_queue *blk_init_allocated_queue(struct request_queue *,
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);