From ca369d51b3e1649be4a72addd6d6a168cfb3f537 Mon Sep 17 00:00:00 2001 From: Martin K. Petersen Date: Fri, 13 Nov 2015 16:46:48 -0500 Subject: 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 Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=93581 Reviewed-by: Christoph Hellwig Tested-by: sweeneygj@gmx.com Tested-by: Arzeets Tested-by: David Eisner Tested-by: Mario Kicherer Signed-off-by: Martin K. Petersen --- drivers/scsi/sd.c | 46 ++++++++++++++++++++++++++++++---------------- drivers/scsi/sd.h | 1 + 2 files changed, 31 insertions(+), 16 deletions(-) (limited to 'drivers/scsi') diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index e868d39c39bb..7af47ed10d90 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -2238,11 +2238,8 @@ 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) @@ -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; + + /* 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); diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h index 63ba5ca7f9a1..5f2a84aff29f 100644 --- a/drivers/scsi/sd.h +++ b/drivers/scsi/sd.h @@ -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; -- cgit v1.2.3-55-g7522