From 397737223c59e89dca7305feb6528caef8fbef84 Mon Sep 17 00:00:00 2001 From: "Martin K. Petersen" Date: Fri, 13 Nov 2015 16:46:47 -0500 Subject: sd: Make discard granularity match logical block size when LBPRZ=1 A device may report an OPTIMAL UNMAP GRANULARITY and UNMAP GRANULARITY ALIGNMENT in the Block Limits VPD. These parameters describe the device's internal provisioning allocation units. By default the block layer will round and align any discard requests based on these limits. If a device reports LBPRZ=1 to guarantee zeroes after discard, however, it is imperative that the block layer does not leave out any parts of the requested block range. Otherwise the device can not do the required zeroing of any partial allocation units and this can lead to data corruption. Since the dm thinp personality relies on the block layer's current behavior and is unable to deal with partial discard blocks we work around the problem by setting the granularity to match the logical block size when LBPRZ is enabled. Signed-off-by: Martin K. Petersen Reviewed-by: Christoph Hellwig Reviewed-by: Johannes Thumshirn Signed-off-by: Martin K. Petersen --- drivers/scsi/sd.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) (limited to 'drivers/scsi/sd.c') diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c index f7247778c225..e868d39c39bb 100644 --- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -637,11 +637,24 @@ static void sd_config_discard(struct scsi_disk *sdkp, unsigned int mode) unsigned int max_blocks = 0; q->limits.discard_zeroes_data = 0; - q->limits.discard_alignment = sdkp->unmap_alignment * - logical_block_size; - q->limits.discard_granularity = - max(sdkp->physical_block_size, - sdkp->unmap_granularity * logical_block_size); + + /* + * When LBPRZ is reported, discard alignment and granularity + * must be fixed to the logical block size. Otherwise the block + * layer will drop misaligned portions of the request which can + * lead to data corruption. If LBPRZ is not set, we honor the + * device preference. + */ + if (sdkp->lbprz) { + q->limits.discard_alignment = 0; + q->limits.discard_granularity = 1; + } else { + q->limits.discard_alignment = sdkp->unmap_alignment * + logical_block_size; + q->limits.discard_granularity = + max(sdkp->physical_block_size, + sdkp->unmap_granularity * logical_block_size); + } sdkp->provisioning_mode = mode; -- cgit v1.2.3 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 ++++++++++++++++++++++++++++++---------------- 1 file changed, 30 insertions(+), 16 deletions(-) (limited to 'drivers/scsi/sd.c') 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); -- cgit v1.2.3