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 --- block/blk-sysfs.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'block/blk-sysfs.c') diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 3e44a9da2a13..55c637b9c42b 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -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; -- cgit v1.2.3