From 627a2d3c29427637f4c5d31ccc7fcbd8d312cd71 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Mon, 8 Mar 2010 16:44:38 +1100 Subject: [PATCH] md: deal with merge_bvec_fn in component devices better. If a component device has a merge_bvec_fn then as we never call it we must ensure we never need to. Currently this is done by setting max_sector to 1 PAGE, however this does not stop a bio being created with several sub-page iovecs that would violate the merge_bvec_fn. So instead set max_segments to 1 and set the segment boundary to the same as a page boundary to ensure there is only ever one single-page segment of IO requested at a time. This can particularly be an issue when 'xen' is used as it is known to submit multiple small buffers in a single bio. Signed-off-by: NeilBrown Cc: stable@kernel.org --- drivers/md/linear.c | 12 +++++++----- drivers/md/multipath.c | 20 ++++++++++++-------- drivers/md/raid0.c | 13 +++++++------ drivers/md/raid1.c | 28 +++++++++++++++++----------- drivers/md/raid10.c | 28 +++++++++++++++++----------- 5 files changed, 60 insertions(+), 41 deletions(-) diff --git a/drivers/md/linear.c b/drivers/md/linear.c index af2d39d603c7..bb2a23159b21 100644 --- a/drivers/md/linear.c +++ b/drivers/md/linear.c @@ -172,12 +172,14 @@ static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks) disk_stack_limits(mddev->gendisk, rdev->bdev, rdev->data_offset << 9); /* as we don't honour merge_bvec_fn, we must never risk - * violating it, so limit ->max_sector to one PAGE, as - * a one page request is never in violation. + * violating it, so limit max_segments to 1 lying within + * a single page. */ - if (rdev->bdev->bd_disk->queue->merge_bvec_fn && - queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9)) - blk_queue_max_hw_sectors(mddev->queue, PAGE_SIZE>>9); + if (rdev->bdev->bd_disk->queue->merge_bvec_fn) { + blk_queue_max_segments(mddev->queue, 1); + blk_queue_segment_boundary(mddev->queue, + PAGE_CACHE_SIZE - 1); + } conf->array_sectors += rdev->sectors; cnt++; diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c index 4b323f45ad74..5558ebc705c8 100644 --- a/drivers/md/multipath.c +++ b/drivers/md/multipath.c @@ -301,14 +301,16 @@ static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev) rdev->data_offset << 9); /* as we don't honour merge_bvec_fn, we must never risk - * violating it, so limit ->max_sector to one PAGE, as - * a one page request is never in violation. + * violating it, so limit ->max_segments to one, lying + * within a single page. * (Note: it is very unlikely that a device with * merge_bvec_fn will be involved in multipath.) */ - if (q->merge_bvec_fn && - queue_max_sectors(q) > (PAGE_SIZE>>9)) - blk_queue_max_hw_sectors(mddev->queue, PAGE_SIZE>>9); + if (q->merge_bvec_fn) { + blk_queue_max_segments(mddev->queue, 1); + blk_queue_segment_boundary(mddev->queue, + PAGE_CACHE_SIZE - 1); + } conf->working_disks++; mddev->degraded--; @@ -476,9 +478,11 @@ static int multipath_run (mddev_t *mddev) /* as we don't honour merge_bvec_fn, we must never risk * violating it, not that we ever expect a device with * a merge_bvec_fn to be involved in multipath */ - if (rdev->bdev->bd_disk->queue->merge_bvec_fn && - queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9)) - blk_queue_max_hw_sectors(mddev->queue, PAGE_SIZE>>9); + if (rdev->bdev->bd_disk->queue->merge_bvec_fn) { + blk_queue_max_segments(mddev->queue, 1); + blk_queue_segment_boundary(mddev->queue, + PAGE_CACHE_SIZE - 1); + } if (!test_bit(Faulty, &rdev->flags)) conf->working_disks++; diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c index a1f7147b757f..377cf2a3c333 100644 --- a/drivers/md/raid0.c +++ b/drivers/md/raid0.c @@ -176,14 +176,15 @@ static int create_strip_zones(mddev_t *mddev) disk_stack_limits(mddev->gendisk, rdev1->bdev, rdev1->data_offset << 9); /* as we don't honour merge_bvec_fn, we must never risk - * violating it, so limit ->max_sector to one PAGE, as - * a one page request is never in violation. + * violating it, so limit ->max_segments to 1, lying within + * a single page. */ - if (rdev1->bdev->bd_disk->queue->merge_bvec_fn && - queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9)) - blk_queue_max_hw_sectors(mddev->queue, PAGE_SIZE>>9); - + if (rdev1->bdev->bd_disk->queue->merge_bvec_fn) { + blk_queue_max_segments(mddev->queue, 1); + blk_queue_segment_boundary(mddev->queue, + PAGE_CACHE_SIZE - 1); + } if (!smallest || (rdev1->sectors < smallest->sectors)) smallest = rdev1; cnt++; diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 5a06122abd3b..f741f77eeb2b 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -1152,13 +1152,17 @@ static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev) disk_stack_limits(mddev->gendisk, rdev->bdev, rdev->data_offset << 9); - /* as we don't honour merge_bvec_fn, we must never risk - * violating it, so limit ->max_sector to one PAGE, as - * a one page request is never in violation. + /* as we don't honour merge_bvec_fn, we must + * never risk violating it, so limit + * ->max_segments to one lying with a single + * page, as a one page request is never in + * violation. */ - if (rdev->bdev->bd_disk->queue->merge_bvec_fn && - queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9)) - blk_queue_max_hw_sectors(mddev->queue, PAGE_SIZE>>9); + if (rdev->bdev->bd_disk->queue->merge_bvec_fn) { + blk_queue_max_segments(mddev->queue, 1); + blk_queue_segment_boundary(mddev->queue, + PAGE_CACHE_SIZE - 1); + } p->head_position = 0; rdev->raid_disk = mirror; @@ -2098,12 +2102,14 @@ static int run(mddev_t *mddev) disk_stack_limits(mddev->gendisk, rdev->bdev, rdev->data_offset << 9); /* as we don't honour merge_bvec_fn, we must never risk - * violating it, so limit ->max_sector to one PAGE, as - * a one page request is never in violation. + * violating it, so limit ->max_segments to 1 lying within + * a single page, as a one page request is never in violation. */ - if (rdev->bdev->bd_disk->queue->merge_bvec_fn && - queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9)) - blk_queue_max_hw_sectors(mddev->queue, PAGE_SIZE>>9); + if (rdev->bdev->bd_disk->queue->merge_bvec_fn) { + blk_queue_max_segments(mddev->queue, 1); + blk_queue_segment_boundary(mddev->queue, + PAGE_CACHE_SIZE - 1); + } } mddev->degraded = 0; diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c index 7584f9ab9bcf..b4ba41ecbd20 100644 --- a/drivers/md/raid10.c +++ b/drivers/md/raid10.c @@ -1155,13 +1155,17 @@ static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev) disk_stack_limits(mddev->gendisk, rdev->bdev, rdev->data_offset << 9); - /* as we don't honour merge_bvec_fn, we must never risk - * violating it, so limit ->max_sector to one PAGE, as - * a one page request is never in violation. + /* as we don't honour merge_bvec_fn, we must + * never risk violating it, so limit + * ->max_segments to one lying with a single + * page, as a one page request is never in + * violation. */ - if (rdev->bdev->bd_disk->queue->merge_bvec_fn && - queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9)) - blk_queue_max_hw_sectors(mddev->queue, PAGE_SIZE>>9); + if (rdev->bdev->bd_disk->queue->merge_bvec_fn) { + blk_queue_max_segments(mddev->queue, 1); + blk_queue_segment_boundary(mddev->queue, + PAGE_CACHE_SIZE - 1); + } p->head_position = 0; rdev->raid_disk = mirror; @@ -2255,12 +2259,14 @@ static int run(mddev_t *mddev) disk_stack_limits(mddev->gendisk, rdev->bdev, rdev->data_offset << 9); /* as we don't honour merge_bvec_fn, we must never risk - * violating it, so limit ->max_sector to one PAGE, as - * a one page request is never in violation. + * violating it, so limit max_segments to 1 lying + * within a single page. */ - if (rdev->bdev->bd_disk->queue->merge_bvec_fn && - queue_max_sectors(mddev->queue) > (PAGE_SIZE>>9)) - blk_queue_max_hw_sectors(mddev->queue, PAGE_SIZE>>9); + if (rdev->bdev->bd_disk->queue->merge_bvec_fn) { + blk_queue_max_segments(mddev->queue, 1); + blk_queue_segment_boundary(mddev->queue, + PAGE_CACHE_SIZE - 1); + } disk->head_position = 0; }