From: NeilBrown Date: Wed, 31 Mar 2010 01:07:16 +0000 (+1100) Subject: md: deal with merge_bvec_fn in component devices better. X-Git-Tag: v2.6.33.3~15 X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=11d0dfa8ce268e40b625e26537f21cf5b74007af;p=karo-tx-linux.git md: deal with merge_bvec_fn in component devices better. commit 627a2d3c29427637f4c5d31ccc7fcbd8d312cd71 upstream. 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_phys_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 Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/md/linear.c b/drivers/md/linear.c index 00435bd20699..001317b50034 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_phys_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_sectors(mddev->queue, PAGE_SIZE>>9); + if (rdev->bdev->bd_disk->queue->merge_bvec_fn) { + blk_queue_max_phys_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 32a662fc55c9..f9ee99f9a94c 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_phys_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_sectors(mddev->queue, PAGE_SIZE>>9); + if (q->merge_bvec_fn) { + blk_queue_max_phys_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_sectors(mddev->queue, PAGE_SIZE>>9); + if (rdev->bdev->bd_disk->queue->merge_bvec_fn) { + blk_queue_max_phys_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 77605cdceaf1..41ee9deed250 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_phys_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_sectors(mddev->queue, PAGE_SIZE>>9); - + if (rdev1->bdev->bd_disk->queue->merge_bvec_fn) { + blk_queue_max_phys_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/raid10.c b/drivers/md/raid10.c index d119b7b75e71..047c468e3d28 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_phys_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_sectors(mddev->queue, PAGE_SIZE>>9); + if (rdev->bdev->bd_disk->queue->merge_bvec_fn) { + blk_queue_max_phys_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_phys_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_sectors(mddev->queue, PAGE_SIZE>>9); + if (rdev->bdev->bd_disk->queue->merge_bvec_fn) { + blk_queue_max_phys_segments(mddev->queue, 1); + blk_queue_segment_boundary(mddev->queue, + PAGE_CACHE_SIZE - 1); + } disk->head_position = 0; }