On Tue, 2010-11-23 at 17:50 +0000, Ben Hutchings wrote: [...] > > Oops, that version was not quite completely adjusted. Please test this > > instead. > > and I have no idea why I thought that, because the first version I sent > you was correct and the second was not.
*sigh* OK, neither of them was correct. This version will really work, I promise. Ben. -- Ben Hutchings Once a job is fouled up, anything done to improve it makes it worse.
From 34df5016f2e8681ae9e99e54a66c826463dd74a5 Mon Sep 17 00:00:00 2001
From: NeilBrown <ne...@suse.de>
Date: Mon, 8 Mar 2010 16:44:38 +1100
Subject: [PATCH] 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_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 <ne...@suse.de>
Cc: sta...@kernel.org
[bwh: Backport to Linux 2.6.26]
---
drivers/md/linear.c | 13 ++++++++-----
drivers/md/multipath.c | 22 ++++++++++++++--------
drivers/md/raid0.c | 14 ++++++++------
drivers/md/raid1.c | 30 +++++++++++++++++++-----------
drivers/md/raid10.c | 30 +++++++++++++++++++-----------
5 files changed, 68 insertions(+), 41 deletions(-)
diff --git a/drivers/md/linear.c b/drivers/md/linear.c
index ec921f5..627cd38 100644
--- a/drivers/md/linear.c
+++ b/drivers/md/linear.c
@@ -136,12 +136,15 @@ static linear_conf_t *linear_conf(mddev_t *mddev, int raid_disks)
blk_queue_stack_limits(mddev->queue,
rdev->bdev->bd_disk->queue);
/* 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 &&
- mddev->queue->max_sectors > (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_max_hw_segments(mddev->queue, 1);
+ blk_queue_segment_boundary(mddev->queue,
+ PAGE_CACHE_SIZE - 1);
+ }
disk->size = rdev->size;
conf->array_size += rdev->size;
diff --git a/drivers/md/multipath.c b/drivers/md/multipath.c
index e968116..9605b21 100644
--- a/drivers/md/multipath.c
+++ b/drivers/md/multipath.c
@@ -293,14 +293,17 @@ static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
blk_queue_stack_limits(mddev->queue, q);
/* 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 &&
- mddev->queue->max_sectors > (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_max_hw_segments(mddev->queue, 1);
+ blk_queue_segment_boundary(mddev->queue,
+ PAGE_CACHE_SIZE - 1);
+ }
conf->working_disks++;
mddev->degraded--;
@@ -453,9 +456,12 @@ 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 &&
- mddev->queue->max_sectors > (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_max_hw_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 914c04d..806e20d 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -141,14 +141,16 @@ static int create_strip_zones (mddev_t *mddev)
blk_queue_stack_limits(mddev->queue,
rdev1->bdev->bd_disk->queue);
/* 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 &&
- mddev->queue->max_sectors > (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_max_hw_segments(mddev->queue, 1);
+ blk_queue_segment_boundary(mddev->queue,
+ PAGE_CACHE_SIZE - 1);
+ }
if (!smallest || (rdev1->size <smallest->size))
smallest = rdev1;
cnt++;
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index c610b94..0c00872 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1109,13 +1109,18 @@ static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
blk_queue_stack_limits(mddev->queue,
rdev->bdev->bd_disk->queue);
- /* 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 &&
- mddev->queue->max_sectors > (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_max_hw_segments(mddev->queue, 1);
+ blk_queue_segment_boundary(mddev->queue,
+ PAGE_CACHE_SIZE - 1);
+ }
p->head_position = 0;
rdev->raid_disk = mirror;
@@ -1971,12 +1976,15 @@ static int run(mddev_t *mddev)
blk_queue_stack_limits(mddev->queue,
rdev->bdev->bd_disk->queue);
/* 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 &&
- mddev->queue->max_sectors > (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_max_hw_segments(mddev->queue, 1);
+ blk_queue_segment_boundary(mddev->queue,
+ PAGE_CACHE_SIZE - 1);
+ }
disk->head_position = 0;
}
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index a71277b..010d632 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1135,13 +1135,18 @@ static int raid10_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
blk_queue_stack_limits(mddev->queue,
rdev->bdev->bd_disk->queue);
- /* 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 &&
- mddev->queue->max_sectors > (PAGE_SIZE>>9))
- mddev->queue->max_sectors = (PAGE_SIZE>>9);
+ if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
+ blk_queue_max_phys_segments(mddev->queue, 1);
+ blk_queue_max_hw_segments(mddev->queue, 1);
+ blk_queue_segment_boundary(mddev->queue,
+ PAGE_CACHE_SIZE - 1);
+ }
p->head_position = 0;
rdev->raid_disk = mirror;
@@ -2107,12 +2112,15 @@ static int run(mddev_t *mddev)
blk_queue_stack_limits(mddev->queue,
rdev->bdev->bd_disk->queue);
/* 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 &&
- mddev->queue->max_sectors > (PAGE_SIZE>>9))
- mddev->queue->max_sectors = (PAGE_SIZE>>9);
+ if (rdev->bdev->bd_disk->queue->merge_bvec_fn) {
+ blk_queue_max_phys_segments(mddev->queue, 1);
+ blk_queue_max_hw_segments(mddev->queue, 1);
+ blk_queue_segment_boundary(mddev->queue,
+ PAGE_CACHE_SIZE - 1);
+ }
disk->head_position = 0;
}
--
1.7.2.3
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