On Tue, 2010-11-23 at 02:31 +0000, Ben Hutchings wrote: > I have attempted to adjust this for Debian's stable kernel version > (2.6.26) and the result is attached. Please could you test this, > following the instructions at > <http://kernel-handbook.alioth.debian.org/ch-common-tasks.html#s-common-official>. Oops, that version was not quite completely adjusted. Please test this instead. Ben. -- Ben Hutchings Once a job is fouled up, anything done to improve it makes it worse.
From: NeilBrown <neilb@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 <neilb@suse.de>
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 af2d39d..bb2a231 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 4b323f4..5558ebc 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 a1f7147..377cf2a 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 5a06122..f741f77 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 7584f9a..b4ba41e 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;
}
--
1.7.2.3
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