From: NeilBrown <neilb@cse.unsw.edu.au>
As no md personalities honour the merge_bvec_fn of underlying devices,
we must make sure never to submit a bio larger than 1 page when a
merge_bvec_fn is defined.
raid5 already does this (it never submits bios larger than one page).
With this patch, all other raid personalities limit their
max_sectors when a merge_bvec_fn is present.
25-akpm/drivers/md/linear.c | 9 +++++++++
25-akpm/drivers/md/multipath.c | 19 +++++++++++++++++++
25-akpm/drivers/md/raid0.c | 10 ++++++++++
25-akpm/drivers/md/raid1.c | 18 ++++++++++++++++++
4 files changed, 56 insertions(+)
diff -puN drivers/md/linear.c~md-1-limit_max_sectors drivers/md/linear.c
--- 25/drivers/md/linear.c~md-1-limit_max_sectors Mon Nov 24 12:49:55 2003
+++ 25-akpm/drivers/md/linear.c Mon Nov 24 12:49:55 2003
@@ -113,8 +113,17 @@ static int linear_run (mddev_t *mddev)
}
disk->rdev = 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.
+ */
+ if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
+ mddev->queue->max_sectors > (PAGE_SIZE>>9))
+ mddev->queue->max_sectors = (PAGE_SIZE>>9);
+
disk->size = rdev->size;
mddev->array_size += rdev->size;
diff -puN drivers/md/multipath.c~md-1-limit_max_sectors drivers/md/multipath.c
--- 25/drivers/md/multipath.c~md-1-limit_max_sectors Mon Nov 24 12:49:55 2003
+++ 25-akpm/drivers/md/multipath.c Mon Nov 24 12:49:55 2003
@@ -273,6 +273,17 @@ static int multipath_add_disk(mddev_t *m
p->rdev = 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.
+ * (Note: it is very unlikely that a device with
+ * merge_bvec_fn will be involved in multipath.)
+ */
+ if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
+ mddev->queue->max_sectors > (PAGE_SIZE>>9))
+ mddev->queue->max_sectors = (PAGE_SIZE>>9);
+
conf->working_disks++;
rdev->raid_disk = path;
rdev->in_sync = 1;
@@ -410,8 +421,16 @@ static int multipath_run (mddev_t *mddev
disk = conf->multipaths + disk_idx;
disk->rdev = 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, 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))
+ mddev->queue->max_sectors = (PAGE_SIZE>>9);
+
if (!rdev->faulty)
conf->working_disks++;
}
diff -puN drivers/md/raid0.c~md-1-limit_max_sectors drivers/md/raid0.c
--- 25/drivers/md/raid0.c~md-1-limit_max_sectors Mon Nov 24 12:49:55 2003
+++ 25-akpm/drivers/md/raid0.c Mon Nov 24 12:49:55 2003
@@ -112,8 +112,18 @@ static int create_strip_zones (mddev_t *
goto abort;
}
zone->dev[j] = rdev1;
+
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.
+ */
+
+ if (rdev1->bdev->bd_disk->queue->merge_bvec_fn &&
+ mddev->queue->max_sectors > (PAGE_SIZE>>9))
+ mddev->queue->max_sectors = (PAGE_SIZE>>9);
+
if (!smallest || (rdev1->size <smallest->size))
smallest = rdev1;
cnt++;
diff -puN drivers/md/raid1.c~md-1-limit_max_sectors drivers/md/raid1.c
--- 25/drivers/md/raid1.c~md-1-limit_max_sectors Mon Nov 24 12:49:55 2003
+++ 25-akpm/drivers/md/raid1.c Mon Nov 24 12:49:55 2003
@@ -677,8 +677,17 @@ static int raid1_add_disk(mddev_t *mddev
for (mirror=0; mirror < mddev->raid_disks; mirror++)
if ( !(p=conf->mirrors+mirror)->rdev) {
p->rdev = 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.
+ */
+ if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
+ mddev->queue->max_sectors > (PAGE_SIZE>>9))
+ mddev->queue->max_sectors = (PAGE_SIZE>>9);
+
p->head_position = 0;
rdev->raid_disk = mirror;
found = 1;
@@ -1077,8 +1086,17 @@ static int run(mddev_t *mddev)
disk = conf->mirrors + disk_idx;
disk->rdev = 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.
+ */
+ if (rdev->bdev->bd_disk->queue->merge_bvec_fn &&
+ mddev->queue->max_sectors > (PAGE_SIZE>>9))
+ mddev->queue->max_sectors = (PAGE_SIZE>>9);
+
disk->head_position = 0;
if (!rdev->faulty && rdev->in_sync)
conf->working_disks++;
_