[PATCH] Fix raid "bio too big" failures

From: Neil Brown <neilb@cse.unsw.edu.au>

Fix "bio too big" problem with md

Whenever a device is attached to an md device, we make sure the sector
limits of the md device do not exceed those of the added device.

drivers/block/ll_rw_blk.c

@@ -369,6 +369,20 @@ void blk_queue_hardsect_size(request_queue_t *q, unsigned short size)
 	q->hardsect_size = size;
 }
 
+/**
+ * blk_queue_stack_limits - inherit underlying queue limits for stacked drivers
+ * @t:	the stacking driver (top)
+ * @b:  the underlying device (bottom)
+ **/
+void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b)
+{
+	t->max_sectors = min(t->max_sectors,b->max_sectors);
+	t->max_phys_segments = min(t->max_phys_segments,b->max_phys_segments);
+	t->max_hw_segments = min(t->max_hw_segments,b->max_hw_segments);
+	t->max_segment_size = min(t->max_segment_size,b->max_segment_size);
+	t->hardsect_size = max(t->hardsect_size,b->hardsect_size);
+}
+
 /**
  * blk_queue_segment_boundary - set boundary rules for segment merging
  * @q:  the request queue for the device
@@ -2804,6 +2818,7 @@ EXPORT_SYMBOL(blk_queue_max_phys_segments);
 EXPORT_SYMBOL(blk_queue_max_hw_segments);
 EXPORT_SYMBOL(blk_queue_max_segment_size);
 EXPORT_SYMBOL(blk_queue_hardsect_size);
+EXPORT_SYMBOL(blk_queue_stack_limits);
 EXPORT_SYMBOL(blk_queue_segment_boundary);
 EXPORT_SYMBOL(blk_queue_dma_alignment);
 EXPORT_SYMBOL(blk_rq_map_sg);

drivers/md/linear.c

@@ -114,6 +114,8 @@ static int linear_run (mddev_t *mddev)
 		}
 
 		disk->rdev = rdev;
+		blk_queue_stack_limits(mddev->queue,
+				       rdev->bdev->bd_disk->queue);
 		disk->size = rdev->size;
 		mddev->array_size += rdev->size;
 

drivers/md/multipath.c

@@ -272,6 +272,8 @@ static int multipath_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
 	for (path=0; path<mddev->raid_disks; path++) 
 		if ((p=conf->multipaths+path)->rdev == NULL) {
 			p->rdev = rdev;
+			blk_queue_stack_limits(mddev->queue,
+					       rdev->bdev->bd_disk->queue);
 			conf->working_disks++;
 			rdev->raid_disk = path;
 			rdev->in_sync = 1;
@@ -409,6 +411,8 @@ 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);
 		if (!rdev->faulty) 
 			conf->working_disks++;
 	}

drivers/md/raid0.c

@@ -113,6 +113,8 @@ static int create_strip_zones (mddev_t *mddev)
 			goto abort;
 		}
 		zone->dev[j] = rdev1;
+		blk_queue_stack_limits(mddev->queue,
+				       rdev1->bdev->bd_disk->queue);
 		if (!smallest || (rdev1->size <smallest->size))
 			smallest = rdev1;
 		cnt++;
@@ -293,7 +295,6 @@ static int raid0_run (mddev_t *mddev)
 		conf->hash_spacing++;
 	}
 
-	blk_queue_max_sectors(mddev->queue, mddev->chunk_size >> 9);
 	blk_queue_merge_bvec(mddev->queue, raid0_mergeable_bvec);
 	return 0;
 

drivers/md/raid1.c

@@ -678,6 +678,8 @@ static int raid1_add_disk(mddev_t *mddev, mdk_rdev_t *rdev)
 	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);
 			p->head_position = 0;
 			rdev->raid_disk = mirror;
 			found = 1;
@@ -1076,6 +1078,8 @@ 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);
 		disk->head_position = 0;
 		if (!rdev->faulty && rdev->in_sync)
 			conf->working_disks++;

include/linux/blkdev.h

@@ -547,6 +547,7 @@ extern void blk_queue_max_phys_segments(request_queue_t *, unsigned short);
 extern void blk_queue_max_hw_segments(request_queue_t *, unsigned short);
 extern void blk_queue_max_segment_size(request_queue_t *, unsigned int);
 extern void blk_queue_hardsect_size(request_queue_t *, unsigned short);
+extern void blk_queue_stack_limits(request_queue_t *t, request_queue_t *b);
 extern void blk_queue_segment_boundary(request_queue_t *, unsigned long);
 extern void blk_queue_prep_rq(request_queue_t *, prep_rq_fn *pfn);
 extern void blk_queue_merge_bvec(request_queue_t *, merge_bvec_fn *);