### Comments for ChangeSet
We abstract out "which_dev" which finds which device a sector is on
and us it to make sure both ends of a to-be-merged request will
be on the same device.
----------- Diffstat output ------------
./drivers/md/linear.c | 69 +++++++++++++++++++++++++++++++++++++-------------
1 files changed, 52 insertions(+), 17 deletions(-)
--- ./drivers/md/linear.c 2002/10/16 04:48:24 1.1
+++ ./drivers/md/linear.c 2002/10/16 04:49:22 1.2
@@ -28,6 +28,45 @@
#define MD_PERSONALITY
#define DEVICE_NR(device) (minor(device))
+/*
+ * find which device holds a particular offset
+ */
+static inline dev_info_t *which_dev(mddev_t *mddev, sector_t sector)
+{
+ struct linear_hash *hash;
+ linear_conf_t *conf = mddev_to_conf(mddev);
+ sector_t block = sector >> 1;
+
+ hash = conf->hash_table + sector_div(block, conf->smallest->size);
+
+ if ((sector>>1) >= (hash->dev0->size + hash->dev0->offset))
+ return hash->dev1;
+ else
+ return hash->dev0;
+}
+
+
+/**
+ * linear_mergeable_bvec -- tell bio layer if a two requests can be merged
+ * @q: request queue
+ * @bio: the buffer head that's been built up so far
+ * @biovec: the request that could be merged to it.
+ *
+ * Return 1 if the merge is not permitted (because the
+ * result would cross a device boundary), 0 otherwise.
+ */
+static int linear_mergeable_bvec(request_queue_t *q, struct bio *bio, struct bio_vec *biovec)
+{
+ mddev_t *mddev = q->queuedata;
+ dev_info_t *dev0, *dev1;
+
+ dev0 = which_dev(mddev, bio->bi_sector);
+ dev1 = which_dev(mddev, bio->bi_sector +
+ ((bio->bi_size + biovec->bv_len - 1) >> 9));
+
+ return dev0 != dev1;
+}
+
static int linear_run (mddev_t *mddev)
{
linear_conf_t *conf;
@@ -110,6 +149,7 @@ static int linear_run (mddev_t *mddev)
if (table-conf->hash_table != nb_zone)
BUG();
+ blk_queue_merge_bvec(&mddev->queue, linear_mergeable_bvec);
return 0;
out:
@@ -134,28 +174,23 @@ static int linear_stop (mddev_t *mddev)
static int linear_make_request (request_queue_t *q, struct bio *bio)
{
mddev_t *mddev = q->queuedata;
- linear_conf_t *conf = mddev_to_conf(mddev);
- struct linear_hash *hash;
dev_info_t *tmp_dev;
- long block;
+ sector_t block;
+ tmp_dev = which_dev(mddev, bio->bi_sector);
block = bio->bi_sector >> 1;
- hash = conf->hash_table + (block / conf->smallest->size);
- if (block >= (hash->dev0->size + hash->dev0->offset)) {
- if (!hash->dev1) {
- printk ("linear_make_request : hash->dev1==NULL for block %ld\n",
- block);
- bio_io_error(bio, bio->bi_size);
- return 0;
- }
- tmp_dev = hash->dev1;
- } else
- tmp_dev = hash->dev0;
+ if (unlikely(!tmp_dev)) {
+ printk ("linear_make_request : hash->dev1==NULL for block %llu\n",
+ (unsigned long long)block);
+ bio_io_error(bio, bio->bi_size);
+ return 0;
+ }
- if (block >= (tmp_dev->size + tmp_dev->offset)
- || block < tmp_dev->offset) {
- printk ("linear_make_request: Block %ld out of bounds on dev %s size %ld offset %ld\n", block, bdevname(tmp_dev->rdev->bdev), tmp_dev->size, tmp_dev->offset);
+ if (unlikely(block >= (tmp_dev->size + tmp_dev->offset)
+ || block < tmp_dev->offset)) {
+ printk ("linear_make_request: Block %llu out of bounds on dev %s size %ld offset %ld\n",
+ (unsigned long long)block, bdevname(tmp_dev->rdev->bdev), tmp_dev->size, tmp_dev->offset);
bio_io_error(bio, bio->bi_size);
return 0;
}
-
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
