nullb: support discard
discard makes sense for memory backed disk. And also it's useful to test
if upper layer supports dicard correctly.
User configures 'discard' attribute to enable/disable dicard support.
Based on original patch from Kyungchan Koh
Signed-off-by: Kyungchan Koh <kkc6196@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/drivers/block/null_blk.c b/drivers/block/null_blk.c
index 45e0b56..1f3cf25 100644
--- a/drivers/block/null_blk.c
+++ b/drivers/block/null_blk.c
@@ -88,6 +88,7 @@
bool use_per_node_hctx; /* use per-node allocation for hardware context */
bool power; /* power on/off the device */
bool memory_backed; /* if data is stored in memory */
+ bool discard; /* if support discard */
};
struct nullb {
@@ -318,6 +319,7 @@
NULLB_DEVICE_ATTR(blocking, bool);
NULLB_DEVICE_ATTR(use_per_node_hctx, bool);
NULLB_DEVICE_ATTR(memory_backed, bool);
+NULLB_DEVICE_ATTR(discard, bool);
static ssize_t nullb_device_power_show(struct config_item *item, char *page)
{
@@ -373,6 +375,7 @@
&nullb_device_attr_use_per_node_hctx,
&nullb_device_attr_power,
&nullb_device_attr_memory_backed,
+ &nullb_device_attr_discard,
NULL,
};
@@ -425,7 +428,7 @@
static ssize_t memb_group_features_show(struct config_item *item, char *page)
{
- return snprintf(page, PAGE_SIZE, "memory_backed\n");
+ return snprintf(page, PAGE_SIZE, "memory_backed,discard\n");
}
CONFIGFS_ATTR_RO(memb_group_, features);
@@ -815,6 +818,20 @@
return 0;
}
+static void null_handle_discard(struct nullb *nullb, sector_t sector, size_t n)
+{
+ size_t temp;
+
+ spin_lock_irq(&nullb->lock);
+ while (n > 0) {
+ temp = min_t(size_t, n, nullb->dev->blocksize);
+ null_free_sector(nullb, sector);
+ sector += temp >> SECTOR_SHIFT;
+ n -= temp;
+ }
+ spin_unlock_irq(&nullb->lock);
+}
+
static int null_transfer(struct nullb *nullb, struct page *page,
unsigned int len, unsigned int off, bool is_write, sector_t sector)
{
@@ -843,6 +860,11 @@
sector = blk_rq_pos(rq);
+ if (req_op(rq) == REQ_OP_DISCARD) {
+ null_handle_discard(nullb, sector, blk_rq_bytes(rq));
+ return 0;
+ }
+
spin_lock_irq(&nullb->lock);
rq_for_each_segment(bvec, rq, iter) {
len = bvec.bv_len;
@@ -871,6 +893,12 @@
sector = bio->bi_iter.bi_sector;
+ if (bio_op(bio) == REQ_OP_DISCARD) {
+ null_handle_discard(nullb, sector,
+ bio_sectors(bio) << SECTOR_SHIFT);
+ return 0;
+ }
+
spin_lock_irq(&nullb->lock);
bio_for_each_segment(bvec, bio, iter) {
len = bvec.bv_len;
@@ -1207,6 +1235,16 @@
dev->nullb = NULL;
}
+static void null_config_discard(struct nullb *nullb)
+{
+ if (nullb->dev->discard == false)
+ return;
+ nullb->q->limits.discard_granularity = nullb->dev->blocksize;
+ nullb->q->limits.discard_alignment = nullb->dev->blocksize;
+ blk_queue_max_discard_sectors(nullb->q, UINT_MAX >> 9);
+ queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, nullb->q);
+}
+
static int null_open(struct block_device *bdev, fmode_t mode)
{
return 0;
@@ -1448,6 +1486,8 @@
blk_queue_logical_block_size(nullb->q, dev->blocksize);
blk_queue_physical_block_size(nullb->q, dev->blocksize);
+ null_config_discard(nullb);
+
sprintf(nullb->disk_name, "nullb%d", nullb->index);
if (dev->use_lightnvm)