dm log writes: fix >512b sectorsize support

512b sectors vs device's physical sectorsize was not maintained
consistently and as such the support for >512b sector devices has bugs.
The log metadata expects native sectorsize but 512b sectors were being
stored. Also, device's sectorsize was assumed when assigning the
bi_sector for blocks that were being logged.

Fix this up by adding two helpers to convert between bio and dev
sectors, and use these in the appropriate places to fix the problem and
make it clear which units go where. Doing so allows dm-log-writes use
with 4k devices.

Signed-off-by: Josef Bacik <[e-mail]>
Signed-off-by: Mike Snitzer <[e-mail]>

drivers/md/dm-log-writes.c

···
 	struct dm_dev *logdev;
 	u64 logged_entries;
 	u32 sectorsize;
+	u32 sectorshift;
 	atomic_t io_blocks;
 	atomic_t pending_blocks;
 	sector_t next_sector;
···
 struct per_bio_data {
 	struct pending_block *block;
 };
+
+static inline sector_t bio_to_dev_sectors(struct log_writes_c *lc,
+					  sector_t sectors)
+{
+	return sectors >> (lc->sectorshift - SECTOR_SHIFT);
+}
+
+static inline sector_t dev_to_bio_sectors(struct log_writes_c *lc,
+					  sector_t sectors)
+{
+	return sectors << (lc->sectorshift - SECTOR_SHIFT);
+}
 
 static void put_pending_block(struct log_writes_c *lc)
 {
···
 
 	if (!block->vec_cnt)
 		goto out;
-	sector++;
+	sector += dev_to_bio_sectors(lc, 1);
 
 	atomic_inc(&lc->io_blocks);
 	bio = bio_alloc(GFP_KERNEL, min(block->vec_cnt, BIO_MAX_PAGES));
···
 				goto next;
 
 			sector = lc->next_sector;
-			if (block->flags & LOG_DISCARD_FLAG)
-				lc->next_sector++;
-			else
-				lc->next_sector += block->nr_sectors + 1;
+			if (!(block->flags & LOG_DISCARD_FLAG))
+				lc->next_sector += dev_to_bio_sectors(lc, block->nr_sectors);
+			lc->next_sector += dev_to_bio_sectors(lc, 1);
 
 			/*
 			 * Apparently the size of the device may not be known
···
 	INIT_LIST_HEAD(&lc->unflushed_blocks);
 	INIT_LIST_HEAD(&lc->logging_blocks);
 	init_waitqueue_head(&lc->wait);
-	lc->sectorsize = 1 << SECTOR_SHIFT;
 	atomic_set(&lc->io_blocks, 0);
 	atomic_set(&lc->pending_blocks, 0);
 
···
 		goto bad;
 	}
 
+	lc->sectorsize = bdev_logical_block_size(lc->dev->bdev);
+	lc->sectorshift = ilog2(lc->sectorsize);
 	lc->log_kthread = kthread_run(log_writes_kthread, lc, "log-write");
 	if (IS_ERR(lc->log_kthread)) {
 		ret = PTR_ERR(lc->log_kthread);
···
 		goto bad;
 	}
 
-	/* We put the super at sector 0, start logging at sector 1 */
-	lc->next_sector = 1;
+	/*
+	 * next_sector is in 512b sectors to correspond to what bi_sector expects.
+	 * The super starts at sector 0, and the next_sector is the next logical
+	 * one based on the sectorsize of the device.
+	 */
+	lc->next_sector = lc->sectorsize >> SECTOR_SHIFT;
 	lc->logging_enabled = true;
 	lc->end_sector = logdev_last_sector(lc);
 	lc->device_supports_discard = true;
···
 	if (discard_bio)
 		block->flags |= LOG_DISCARD_FLAG;
 
-	block->sector = bio->bi_iter.bi_sector;
-	block->nr_sectors = bio_sectors(bio);
+	block->sector = bio_to_dev_sectors(lc, bio->bi_iter.bi_sector);
+	block->nr_sectors = bio_to_dev_sectors(lc, bio_sectors(bio));
 
 	/* We don't need the data, just submit */
 	if (discard_bio) {
···
 
 	if (!q || !blk_queue_discard(q)) {
 		lc->device_supports_discard = false;
-		limits->discard_granularity = 1 << SECTOR_SHIFT;
+		limits->discard_granularity = lc->sectorsize;
 		limits->max_discard_sectors = (UINT_MAX >> SECTOR_SHIFT);
 	}
+	limits->logical_block_size = bdev_logical_block_size(lc->dev->bdev);
+	limits->physical_block_size = bdev_physical_block_size(lc->dev->bdev);
+	limits->io_min = limits->physical_block_size;
 }
 
 static struct target_type log_writes_target = {