zram: move discard handling to zram_submit_bio

Switch on the bio operation in zram_submit_bio and only call into
__zram_make_request for read and write operations.

Link: https://lkml.kernel.org/r/20230411171459.567614-6-hch@lst.deSigned-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

drivers/block/zram/zram_drv.c

@@ -1958,15 +1958,6 @@ static void __zram_make_request(struct zram *zram, struct bio *bio)
 	struct bio_vec bv;
 	unsigned long start_time;
 
-	switch (bio_op(bio)) {
-	case REQ_OP_DISCARD:
-	case REQ_OP_WRITE_ZEROES:
-		zram_bio_discard(zram, bio);
-		return;
-	default:
-		break;
-	}
-
 	start_time = bio_start_io_acct(bio);
 	bio_for_each_segment(bv, bio, iter) {
 		u32 index = iter.bi_sector >> SECTORS_PER_PAGE_SHIFT;
@@ -1990,7 +1981,19 @@ static void zram_submit_bio(struct bio *bio)
 {
 	struct zram *zram = bio->bi_bdev->bd_disk->private_data;
 
-	__zram_make_request(zram, bio);
+	switch (bio_op(bio)) {
+	case REQ_OP_READ:
+	case REQ_OP_WRITE:
+		__zram_make_request(zram, bio);
+		break;
+	case REQ_OP_DISCARD:
+	case REQ_OP_WRITE_ZEROES:
+		zram_bio_discard(zram, bio);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		bio_endio(bio);
+	}
 }
 
 static void zram_slot_free_notify(struct block_device *bdev,