From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Date: Tue, 12 May 2020 17:55:48 +0900
Subject: [PATCH] block: introduce blk_req_zone_write_trylock
References: bsc#1175995,jsc#SLE-15608
Git-commit: 1392d37018d4f68c5bb2c98dae9a018b73926865
Patch-mainline: v5.8-rc1

Introduce blk_req_zone_write_trylock(), which either grabs the write-lock
for a sequential zone or returns false, if the zone is already locked.

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
 block/blk-zoned.c      | 14 ++++++++++++++
 include/linux/blkdev.h |  1 +
 2 files changed, 15 insertions(+)

diff --git a/block/blk-zoned.c b/block/blk-zoned.c
index 59892bbc2252..5faada6518dc 100644
--- a/block/blk-zoned.c
+++ b/block/blk-zoned.c
@@ -82,6 +82,20 @@ bool blk_req_needs_zone_write_lock(struct request *rq)
 }
 EXPORT_SYMBOL_GPL(blk_req_needs_zone_write_lock);
 
+bool blk_req_zone_write_trylock(struct request *rq)
+{
+	unsigned int zno = blk_rq_zone_no(rq);
+
+	if (test_and_set_bit(zno, rq->q->seq_zones_wlock))
+		return false;
+
+	WARN_ON_ONCE(rq->rq_flags & RQF_ZONE_WRITE_LOCKED);
+	rq->rq_flags |= RQF_ZONE_WRITE_LOCKED;
+
+	return true;
+}
+EXPORT_SYMBOL_GPL(blk_req_zone_write_trylock);
+
 void __blk_req_zone_write_lock(struct request *rq)
 {
 	if (WARN_ON_ONCE(test_and_set_bit(blk_rq_zone_no(rq),
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 8d4d6df5bb93..053829d76ecc 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1744,6 +1744,7 @@ extern int bdev_write_page(struct block_device *, sector_t, struct page *,
 
 #ifdef CONFIG_BLK_DEV_ZONED
 bool blk_req_needs_zone_write_lock(struct request *rq);
+bool blk_req_zone_write_trylock(struct request *rq);
 void __blk_req_zone_write_lock(struct request *rq);
 void __blk_req_zone_write_unlock(struct request *rq);
 
-- 
2.16.4