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From: Christoph Hellwig <hch@lst.de>
Date: Tue, 5 Sep 2023 14:47:31 +0200
Subject: [PATCH] block: fix pin count management when merging same-page
 segments
Git-commit: 5905afc2c7bb713d52c7c7585565feecbb686b44
Patch-mainline: v6.6-rc1
References: bsc#1216436

There is no need to unpin the added page when adding it to the bio fails
as that is done by the loop below.  Instead we want to unpin it when adding
a single page to the bio more than once as bio_release_pages will only
unpin it once.

Fixes: d1916c86ccdc ("block: move same page handling from __bio_add_pc_page to the callers")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20230905124731.328255-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
 block/blk-map.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/block/blk-map.c b/block/blk-map.c
index 44d74a30ddac..8584babf3ea0 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -315,12 +315,11 @@ static int bio_map_user_iov(struct request *rq, struct iov_iter *iter,
 					n = bytes;
 
 				if (!bio_add_hw_page(rq->q, bio, page, n, offs,
-						     max_sectors, &same_page)) {
-					if (same_page)
-						bio_release_page(bio, page);
+						     max_sectors, &same_page))
 					break;
-				}
 
+				if (same_page)
+					bio_release_page(bio, page);
 				bytes -= n;
 				offs = 0;
 			}
-- 
2.35.3