From: Christoph Hellwig <hch@lst.de>
Date: Tue, 14 Apr 2026 08:17:46 +0000 (+0200)
Subject: zloop: fix write pointer calculation in zloop_forget_cache
X-Git-Tag: v7.1-rc1~10^2~20
X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=32be3c01c3b8e948a4326ab7e76c1c63dd3e27bc;p=thirdparty%2Fkernel%2Flinux.git

zloop: fix write pointer calculation in zloop_forget_cache

The write pointer is absolute and in sector units, so we need to
convert it to a relative byte address first.

Fixes: c505448748f7 ("zloop: forget write cache on force removal")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://patch.msgid.link/20260414081811.549755-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/drivers/block/zloop.c b/drivers/block/zloop.c
index 8baf642037fd8..672948d3653e3 100644
--- a/drivers/block/zloop.c
+++ b/drivers/block/zloop.c
@@ -1401,8 +1401,17 @@ static void zloop_forget_cache(struct zloop_device *zlo)
 				zlo->disk->part0, ret);
 			continue;
 		}
-		if (old_wp < zone->wp)
-			zloop_truncate(file, old_wp);
+
+		if (old_wp > zone->wp)
+			continue;
+		/*
+		 * This should not happen, if we recored a full zone, it can't
+		 * be active.
+		 */
+		if (WARN_ON_ONCE(old_wp == ULLONG_MAX))
+			continue;
+
+		zloop_truncate(file, (old_wp - zone->start) << SECTOR_SHIFT);
 	}
 }