linux-kernel - [PATCH 1/2] dm cache: drop redundant origin size check

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Message-ID: <20251210031757.66037-1-me@linux.beauty>
Date: Wed, 10 Dec 2025 11:17:56 +0800
From: Li Chen <me@...ux.beauty>
To: Alasdair Kergon <agk@...hat.com>,
	Mike Snitzer <snitzer@...nel.org>,
	Mikulas Patocka <mpatocka@...hat.com>,
	dm-devel@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Cc: Li Chen <me@...ux.beauty>
Subject: [PATCH 1/2] dm cache: drop redundant origin size check

The cache target already exposes the origin device through
cache_iterate_devices(), which allows dm-table to call
device_area_is_invalid() and verify that the mapping fits inside the
underlying block device.

The explicit ti->len > origin_sectors test in parse_origin_dev() is
therefore redundant. Drop this check and rely on the core device
validation instead. This changes the user-visible error string when the
origin is too small, but preserves the failure behaviour.

Signed-off-by: Li Chen <me@...ux.beauty>
---
 drivers/md/dm-cache-target.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index a10d75a562db..350a0aa53365 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -2099,7 +2099,6 @@ static int parse_cache_dev(struct cache_args *ca, struct dm_arg_set *as,
 static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as,
 			    char **error)
 {
-	sector_t origin_sectors;
 	int r;
 
 	if (!at_least_one_arg(as, error))
@@ -2112,12 +2111,6 @@ static int parse_origin_dev(struct cache_args *ca, struct dm_arg_set *as,
 		return r;
 	}
 
-	origin_sectors = get_dev_size(ca->origin_dev);
-	if (ca->ti->len > origin_sectors) {
-		*error = "Device size larger than cached device";
-		return -EINVAL;
-	}
-
 	return 0;
 }
 
-- 
2.51.0