linux-kernel - [PATCH 17/24] dm-snap: simplify the origin_dev == cow_dev check in snapshot

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Message-Id: <20230523074535.249802-18-hch@lst.de>
Date:   Tue, 23 May 2023 09:45:28 +0200
From:   Christoph Hellwig <hch@....de>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Mike Snitzer <snitzer@...nel.org>,
        Joern Engel <joern@...ybastard.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Pavel Machek <pavel@....cz>, dm-devel@...hat.com,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        linux-mtd@...ts.infradead.org, linux-pm@...r.kernel.org
Subject: [PATCH 17/24] dm-snap: simplify the origin_dev == cow_dev check in snapshot_ctr

Use the block_device acquired in dm_get_device for the check instead
of doing an extra lookup.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 drivers/md/dm-snap.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 9c49f53760d066..7832974b73eb03 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1241,7 +1241,6 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	int i;
 	int r = -EINVAL;
 	char *origin_path, *cow_path;
-	dev_t origin_dev, cow_dev;
 	unsigned int args_used, num_flush_bios = 1;
 	fmode_t origin_mode = FMODE_READ;
 
@@ -1279,24 +1278,21 @@ static int snapshot_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		ti->error = "Cannot get origin device";
 		goto bad_origin;
 	}
-	origin_dev = s->origin->bdev->bd_dev;
 
 	cow_path = argv[0];
 	argv++;
 	argc--;
 
-	cow_dev = dm_get_dev_t(cow_path);
-	if (cow_dev && cow_dev == origin_dev) {
-		ti->error = "COW device cannot be the same as origin device";
-		r = -EINVAL;
-		goto bad_cow;
-	}
-
 	r = dm_get_device(ti, cow_path, dm_table_get_mode(ti->table), &s->cow);
 	if (r) {
 		ti->error = "Cannot get COW device";
 		goto bad_cow;
 	}
+	if (s->cow->bdev && s->cow->bdev == s->origin->bdev) {
+		ti->error = "COW device cannot be the same as origin device";
+		r = -EINVAL;
+		goto bad_store;
+	}
 
 	r = dm_exception_store_create(ti, argc, argv, s, &args_used, &s->store);
 	if (r) {
-- 
2.39.2