linux-kernel - [PATCH v4 12/13] dm snapshot: redirect accesses to origin if merging snap invalidated

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1258748873-24185-13-git-send-email-snitzer@redhat.com>
Date:	Fri, 20 Nov 2009 15:27:52 -0500
From:	Mike Snitzer <snitzer@...hat.com>
To:	dm-devel@...hat.com
Cc:	linux-kernel@...r.kernel.org, Mikulas Patocka <mpatocka@...hat.com>
Subject: [PATCH v4 12/13] dm snapshot: redirect accesses to origin if merging snap invalidated

From: Mikulas Patocka <mpatocka@...hat.com>

If we are merging an invalidated snapshot, redirect all accesses to the
origin device.  This is safe because snapshot_merge_process() will
stop_merge() if the merging snapshot becomes invalid.

Allowing the origin device to remain functional is important because it
may contain the root filesystem.

Signed-off-by: Mikulas Patocka <mpatocka@...hat.com>
Reviewed-by: Mike Snitzer <snitzer@...hat.com>
---
 drivers/md/dm-snap.c |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 2b5b083..74f7f38 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -1554,11 +1554,9 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio,
 
 	down_write(&s->lock);
 
-	/* Full snapshots are not usable */
-	if (!s->valid) {
-		r = -EIO;
-		goto out_unlock;
-	}
+	/* Full merging snapshots are redirected to the origin */
+	if (!s->valid)
+		goto redirect_to_origin;
 
 	/* If the block is already remapped - use that */
 	e = dm_lookup_exception(&s->complete, chunk);
@@ -1581,6 +1579,7 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio,
 		goto out_unlock;
 	}
 
+ redirect_to_origin:
 	bio->bi_bdev = s->origin->bdev;
 
 	if (bio_rw(bio) == WRITE) {
-- 
1.6.5.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/