[PATCH] device-mapper snapshots: Handle origin extension

Handle writes to a snapshot-origin device that has been extended since the
snapshot was taken.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 5 insertions, 0 deletions

diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 594d1f6b4789..ab54f99b7c3b 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -931,6 +931,10 @@ static int __origin_write(struct list_head *snapshots, struct bio *bio)
                 if (!snap->valid)
                         continue;
 
+                /* Nothing to do if writing beyond end of snapshot */
+                if (bio->bi_sector >= dm_table_get_size(snap->table))
+                        continue;
+
                 down_write(&snap->lock);
 
                 /*
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 18e9b9953fcd..a5a4c0ed8a14 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -943,6 +943,7 @@ EXPORT_SYMBOL(dm_vcalloc);
 EXPORT_SYMBOL(dm_get_device);
 EXPORT_SYMBOL(dm_put_device);
 EXPORT_SYMBOL(dm_table_event);
+EXPORT_SYMBOL(dm_table_get_size);
 EXPORT_SYMBOL(dm_table_get_mode);
 EXPORT_SYMBOL(dm_table_put);
 EXPORT_SYMBOL(dm_table_get);