[dm-devel] [PATCH 1/2] dm snapshot: remove usage of list iterator for list_add() after the loop body
Jakob Koschel
jakobkoschel at gmail.com
Thu Mar 31 22:02:35 UTC 2022
In preparation to limit the scope of a list iterator to the list
traversal loop, use a dedicated pointer to point to the found element
[1].
Before, the code implicitly used the head when no element was found
when using &pos->list. Since the new variable is only set if an
element was found, the list_add() is performed within the loop
and only done after the loop if it is done on the list head directly.
Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <jakobkoschel at gmail.com>
---
drivers/md/dm-snap.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index 0d336b5ec571..23386a6e67e7 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -528,13 +528,17 @@ static int __validate_exception_handover(struct dm_snapshot *snap)
static void __insert_snapshot(struct origin *o, struct dm_snapshot *s)
{
- struct dm_snapshot *l;
+ struct dm_snapshot *l = NULL, *iter;
/* Sort the list according to chunk size, largest-first smallest-last */
- list_for_each_entry(l, &o->snapshots, list)
- if (l->store->chunk_size < s->store->chunk_size)
+ list_for_each_entry(iter, &o->snapshots, list)
+ if (iter->store->chunk_size < s->store->chunk_size) {
+ l = iter;
+ list_add_tail(&s->list, &iter->list);
break;
- list_add_tail(&s->list, &l->list);
+ }
+ if (!l)
+ list_add_tail(&s->list, &o->snapshots);
}
/*
base-commit: f82da161ea75dc4db21b2499e4b1facd36dab275
--
2.25.1
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