btree: simplify merge logic by using btree_last() return value

Previously btree_merge() called btree_last() only to test existence, then
performed an extra btree_lookup() to fetch the value.  This patch changes
it to directly use the value returned by btree_last(), avoiding redundant
lookups and simplifying the merge loop.

Link: https://lkml.kernel.org/r/20250826161741.686704-1-409411716@gms.tku.edu.tw
Signed-off-by: Guan-Chun Wu <409411716@gms.tku.edu.tw>
Cc: Kuan-Wei Chiu <visitorckw@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/lib/btree.c b/lib/btree.c
index bb81d3393ac5c52cd2a80e2712380e6dfe8b8e47..9c80c0c7bba856ca03e8816a3b6827bb2717ac6f 100644 (file)
--- a/lib/btree.c
+++ b/lib/btree.c
@@ -653,9 +653,9 @@ int btree_merge(struct btree_head *target, struct btree_head *victim,
         * walks to remove a single object from the victim.
         */
        for (;;) {
-               if (!btree_last(victim, geo, key))
+               val = btree_last(victim, geo, key);
+               if (!val)
                        break;
-               val = btree_lookup(victim, geo, key);
                err = btree_insert(target, geo, key, val, gfp);
                if (err)
                        return err;