linux-kernel - [PATCH] erofs-utils: avoid redundant memcpy and sha256() for dedupe

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Message-ID: <20250815084428.4157034-1-wangzijie1@honor.com>
Date: Fri, 15 Aug 2025 16:44:28 +0800
From: wangzijie <wangzijie1@...or.com>
To: <xiang@...nel.org>
CC: <linux-erofs@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>,
	<bintian.wang@...or.com>, <feng.han@...or.com>, wangzijie
	<wangzijie1@...or.com>
Subject: [PATCH] erofs-utils: avoid redundant memcpy and sha256() for dedupe

We have already use xxh64() for filtering first for dedupe, when we
need to skip the same xxh64 hash, no need to do memcpy and sha256(),
relocate the code to avoid it.

Signed-off-by: wangzijie <wangzijie1@...or.com>
---
 lib/dedupe.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/lib/dedupe.c b/lib/dedupe.c
index 074cae3..bdd890c 100644
--- a/lib/dedupe.c
+++ b/lib/dedupe.c
@@ -162,18 +162,9 @@ int z_erofs_dedupe_insert(struct z_erofs_inmem_extent *e,
 	if (!di)
 		return -ENOMEM;
 
-	di->original_length = e->length;
-	erofs_sha256(original_data, window_size, di->prefix_sha256);
-
 	di->prefix_xxh64 = xxh64(original_data, window_size, 0);
 	di->hash = erofs_rolling_hash_init(original_data,
 			window_size, true);
-	memcpy(di->extra_data, original_data + window_size,
-	       e->length - window_size);
-	di->pstart = e->pstart;
-	di->plen = e->plen;
-	di->partial = e->partial;
-	di->raw = e->raw;
 
 	/* skip the same xxh64 hash */
 	p = &dedupe_tree[di->hash & (ARRAY_SIZE(dedupe_tree) - 1)];
@@ -183,6 +174,15 @@ int z_erofs_dedupe_insert(struct z_erofs_inmem_extent *e,
 			return 0;
 		}
 	}
+
+	di->original_length = e->length;
+	erofs_sha256(original_data, window_size, di->prefix_sha256);
+	memcpy(di->extra_data, original_data + window_size,
+	       e->length - window_size);
+	di->pstart = e->pstart;
+	di->plen = e->plen;
+	di->partial = e->partial;
+	di->raw = e->raw;
 	di->chain = dedupe_subtree;
 	dedupe_subtree = di;
 	list_add_tail(&di->list, p);
-- 
2.25.1