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From:   Wang Shilong <wangshilong1991@gmail.com>
To:     linux-ext4@vger.kernel.org
Cc:     lixi@ddn.com, adilger@dilger.ca, sihara@ddn.com,
        Wang Shilong <wshilong@ddn.com>
Subject: [RFC PATCH 28/46] e2fsck: make threads splitting aware of flex_bg
Date:   Wed,  8 Apr 2020 19:44:56 +0900
Message-Id: <1586342714-12536-29-git-send-email-wangshilong1991@gmail.com>
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From: Wang Shilong <wshilong@ddn.com>

Flex_bg might be enabled, if this is enabled it makes
more sense to split based on this.

Signed-off-by: Wang Shilong <wshilong@ddn.com>
---
 e2fsck/pass1.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index 6789b701..0044d7e8 100644
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -2854,6 +2854,23 @@ static void e2fsck_pass1_multithread(e2fsck_t global_ctx)
 	struct e2fsck_thread_info	*infos = NULL;
 	int				 num_threads = 1;
 	errcode_t			 retval;
+	unsigned flexbg_size = 1;
+	int max_threads;
+
+	if (ext2fs_has_feature_flex_bg(global_ctx->fs->super))
+		flexbg_size = 1 << global_ctx->fs->super->s_log_groups_per_flex;
+
+	max_threads = global_ctx->fs->group_desc_count / flexbg_size;
+	if (max_threads == 0)
+		num_threads = 1;
+	else if (max_threads % num_threads) {
+		int times = max_threads / num_threads;
+
+		if (times == 0)
+			num_threads = 1;
+		else
+			num_threads = max_threads / times;
+	}
 
 	init_ext2_max_sizes();
 	retval = e2fsck_pass1_threads_start(&infos, num_threads, global_ctx);
-- 
2.25.2