From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A2E22C43334 for ; Mon, 6 Jun 2022 09:36:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232895AbiFFJgh (ORCPT ); Mon, 6 Jun 2022 05:36:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46020 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232859AbiFFJgd (ORCPT ); Mon, 6 Jun 2022 05:36:33 -0400 Received: from mail-m2836.qiye.163.com (mail-m2836.qiye.163.com [103.74.28.36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A749B1BF166 for ; Mon, 6 Jun 2022 02:36:32 -0700 (PDT) Received: from [192.168.0.234] (unknown [218.94.118.90]) by mail-m2836.qiye.163.com (Hmail) with ESMTPA id BB2BEC02A1; Mon, 6 Jun 2022 17:36:29 +0800 (CST) Message-ID: <34d760d4-9d1b-7ec0-af90-3c8777fbe971@easystack.cn> Date: Mon, 6 Jun 2022 17:36:24 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH] bcache: try to reuse the slot of invalid_uuid Content-Language: en-US To: Coly Li Cc: linux-bcache@vger.kernel.org, dongsheng.yang@easystack.cn, zoumingzhe@qq.com References: <20220606084522.12680-1-mingzhe.zou@easystack.cn> <780B6E6E-F4A8-4801-AED3-8DF81054D491@suse.de> From: Zou Mingzhe In-Reply-To: <780B6E6E-F4A8-4801-AED3-8DF81054D491@suse.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-HM-Spam-Status: e1kfGhgUHx5ZQUtXWQgPGg8OCBgUHx5ZQUlOS1dZCBgUCR5ZQVlLVUtZV1 kWDxoPAgseWUFZKDYvK1lXWShZQUlCN1dZLVlBSVdZDwkaFQgSH1lBWUNCTk1WHU9JQ0xDTxpPTk JJVRkRExYaEhckFA4PWVdZFhoPEhUdFFlBWU9LSFVKSktITkhVS1kG X-HM-Sender-Digest: e1kMHhlZQR0aFwgeV1kSHx4VD1lBWUc6OFE6Nww6MDIVUSkJLRIzEEsB Vg4KCRFVSlVKTU5PTktDSkJLSElIVTMWGhIXVRYSFRwBEx5VARQOOx4aCAIIDxoYEFUYFUVZV1kS C1lBWUlKQ1VCT1VKSkNVQktZV1kIAVlBTktOTTcG X-HM-Tid: 0a81385f78c9841ekuqwbb2bec02a1 Precedence: bulk List-ID: X-Mailing-List: linux-bcache@vger.kernel.org 在 2022/6/6 16:57, Coly Li 写道: > >> 2022年6月6日 16:45，mingzhe.zou@easystack.cn 写道： >> >> From: mingzhe >> >> > [snipped] > >> We want to use those invalid_uuid slots carefully. Because, the bkey of the inode >> may still exist in the btree. So, we need to check the btree before reuse it. >> >> Signed-off-by: mingzhe >> --- >> drivers/md/bcache/btree.c | 35 +++++++++++++++++++++++++++++++++++ >> drivers/md/bcache/btree.h | 1 + >> drivers/md/bcache/super.c | 15 ++++++++++++++- >> 3 files changed, 50 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c >> index e136d6edc1ed..a5d54af73111 100644 >> --- a/drivers/md/bcache/btree.c >> +++ b/drivers/md/bcache/btree.c >> @@ -2755,6 +2755,41 @@ struct keybuf_key *bch_keybuf_next_rescan(struct cache_set *c, >> return ret; >> } >> >> +static bool check_pred(struct keybuf *buf, struct bkey *k) >> +{ >> + return true; >> +} >> + >> +bool bch_btree_can_inode_reuse(struct cache_set *c, size_t inode) >> +{ >> + bool ret = true; >> + struct keybuf_key *k; >> + struct bkey end_key = KEY(inode, MAX_KEY_OFFSET, 0); >> + struct keybuf *keys = kzalloc(sizeof(struct keybuf), GFP_KERNEL); >> + >> + if (!keys) { >> + ret = false; >> + goto out; >> + } >> + >> + bch_keybuf_init(keys); >> + keys->last_scanned = KEY(inode, 0, 0); >> + >> + while (ret) { >> + k = bch_keybuf_next_rescan(c, keys, &end_key, check_pred); >> + if (!k) > > This is a single thread iteration, for a large filled cache device it can be very slow. I observed 40+ minutes during my testing. > > > Coly Li > Hi, Coly We first use the zero_uuid slot, and reuse only if there is no zero_uuid slot. This is just an imperfect solution to make bcache available, so we haven't tested its performance. We think we will eventually need to actively clean up these bkeys in a new thread and reset the invalid_uuid to zero_uuid. mingzhe > >> + break; >> + >> + if (KEY_INODE(&k->key) == inode) >> + ret = false; >> + bch_keybuf_del(keys, k); >> + } >> + >> + kfree(keys); >> +out: >> + return ret; >> +} >> + >> void bch_keybuf_init(struct keybuf *buf) >> { >> buf->last_scanned = MAX_KEY; >> diff --git a/drivers/md/bcache/btree.h b/drivers/md/bcache/btree.h >> index 1b5fdbc0d83e..c3e6094adb62 100644 >> --- a/drivers/md/bcache/btree.h >> +++ b/drivers/md/bcache/btree.h >> @@ -413,4 +413,5 @@ struct keybuf_key *bch_keybuf_next_rescan(struct cache_set *c, >> struct bkey *end, >> keybuf_pred_fn *pred); >> void bch_update_bucket_in_use(struct cache_set *c, struct gc_stat *stats); >> +bool bch_btree_can_inode_reuse(struct cache_set *c, size_t inode); >> #endif >> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c >> index 3563d15dbaf2..31f7aa347561 100644 >> --- a/drivers/md/bcache/super.c >> +++ b/drivers/md/bcache/super.c >> @@ -544,11 +544,24 @@ static struct uuid_entry *uuid_find(struct cache_set *c, const char *uuid) >> return NULL; >> } >> >> +static struct uuid_entry *uuid_find_reuse(struct cache_set *c) >> +{ >> + struct uuid_entry *u; >> + >> + for (u = c->uuids; u < c->uuids + c->nr_uuids; u++) >> + if (!memcmp(u->uuid, invalid_uuid, 16) && >> + bch_btree_can_inode_reuse(c, u - c->uuids)) >> + return u; >> + >> + return NULL; >> +} >> + >> static struct uuid_entry *uuid_find_empty(struct cache_set *c) >> { >> static const char zero_uuid[16] = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"; >> + struct uuid_entry *u = uuid_find(c, zero_uuid); >> >> - return uuid_find(c, zero_uuid); >> + return u ? u : uuid_find_reuse(c); >> } >> >> /* >> -- >> 2.17.1 >> >