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 A07C8C433EF for ; Tue, 10 May 2022 08:52:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238256AbiEJI4R (ORCPT ); Tue, 10 May 2022 04:56:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59830 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238279AbiEJI4E (ORCPT ); Tue, 10 May 2022 04:56:04 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0CEB415A3C7 for ; Tue, 10 May 2022 01:52:08 -0700 (PDT) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id BDB2D1FA34; Tue, 10 May 2022 08:52:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1652172726; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZuV0rubJcUw+nT779qgTrdrZggFZiG5i6+LwKZvq2T0=; b=bWcBFcgjyk/ZXw5DkeCChrHRlrqDlxhUuL1D+vSlSTnUj2U2QyrbFZi6JsBuT2vkhEnjgh Jooc+ONhN4cSjtrFeTaNWjdr96uMsiD6YDa634gyl+t1wLbFUKK+nNQ/W8Ff0eoiqVtyhr /tRDH8UAxuDD6b+08eiOdiCJqqexBsM= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 94CF013AA5; Tue, 10 May 2022 08:52:06 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id jNmxIbYnemIzHwAAMHmgww (envelope-from ); Tue, 10 May 2022 08:52:06 +0000 Message-ID: Date: Tue, 10 May 2022 11:52:06 +0300 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] btrfs: do not account twice for inode ref when reserving metadata units Content-Language: en-US To: fdmanana@kernel.org, linux-btrfs@vger.kernel.org References: From: Nikolay Borisov In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 9.05.22 г. 18:29 ч., fdmanana@kernel.org wrote: > From: Filipe Manana > > When reserving metadata units for creating an inode, we don't need to > reserve one extra unit for the inode ref item because when creating the > inode, at btrfs_create_new_inode(), we always insert the inode item and > the inode ref item in a single batch (a single btree insert operation, > and both ending up in the same leaf). > > As we have accounted already one unit for the inode item, the extra unit > for the inode ref item is superfluous, it only makes us reserve more > metadata than necessary and often adding more reclaim pressure if we are > low on available metadata space. > > Signed-off-by: Filipe Manana That's a neat little optimisation. Reviewed-by: Nikolay Borisov > --- > fs/btrfs/inode.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index b42d6e7e4049..adc8b684fe31 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -6138,12 +6138,15 @@ int btrfs_new_inode_prepare(struct btrfs_new_inode_args *args, > (*trans_num_items)++; > } else { > /* > - * 1 to add inode ref > * 1 to add dir item > * 1 to add dir index > * 1 to update parent inode item > + * > + * No need for 1 unit for the inode ref item because it is > + * inserted in a batch together with the inode item at > + * btrfs_create_new_inode(). > */ > - *trans_num_items += 4; > + *trans_num_items += 3; > } > return 0; > }