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 X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6A42BC47080 for ; Mon, 31 May 2021 12:55:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3A174610E7 for ; Mon, 31 May 2021 12:55:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231397AbhEaM4r (ORCPT ); Mon, 31 May 2021 08:56:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51300 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231370AbhEaM4r (ORCPT ); Mon, 31 May 2021 08:56:47 -0400 Received: from mail-pf1-x42a.google.com (mail-pf1-x42a.google.com [IPv6:2607:f8b0:4864:20::42a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99A0FC061574 for ; Mon, 31 May 2021 05:55:07 -0700 (PDT) Received: by mail-pf1-x42a.google.com with SMTP id c12so8973749pfl.3 for ; Mon, 31 May 2021 05:55:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=references:user-agent:from:to:cc:subject:in-reply-to:date :message-id:mime-version; bh=1kOa/InqQOhomoTltkOMpNUhz9d+d0cHta9R3KebJIg=; b=uzjMEqpwsBh0ar/rkdGE0zlEThVHzKjks5dsqZxyxe+41aQEqFw82rRBRW4HuR4DcK fop2IH929Wvr0xuwu8USbrkdk34eq9vYvJcXlxo5ycarADi4cz79DgaS6H6d+L04szC9 SIFvdWlFgu1/UiZHRCndk799nsAZj5jjLqsThrqFLU5LNl++k8M6tKa1ShQRJA0bvnKg 9bu72fYA5odenq0XxO8L++IMWzlHPiCpez6LxCZJU4O1571Q+JqdnEA7iekds6Fag2dS 2RDLERGd+JdGoull2ePh9cuyCV9F1YgkfL3pXM5Bbo/qBC39LH6NI7GP1bPNVnD0hW8Y HKGA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:references:user-agent:from:to:cc:subject :in-reply-to:date:message-id:mime-version; bh=1kOa/InqQOhomoTltkOMpNUhz9d+d0cHta9R3KebJIg=; b=kJmgXIg5iDlSUAKdRhzOOmDMka6T5Bwtp+xhlLTuc6zF2QI8cAlxu4F5eQByT98nrx eZMiS4ddqMJ6TauBhYZFHhuirPoSKvdrNT8SwZg3r1bPq8+9XFuAVRnMqAcq9XgCvUkB SvDjVhw1O2z9y/Qw94TaqBijZmjRE7BNaImhtsVSFBNzK6GzYzOXfh9YEq3uFVn0wQIF GvYPol3bQwN3y4fVfRim3UlULnSv5l0Lk+b5CscKHXXZ51B0btFUSzsAxA38Fdm3zljZ bfXz7XpE7MuJ6jHruHkJRV7TJjC+GSBJ3hSA5GO01F9TOkDZxpvBa+TtIlZWccTyAKLm 0yrw== X-Gm-Message-State: AOAM531S4DhYv0X//Ao0bGTROabWdg1J0l7HFN4Ow5xZ5138cut/Jos6 O4W7uzV/Onj8+lbIsAHeoNrhtHil1MTicA== X-Google-Smtp-Source: ABdhPJxxxjxB79j7ISSXyV9FbAwgGLViujLtsMql8rgSIFUCjtlSSN5IJIN6Dd70SsJDtp8Hmlz9sg== X-Received: by 2002:a05:6a00:16cd:b029:2d0:d876:4707 with SMTP id l13-20020a056a0016cdb02902d0d8764707mr17324425pfc.64.1622465706844; Mon, 31 May 2021 05:55:06 -0700 (PDT) Received: from garuda ([122.171.220.253]) by smtp.gmail.com with ESMTPSA id s48sm10861269pfw.205.2021.05.31.05.55.05 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Mon, 31 May 2021 05:55:06 -0700 (PDT) References: <20210527045202.1155628-1-david@fromorbit.com> <20210527045202.1155628-4-david@fromorbit.com> User-agent: mu4e 1.0; emacs 26.1 From: Chandan Babu R To: Dave Chinner Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH 3/6] xfs: xfs_itruncate_extents has no extent count limitation In-reply-to: <20210527045202.1155628-4-david@fromorbit.com> Date: Mon, 31 May 2021 18:25:03 +0530 Message-ID: <87eednukpk.fsf@garuda> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On 27 May 2021 at 10:21, Dave Chinner wrote: > From: Dave Chinner > > Ever since we moved to freeing of extents by deferred operations, > we've already freed extents via individual transactions. Hence the > only limitation of how many extents we can mark for freeing in a > single xfs_bunmapi() call bound only by how many deferrals we want > to queue. > > That is xfs_bunmapi() doesn't actually do any AG based extent > freeing, so there's no actually transaction reservation used up by > calling bunmapi with a large count of extents to be freed. RT > extents have always been freed directly by bunmapi, but that doesn't > require modification of large number of blocks as there are no > btrees to split. > > Some callers of xfs_bunmapi assume that the extent count being freed > is bound by geometry (e.g. directories) and these can ask bunmapi to > free up to 64 extents in a single call. These functions just work as > tehy stand, so there's no reason for truncate to have a limit of > just two extents per bunmapi call anymore. > > Increase XFS_ITRUNC_MAX_EXTENTS to 64 to match the number of extents > that can be deferred in a single loop to match what the directory > code already uses. > > For realtime inodes, where xfs_bunmapi() directly frees extents, > leave the limit at 2 extents per loop as this is all the space that > the transaction reservation will cover. > > Signed-off-by: Dave Chinner > --- > fs/xfs/xfs_inode.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c > index 0369eb22c1bb..db220eaa34b8 100644 > --- a/fs/xfs/xfs_inode.c > +++ b/fs/xfs/xfs_inode.c > @@ -40,9 +40,18 @@ kmem_zone_t *xfs_inode_zone; > > /* > * Used in xfs_itruncate_extents(). This is the maximum number of extents > - * freed from a file in a single transaction. > + * we will unmap and defer for freeing in a single call to xfs_bunmapi(). > + * Realtime inodes directly free extents in xfs_bunmapi(), so are bound > + * by transaction reservation size to 2 extents. > */ > -#define XFS_ITRUNC_MAX_EXTENTS 2 > +static inline int > +xfs_itrunc_max_extents( > + struct xfs_inode *ip) > +{ > + if (XFS_IS_REALTIME_INODE(ip)) > + return 2; > + return 64; > +} > > STATIC int xfs_iunlink(struct xfs_trans *, struct xfs_inode *); > STATIC int xfs_iunlink_remove(struct xfs_trans *, struct xfs_inode *); > @@ -1402,7 +1411,7 @@ xfs_itruncate_extents_flags( > while (unmap_len > 0) { > ASSERT(tp->t_firstblock == NULLFSBLOCK); > error = __xfs_bunmapi(tp, ip, first_unmap_block, &unmap_len, > - flags, XFS_ITRUNC_MAX_EXTENTS); > + flags, xfs_itrunc_max_extents(ip)); > if (error) > goto out; The list of free extent items at xfs_defer_pending->dfp_work could now contain XFS_EFI_MAX_FAST_EXTENTS (i.e. 16) entries in the worst case. For a single transaction, xfs_calc_itruncate_reservation() reserves space for logging only 4 extents (i.e. 4 exts * 2 trees * (2 * max depth - 1) * block size). But with the above change, a single transaction can now free upto 16 extents. Wouldn't this overflow the reserved log space? -- chandan