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=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 F1DDEC433E0 for ; Tue, 22 Dec 2020 17:21:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C062423130 for ; Tue, 22 Dec 2020 17:21:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727486AbgLVRVx (ORCPT ); Tue, 22 Dec 2020 12:21:53 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:49097 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727384AbgLVRVx (ORCPT ); Tue, 22 Dec 2020 12:21:53 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1608657626; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=LpPlT8dsacUm/spVyjHCrHUF3o7AFxaTtYJuAxdvEBg=; b=cYmh0t7GWn5/Z41qM2w2PkChB5Ve477geTtfWyjIQIz/T2kYIT3BPmHsowWBHfsQNq9Ley R+yZmpB7GAr3JVQKzMYmnj6iuxzNSgv1FiJfOK32NXGZ4+hJYCwDEkrBHK4WelxjYG2VBG nCn80lMpwMGE2QPhBeq4OfgPmYDRzZg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-192-8bQwnas9NW-9UEU4hzhwlg-1; Tue, 22 Dec 2020 12:20:24 -0500 X-MC-Unique: 8bQwnas9NW-9UEU4hzhwlg-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 31C3C801817; Tue, 22 Dec 2020 17:20:23 +0000 (UTC) Received: from bfoster (ovpn-112-184.rdu2.redhat.com [10.10.112.184]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CA39410013C1; Tue, 22 Dec 2020 17:20:22 +0000 (UTC) Date: Tue, 22 Dec 2020 12:20:20 -0500 From: Brian Foster To: Allison Henderson Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH v14 04/15] xfs: Add delay ready attr remove routines Message-ID: <20201222172020.GD2808393@bfoster> References: <20201218072917.16805-1-allison.henderson@oracle.com> <20201218072917.16805-5-allison.henderson@oracle.com> <20201222171148.GC2808393@bfoster> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201222171148.GC2808393@bfoster> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Tue, Dec 22, 2020 at 12:11:48PM -0500, Brian Foster wrote: > On Fri, Dec 18, 2020 at 12:29:06AM -0700, Allison Henderson wrote: > > This patch modifies the attr remove routines to be delay ready. This > > means they no longer roll or commit transactions, but instead return > > -EAGAIN to have the calling routine roll and refresh the transaction. In > > this series, xfs_attr_remove_args has become xfs_attr_remove_iter, which > > uses a sort of state machine like switch to keep track of where it was > > when EAGAIN was returned. xfs_attr_node_removename has also been > > modified to use the switch, and a new version of xfs_attr_remove_args > > consists of a simple loop to refresh the transaction until the operation > > is completed. A new XFS_DAC_DEFER_FINISH flag is used to finish the > > transaction where ever the existing code used to. > > > > Calls to xfs_attr_rmtval_remove are replaced with the delay ready > > version __xfs_attr_rmtval_remove. We will rename > > __xfs_attr_rmtval_remove back to xfs_attr_rmtval_remove when we are > > done. > > > > xfs_attr_rmtval_remove itself is still in use by the set routines (used > > during a rename). For reasons of preserving existing function, we > > modify xfs_attr_rmtval_remove to call xfs_defer_finish when the flag is > > set. Similar to how xfs_attr_remove_args does here. Once we transition > > the set routines to be delay ready, xfs_attr_rmtval_remove is no longer > > used and will be removed. > > > > This patch also adds a new struct xfs_delattr_context, which we will use > > to keep track of the current state of an attribute operation. The new > > xfs_delattr_state enum is used to track various operations that are in > > progress so that we know not to repeat them, and resume where we left > > off before EAGAIN was returned to cycle out the transaction. Other > > members take the place of local variables that need to retain their > > values across multiple function recalls. See xfs_attr.h for a more > > detailed diagram of the states. > > > > Signed-off-by: Allison Henderson > > --- > > I started with a couple small comments on this patch but inevitably > started thinking more about the factoring again and ended up with a > couple patches on top. The first is more of some small tweaks and > open-coding that IMO makes this patch a bit easier to follow. The > second is more of an RFC so I'll follow up with that in a second email. > I'm curious what folks' thoughts might be on either. Also note that I'm > primarily focusing on code structure and whatnot here, so these are fast > and loose, compile tested only and likely to be broken. > ... and here's the second diff (applies on top of the first). This one popped up after staring at the previous changes for a bit and wondering whether using "done flags" might make the whole thing easier to follow than incremental state transitions. I think the attr remove path is easy enough to follow with either method, but the attr set path is a beast and so this is more with that in mind. Initial thoughts? diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c index 2e466c4ac283..106e3c070131 100644 --- a/fs/xfs/libxfs/xfs_attr.c +++ b/fs/xfs/libxfs/xfs_attr.c @@ -1271,14 +1271,12 @@ int xfs_attr_node_removename_setup( * successful error code is returned. */ STATIC int -xfs_attr_node_remove_step( - struct xfs_delattr_context *dac, - bool *joined) +xfs_attr_node_remove_rmt_step( + struct xfs_delattr_context *dac) { struct xfs_da_args *args = dac->da_args; struct xfs_da_state *state = dac->da_state; - struct xfs_da_state_blk *blk; - int error = 0, retval, done; + int error, done; /* * If there is an out-of-line value, de-allocate the blocks. This is @@ -1300,6 +1298,19 @@ xfs_attr_node_remove_step( return error; } + dac->dela_state |= XFS_DAS_RMT_DONE; + return error; +} + +STATIC int +xfs_attr_node_remove_join_step( + struct xfs_delattr_context *dac) +{ + struct xfs_da_args *args = dac->da_args; + struct xfs_da_state *state = dac->da_state; + struct xfs_da_state_blk *blk; + int error, retval; + /* * Remove the name and update the hashvals in the tree. */ @@ -1317,9 +1328,12 @@ xfs_attr_node_remove_step( error = xfs_da3_join(state); if (error) return error; - *joined = true; + + error = -EAGAIN; + dac->flags |= XFS_DAC_DEFER_FINISH; } + dac->dela_state |= XFS_DAS_JOIN_DONE; return error; } @@ -1342,36 +1356,23 @@ xfs_attr_node_removename_iter( struct xfs_da_state *state = dac->da_state; int error; struct xfs_inode *dp = args->dp; - bool joined = false; - switch (dac->dela_state) { - case XFS_DAS_UNINIT: - /* - * repeatedly remove remote blocks, remove the entry and join. - * returns -EAGAIN or 0 for completion of the step. - */ - error = xfs_attr_node_remove_step(dac, &joined); + if (!(dac->dela_state & XFS_DAS_RMT_DONE)) { + error = xfs_attr_node_remove_rmt_step(dac); if (error) goto out; - if (joined) { - dac->flags |= XFS_DAC_DEFER_FINISH; - dac->dela_state = XFS_DAS_RM_SHRINK; - return -EAGAIN; - } - /* fallthrough */ - case XFS_DAS_RM_SHRINK: - /* - * If the result is small enough, push it all into the inode. - */ - if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) - error = xfs_attr_node_shrink(args, state); - break; - default: - ASSERT(0); - error = -EINVAL; - goto out; } + if (!(dac->dela_state & XFS_DAS_JOIN_DONE)) { + error = xfs_attr_node_remove_join_step(dac); + if (error) + goto out; + } + + if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) + error = xfs_attr_node_shrink(args, state); + ASSERT(error != -EAGAIN); + out: if (state && error != -EAGAIN) xfs_da_state_free(state); diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h index 3154ef4b7833..67e730cd3267 100644 --- a/fs/xfs/libxfs/xfs_attr.h +++ b/fs/xfs/libxfs/xfs_attr.h @@ -151,6 +151,9 @@ enum xfs_delattr_state { XFS_DAS_RM_SHRINK, /* We are shrinking the tree */ }; +#define XFS_DAS_RMT_DONE 0x1 +#define XFS_DAS_JOIN_DONE 0x2 + /* * Defines for xfs_delattr_context.flags */