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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 C987BC11D2F for ; Mon, 24 Feb 2020 15:26:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 81D6D20836 for ; Mon, 24 Feb 2020 15:26:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="J9l2lNj4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727916AbgBXP0D (ORCPT ); Mon, 24 Feb 2020 10:26:03 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:51492 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727539AbgBXP0C (ORCPT ); Mon, 24 Feb 2020 10:26:02 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582557960; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fI2M3NPY7i3NCrqDce5o9WjefMuaib1PzzxQDCXm0z8=; b=J9l2lNj4tJzyHdL4zVVfzpbNRnHYA1woTZxGIzDCJsuCIo3DhJkSUZcKqd3JJuM8meselz 79+JZEUlo6dFSN3gnyL+VJo7SR4RobFRj1Qc/JnEKa5EDrVCFOqZiMXr+Lzwp8gkrzLwy6 TD+dmZT3Qgd+6ZZClcp4TFwLQ9wrxdk= 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-293-Q-VWndbUP_aE5IW7AIHSvQ-1; Mon, 24 Feb 2020 10:25:58 -0500 X-MC-Unique: Q-VWndbUP_aE5IW7AIHSvQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 78A70477; Mon, 24 Feb 2020 15:25:57 +0000 (UTC) Received: from bfoster (dhcp-41-2.bos.redhat.com [10.18.41.2]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E70CA5C1D6; Mon, 24 Feb 2020 15:25:56 +0000 (UTC) Date: Mon, 24 Feb 2020 10:25:55 -0500 From: Brian Foster To: Allison Collins Cc: linux-xfs@vger.kernel.org Subject: Re: [PATCH v7 13/19] xfs: Add delay ready attr remove routines Message-ID: <20200224152555.GG15761@bfoster> References: <20200223020611.1802-1-allison.henderson@oracle.com> <20200223020611.1802-14-allison.henderson@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200223020611.1802-14-allison.henderson@oracle.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Content-Transfer-Encoding: quoted-printable Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Sat, Feb 22, 2020 at 07:06:05PM -0700, Allison Collins wrote: > This patch modifies the attr remove routines to be delay ready. This me= ans 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_remo= ve_args has > become xfs_attr_remove_iter, which uses a sort of state machine like sw= itch to keep > track of where it was when EAGAIN was returned. xfs_attr_node_removenam= e 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 operatio= n is > completed. >=20 > This patch also adds a new struct xfs_delattr_context, which we will us= e to keep > track of the current state of an attribute operation. The new xfs_delat= tr_state > enum is used to track various operations that are in progress so that w= e 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 th= at need > to retain their values across multiple function recalls. >=20 > Below is a state machine diagram for attr remove operations. The XFS_DA= S_* states > indicate places where the function would return -EAGAIN, and then immed= iately > resume from after being recalled by the calling function. States marke= d as a > "subroutine state" indicate that they belong to a subroutine, and so th= e calling > function needs to pass them back to that subroutine to allow it to fini= sh where > it left off. But they otherwise do not have a role in the calling funct= ion other > than just passing through. >=20 > xfs_attr_remove_iter() > XFS_DAS_RM_SHRINK =E2=94=80=E2=94=90 > (subroutine state) =E2=94=82 > =E2=94=82 > XFS_DAS_RMTVAL_REMOVE =E2=94=80=E2=94=A4 > (subroutine state) =E2=94=82 > =E2=94=94=E2=94=80>xfs_attr_node_remove= name() > =E2=94=82 > v > need to remove > =E2=94=8C=E2=94=80n=E2=94=80=E2=94=80= rmt blocks? > =E2=94=82 =E2=94=82 > =E2=94=82 y > =E2=94=82 =E2=94=82 > =E2=94=82 v > =E2=94=82 =E2=94=8C=E2=94=80>XFS_DA= S_RMTVAL_REMOVE > =E2=94=82 =E2=94=82 =E2=94= =82 > =E2=94=82 =E2=94=82 v > =E2=94=82 =E2=94=94=E2=94=80=E2=94=80= y=E2=94=80=E2=94=80 more blks > =E2=94=82 to remove? > =E2=94=82 =E2=94=82 > =E2=94=82 n > =E2=94=82 =E2=94=82 > =E2=94=82 v > =E2=94=82 need to > =E2=94=94=E2=94=80=E2=94=80=E2=94=80= =E2=94=80=E2=94=80> shrink tree? =E2=94=80n=E2=94=80=E2=94=90 > =E2=94=82 =E2=94= =82 > y =E2=94=82 > =E2=94=82 =E2=94= =82 > v =E2=94=82 > XFS_DAS_RM_SHRINK =E2=94=82 > =E2=94=82 =E2=94= =82 > v =E2=94=82 > done <=E2=94=80=E2=94=80= =E2=94=80=E2=94=80=E2=94=80=E2=94=98 >=20 Wow. :P I guess I have nothing against verbose commit logs, but I wonder how useful this level of documentation is for a patch that shouldn't really change the existing flow of the operation. > Signed-off-by: Allison Collins > --- > fs/xfs/libxfs/xfs_attr.c | 114 +++++++++++++++++++++++++++++++++++= ++------ > fs/xfs/libxfs/xfs_attr.h | 1 + > fs/xfs/libxfs/xfs_da_btree.h | 30 ++++++++++++ > fs/xfs/scrub/common.c | 2 + > fs/xfs/xfs_acl.c | 2 + > fs/xfs/xfs_attr_list.c | 1 + > fs/xfs/xfs_ioctl.c | 2 + > fs/xfs/xfs_ioctl32.c | 2 + > fs/xfs/xfs_iops.c | 2 + > fs/xfs/xfs_xattr.c | 1 + > 10 files changed, 141 insertions(+), 16 deletions(-) >=20 > diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c > index 5d73bdf..cd3a3f7 100644 > --- a/fs/xfs/libxfs/xfs_attr.c > +++ b/fs/xfs/libxfs/xfs_attr.c > @@ -368,11 +368,60 @@ xfs_has_attr( > */ > int > xfs_attr_remove_args( > + struct xfs_da_args *args) > +{ > + int error =3D 0; > + int err2 =3D 0; > + > + do { > + error =3D xfs_attr_remove_iter(args); > + if (error && error !=3D -EAGAIN) > + goto out; > + I'm a little confused on the logic of this loop given that the only caller commits the transaction (which also finishes dfops). IOW, it seems we shouldn't ever need to finish/roll when error !=3D -EAGAIN. If that is the case, this can be simplified to something like: int xfs_attr_remove_args( struct xfs_da_args *args) { int error; do { error =3D xfs_attr_remove_iter(args); if (error !=3D -EAGAIN) break; if (args->dac.flags & XFS_DAC_FINISH_TRANS) { args->dac.flags &=3D ~XFS_DAC_FINISH_TRANS; error =3D xfs_defer_finish(&args->trans); if (error) break; } error =3D xfs_trans_roll_inode(&args->trans, args->dp); if (error) break; } while (true); return error; } That has the added benefit of eliminating the whole err2 pattern, which always strikes me as a landmine. > + if (args->dac.flags & XFS_DAC_FINISH_TRANS) { BTW, _FINISH_TRANS also seems misnamed given that we finish deferred operations, not necessarily the transaction. XFS_DAC_DEFER_FINISH? > + args->dac.flags &=3D ~XFS_DAC_FINISH_TRANS; > + > + err2 =3D xfs_defer_finish(&args->trans); > + if (err2) { > + error =3D err2; > + goto out; > + } > + } > + > + err2 =3D xfs_trans_roll_inode(&args->trans, args->dp); > + if (err2) { > + error =3D err2; > + goto out; > + } > + > + } while (error =3D=3D -EAGAIN); > +out: > + return error; > +} > + > +/* > + * Remove the attribute specified in @args. > + * > + * This function may return -EAGAIN to signal that the transaction nee= ds to be > + * rolled. Callers should continue calling this function until they r= eceive a > + * return value other than -EAGAIN. > + */ > +int > +xfs_attr_remove_iter( > struct xfs_da_args *args) > { > struct xfs_inode *dp =3D args->dp; > int error; > =20 > + /* State machine switch */ > + switch (args->dac.dela_state) { > + case XFS_DAS_RM_SHRINK: > + case XFS_DAS_RMTVAL_REMOVE: > + goto node; > + default: > + break; > + } > + > if (!xfs_inode_hasattr(dp)) { > error =3D -ENOATTR; > } else if (dp->i_d.di_aformat =3D=3D XFS_DINODE_FMT_LOCAL) { > @@ -381,6 +430,7 @@ xfs_attr_remove_args( > } else if (xfs_bmap_one_block(dp, XFS_ATTR_FORK)) { > error =3D xfs_attr_leaf_removename(args); > } else { > +node: > error =3D xfs_attr_node_removename(args); > } > =20 > @@ -895,9 +945,8 @@ xfs_attr_leaf_removename( > /* bp is gone due to xfs_da_shrink_inode */ > if (error) > return error; > - error =3D xfs_defer_finish(&args->trans); > - if (error) > - return error; > + > + args->dac.flags |=3D XFS_DAC_FINISH_TRANS; > } > return 0; > } > @@ -1218,6 +1267,11 @@ xfs_attr_node_addname( > * This will involve walking down the Btree, and may involve joining > * leaf nodes and even joining intermediate nodes up to and including > * the root node (a special case of an intermediate node). > + * > + * This routine is meant to function as either an inline or delayed op= eration, > + * and may return -EAGAIN when the transaction needs to be rolled. Ca= lling > + * functions will need to handle this, and recall the function until a > + * successful error code is returned. > */ > STATIC int > xfs_attr_node_removename( > @@ -1230,10 +1284,24 @@ xfs_attr_node_removename( > struct xfs_inode *dp =3D args->dp; > =20 > trace_xfs_attr_node_removename(args); > + state =3D args->dac.da_state; > + blk =3D args->dac.blk; > + > + /* State machine switch */ > + switch (args->dac.dela_state) { > + case XFS_DAS_RMTVAL_REMOVE: > + goto rm_node_blks; > + case XFS_DAS_RM_SHRINK: > + goto rm_shrink; > + default: > + break; > + } > =20 > error =3D xfs_attr_node_hasname(args, &state); > if (error !=3D -EEXIST) > goto out; > + else > + error =3D 0; This doesn't look necessary. > =20 > /* > * If there is an out-of-line value, de-allocate the blocks. > @@ -1243,6 +1311,14 @@ xfs_attr_node_removename( > blk =3D &state->path.blk[ state->path.active-1 ]; > ASSERT(blk->bp !=3D NULL); > ASSERT(blk->magic =3D=3D XFS_ATTR_LEAF_MAGIC); > + > + /* > + * Store blk and state in the context incase we need to cycle out the > + * transaction > + */ > + args->dac.blk =3D blk; > + args->dac.da_state =3D state; > + > if (args->rmtblkno > 0) { > /* > * Fill in disk block numbers in the state structure > @@ -1261,13 +1337,21 @@ xfs_attr_node_removename( > if (error) > goto out; > =20 > - error =3D xfs_trans_roll_inode(&args->trans, args->dp); > + error =3D xfs_attr_rmtval_invalidate(args); Remind me why we lose the above trans roll? I vaguely recall that this was intentional, but I could be mistaken... > if (error) > goto out; > + } > =20 > - error =3D xfs_attr_rmtval_remove(args); > - if (error) > - goto out; > +rm_node_blks: > + > + if (args->rmtblkno > 0) { > + error =3D xfs_attr_rmtval_unmap(args); > + > + if (error) { > + if (error =3D=3D -EAGAIN) > + args->dac.dela_state =3D XFS_DAS_RMTVAL_REMOVE; Might be helpful for the code labels to match the state names. I.e., use das_rmtval_remove: for the label above. > + return error; > + } > =20 > /* > * Refill the state structure with buffers, the prior calls > @@ -1293,17 +1377,15 @@ xfs_attr_node_removename( > error =3D xfs_da3_join(state); > if (error) > goto out; > - error =3D xfs_defer_finish(&args->trans); > - if (error) > - goto out; > - /* > - * Commit the Btree join operation and start a new trans. > - */ > - error =3D xfs_trans_roll_inode(&args->trans, dp); > - if (error) > - goto out; > + > + args->dac.flags |=3D XFS_DAC_FINISH_TRANS; > + args->dac.dela_state =3D XFS_DAS_RM_SHRINK; > + return -EAGAIN; > } > =20 > +rm_shrink: > + args->dac.dela_state =3D XFS_DAS_RM_SHRINK; > + There's an xfs_defer_finish() call further down this function. Should that be replaced with the flag? Finally, I mentioned in a previous review that this function should probably be further broken down before fitting in the state management stuff. It doesn't look like that happened so I've attached a diff that is just intended to give an idea of what I mean by sectioning off the hunks that might be able to break down into helpers. The helpers wouldn't contain any state management, so we create a clear separation between the state code and functional components. I think this initial refactoring would make the introduction of state much more simple (and perhaps alleviate the need for the huge diagram). It might also be interesting to see how much of the result could be folded up further into _removename_iter()... Brian > /* > * If the result is small enough, push it all into the inode. > */ > diff --git a/fs/xfs/libxfs/xfs_attr.h b/fs/xfs/libxfs/xfs_attr.h > index ce7b039..ea873a5 100644 > --- a/fs/xfs/libxfs/xfs_attr.h > +++ b/fs/xfs/libxfs/xfs_attr.h > @@ -155,6 +155,7 @@ int xfs_attr_set_args(struct xfs_da_args *args); > int xfs_attr_remove(struct xfs_inode *dp, struct xfs_name *name, int f= lags); > int xfs_has_attr(struct xfs_da_args *args); > int xfs_attr_remove_args(struct xfs_da_args *args); > +int xfs_attr_remove_iter(struct xfs_da_args *args); > int xfs_attr_list(struct xfs_inode *dp, char *buffer, int bufsize, > int flags, struct attrlist_cursor_kern *cursor); > bool xfs_attr_namecheck(const void *name, size_t length); > diff --git a/fs/xfs/libxfs/xfs_da_btree.h b/fs/xfs/libxfs/xfs_da_btree.= h > index 14f1be3..3c78498 100644 > --- a/fs/xfs/libxfs/xfs_da_btree.h > +++ b/fs/xfs/libxfs/xfs_da_btree.h > @@ -50,9 +50,39 @@ enum xfs_dacmp { > }; > =20 > /* > + * Enum values for xfs_delattr_context.da_state > + * > + * These values are used by delayed attribute operations to keep track= of where > + * they were before they returned -EAGAIN. A return code of -EAGAIN s= ignals the > + * calling function to roll the transaction, and then recall the subro= utine to > + * finish the operation. The enum is then used by the subroutine to j= ump back > + * to where it was and resume executing where it left off. > + */ > +enum xfs_delattr_state { > + XFS_DAS_RM_SHRINK, /* We are shrinking the tree */ > + XFS_DAS_RMTVAL_REMOVE, /* We are removing remote value blocks */ > +}; > + > +/* > + * Defines for xfs_delattr_context.flags > + */ > +#define XFS_DAC_FINISH_TRANS 0x1 /* indicates to finish the transactio= n */ > + > +/* > + * Context used for keeping track of delayed attribute operations > + */ > +struct xfs_delattr_context { > + struct xfs_da_state *da_state; > + struct xfs_da_state_blk *blk; > + unsigned int flags; > + enum xfs_delattr_state dela_state; > +}; > + > +/* > * Structure to ease passing around component names. > */ > typedef struct xfs_da_args { > + struct xfs_delattr_context dac; /* context used for delay attr ops */ > struct xfs_da_geometry *geo; /* da block geometry */ > struct xfs_name name; /* name, length and argument flags*/ > uint8_t filetype; /* filetype of inode for directories */ > diff --git a/fs/xfs/scrub/common.c b/fs/xfs/scrub/common.c > index 1887605..9a649d1 100644 > --- a/fs/xfs/scrub/common.c > +++ b/fs/xfs/scrub/common.c > @@ -24,6 +24,8 @@ > #include "xfs_rmap_btree.h" > #include "xfs_log.h" > #include "xfs_trans_priv.h" > +#include "xfs_da_format.h" > +#include "xfs_da_btree.h" > #include "xfs_attr.h" > #include "xfs_reflink.h" > #include "scrub/scrub.h" > diff --git a/fs/xfs/xfs_acl.c b/fs/xfs/xfs_acl.c > index 42ac847..d65e6d8 100644 > --- a/fs/xfs/xfs_acl.c > +++ b/fs/xfs/xfs_acl.c > @@ -10,6 +10,8 @@ > #include "xfs_trans_resv.h" > #include "xfs_mount.h" > #include "xfs_inode.h" > +#include "xfs_da_format.h" > +#include "xfs_da_btree.h" > #include "xfs_attr.h" > #include "xfs_trace.h" > #include "xfs_error.h" > diff --git a/fs/xfs/xfs_attr_list.c b/fs/xfs/xfs_attr_list.c > index d37743b..881b9a4 100644 > --- a/fs/xfs/xfs_attr_list.c > +++ b/fs/xfs/xfs_attr_list.c > @@ -12,6 +12,7 @@ > #include "xfs_trans_resv.h" > #include "xfs_mount.h" > #include "xfs_da_format.h" > +#include "xfs_da_btree.h" > #include "xfs_inode.h" > #include "xfs_trans.h" > #include "xfs_bmap.h" > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c > index 28c07c9..7c1d9da 100644 > --- a/fs/xfs/xfs_ioctl.c > +++ b/fs/xfs/xfs_ioctl.c > @@ -15,6 +15,8 @@ > #include "xfs_iwalk.h" > #include "xfs_itable.h" > #include "xfs_error.h" > +#include "xfs_da_format.h" > +#include "xfs_da_btree.h" > #include "xfs_attr.h" > #include "xfs_bmap.h" > #include "xfs_bmap_util.h" > diff --git a/fs/xfs/xfs_ioctl32.c b/fs/xfs/xfs_ioctl32.c > index 769581a..d504f8f 100644 > --- a/fs/xfs/xfs_ioctl32.c > +++ b/fs/xfs/xfs_ioctl32.c > @@ -17,6 +17,8 @@ > #include "xfs_itable.h" > #include "xfs_fsops.h" > #include "xfs_rtalloc.h" > +#include "xfs_da_format.h" > +#include "xfs_da_btree.h" > #include "xfs_attr.h" > #include "xfs_ioctl.h" > #include "xfs_ioctl32.h" > diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c > index e85bbf5..a2d299f 100644 > --- a/fs/xfs/xfs_iops.c > +++ b/fs/xfs/xfs_iops.c > @@ -13,6 +13,8 @@ > #include "xfs_inode.h" > #include "xfs_acl.h" > #include "xfs_quota.h" > +#include "xfs_da_format.h" > +#include "xfs_da_btree.h" > #include "xfs_attr.h" > #include "xfs_trans.h" > #include "xfs_trace.h" > diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c > index 74133a5..d8dc72d 100644 > --- a/fs/xfs/xfs_xattr.c > +++ b/fs/xfs/xfs_xattr.c > @@ -10,6 +10,7 @@ > #include "xfs_log_format.h" > #include "xfs_da_format.h" > #include "xfs_inode.h" > +#include "xfs_da_btree.h" > #include "xfs_attr.h" > #include "xfs_acl.h" > =20 > --=20 > 2.7.4 >=20