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 8B9E1C77B73 for ; Thu, 27 Apr 2023 06:11:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233414AbjD0GLc (ORCPT ); Thu, 27 Apr 2023 02:11:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33284 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229436AbjD0GLb (ORCPT ); Thu, 27 Apr 2023 02:11:31 -0400 Received: from out30-111.freemail.mail.aliyun.com (out30-111.freemail.mail.aliyun.com [115.124.30.111]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EAEB335A5 for ; Wed, 26 Apr 2023 23:11:29 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R621e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046049;MF=hsiangkao@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0Vh6EtZW_1682575886; Received: from 30.97.48.233(mailfrom:hsiangkao@linux.alibaba.com fp:SMTPD_---0Vh6EtZW_1682575886) by smtp.aliyun-inc.com; Thu, 27 Apr 2023 14:11:27 +0800 Message-ID: <8c06f467-2ce5-5e99-a5a6-5c0f1e31a00a@linux.alibaba.com> Date: Thu, 27 Apr 2023 14:11:25 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH 1/7] ovl: update of dentry revalidate flags after copy up To: Amir Goldstein Cc: Miklos Szeredi , Alexander Larsson , linux-unionfs@vger.kernel.org References: <20230408164302.1392694-1-amir73il@gmail.com> <20230408164302.1392694-2-amir73il@gmail.com> From: Gao Xiang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-unionfs@vger.kernel.org On 2023/4/27 13:48, Amir Goldstein wrote: > On Fri, Apr 14, 2023 at 10:21 AM Gao Xiang wrote: >> >> >> >> On 2023/4/9 00:42, Amir Goldstein wrote: >>> After copy up, we may need to update d_flags if upper dentry is on a >>> remote fs and lower dentries are not. >>> >>> Add helpers to allow incremental update of the revalidate flags. >>> >>> Fixes: bccece1ead36 ("ovl: allow remote upper") >>> Signed-off-by: Amir Goldstein >> >> Reviewed-by: Gao Xiang >> >>> --- >>> fs/overlayfs/copy_up.c | 2 ++ >>> fs/overlayfs/dir.c | 3 +-- >>> fs/overlayfs/export.c | 3 +-- >>> fs/overlayfs/namei.c | 3 +-- >>> fs/overlayfs/overlayfs.h | 6 ++++-- >>> fs/overlayfs/super.c | 2 +- >>> fs/overlayfs/util.c | 24 ++++++++++++++++++++---- >>> 7 files changed, 30 insertions(+), 13 deletions(-) >>> >>> diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c >>> index c14e90764e35..7bf101e756c8 100644 >>> --- a/fs/overlayfs/copy_up.c >>> +++ b/fs/overlayfs/copy_up.c >>> @@ -576,6 +576,7 @@ static int ovl_link_up(struct ovl_copy_up_ctx *c) >>> /* Restore timestamps on parent (best effort) */ >>> ovl_set_timestamps(ofs, upperdir, &c->pstat); >>> ovl_dentry_set_upper_alias(c->dentry); >>> + ovl_dentry_update_reval(c->dentry, upper); >>> } >>> } >>> inode_unlock(udir); >>> @@ -895,6 +896,7 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c) >>> inode_unlock(udir); >>> >>> ovl_dentry_set_upper_alias(c->dentry); >>> + ovl_dentry_update_reval(c->dentry, ovl_dentry_upper(c->dentry)); >>> } >>> >>> out: >>> diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c >>> index fc25fb95d5fc..9be52d8013c8 100644 >>> --- a/fs/overlayfs/dir.c >>> +++ b/fs/overlayfs/dir.c >>> @@ -269,8 +269,7 @@ static int ovl_instantiate(struct dentry *dentry, struct inode *inode, >>> >>> ovl_dir_modified(dentry->d_parent, false); >>> ovl_dentry_set_upper_alias(dentry); >>> - ovl_dentry_update_reval(dentry, newdentry, >>> - DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE); >>> + ovl_dentry_init_reval(dentry, newdentry); >>> >>> if (!hardlink) { >>> /* >>> diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c >>> index defd4e231ad2..5c36fb3a7bab 100644 >>> --- a/fs/overlayfs/export.c >>> +++ b/fs/overlayfs/export.c >>> @@ -326,8 +326,7 @@ static struct dentry *ovl_obtain_alias(struct super_block *sb, >>> if (upper_alias) >>> ovl_dentry_set_upper_alias(dentry); >>> >>> - ovl_dentry_update_reval(dentry, upper, >>> - DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE); >>> + ovl_dentry_init_reval(dentry, upper); >>> >>> return d_instantiate_anon(dentry, inode); >>> >>> diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c >>> index cfb3420b7df0..100a492d2b2a 100644 >>> --- a/fs/overlayfs/namei.c >>> +++ b/fs/overlayfs/namei.c >>> @@ -1122,8 +1122,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, >>> ovl_set_flag(OVL_UPPERDATA, inode); >>> } >>> >>> - ovl_dentry_update_reval(dentry, upperdentry, >>> - DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE); >>> + ovl_dentry_init_reval(dentry, upperdentry); >>> >>> revert_creds(old_cred); >>> if (origin_path) { >>> diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h >>> index 4d0b278f5630..e100c55bb924 100644 >>> --- a/fs/overlayfs/overlayfs.h >>> +++ b/fs/overlayfs/overlayfs.h >>> @@ -375,8 +375,10 @@ bool ovl_index_all(struct super_block *sb); >>> bool ovl_verify_lower(struct super_block *sb); >>> struct ovl_entry *ovl_alloc_entry(unsigned int numlower); >>> bool ovl_dentry_remote(struct dentry *dentry); >>> -void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry, >>> - unsigned int mask); >>> +void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *realdentry); >>> +void ovl_dentry_init_reval(struct dentry *dentry, struct dentry *upperdentry); >>> +void ovl_dentry_init_flags(struct dentry *dentry, struct dentry *upperdentry, >>> + unsigned int mask); >>> bool ovl_dentry_weird(struct dentry *dentry); >>> enum ovl_path_type ovl_path_type(struct dentry *dentry); >>> void ovl_path_upper(struct dentry *dentry, struct path *path); >>> diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c >>> index f1d9f75f8786..49b6956468f9 100644 >>> --- a/fs/overlayfs/super.c >>> +++ b/fs/overlayfs/super.c >>> @@ -1885,7 +1885,7 @@ static struct dentry *ovl_get_root(struct super_block *sb, >>> ovl_dentry_set_flag(OVL_E_CONNECTED, root); >>> ovl_set_upperdata(d_inode(root)); >>> ovl_inode_init(d_inode(root), &oip, ino, fsid); >>> - ovl_dentry_update_reval(root, upperdentry, DCACHE_OP_WEAK_REVALIDATE); >>> + ovl_dentry_init_flags(root, upperdentry, DCACHE_OP_WEAK_REVALIDATE); >>> >>> return root; >>> } >>> diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c >>> index 923d66d131c1..6a0652bd51f2 100644 >>> --- a/fs/overlayfs/util.c >>> +++ b/fs/overlayfs/util.c >>> @@ -94,14 +94,30 @@ struct ovl_entry *ovl_alloc_entry(unsigned int numlower) >>> return oe; >>> } >>> >>> +#define OVL_D_REVALIDATE (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE) >>> + >>> bool ovl_dentry_remote(struct dentry *dentry) >>> { >>> - return dentry->d_flags & >>> - (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE); >>> + return dentry->d_flags & OVL_D_REVALIDATE; >>> +} >>> + >>> +void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *realdentry) >>> +{ >>> + if (!ovl_dentry_remote(realdentry)) >>> + return; >>> + >>> + spin_lock(&dentry->d_lock); >>> + dentry->d_flags |= realdentry->d_flags & OVL_D_REVALIDATE; >> >> Although I'm not sure if it could cause some lazy awareness due to dcache >> RCU-walk, but maybe that is fine since such window is small? >> > > Good question. > I am not sure. > The alternative would be to the set revalidate flags on non-upper dentry > if the upper fs is remote. Yeah, I think that may be safer because I'm not sure (DCACHE_OP_REVALIDATE, DCACHE_OP_WEAK_REVALIDATE) could be changed dynamicly as safe after d_obtain_alias().. Thanks, Gao Xiang > > Thanks, > Amir.