From patchwork Fri Aug 20 21:02:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bruce Fields X-Patchwork-Id: 12450465 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 EED95C4320A for ; Fri, 20 Aug 2021 21:02:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D67A26103B for ; Fri, 20 Aug 2021 21:02:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240038AbhHTVCx (ORCPT ); Fri, 20 Aug 2021 17:02:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240192AbhHTVCs (ORCPT ); Fri, 20 Aug 2021 17:02:48 -0400 Received: from fieldses.org (fieldses.org [IPv6:2600:3c00:e000:2f7::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A76FCC06175F for ; Fri, 20 Aug 2021 14:02:09 -0700 (PDT) Received: by fieldses.org (Postfix, from userid 2815) id 1D6037C34; Fri, 20 Aug 2021 17:02:08 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.11.0 fieldses.org 1D6037C34 From: "J. Bruce Fields" To: Chuck Lever , Trond Myklebust , Anna Schumaker Cc: daire@dneg.com, linux-nfs@vger.kernel.org, "J. Bruce Fields" Subject: [PATCH 6/8] nfs: don't atempt blocking locks on nfs reexports Date: Fri, 20 Aug 2021 17:02:04 -0400 Message-Id: <1629493326-28336-7-git-send-email-bfields@redhat.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1629493326-28336-1-git-send-email-bfields@redhat.com> References: <1629493326-28336-1-git-send-email-bfields@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org From: "J. Bruce Fields" NFS implements blocking locks by blocking inside its lock method. In the reexport case, this blocks the nfs server thread, which could lead to deadlocks since an nfs server thread might be required to unlock the conflicting lock. It also causes a crash, since the nfs server thread assumes it can free the lock when its lm_notify lock callback is called. Ideal would be to make the nfs lock method return without blocking in this case, but for now it works just not to attempt blocking locks. The difference is just that the original client will have to poll (as it does in the v4.0 case) instead of getting a callback when the lock's available. Signed-off-by: J. Bruce Fields --- fs/nfs/export.c | 2 +- fs/nfsd/nfs4state.c | 8 ++++++-- include/linux/exportfs.h | 2 ++ 3 files changed, 9 insertions(+), 3 deletions(-) diff --git a/fs/nfs/export.c b/fs/nfs/export.c index 37a1a88df771..d772c20bbfd1 100644 --- a/fs/nfs/export.c +++ b/fs/nfs/export.c @@ -180,5 +180,5 @@ const struct export_operations nfs_export_ops = { .fetch_iversion = nfs_fetch_iversion, .flags = EXPORT_OP_NOWCC|EXPORT_OP_NOSUBTREECHK| EXPORT_OP_CLOSE_BEFORE_UNLINK|EXPORT_OP_REMOTE_FS| - EXPORT_OP_NOATOMIC_ATTR, + EXPORT_OP_NOATOMIC_ATTR|EXPORT_OP_SYNC_LOCKS, }; diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index fa67ecd5fe63..bebe86cce7c7 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -6835,6 +6835,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, struct nfsd4_blocked_lock *nbl = NULL; struct file_lock *file_lock = NULL; struct file_lock *conflock = NULL; + struct super_block *sb; __be32 status = 0; int lkflg; int err; @@ -6856,6 +6857,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, dprintk("NFSD: nfsd4_lock: permission denied!\n"); return status; } + sb = cstate->current_fh.fh_dentry->d_sb; if (lock->lk_is_new) { if (nfsd4_has_session(cstate)) @@ -6904,7 +6906,8 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, fp = lock_stp->st_stid.sc_file; switch (lock->lk_type) { case NFS4_READW_LT: - if (nfsd4_has_session(cstate)) + if (nfsd4_has_session(cstate) && + !(sb->s_export_op->flags & EXPORT_OP_SYNC_LOCKS)) fl_flags |= FL_SLEEP; fallthrough; case NFS4_READ_LT: @@ -6916,7 +6919,8 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, fl_type = F_RDLCK; break; case NFS4_WRITEW_LT: - if (nfsd4_has_session(cstate)) + if (nfsd4_has_session(cstate) && + !(sb->s_export_op->flags & EXPORT_OP_SYNC_LOCKS)) fl_flags |= FL_SLEEP; fallthrough; case NFS4_WRITE_LT: diff --git a/include/linux/exportfs.h b/include/linux/exportfs.h index fe848901fcc3..3260fe714846 100644 --- a/include/linux/exportfs.h +++ b/include/linux/exportfs.h @@ -221,6 +221,8 @@ struct export_operations { #define EXPORT_OP_NOATOMIC_ATTR (0x10) /* Filesystem cannot supply atomic attribute updates */ +#define EXPORT_OP_SYNC_LOCKS (0x20) /* Filesystem can't do + asychronous blocking locks */ unsigned long flags; };