From patchwork Thu Feb 20 16:47:13 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeff Layton X-Patchwork-Id: 13984281 X-Patchwork-Delegate: cel@kernel.org Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 767BD213E66; Thu, 20 Feb 2025 16:47:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740070049; cv=none; b=Z9wMPE8C9yPQ0Dm3JGrKwWMnlxwwQ9MEjsXlTpQsE0cbr8dTjxizR67n4ElHO1xn5zAykXmNF4GAHxEPl7HNuEakKKA0QAkScSKFSK1bz89sZwn/BGPaXkd8Pcs42HkmZ1LklYzdwZdappL9YeXQ7okDLbF21whk2SAoCBY0MQM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740070049; c=relaxed/simple; bh=cM51zXKQgB7chVb7HCS+hb5p+nJh2B05fSYFZWc6QqA=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=RBPO1ybkULX9KvfjcTRjXNN8n/YSn2cczQPNt8fGfeYRwtgWE+jiSAEABtQdcIsw+s8Wbvk6P6endR+iDkqBKDOMkDt2g05Y9BoP2aOzifpkKRdPyBj8pDZ02WnKb7lmiag6k1MS+r2SS2FRr5o086geok0MQrVmUnaHforwHys= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Jr9g/zM0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Jr9g/zM0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2EB9EC4CEDD; Thu, 20 Feb 2025 16:47:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1740070048; bh=cM51zXKQgB7chVb7HCS+hb5p+nJh2B05fSYFZWc6QqA=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=Jr9g/zM0r5mTY0Wmbw4q7Rc92zwe+qqD8Vmi/QJ4ZBqtYtx28tgqtIPJjR9bwrIDV sXAYsfslIu+Pt8zskVDGAsYseQVDJ1C5dVX55jME9bwNXXWBFfze/cC7nGejbx1tvL 2hNgunvZFe80OhUzt1G2JVmcaN1ba2toS8OE0N2J19mOrDMzoL+avlt2Xq/WDGopZ+ l7HfKNpm6NJZmTTtG6+dVyBVPfEzWTt2BrIDgGVHLn7kv7SNdqzB3ieXsvFdeuVP8M sTEf3tA5uPn4oKobLvD/l9gRpgIpTofdIB1ZNyt0/HDXJQy+/yn2A7BOnQCv4k8IZw DPx6jrRONVayg== From: Jeff Layton Date: Thu, 20 Feb 2025 11:47:13 -0500 Subject: [PATCH v2 1/5] nfsd: prevent callback tasks running concurrently Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250220-nfsd-callback-v2-1-6a57f46e1c3a@kernel.org> References: <20250220-nfsd-callback-v2-0-6a57f46e1c3a@kernel.org> In-Reply-To: <20250220-nfsd-callback-v2-0-6a57f46e1c3a@kernel.org> To: Chuck Lever , Neil Brown , Olga Kornievskaia , Dai Ngo , Tom Talpey Cc: Li Lingfeng , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, Jeff Layton X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=6190; i=jlayton@kernel.org; h=from:subject:message-id; bh=cM51zXKQgB7chVb7HCS+hb5p+nJh2B05fSYFZWc6QqA=; b=owEBbQKS/ZANAwAIAQAOaEEZVoIVAcsmYgBnt1yetRj0At3wEXKZLmmVcWst+WHAgQSRfg5o8 AR6RO/tNcuJAjMEAAEIAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCZ7dcngAKCRAADmhBGVaC FZqoEACRp1d+ELs8oaCUJgU7jqBtu6TQoZdOe/Rd3/aW8EdGN3Iv5TQfIjJ8dFfUxyUKNjgqINf IpjJ7P+fPMt1ENWd08OHcUUXG+URVHaEdqgDIuJvANmiiuzXyCG2vhmT112ZF0lXwHAUB79ad+t j0XoMqv3Ze0vL4rpImvo3kvDBi5sqRnRCpXVywZg+v9Qal2h0f72KntvN0D0/SEsIthM5Pc/4ST lk3UNKpIVAmv0F13Sa/zVI/h7xJo46SXa61EsbMxj0I3YyoyCGqW9atxIG0jJ/PMQx11S4S9qMs 4XBrSEiBbKj7CjygYGw9yLmV55pWILKc0a6zgbj4EqJuK0TYjYB9fMqOMHRD7re8ii66dfkQawT NeeIs2TCHzhLjQW1bSmLZ7QVjMaZeAdwuGyinNMDxmLTsraqICScNliJ+BK4Pz+Qb+Dn4IISt/l ReRVzCU1y4Z2rrXZXbbnjTEur17okuKCv0H5By0K+mBDGVwR7V3tdfsVFJemp74m3NoWfODUzNA qdxLb0CjFAWE5Eo8yRGYQ/Jj3wHiZrKb+Q7I0epItmw8iJDd7RRvDzxykt7DNJqABqsnzd5N3lg 3cOynuq0JxHrj7arX1Vygtw7hg0N8Bc9FhSzxwkf0RcdRpZyxqpdhScBGmeNUa3B6PxGZKeCYed zTGw4IGMuXfV4BA== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 The nfsd4_callback workqueue jobs exist to queue backchannel RPCs to rpciod. Because they run in different workqueue contexts, the rpc_task can run concurrently with the workqueue job itself, should it become requeued. This is problematic as there is no locking when accessing the fields in the nfsd4_callback. Add a new unsigned long to nfsd4_callback and declare a new NFSD4_CALLBACK_RUNNING flag to be set in it. When attempting to run a workqueue job, do a test_and_set_bit() on that flag first, and don't queue the workqueue job if it returns true. Clear NFSD4_CALLBACK_RUNNING in nfsd41_destroy_cb(). This also gives us a more reliable mechanism for handling queueing failures in codepaths where we have to take references under spinlocks. We can now do the test_and_set_bit on NFSD4_CALLBACK_RUNNING first, and only take references to the objects if that returns false. Most of the nfsd4_run_cb() callers are converted to use this new flag or the nfsd4_try_run_cb() wrapper. The main exception is the callback channel probe, which has its own synchronization. Signed-off-by: Jeff Layton --- fs/nfsd/nfs4callback.c | 2 ++ fs/nfsd/nfs4layouts.c | 7 ++++--- fs/nfsd/nfs4proc.c | 2 +- fs/nfsd/nfs4state.c | 14 ++++++++++---- fs/nfsd/state.h | 9 +++++++++ 5 files changed, 26 insertions(+), 8 deletions(-) diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c index ae4b7b6df47ff054db197bd2f6083905e4149bee..1f26c811e5f73c2e745ee68d0b6e668d1dd7c704 100644 --- a/fs/nfsd/nfs4callback.c +++ b/fs/nfsd/nfs4callback.c @@ -1312,6 +1312,7 @@ static void nfsd41_destroy_cb(struct nfsd4_callback *cb) trace_nfsd_cb_destroy(clp, cb); nfsd41_cb_release_slot(cb); + clear_bit(NFSD4_CALLBACK_RUNNING, &cb->cb_flags); if (cb->cb_ops && cb->cb_ops->release) cb->cb_ops->release(cb); nfsd41_cb_inflight_end(clp); @@ -1632,6 +1633,7 @@ void nfsd4_init_cb(struct nfsd4_callback *cb, struct nfs4_client *clp, cb->cb_msg.rpc_proc = &nfs4_cb_procedures[op]; cb->cb_msg.rpc_argp = cb; cb->cb_msg.rpc_resp = cb; + cb->cb_flags = 0; cb->cb_ops = ops; INIT_WORK(&cb->cb_work, nfsd4_run_cb_work); cb->cb_status = 0; diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c index fbfddd3c4c943c34aa3991328eacb5759e311cc4..290271ac424540e4405a5fd0eacc8db9f47603cd 100644 --- a/fs/nfsd/nfs4layouts.c +++ b/fs/nfsd/nfs4layouts.c @@ -344,9 +344,10 @@ nfsd4_recall_file_layout(struct nfs4_layout_stateid *ls) atomic_inc(&ls->ls_stid.sc_file->fi_lo_recalls); trace_nfsd_layout_recall(&ls->ls_stid.sc_stateid); - refcount_inc(&ls->ls_stid.sc_count); - nfsd4_run_cb(&ls->ls_recall); - + if (!test_and_set_bit(NFSD4_CALLBACK_RUNNING, &ls->ls_recall.cb_flags)) { + refcount_inc(&ls->ls_stid.sc_count); + nfsd4_run_cb(&ls->ls_recall); + } out_unlock: spin_unlock(&ls->ls_lock); } diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c index f6e06c779d09dacdcea81fb3b4135bf600f6cc63..b397246dae7b7e8c2a0ba436bb3813213cfe4fa2 100644 --- a/fs/nfsd/nfs4proc.c +++ b/fs/nfsd/nfs4proc.c @@ -1847,7 +1847,7 @@ static void nfsd4_send_cb_offload(struct nfsd4_copy *copy) NFSPROC4_CLNT_CB_OFFLOAD); trace_nfsd_cb_offload(copy->cp_clp, &cbo->co_res.cb_stateid, &cbo->co_fh, copy->cp_count, copy->nfserr); - nfsd4_run_cb(&cbo->co_cb); + nfsd4_try_run_cb(&cbo->co_cb); } /** diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index e806fd97cca972559d1929d37c1a24e760d9d6d8..fabcd979c40695ebcc795cfd2d8a035b7d589a37 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -3232,8 +3232,10 @@ static void nfs4_cb_getattr(struct nfs4_cb_fattr *ncf) /* set to proper status when nfsd4_cb_getattr_done runs */ ncf->ncf_cb_status = NFS4ERR_IO; - refcount_inc(&dp->dl_stid.sc_count); - nfsd4_run_cb(&ncf->ncf_getattr); + if (!test_and_set_bit(NFSD4_CALLBACK_RUNNING, &ncf->ncf_getattr.cb_flags)) { + refcount_inc(&dp->dl_stid.sc_count); + nfsd4_run_cb(&ncf->ncf_getattr); + } } static struct nfs4_client *create_client(struct xdr_netobj name, @@ -5422,6 +5424,10 @@ static const struct nfsd4_callback_ops nfsd4_cb_recall_ops = { static void nfsd_break_one_deleg(struct nfs4_delegation *dp) { bool queued; + + if (test_and_set_bit(NFSD4_CALLBACK_RUNNING, &dp->dl_recall.cb_flags)) + return; + /* * We're assuming the state code never drops its reference * without first removing the lease. Since we're in this lease @@ -6910,7 +6916,7 @@ deleg_reaper(struct nfsd_net *nn) clp->cl_ra->ra_bmval[0] = BIT(RCA4_TYPE_MASK_RDATA_DLG) | BIT(RCA4_TYPE_MASK_WDATA_DLG); trace_nfsd_cb_recall_any(clp->cl_ra); - nfsd4_run_cb(&clp->cl_ra->ra_cb); + nfsd4_try_run_cb(&clp->cl_ra->ra_cb); } } @@ -7839,7 +7845,7 @@ nfsd4_lm_notify(struct file_lock *fl) if (queue) { trace_nfsd_cb_notify_lock(lo, nbl); - nfsd4_run_cb(&nbl->nbl_cb); + nfsd4_try_run_cb(&nbl->nbl_cb); } } diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h index 74d2d7b42676d907bec9159b927aeed223d668c3..e6af969a03f26b1feb6768af5baa4887bf5fa5e9 100644 --- a/fs/nfsd/state.h +++ b/fs/nfsd/state.h @@ -67,6 +67,8 @@ typedef struct { struct nfsd4_callback { struct nfs4_client *cb_clp; struct rpc_message cb_msg; +#define NFSD4_CALLBACK_RUNNING BIT(0) // Callback is running + unsigned long cb_flags; const struct nfsd4_callback_ops *cb_ops; struct work_struct cb_work; int cb_seq_status; @@ -780,6 +782,13 @@ extern void nfsd4_change_callback(struct nfs4_client *clp, struct nfs4_cb_conn * extern void nfsd4_init_cb(struct nfsd4_callback *cb, struct nfs4_client *clp, const struct nfsd4_callback_ops *ops, enum nfsd4_cb_op op); extern bool nfsd4_run_cb(struct nfsd4_callback *cb); + +static inline void nfsd4_try_run_cb(struct nfsd4_callback *cb) +{ + if (!test_and_set_bit(NFSD4_CALLBACK_RUNNING, &cb->cb_flags)) + WARN_ON_ONCE(!nfsd4_run_cb(cb)); +} + extern void nfsd4_shutdown_callback(struct nfs4_client *); extern void nfsd4_shutdown_copy(struct nfs4_client *clp); void nfsd4_async_copy_reaper(struct nfsd_net *nn);