Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 2974636C0C8 for ; Sat, 5 Sep 2026 03:28:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788578920; cv=none; b=c2UiFvhpe6xijBoRrYzq63GsshkSIhXqskbMwr7lSMrlmclD7DR6uXpcAbSMHHeQvB/yr0OjQsOt/xraF0hsk3p5IJrHhbjzVmjCn1NM41MQgA1c3nXbNwL1rImPFCuRFXIHiTYbdZzXJHcGwSchL3KVKoGI4lzjKa6cWlMKgj8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788578920; c=relaxed/simple; bh=JgZszOJHDpPmJyDCXgLt3gVa04wok/ySVJtR2fYWnnY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Cp/uEpPXpgrJqsbXg3ZhthMrYxEaZDM66p0KQ1UrD2P+DrdajuSpy5hVnpBiRdbvSFho3kYBToez0+V7PzsxC/QfzvX+SM7kVnX6u+qKZU74JL+D1Y2khNRXHRf8ARVgY5cQ1s9h27OF48j+Q4QWw/3uDsu5/jVTuXppTtqpT3w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nqfyqDdB; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nqfyqDdB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7713C1F00ACA; Sat, 5 Sep 2026 03:28:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788578918; bh=m7rMG8qdjuZgIpoZeYynYuhtlhO1jAFuB2KfRqu6W1g=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=nqfyqDdBUWayqb76yjfrWzzXas3mPUPHJMttv/V1cRg3uicgRKG2nRZ3UNwYm8FwO hdnKr6rairgMJu69dd+bsxMyb4Id+rj+eHPZ1zQtrMZMgopnIOOBYXR7v+kNaeeT8F xHhgFatEpR2QBobeAnNTaQIt9cDpSWkT4zesfIiHwDwd7ydDdn5ld4xo1UFd9jDZvv 3Gjxgqsne9460cgPWjWcmEfgLdBKsusw4ynHfNps6//GZkUWTvZ1Qn5ujJ9BOep4Mc KMvQEDcPuY435tCRIL1EoRQhKYncDwDJHfBVEC+nvCjuZ/c/x/jYsv7De28LP5455z Afd8e8Zx2OpQw== From: Sasha Levin To: stable@vger.kernel.org Cc: Jeff Layton , Chris Mason , Chuck Lever , Sasha Levin Subject: [PATCH 6.18.y 3/3] nfsd: dedup nfs4_client_to_reclaim inserts Date: Fri, 4 Sep 2026 23:28:34 -0400 Message-ID: <20260905032834.1915305-3-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260905032834.1915305-1-sashal@kernel.org> References: <2026090325-overpass-emoticon-993a@gregkh> <20260905032834.1915305-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jeff Layton [ Upstream commit 9b57793863f69c608691c98e57c2f9be2db9dfed ] nfs4_client_to_reclaim() unconditionally allocates a new nfs4_client_reclaim, prepends it to reclaim_str_hashtbl[], and bumps reclaim_str_hashtbl_size with no check for an existing entry for the same client name. After a reboot with a populated recovery directory that inflates the counter by one for every client that reclaims: boot: load_recdir() nfs4_client_to_reclaim(name) /* entry #1, size++ */ grace: RECLAIM_COMPLETE __nfsd4_create_reclaim_record_grace() nfs4_client_to_reclaim(name) /* entry #2, size++ */ inc_reclaim_complete() ends the grace period early only when atomic_inc_return(&nn->nr_reclaim_complete) == nn->reclaim_str_hashtbl_size With reclaim_str_hashtbl_size at 2N and nr_reclaim_complete capped at N, the equality never holds and the fast end-of-grace path is dead. The grace period always runs out the full 90-second laundromat timer, and the shadow entry left in the hash table carries a dangling cr_clp for any reader that walks it. Fix nfs4_client_to_reclaim() to look the name up with nfsd4_find_reclaim_client() first and, on a hit, fold the new princhash into the existing record (if it lacks one) and return that record without allocating or touching reclaim_str_hashtbl_size. On kmemdup() failure during the fold-in, return NULL so __cld_pipe_inprogress_downcall() surfaces -EFAULT to nfsdcld, matching the miss-path contract. Add an rw_semaphore (reclaim_str_hashtbl_lock) to struct nfsd_net that serialises all access to reclaim_str_hashtbl[] and reclaim_str_hashtbl_size. Writers (nfs4_client_to_reclaim, nfs4_remove_reclaim_record callers) hold the write side; readers (nfsd4_cld_check*, inc_reclaim_complete, clients_still_reclaiming, nfs4_has_reclaimed_state, nfsd4_check_legacy_client) hold the read side. All call sites are in sleepable context, and none is a hot path, so the rwsem cost is negligible. Reported-by: Chris Mason Fixes: 362063a595be ("nfsd: keep a tally of RECLAIM_COMPLETE operations when using nfsdcld") Cc: stable@vger.kernel.org Assisted-by: kres:claude-opus-4-7 Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20260530-nfsd-fixes-v2-4-f27e8eb4d974@kernel.org Signed-off-by: Chuck Lever Signed-off-by: Sasha Levin --- fs/nfsd/netns.h | 6 ++++- fs/nfsd/nfs4recover.c | 36 ++++++++++++++++++++----- fs/nfsd/nfs4state.c | 61 ++++++++++++++++++++++++++++++++++++++----- 3 files changed, 89 insertions(+), 14 deletions(-) diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h index 734b21132a99f..42755ca098956 100644 --- a/fs/nfsd/netns.h +++ b/fs/nfsd/netns.h @@ -92,6 +92,7 @@ struct nfsd_net { */ struct list_head *reclaim_str_hashtbl; int reclaim_str_hashtbl_size; + struct rw_semaphore reclaim_str_hashtbl_lock; struct list_head *conf_id_hashtbl; struct rb_root conf_name_tree; struct list_head *unconf_id_hashtbl; @@ -104,7 +105,10 @@ struct nfsd_net { * close_lru holds (open) stateowner queue ordered by nfs4_stateowner.so_time * for last close replay. * - * All of the above fields are protected by the client_mutex. + * reclaim_str_hashtbl[], reclaim_str_hashtbl_size are protected by + * reclaim_str_hashtbl_lock. + * + * All of the remaining fields are protected by the client_lock. */ struct list_head client_lru; struct list_head close_lru; diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c index 37006d0776ebd..b78b41fbbd4ff 100644 --- a/fs/nfsd/nfs4recover.c +++ b/fs/nfsd/nfs4recover.c @@ -337,10 +337,12 @@ __nfsd4_remove_reclaim_record_grace(const char *dname, int len, return; } name.len = len; + down_write(&nn->reclaim_str_hashtbl_lock); crp = nfsd4_find_reclaim_client(name, nn); - kfree(name.data); if (crp) nfs4_remove_reclaim_record(crp, nn); + up_write(&nn->reclaim_str_hashtbl_lock); + kfree(name.data); } static void @@ -541,6 +543,7 @@ nfs4_legacy_state_init(struct net *net) for (i = 0; i < CLIENT_HASH_SIZE; i++) INIT_LIST_HEAD(&nn->reclaim_str_hashtbl[i]); nn->reclaim_str_hashtbl_size = 0; + init_rwsem(&nn->reclaim_str_hashtbl_lock); return 0; } @@ -660,13 +663,16 @@ nfsd4_check_legacy_client(struct nfs4_client *clp) goto out_enoent; } name.len = HEXDIR_LEN; + down_read(&nn->reclaim_str_hashtbl_lock); crp = nfsd4_find_reclaim_client(name, nn); - kfree(name.data); if (crp) { set_bit(NFSD4_CLIENT_STABLE, &clp->cl_flags); crp->cr_clp = clp; - return 0; } + up_read(&nn->reclaim_str_hashtbl_lock); + kfree(name.data); + if (crp) + return 0; out_enoent: return -ENOENT; @@ -1238,6 +1244,7 @@ nfsd4_cld_check(struct nfs4_client *clp) return 0; /* look for it in the reclaim hashtable otherwise */ + down_read(&nn->reclaim_str_hashtbl_lock); crp = nfsd4_find_reclaim_client(clp->cl_name, nn); if (crp) goto found; @@ -1256,6 +1263,7 @@ nfsd4_cld_check(struct nfs4_client *clp) if (!name.data) { dprintk("%s: failed to allocate memory for name.data!\n", __func__); + up_read(&nn->reclaim_str_hashtbl_lock); return -ENOENT; } name.len = HEXDIR_LEN; @@ -1266,9 +1274,11 @@ nfsd4_cld_check(struct nfs4_client *clp) } #endif + up_read(&nn->reclaim_str_hashtbl_lock); return -ENOENT; found: crp->cr_clp = clp; + up_read(&nn->reclaim_str_hashtbl_lock); return 0; } @@ -1280,6 +1290,7 @@ nfsd4_cld_check_v2(struct nfs4_client *clp) struct cld_net *cn = nn->cld_net; #endif struct nfs4_client_reclaim *crp; + unsigned int princhashlen; char *principal = NULL; /* did we already find that this client is stable? */ @@ -1287,6 +1298,7 @@ nfsd4_cld_check_v2(struct nfs4_client *clp) return 0; /* look for it in the reclaim hashtable otherwise */ + down_read(&nn->reclaim_str_hashtbl_lock); crp = nfsd4_find_reclaim_client(clp->cl_name, nn); if (crp) goto found; @@ -1305,6 +1317,7 @@ nfsd4_cld_check_v2(struct nfs4_client *clp) if (!name.data) { dprintk("%s: failed to allocate memory for name.data\n", __func__); + up_read(&nn->reclaim_str_hashtbl_lock); return -ENOENT; } name.len = HEXDIR_LEN; @@ -1315,23 +1328,31 @@ nfsd4_cld_check_v2(struct nfs4_client *clp) } #endif + up_read(&nn->reclaim_str_hashtbl_lock); return -ENOENT; found: - if (crp->cr_princhash.len) { + princhashlen = crp->cr_princhash.len; + if (princhashlen) { u8 digest[SHA256_DIGEST_SIZE]; + u8 *pdata; if (clp->cl_cred.cr_raw_principal) principal = clp->cl_cred.cr_raw_principal; else if (clp->cl_cred.cr_principal) principal = clp->cl_cred.cr_principal; - if (principal == NULL) + if (principal == NULL) { + up_read(&nn->reclaim_str_hashtbl_lock); return -ENOENT; + } sha256(principal, strlen(principal), digest); - if (memcmp(crp->cr_princhash.data, digest, - crp->cr_princhash.len)) + pdata = crp->cr_princhash.data; + if (memcmp(pdata, digest, princhashlen)) { + up_read(&nn->reclaim_str_hashtbl_lock); return -ENOENT; + } } crp->cr_clp = clp; + up_read(&nn->reclaim_str_hashtbl_lock); return 0; } @@ -1431,6 +1452,7 @@ nfs4_cld_state_init(struct net *net) for (i = 0; i < CLIENT_HASH_SIZE; i++) INIT_LIST_HEAD(&nn->reclaim_str_hashtbl[i]); nn->reclaim_str_hashtbl_size = 0; + init_rwsem(&nn->reclaim_str_hashtbl_lock); set_bit(NFSD_NET_TRACK_RECLAIM_COMPLETES, &nn->flags); atomic_set(&nn->nr_reclaim_complete, 0); diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 8d137516ae4b5..0a746d2245766 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -2555,14 +2555,21 @@ static void inc_reclaim_complete(struct nfs4_client *clp) if (!test_bit(NFSD_NET_TRACK_RECLAIM_COMPLETES, &nn->flags)) return; - if (!nfsd4_find_reclaim_client(clp->cl_name, nn)) + + down_read(&nn->reclaim_str_hashtbl_lock); + if (!nfsd4_find_reclaim_client(clp->cl_name, nn)) { + up_read(&nn->reclaim_str_hashtbl_lock); return; + } if (atomic_inc_return(&nn->nr_reclaim_complete) == nn->reclaim_str_hashtbl_size) { + up_read(&nn->reclaim_str_hashtbl_lock); printk(KERN_INFO "NFSD: all clients done reclaiming, ending NFSv4 grace period (net %x)\n", clp->net->ns.inum); nfsd4_end_grace(nn); + return; } + up_read(&nn->reclaim_str_hashtbl_lock); } static void expire_client(struct nfs4_client *clp) @@ -6682,10 +6689,15 @@ static bool clients_still_reclaiming(struct nfsd_net *nn) if (test_bit(NFSD_NET_GRACE_END_FORCED, &nn->flags)) return false; - if (test_bit(NFSD_NET_TRACK_RECLAIM_COMPLETES, &nn->flags) && - atomic_read(&nn->nr_reclaim_complete) == - nn->reclaim_str_hashtbl_size) - return false; + if (test_bit(NFSD_NET_TRACK_RECLAIM_COMPLETES, &nn->flags)) { + int size; + + down_read(&nn->reclaim_str_hashtbl_lock); + size = nn->reclaim_str_hashtbl_size; + up_read(&nn->reclaim_str_hashtbl_lock); + if (atomic_read(&nn->nr_reclaim_complete) == size) + return false; + } if (!test_bit(NFSD_NET_SOMEBODY_RECLAIMED, &nn->flags)) return false; clear_bit(NFSD_NET_SOMEBODY_RECLAIMED, &nn->flags); @@ -8845,9 +8857,13 @@ bool nfs4_has_reclaimed_state(struct xdr_netobj name, struct nfsd_net *nn) { struct nfs4_client_reclaim *crp; + bool found; + down_read(&nn->reclaim_str_hashtbl_lock); crp = nfsd4_find_reclaim_client(name, nn); - return (crp && crp->cr_clp); + found = (crp && crp->cr_clp); + up_read(&nn->reclaim_str_hashtbl_lock); + return found; } /* @@ -8860,10 +8876,39 @@ nfs4_client_to_reclaim(struct xdr_netobj name, struct xdr_netobj princhash, unsigned int strhashval; struct nfs4_client_reclaim *crp; + down_write(&nn->reclaim_str_hashtbl_lock); + + /* + * A reclaim record for this client name may already exist (for + * example, populated at boot from the recovery directory before + * an in-grace RECLAIM_COMPLETE or an nfsdcld downcall delivers + * the same name). Dedup here so reclaim_str_hashtbl_size stays + * equal to the number of distinct client names; inc_reclaim_complete + * relies on that equality to end the grace period via the fast path. + */ + crp = nfsd4_find_reclaim_client(name, nn); + if (crp) { + if (princhash.len && crp->cr_princhash.len == 0) { + void *pdata = kmemdup(princhash.data, princhash.len, + GFP_KERNEL); + if (pdata) { + crp->cr_princhash.data = pdata; + crp->cr_princhash.len = princhash.len; + } else { + dprintk("%s: failed to allocate memory for princhash.data!\n", + __func__); + crp = NULL; + } + } + up_write(&nn->reclaim_str_hashtbl_lock); + return crp; + } + name.data = kmemdup(name.data, name.len, GFP_KERNEL); if (!name.data) { dprintk("%s: failed to allocate memory for name.data!\n", __func__); + up_write(&nn->reclaim_str_hashtbl_lock); return NULL; } if (princhash.len) { @@ -8872,6 +8917,7 @@ nfs4_client_to_reclaim(struct xdr_netobj name, struct xdr_netobj princhash, dprintk("%s: failed to allocate memory for princhash.data!\n", __func__); kfree(name.data); + up_write(&nn->reclaim_str_hashtbl_lock); return NULL; } } else @@ -8891,6 +8937,7 @@ nfs4_client_to_reclaim(struct xdr_netobj name, struct xdr_netobj princhash, kfree(name.data); kfree(princhash.data); } + up_write(&nn->reclaim_str_hashtbl_lock); return crp; } @@ -8910,6 +8957,7 @@ nfs4_release_reclaim(struct nfsd_net *nn) struct nfs4_client_reclaim *crp = NULL; int i; + down_write(&nn->reclaim_str_hashtbl_lock); for (i = 0; i < CLIENT_HASH_SIZE; i++) { while (!list_empty(&nn->reclaim_str_hashtbl[i])) { crp = list_entry(nn->reclaim_str_hashtbl[i].next, @@ -8918,6 +8966,7 @@ nfs4_release_reclaim(struct nfsd_net *nn) } } WARN_ON_ONCE(nn->reclaim_str_hashtbl_size); + up_write(&nn->reclaim_str_hashtbl_lock); } /* -- 2.53.0