From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793831252; b=UeAHR/DM5ZxAq54diVgpbbljNtwegK0MHJkvSxS5hKieNh8Yl/+GsNvART/yujSdfcib i0S7CsiHgCmka3ATIX8mtCog6+rQrIATbQHj824Ld5RrKISMXo142FOtepQmZP/K0Gvdk nJ2InuJViQzmQDi0TA2awnOXJa4RAQgc2PVJwhTPE/avUn1Z+/664Q4442VIYSpIfJRyw toAnjBPg4lbiEx+AegNqvJOAL0ypEWCNd/l12rG96xLO+N9a4mG+MDMGLRHUMy+bDxj42 pSNbmWuL2CjYYZ/l73lg8D9x3o5IZlBkAZtUGho6Vm9nhJTKiBH61ZtNFUgrtIY0kQA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793831252; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=bn/59gm+3kpuRf+GRKa8FUGw5V+VtApXq8zBj8EzOhk=; b=Vnyfh/YerSPNJDGLoA4x7HC7lJUgdGvOIUTRclOklSzg+eaQa/LraqzjWfwSekdfSEh4 Uoe2a/+RjkM/EDDt/1RDzENxnxvaiPguTRzcRkr7Sh7qvMwwkEygYaINM++I6k5M03/b9 ixG4/cnHDxNqpn/yb2IYhtG1JCP1XNy93wlR1r7J3PAFaSuwMNoTxlB+xqcCnZzBiTdxK DYuV/K4ae2clCi3anMAGmpegR+pWAe7Bttuon//qBavYNYM7MDF4al4fn/0KTn+RAO0VK 094PRfKPeOXwj3Qpn7P8QkbMUye8xfeY48MmyFqddhPnWAwCoKEx2AJI3+2AdB8GVZg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=IP5xHELR; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7E4B5606B382; Wed, 4 Nov 2026 22:27:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=IP5xHELR Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A0C41F00919; Wed, 4 Nov 2026 22:27:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793831252; bh=bn/59gm+3kpuRf+GRKa8FUGw5V+VtApXq8zBj8EzOhk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=IP5xHELRW80cRn1/fprVR0SViEXRk1Q1W3PL6yoF2rpaYaDXyeqR7L33eMuWm0jaG am4KEziuHwBrsB01Msm9bSmhI12FSljqDvQvQak/zRg6vAv1fpZAmDQ2KDZVlZMRw9 o2trMlUduPI9mzOkJJVSscuWdU4Zm/TAIEqVD5Qk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chris Mason , Jeff Layton , Chuck Lever , Sasha Levin Subject: [PATCH 6.18 0553/1005] nfsd: dedup nfs4_client_to_reclaim inserts Date: Wed, 4 Nov 2026 16:04:46 -0500 Message-ID: <20261104211059.382824604@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ 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 b9485b24df0a5..ccb0256b9366e 100644 --- a/fs/nfsd/netns.h +++ b/fs/nfsd/netns.h @@ -93,6 +93,7 @@ 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; @@ -105,7 +106,10 @@ 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 b3ad502d89eb3..f5671861ef7e7 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -2689,14 +2689,21 @@ 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) @@ -6840,10 +6847,15 @@ 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); @@ -9056,9 +9068,13 @@ 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; } /* @@ -9071,10 +9087,39 @@ 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) { @@ -9083,6 +9128,7 @@ 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 @@ -9102,6 +9148,7 @@ 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; } @@ -9121,6 +9168,7 @@ 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, @@ -9129,6 +9177,7 @@ 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