From mboxrd@z Thu Jan 1 00:00:00 1970 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 0BFC71DE2D5; Mon, 28 Oct 2024 14:46:14 +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=1730126775; cv=none; b=cpKvm/0P/j+8SyyNA/9iVPuKuO1DMFsBy6r4LhLzm94FzIaDKBSoPajVyAoqymTUcyvXutI8/ArVAcxViCPKW+OJZyYubQSKqNUArxyO+Uv/ls8LLzTWqL0Fi5l2Gr9lJPShaLz2g1J6dAPNbHuMGYi0btNAN0Th91s39xVotLI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730126775; c=relaxed/simple; bh=wzNojl+T7NDvnnm/yCgNXawTAX8j3SlNRtud7MrNRMU=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=K9LV0sIF3cFk/CTXYW+p0PpE4a0azaJJNrET1U4IelLA8weNkg1t8+Xp5oa0yqOn1Dpq5rfyssBMbgB5wiqmTvezmbmGufXTzjncSohQ778y/Gpoclix/TBHEcsgbomo83gD3+qb7BPcyHz/EzoHtENSNoAnwexeHkaAotLfq9M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=oyLArzAf; 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="oyLArzAf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D661EC4CEC3; Mon, 28 Oct 2024 14:46:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730126774; bh=wzNojl+T7NDvnnm/yCgNXawTAX8j3SlNRtud7MrNRMU=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=oyLArzAf3cWTNyDKX0ED6Bs6DiIy+bCbcetMM+ZDSVdcePdhTa+jPCVMUWtbPYL/U VV3RRAwlButyLSvYXLxST6KTNdqwRg9T20sfqHC3S7f9iIPJGlaG2wD8Iqkk4nZCf5 M+a7E7eSI07c3ocSvsqIrc+QEa9rnKC4w3hfL3qIKzHJRVSLQPOdEHB9QzrTa9MGO9 tVhCfdE638TKeBaz0GSj78zPLORh7l1fVYyjjWNA/mNX1jKsAlm4Nae+GdhggIsZBz ylp58FQF2+eBPLCYL1EI9r5HH/9FCTdd5T3zp00rCs6w1gHRpEHyu7cJglUlVnaG9F IEReD+bR7Mf3A== Message-ID: Subject: Re: [PATCH 2/2] nfsd: allow for more callback session slots From: Jeff Layton To: Chuck Lever , Neil Brown , Dai Ngo , Tom Talpey Cc: Olga Kornievskaia , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Date: Mon, 28 Oct 2024 10:46:12 -0400 In-Reply-To: <20241028-bcwide-v1-2-0e75a8219dc0@kernel.org> References: <20241028-bcwide-v1-0-0e75a8219dc0@kernel.org> <20241028-bcwide-v1-2-0e75a8219dc0@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 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single slot in the callback channel, which is > proving to be a bottleneck in some cases. Widen the callback channel to > a max of 32 slots (subject to the client's target_maxreqs value). >=20 > Change the cb_holds_slot boolean to an integer that tracks the current > slot number (with -1 meaning "unassigned"). Move the callback slot > tracking info into the session. Add a new u32 that acts as a bitmap to > track which slots are in use, and a u32 to track the latest callback > target_slotid that the client reports. While they are part of the > session, the fields are protected by the cl_lock. >=20 > Fix nfsd41_cb_get_slot to always search for the lowest slotid (using > ffs()), and change it to continually retry until there is a slot > available. >=20 > Finally, convert the session->se_cb_seq_nr field into an array of > counters and add the necessary handling to ensure that the seqids get > reset at the appropriate times. >=20 > Signed-off-by: Jeff Layton > --- > fs/nfsd/nfs4callback.c | 107 +++++++++++++++++++++++++++++++++++--------= ------ > fs/nfsd/nfs4state.c | 7 +++- > fs/nfsd/state.h | 12 +++--- > fs/nfsd/trace.h | 2 +- > 4 files changed, 89 insertions(+), 39 deletions(-) >=20 > diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c > index e38fa834b3d91333acf1425eb14c644e5d5f2601..64b85b164125b244494f98058= 40a0d8a1ccb4c1b 100644 > --- a/fs/nfsd/nfs4callback.c > +++ b/fs/nfsd/nfs4callback.c > @@ -406,6 +406,16 @@ encode_cb_getattr4args(struct xdr_stream *xdr, struc= t nfs4_cb_compound_hdr *hdr, > hdr->nops++; > } > =20 > +static u32 highest_unset_index(u32 word) > +{ > + int i; > + > + for (i =3D sizeof(word) * 8 - 1; i > 0; --i) > + if (!(word & BIT(i))) > + return i; > + return 0; > +} > + > /* > * CB_SEQUENCE4args > * > @@ -432,15 +442,38 @@ static void encode_cb_sequence4args(struct xdr_stre= am *xdr, > encode_sessionid4(xdr, session); > =20 > p =3D xdr_reserve_space(xdr, 4 + 4 + 4 + 4 + 4); > - *p++ =3D cpu_to_be32(session->se_cb_seq_nr); /* csa_sequenceid */ > - *p++ =3D xdr_zero; /* csa_slotid */ > - *p++ =3D xdr_zero; /* csa_highest_slotid */ > + *p++ =3D cpu_to_be32(session->se_cb_seq_nr[cb->cb_held_slot]); /* csa_s= equenceid */ > + *p++ =3D cpu_to_be32(cb->cb_held_slot); /* csa_slotid */ > + *p++ =3D cpu_to_be32(max(highest_unset_index(session->se_cb_slot_avail)= , > + session->se_cb_highest_slot)); /* csa_highest_slotid */ > *p++ =3D xdr_zero; /* csa_cachethis */ > xdr_encode_empty_array(p); /* csa_referring_call_lists */ > =20 > hdr->nops++; > } > =20 > +static void update_cb_slot_table(struct nfsd4_session *ses, u32 highest) > +{ > + /* No need to do anything if nothing changed */ > + if (likely(highest =3D=3D READ_ONCE(ses->se_cb_highest_slot))) > + return; > + > + spin_lock(&ses->se_client->cl_lock); > + /* If growing the slot table, reset any new sequences to 1 */ > + if (highest > ses->se_cb_highest_slot) { > + int i; > + > + for (i =3D ses->se_cb_highest_slot; i <=3D highest; ++i) { That should be: for (i =3D ses->se_cb_highest_slot + 1; i <=3D highest; ++i) { IOW, we only want to reset the new slots, not any that could be in use. Fixed in my tree. > + /* beyond the end of the array? */ > + if (i >=3D NFSD_BC_SLOT_TABLE_MAX) > + break; > + ses->se_cb_seq_nr[i] =3D 1; > + } > + } > + ses->se_cb_highest_slot =3D highest; > + spin_unlock(&ses->se_client->cl_lock); > +} > + > /* > * CB_SEQUENCE4resok > * > @@ -485,7 +518,7 @@ static int decode_cb_sequence4resok(struct xdr_stream= *xdr, > p +=3D XDR_QUADLEN(NFS4_MAX_SESSIONID_LEN); > =20 > dummy =3D be32_to_cpup(p++); > - if (dummy !=3D session->se_cb_seq_nr) { > + if (dummy !=3D session->se_cb_seq_nr[cb->cb_held_slot]) { > dprintk("NFS: %s Invalid sequence number\n", __func__); > goto out; > } > @@ -496,9 +529,15 @@ static int decode_cb_sequence4resok(struct xdr_strea= m *xdr, > goto out; > } > =20 > - /* > - * FIXME: process highest slotid and target highest slotid > - */ > + p++; // ignore current highest slot value > + > + dummy =3D be32_to_cpup(p++); > + if (dummy =3D=3D 0) { > + dprintk("NFS: %s Invalid target highest slotid\n", __func__); > + goto out; > + } > + > + update_cb_slot_table(session, dummy); > status =3D 0; > out: > cb->cb_seq_status =3D status; > @@ -1208,31 +1247,38 @@ void nfsd4_change_callback(struct nfs4_client *cl= p, struct nfs4_cb_conn *conn) > * If the slot is available, then mark it busy. Otherwise, set the > * thread for sleeping on the callback RPC wait queue. > */ > -static bool nfsd41_cb_get_slot(struct nfsd4_callback *cb, struct rpc_tas= k *task) > +static void nfsd41_cb_get_slot(struct nfsd4_callback *cb, struct rpc_tas= k *task) > { > struct nfs4_client *clp =3D cb->cb_clp; > + struct nfsd4_session *ses =3D clp->cl_cb_session; > + int idx; > =20 > - if (!cb->cb_holds_slot && > - test_and_set_bit(0, &clp->cl_cb_slot_busy) !=3D 0) { > + if (cb->cb_held_slot >=3D 0) > + return; > +retry: > + spin_lock(&clp->cl_lock); > + idx =3D ffs(ses->se_cb_slot_avail) - 1; > + if (idx < 0 || idx > ses->se_cb_highest_slot) { > + spin_unlock(&clp->cl_lock); > rpc_sleep_on(&clp->cl_cb_waitq, task, NULL); > - /* Race breaker */ > - if (test_and_set_bit(0, &clp->cl_cb_slot_busy) !=3D 0) { > - dprintk("%s slot is busy\n", __func__); > - return false; > - } > - rpc_wake_up_queued_task(&clp->cl_cb_waitq, task); > + goto retry; > } > - cb->cb_holds_slot =3D true; > - return true; > + /* clear the bit for the slot */ > + ses->se_cb_slot_avail &=3D ~BIT(idx); > + spin_unlock(&clp->cl_lock); > + cb->cb_held_slot =3D idx; > } > =20 > static void nfsd41_cb_release_slot(struct nfsd4_callback *cb) > { > struct nfs4_client *clp =3D cb->cb_clp; > + struct nfsd4_session *ses =3D clp->cl_cb_session; > =20 > - if (cb->cb_holds_slot) { > - cb->cb_holds_slot =3D false; > - clear_bit(0, &clp->cl_cb_slot_busy); > + if (cb->cb_held_slot >=3D 0) { > + spin_lock(&clp->cl_lock); > + ses->se_cb_slot_avail |=3D BIT(cb->cb_held_slot); > + spin_unlock(&clp->cl_lock); > + cb->cb_held_slot =3D -1; > rpc_wake_up_next(&clp->cl_cb_waitq); > } > } > @@ -1265,8 +1311,8 @@ static void nfsd4_cb_prepare(struct rpc_task *task,= void *calldata) > trace_nfsd_cb_rpc_prepare(clp); > cb->cb_seq_status =3D 1; > cb->cb_status =3D 0; > - if (minorversion && !nfsd41_cb_get_slot(cb, task)) > - return; > + if (minorversion) > + nfsd41_cb_get_slot(cb, task); > rpc_call_start(task); > } > =20 > @@ -1292,7 +1338,7 @@ static bool nfsd4_cb_sequence_done(struct rpc_task = *task, struct nfsd4_callback > return true; > } > =20 > - if (!cb->cb_holds_slot) > + if (cb->cb_held_slot < 0) > goto need_restart; > =20 > /* This is the operation status code for CB_SEQUENCE */ > @@ -1306,10 +1352,10 @@ static bool nfsd4_cb_sequence_done(struct rpc_tas= k *task, struct nfsd4_callback > * If CB_SEQUENCE returns an error, then the state of the slot > * (sequence ID, cached reply) MUST NOT change. > */ > - ++session->se_cb_seq_nr; > + ++session->se_cb_seq_nr[cb->cb_held_slot]; > break; > case -ESERVERFAULT: > - ++session->se_cb_seq_nr; > + ++session->se_cb_seq_nr[cb->cb_held_slot]; > nfsd4_mark_cb_fault(cb->cb_clp); > ret =3D false; > break; > @@ -1335,17 +1381,16 @@ static bool nfsd4_cb_sequence_done(struct rpc_tas= k *task, struct nfsd4_callback > case -NFS4ERR_BADSLOT: > goto retry_nowait; > case -NFS4ERR_SEQ_MISORDERED: > - if (session->se_cb_seq_nr !=3D 1) { > - session->se_cb_seq_nr =3D 1; > + if (session->se_cb_seq_nr[cb->cb_held_slot] !=3D 1) { > + session->se_cb_seq_nr[cb->cb_held_slot] =3D 1; > goto retry_nowait; > } > break; > default: > nfsd4_mark_cb_fault(cb->cb_clp); > } > - nfsd41_cb_release_slot(cb); > - > trace_nfsd_cb_free_slot(task, cb); > + nfsd41_cb_release_slot(cb); > =20 > if (RPC_SIGNALLED(task)) > goto need_restart; > @@ -1565,7 +1610,7 @@ void nfsd4_init_cb(struct nfsd4_callback *cb, struc= t nfs4_client *clp, > INIT_WORK(&cb->cb_work, nfsd4_run_cb_work); > cb->cb_status =3D 0; > cb->cb_need_restart =3D false; > - cb->cb_holds_slot =3D false; > + cb->cb_held_slot =3D -1; > } > =20 > /** > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c > index 5b718b349396f1aecd0ad4c63b2f43342841bbd4..20a0d40202e40eed1c84d5d6c= 0a85b908804a6ba 100644 > --- a/fs/nfsd/nfs4state.c > +++ b/fs/nfsd/nfs4state.c > @@ -2002,6 +2002,8 @@ static struct nfsd4_session *alloc_session(struct n= fsd4_channel_attrs *fattrs, > } > =20 > memcpy(&new->se_fchannel, fattrs, sizeof(struct nfsd4_channel_attrs)); > + new->se_cb_slot_avail =3D ~0U; > + new->se_cb_highest_slot =3D battrs->maxreqs - 1; > return new; > out_free: > while (i--) > @@ -2132,7 +2134,9 @@ static void init_session(struct svc_rqst *rqstp, st= ruct nfsd4_session *new, stru > =20 > INIT_LIST_HEAD(&new->se_conns); > =20 > - new->se_cb_seq_nr =3D 1; > + for (idx =3D 0; idx < NFSD_BC_SLOT_TABLE_MAX; ++idx) > + new->se_cb_seq_nr[idx] =3D 1; > + > new->se_flags =3D cses->flags; > new->se_cb_prog =3D cses->callback_prog; > new->se_cb_sec =3D cses->cb_sec; > @@ -3159,7 +3163,6 @@ static struct nfs4_client *create_client(struct xdr= _netobj name, > kref_init(&clp->cl_nfsdfs.cl_ref); > nfsd4_init_cb(&clp->cl_cb_null, clp, NULL, NFSPROC4_CLNT_CB_NULL); > clp->cl_time =3D ktime_get_boottime_seconds(); > - clear_bit(0, &clp->cl_cb_slot_busy); > copy_verf(clp, verf); > memcpy(&clp->cl_addr, sa, sizeof(struct sockaddr_storage)); > clp->cl_cb_session =3D NULL; > diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h > index 41cda86fea1f6166a0fd0215d3d458c93ced3e6a..2987c362bdd56251e736879dc= 89302ada2259be8 100644 > --- a/fs/nfsd/state.h > +++ b/fs/nfsd/state.h > @@ -71,8 +71,8 @@ struct nfsd4_callback { > struct work_struct cb_work; > int cb_seq_status; > int cb_status; > + int cb_held_slot; > bool cb_need_restart; > - bool cb_holds_slot; > }; > =20 > struct nfsd4_callback_ops { > @@ -307,6 +307,9 @@ struct nfsd4_conn { > unsigned char cn_flags; > }; > =20 > +/* Max number of slots that the server will use in the backchannel */ > +#define NFSD_BC_SLOT_TABLE_MAX 32 > + > /* > * Representation of a v4.1+ session. These are refcounted in a similar = fashion > * to the nfs4_client. References are only taken when the server is acti= vely > @@ -325,7 +328,9 @@ struct nfsd4_session { > struct nfsd4_cb_sec se_cb_sec; > struct list_head se_conns; > u32 se_cb_prog; > - u32 se_cb_seq_nr; > + u32 se_cb_slot_avail; /* bitmap of available slots */ > + u32 se_cb_highest_slot; /* highest slot client wants */ > + u32 se_cb_seq_nr[NFSD_BC_SLOT_TABLE_MAX]; > struct nfsd4_slot *se_slots[]; /* forward channel slots */ > }; > =20 > @@ -459,9 +464,6 @@ struct nfs4_client { > */ > struct dentry *cl_nfsd_info_dentry; > =20 > - /* for nfs41 callbacks */ > - /* We currently support a single back channel with a single slot */ > - unsigned long cl_cb_slot_busy; > struct rpc_wait_queue cl_cb_waitq; /* backchannel callers may */ > /* wait here for slots */ > struct net *net; > diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h > index f318898cfc31614b5a84a4867e18c2b3a07122c9..a9c17186b6892f1df8d7f7b90= e250c2913ab23fe 100644 > --- a/fs/nfsd/trace.h > +++ b/fs/nfsd/trace.h > @@ -1697,7 +1697,7 @@ TRACE_EVENT(nfsd_cb_free_slot, > __entry->cl_id =3D sid->clientid.cl_id; > __entry->seqno =3D sid->sequence; > __entry->reserved =3D sid->reserved; > - __entry->slot_seqno =3D session->se_cb_seq_nr; > + __entry->slot_seqno =3D session->se_cb_seq_nr[cb->cb_held_slot]; > ), > TP_printk(SUNRPC_TRACE_TASK_SPECIFIER > " sessionid=3D%08x:%08x:%08x:%08x new slot seqno=3D%u", >=20 --=20 Jeff Layton