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 8232513D278; Tue, 3 Sep 2024 14:40:30 +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=1725374430; cv=none; b=ftRGO+i7+Pg9PVShuoSSxgcJD4kN+Yi3Mk/q15cu+S0Pltc2gInTYmmxUR6IqbiVZVQA2Q6/K3m1XILNE8Nxjm6+nmd1HsLs5K0iT14u8qRK5iLIfoPCN/RxZwaFQSVEMHmDPEGQ40kjF0r4zIxI1cwP62yPDz2NnWvJfyeqZA4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725374430; c=relaxed/simple; bh=nN3Oad2MShm7iw41e7lEUXNxvnPVyXpBrnxL4+zRq+8=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=pne30H1VzT6MaZQ4RVa4KuynCXxdm7TrgFvDiM3KCmAmDsqTUSAvQ0e1MXAY44gnVW6k7+b8YvxlZQ6MPQ43KXfH7ZhwQ34oYi7Qk6WeRLDpFk6RXXwnClkKvD6TFjswWh/jHPtnx+1Q6YC+WAcibcoBKTGvCKujLuLveG8E6+k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Jo/1koHa; 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="Jo/1koHa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5D625C4CEC4; Tue, 3 Sep 2024 14:40:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1725374430; bh=nN3Oad2MShm7iw41e7lEUXNxvnPVyXpBrnxL4+zRq+8=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=Jo/1koHaZZsmaEZgpU5KggR0M0hBaFApgbASdeHXkXQ5KLeOGAhjAscFoy5FmYzbt XD9ryXxqR9FOd0ykHuqJdZLcyoc564iZZWbdTfTZc44NysV4YyWJkNO63yoJzZqQq/ C4GsKk102Jc7KZdvSURig3MtDWS9rZxUC2lzrIixszIgGFKPv0ijGwSXEuruFBBYbc WqbQjasdq5Lb/2gX3ciUmuPi5jcPLWZhAqrICH2hwrzaEvSQ4x2fm2OZwZ+p1C9euO dbReu1pIscDZ01E9qNpFX2OWsPMavIPqTJO+IOE2X5bq0aOcNDU1CYI3I/aivsMdm1 PTfRwzq+pJvTQ== Message-ID: Subject: Re: [PATCH v15 16/26] nfsd: add LOCALIO support From: Jeff Layton To: Chuck Lever , Mike Snitzer Cc: linux-nfs@vger.kernel.org, Anna Schumaker , Trond Myklebust , NeilBrown , linux-fsdevel@vger.kernel.org Date: Tue, 03 Sep 2024 10:40:28 -0400 In-Reply-To: References: <20240831223755.8569-1-snitzer@kernel.org> <20240831223755.8569-17-snitzer@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV T2h6v8i8YqsATFPwO4nuiTmL6I40ZofxVd+9wdRI4Db8yUNA4ZSP2nqLcLtFjClYRBoJvRWvsv4lm 0OX6MYPtv76hka8lW4mnRmZqqx3UtfHX/hF/zH24Gj7A6sYKYLCU3YrI2Ogiu7/ksKcl7goQjpvtV 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> Add server support for bypassing NFS for localhost reads, writes, and > > commits. This is only useful when both the client and server are > > running on the same host. > >=20 > > If nfsd_open_local_fh() fails then the NFS client will both retry and > > fallback to normal network-based read, write and commit operations if > > localio is no longer supported. > >=20 > > Care is taken to ensure the same NFS security mechanisms are used > > (authentication, etc) regardless of whether localio or regular NFS > > access is used. The auth_domain established as part of the traditional > > NFS client access to the NFS server is also used for localio. Store > > auth_domain for localio in nfsd_uuid_t and transfer it to the client > > if it is local to the server. > >=20 > > Relative to containers, localio gives the client access to the network > > namespace the server has. This is required to allow the client to > > access the server's per-namespace nfsd_net struct. > >=20 > > This commit also introduces the use of NFSD's percpu_ref to interlock > > nfsd_destroy_serv and nfsd_open_local_fh, to ensure nn->nfsd_serv is > > not destroyed while in use by nfsd_open_local_fh and other LOCALIO > > client code. > >=20 > > CONFIG_NFS_LOCALIO enables NFS server support for LOCALIO. > >=20 > > Signed-off-by: Weston Andros Adamson > > Signed-off-by: Trond Myklebust > > Co-developed-by: Mike Snitzer > > Signed-off-by: Mike Snitzer > > Co-developed-by: NeilBrown > > Signed-off-by: NeilBrown > >=20 > > Not-Acked-by: Chuck Lever > > Not-Reviewed-by: Jeff Layton > > --- > > fs/nfsd/Makefile | 1 + > > fs/nfsd/filecache.c | 2 +- > > fs/nfsd/localio.c | 112 +++++++++++++++++++++++++++++++++++++ > > fs/nfsd/netns.h | 4 ++ > > fs/nfsd/nfsctl.c | 25 ++++++++- > > fs/nfsd/trace.h | 3 +- > > fs/nfsd/vfs.h | 2 + > > include/linux/nfslocalio.h | 8 +++ > > 8 files changed, 154 insertions(+), 3 deletions(-) > > create mode 100644 fs/nfsd/localio.c > >=20 > > diff --git a/fs/nfsd/Makefile b/fs/nfsd/Makefile > > index b8736a82e57c..18cbd3fa7691 100644 > > --- a/fs/nfsd/Makefile > > +++ b/fs/nfsd/Makefile > > @@ -23,3 +23,4 @@ nfsd-$(CONFIG_NFSD_PNFS) +=3D nfs4layouts.o > > nfsd-$(CONFIG_NFSD_BLOCKLAYOUT) +=3D blocklayout.o blocklayoutxdr.o > > nfsd-$(CONFIG_NFSD_SCSILAYOUT) +=3D blocklayout.o blocklayoutxdr.o > > nfsd-$(CONFIG_NFSD_FLEXFILELAYOUT) +=3D flexfilelayout.o flexfilelayou= txdr.o > > +nfsd-$(CONFIG_NFS_LOCALIO) +=3D localio.o > > diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c > > index 89ff380ec31e..348c1b97092e 100644 > > --- a/fs/nfsd/filecache.c > > +++ b/fs/nfsd/filecache.c > > @@ -52,7 +52,7 @@ > > #define NFSD_FILE_CACHE_UP (0) > > =20 > > /* We only care about NFSD_MAY_READ/WRITE for this cache */ > > -#define NFSD_FILE_MAY_MASK (NFSD_MAY_READ|NFSD_MAY_WRITE) > > +#define NFSD_FILE_MAY_MASK (NFSD_MAY_READ|NFSD_MAY_WRITE|NFSD_MAY_LOCA= LIO) > > =20 > > static DEFINE_PER_CPU(unsigned long, nfsd_file_cache_hits); > > static DEFINE_PER_CPU(unsigned long, nfsd_file_acquisitions); > > diff --git a/fs/nfsd/localio.c b/fs/nfsd/localio.c > > new file mode 100644 > > index 000000000000..75df709c6903 > > --- /dev/null > > +++ b/fs/nfsd/localio.c > > @@ -0,0 +1,112 @@ > > +// SPDX-License-Identifier: GPL-2.0-only > > +/* > > + * NFS server support for local clients to bypass network stack > > + * > > + * Copyright (C) 2014 Weston Andros Adamson > > + * Copyright (C) 2019 Trond Myklebust > > + * Copyright (C) 2024 Mike Snitzer > > + * Copyright (C) 2024 NeilBrown > > + */ > > + > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > + > > +#include "nfsd.h" > > +#include "vfs.h" > > +#include "netns.h" > > +#include "filecache.h" > > + > > +static const struct nfsd_localio_operations nfsd_localio_ops =3D { > > + .nfsd_open_local_fh =3D nfsd_open_local_fh, > > + .nfsd_file_put_local =3D nfsd_file_put_local, > > + .nfsd_file_file =3D nfsd_file_file, > > +}; > > + > > +void nfsd_localio_ops_init(void) > > +{ > > + memcpy(&nfs_to, &nfsd_localio_ops, sizeof(nfsd_localio_ops)); > > +} >=20 > Same comment as Neil: this should surface a pointer to the > localio_ops struct. Copying the whole set of function pointers is > generally unnecessary. >=20 >=20 > > + > > +/** > > + * nfsd_open_local_fh - lookup a local filehandle @nfs_fh and map to n= fsd_file > > + * > > + * @uuid: nfs_uuid_t which provides the 'struct net' to get the proper= nfsd_net > > + * and the 'struct auth_domain' required for LOCALIO access > > + * @rpc_clnt: rpc_clnt that the client established, used for sockaddr = and cred > > + * @cred: cred that the client established > > + * @nfs_fh: filehandle to lookup > > + * @fmode: fmode_t to use for open > > + * > > + * This function maps a local fh to a path on a local filesystem. > > + * This is useful when the nfs client has the local server mounted - i= t can > > + * avoid all the NFS overhead with reads, writes and commits. > > + * > > + * On successful return, returned nfsd_file will have its nf_net membe= r > > + * set. Caller (NFS client) is responsible for calling nfsd_serv_put a= nd > > + * nfsd_file_put (via nfs_to.nfsd_file_put_local). > > + */ > > +struct nfsd_file * > > +nfsd_open_local_fh(nfs_uuid_t *uuid, > > + struct rpc_clnt *rpc_clnt, const struct cred *cred, > > + const struct nfs_fh *nfs_fh, const fmode_t fmode) > > + __must_hold(rcu) > > +{ > > + int mayflags =3D NFSD_MAY_LOCALIO; > > + struct nfsd_net *nn =3D NULL; > > + struct net *net; > > + struct svc_cred rq_cred; > > + struct svc_fh fh; > > + struct nfsd_file *localio; > > + __be32 beres; > > + > > + if (nfs_fh->size > NFS4_FHSIZE) > > + return ERR_PTR(-EINVAL); > > + > > + /* > > + * Not running in nfsd context, so must safely get reference on nfsd_= serv. > > + * But the server may already be shutting down, if so disallow new lo= calio. > > + * uuid->net is NOT a counted reference, but caller's rcu_read_lock()= ensures > > + * that if uuid->net is not NULL, then calling nfsd_serv_try_get() is= safe > > + * and if it succeeds we will have an implied reference to the net. > > + */ > > + net =3D rcu_dereference(uuid->net); > > + if (net) > > + nn =3D net_generic(net, nfsd_net_id); > > + if (unlikely(!nn || !nfsd_serv_try_get(nn))) > > + return ERR_PTR(-ENXIO); > > + > > + /* Drop the rcu lock for nfsd_file_acquire_local() */ > > + rcu_read_unlock(); >=20 > I'm struggling with the locking logistics. Caller takes the RCU read > lock, this function drops the lock, then takes it again. So: >=20 > - A caller might rely on the lock being held continuously, but > - The API contract documented above doesn't indicate that this > function drops that lock > - The __must_hold(rcu) annotation doesn't indicate that this > function drops that lock, IIUC >=20 > Dropping and retaking the lock in here is an anti-pattern that > should be avoided. I suggest we are better off in the long run if > the caller does not need to take the RCU read lock, but instead, > nfsd_open_local_fh takes it right here just for the rcu_dereference. >=20 > OTOH, Why drop the lock before calling nfsd_file_acquire_local()? > The RCU read lock can safely be taken more than once in succession. >=20 > Let's rethink the locking strategy. >=20 Agreed. The only caller does this: rcu_read_lock(); if (!rcu_access_pointer(uuid->net)) { rcu_read_unlock(); return ERR_PTR(-ENXIO); } localio =3D nfs_to.nfsd_open_local_fh(uuid, rpc_clnt, cred, nfs_fh, fmode); rcu_read_unlock(); Maybe just move the check for uuid->net down into nfsd_open_local_fh, and it can acquire the rcu_read_lock for itself? >=20 > > + > > + /* nfs_fh -> svc_fh */ > > + fh_init(&fh, NFS4_FHSIZE); > > + fh.fh_handle.fh_size =3D nfs_fh->size; > > + memcpy(fh.fh_handle.fh_raw, nfs_fh->data, nfs_fh->size); > > + > > + if (fmode & FMODE_READ) > > + mayflags |=3D NFSD_MAY_READ; > > + if (fmode & FMODE_WRITE) > > + mayflags |=3D NFSD_MAY_WRITE; > > + > > + svcauth_map_clnt_to_svc_cred_local(rpc_clnt, cred, &rq_cred); > > + > > + beres =3D nfsd_file_acquire_local(uuid->net, &rq_cred, uuid->dom, > > + &fh, mayflags, &localio); > > + if (beres) { > > + localio =3D ERR_PTR(nfs_stat_to_errno(be32_to_cpu(beres))); > > + nfsd_serv_put(nn); > > + } > > + > > + fh_put(&fh); > > + if (rq_cred.cr_group_info) > > + put_group_info(rq_cred.cr_group_info); > > + > > + rcu_read_lock(); > > + return localio; > > +} > > +EXPORT_SYMBOL_GPL(nfsd_open_local_fh); > > diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h > > index e2d953f21dde..0fd31188a951 100644 > > --- a/fs/nfsd/netns.h > > +++ b/fs/nfsd/netns.h > > @@ -216,6 +216,10 @@ struct nfsd_net { > > /* last time an admin-revoke happened for NFSv4.0 */ > > time64_t nfs40_last_revoke; > > =20 > > +#if IS_ENABLED(CONFIG_NFS_LOCALIO) > > + /* Local clients to be invalidated when net is shut down */ > > + struct list_head local_clients; > > +#endif > > }; > > =20 > > /* Simple check to find out if a given net was properly initialized */ > > diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c > > index 64c1b4d649bc..3adbc05ebaac 100644 > > --- a/fs/nfsd/nfsctl.c > > +++ b/fs/nfsd/nfsctl.c > > @@ -18,6 +18,7 @@ > > #include > > #include > > #include > > +#include > > =20 > > #include "idmap.h" > > #include "nfsd.h" > > @@ -2257,7 +2258,9 @@ static __net_init int nfsd_net_init(struct net *n= et) > > get_random_bytes(&nn->siphash_key, sizeof(nn->siphash_key)); > > seqlock_init(&nn->writeverf_lock); > > nfsd_proc_stat_init(net); > > - > > +#if IS_ENABLED(CONFIG_NFS_LOCALIO) > > + INIT_LIST_HEAD(&nn->local_clients); > > +#endif > > return 0; > > =20 > > out_repcache_error: > > @@ -2268,6 +2271,22 @@ static __net_init int nfsd_net_init(struct net *= net) > > return retval; > > } > > =20 > > +#if IS_ENABLED(CONFIG_NFS_LOCALIO) > > +/** > > + * nfsd_net_pre_exit - Disconnect localio clients from net namespace > > + * @net: a network namespace that is about to be destroyed > > + * > > + * This invalidated ->net pointers held by localio clients > > + * while they can still safely access nn->counter. > > + */ > > +static __net_exit void nfsd_net_pre_exit(struct net *net) > > +{ > > + struct nfsd_net *nn =3D net_generic(net, nfsd_net_id); > > + > > + nfs_uuid_invalidate_clients(&nn->local_clients); > > +} > > +#endif > > + > > /** > > * nfsd_net_exit - Release the nfsd_net portion of a net namespace > > * @net: a network namespace that is about to be destroyed > > @@ -2285,6 +2304,9 @@ static __net_exit void nfsd_net_exit(struct net *= net) > > =20 > > static struct pernet_operations nfsd_net_ops =3D { > > .init =3D nfsd_net_init, > > +#if IS_ENABLED(CONFIG_NFS_LOCALIO) > > + .pre_exit =3D nfsd_net_pre_exit, > > +#endif > > .exit =3D nfsd_net_exit, > > .id =3D &nfsd_net_id, > > .size =3D sizeof(struct nfsd_net), > > @@ -2322,6 +2344,7 @@ static int __init init_nfsd(void) > > retval =3D genl_register_family(&nfsd_nl_family); > > if (retval) > > goto out_free_all; > > + nfsd_localio_ops_init(); > > =20 > > return 0; > > out_free_all: > > diff --git a/fs/nfsd/trace.h b/fs/nfsd/trace.h > > index d22027e23761..82bcefcd1f21 100644 > > --- a/fs/nfsd/trace.h > > +++ b/fs/nfsd/trace.h > > @@ -86,7 +86,8 @@ DEFINE_NFSD_XDR_ERR_EVENT(cant_encode); > > { NFSD_MAY_NOT_BREAK_LEASE, "NOT_BREAK_LEASE" }, \ > > { NFSD_MAY_BYPASS_GSS, "BYPASS_GSS" }, \ > > { NFSD_MAY_READ_IF_EXEC, "READ_IF_EXEC" }, \ > > - { NFSD_MAY_64BIT_COOKIE, "64BIT_COOKIE" }) > > + { NFSD_MAY_64BIT_COOKIE, "64BIT_COOKIE" }, \ > > + { NFSD_MAY_LOCALIO, "LOCALIO" }) > > =20 > > TRACE_EVENT(nfsd_compound, > > TP_PROTO( > > diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h > > index 01947561d375..3ff146522556 100644 > > --- a/fs/nfsd/vfs.h > > +++ b/fs/nfsd/vfs.h > > @@ -33,6 +33,8 @@ > > =20 > > #define NFSD_MAY_64BIT_COOKIE 0x1000 /* 64 bit readdir cookies for >= =3D NFSv3 */ > > =20 > > +#define NFSD_MAY_LOCALIO 0x2000 /* for tracing, reflects when localio= used */ > > + > > #define NFSD_MAY_CREATE (NFSD_MAY_EXEC|NFSD_MAY_WRITE) > > #define NFSD_MAY_REMOVE (NFSD_MAY_EXEC|NFSD_MAY_WRITE|NFSD_MAY_TRUNC) > > =20 > > diff --git a/include/linux/nfslocalio.h b/include/linux/nfslocalio.h > > index 62419c4bc8f1..61f2c781dd50 100644 > > --- a/include/linux/nfslocalio.h > > +++ b/include/linux/nfslocalio.h > > @@ -6,6 +6,8 @@ > > #ifndef __LINUX_NFSLOCALIO_H > > #define __LINUX_NFSLOCALIO_H > > =20 > > +#if IS_ENABLED(CONFIG_NFS_LOCALIO) > > + > > #include > > #include > > #include > > @@ -63,4 +65,10 @@ struct nfsd_localio_operations { > > extern void nfsd_localio_ops_init(void); > > extern struct nfsd_localio_operations nfs_to; > > =20 > > +#else /* CONFIG_NFS_LOCALIO */ > > +static inline void nfsd_localio_ops_init(void) > > +{ > > +} > > +#endif /* CONFIG_NFS_LOCALIO */ > > + > > #endif /* __LINUX_NFSLOCALIO_H */ > > --=20 > > 2.44.0 > >=20 >=20 --=20 Jeff Layton