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 B00051AB505; Thu, 29 Aug 2024 16:40:29 +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=1724949629; cv=none; b=hEMzdRDhMLt5Ck/U3w7bLTTGnR7RfDO4Ob7uvjwN8AdK94rGRTTx2dxFvXMgCycc6/a2eCINSMKEtVxJS3drtQFCS+ImnEE5woVj+IOtgAa1GIXJ8QjMzh49g0UxiEehEHvEIoCI/wmvCDklyCZt6PCbQgzobRuJJllyT8n1krc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724949629; c=relaxed/simple; bh=+vas9FIvy57xLalqCJGi5kcVAENb9TBrhTuPOtN4omY=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=ZMnzDsq9/Mz1nTpsFUQHoiNBG9R6EBC0h2EdOHsAN0YG9ddl31h8e/ZK7pBrKS1QBLG+IHtEYOmDt33VzEWQcH8E6CzyCNU1WOCGhoeooZsGher8MibcZ8DybtwcmMoIgbPIJ1tz9REhlO+syMa/2mqWQ6J0p5jF56WCThwUBBg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=VYr81UFW; 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="VYr81UFW" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8BECAC4CEC1; Thu, 29 Aug 2024 16:40:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724949629; bh=+vas9FIvy57xLalqCJGi5kcVAENb9TBrhTuPOtN4omY=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=VYr81UFWlbAFz/XM/VAH95ukOe52U0oWQ6hOIKzd0z7fnjRjAX+GGYraZ6s3T2GVy KHNSz0rTkT6yTxidzaCbT8k03t31VM4W4YNuuFfg3mA1AIT9d8zW0bFrrPMs3r9mnn PVZqkwz1DyGhTjYUWe2BbhUNSwhE0lORpo9/KFbJeG69PcZpGBdoxqAzkgPgUtN+ZH PmYPOeYPop1rpJeWsN1Wz+i6tggIwF1wDjARVCQKJMWHIndh89z7crqDPvxIkSxBms 3eaAw3V0Zju8ytYUjNhNypbpuMvIfpqlQGoTZePTBb+57GTSb00i/RnxOevgCF9lux sbMnecuF93ohA== Message-ID: <43d5ce3b7b374ed2ac7595932e2109e14ffd13e7.camel@kernel.org> Subject: Re: [PATCH v14 15/25] nfs_common: introduce nfs_localio_ctx struct and interfaces From: Jeff Layton To: Mike Snitzer , linux-nfs@vger.kernel.org Cc: Chuck Lever , Anna Schumaker , Trond Myklebust , NeilBrown , linux-fsdevel@vger.kernel.org Date: Thu, 29 Aug 2024 12:40:27 -0400 In-Reply-To: <20240829010424.83693-16-snitzer@kernel.org> References: <20240829010424.83693-1-snitzer@kernel.org> <20240829010424.83693-16-snitzer@kernel.org> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Wed, 2024-08-28 at 21:04 -0400, Mike Snitzer wrote: > Introduce struct nfs_localio_ctx and the interfaces > nfs_localio_ctx_alloc() and nfs_localio_ctx_free(). The next commit > will introduce nfsd_open_local_fh() which returns a nfs_localio_ctx > structure. >=20 > Also, expose localio's required NFSD symbols to NFS client: > - Cache nfsd_open_local_fh symbol and other required NFSD symbols in a > globally accessible 'nfs_to' nfs_to_nfsd_t struct. Add interfaces > get_nfs_to_nfsd_symbols() and put_nfs_to_nfsd_symbols() to allow > each NFS client to take a reference on NFSD symbols. >=20 > - Apologies for the DEFINE_NFS_TO_NFSD_SYMBOL macro that makes > defining get_##NFSD_SYMBOL() and put_##NFSD_SYMBOL() functions far > simpler (and avoids cut-n-paste bugs, which is what motivated the > development and use of a macro for this). But as C macros go it is a > very simple one and there are many like it all over the kernel. >=20 > - Given the unique nature of NFS LOCALIO being an optional feature > that when used requires NFS share access to NFSD memory: a unique > bridging of NFSD resources to NFS (via nfs_common) is needed. But > that bridge must be dynamic, hence the use of symbol_request() and > symbol_put(). Proposed ideas to accomolish the same without using > symbol_{request,put} would be far more tedious to implement and > very likely no easier to review. Anyway: sorry NeilBrown... >=20 > - Despite the use of indirect function calls, caching these nfsd > symbols for use by the client offers a ~10% performance win > (compared to always doing get+call+put) for high IOPS workloads. >=20 > - Introduce nfsd_file_file() wrapper that provides access to > nfsd_file's backing file. Keeps nfsd_file structure opaque to NFS > client (as suggested by Jeff Layton). >=20 > - The addition of nfsd_file_get, nfsd_file_put and nfsd_file_file > symbols prepares for the NFS client to use nfsd_file for localio. >=20 > Suggested-by: Trond Myklebust # nfs_to > Suggested-by: Jeff Layton # nfsd_file_file > Signed-off-by: Mike Snitzer > --- > fs/nfs_common/nfslocalio.c | 159 +++++++++++++++++++++++++++++++++++++ > fs/nfsd/filecache.c | 25 ++++++ > fs/nfsd/filecache.h | 1 + > fs/nfsd/nfssvc.c | 5 ++ > include/linux/nfslocalio.h | 38 +++++++++ > 5 files changed, 228 insertions(+) >=20 > diff --git a/fs/nfs_common/nfslocalio.c b/fs/nfs_common/nfslocalio.c > index 1a35a4a6dbe0..cc30fdb0cb46 100644 > --- a/fs/nfs_common/nfslocalio.c > +++ b/fs/nfs_common/nfslocalio.c > @@ -72,3 +72,162 @@ bool nfs_uuid_is_local(const uuid_t *uuid, struct net= *net, struct auth_domain * > return is_local; > } > EXPORT_SYMBOL_GPL(nfs_uuid_is_local); > + > +/* > + * The nfs localio code needs to call into nfsd using various symbols (b= elow), > + * but cannot be statically linked, because that will make the nfs modul= e > + * depend on the nfsd module. > + * > + * Instead, do dynamic linking to the nfsd module (via nfs_common module= ). The > + * nfs_common module will only hold a reference on nfsd when localio is = in use. > + * This allows some sanity checking, like giving up on localio if nfsd i= sn't loaded. > + */ > +static DEFINE_SPINLOCK(nfs_to_nfsd_lock); > +nfs_to_nfsd_t nfs_to; > +EXPORT_SYMBOL_GPL(nfs_to); > + > +/* Macro to define nfs_to get and put methods, avoids copy-n-paste bugs = */ > +#define DEFINE_NFS_TO_NFSD_SYMBOL(NFSD_SYMBOL) \ > +static nfs_to_##NFSD_SYMBOL##_t get_##NFSD_SYMBOL(void) \ > +{ \ > + return symbol_request(NFSD_SYMBOL); \ > +} \ > +static void put_##NFSD_SYMBOL(void) \ > +{ \ > + symbol_put(NFSD_SYMBOL); \ > + nfs_to.NFSD_SYMBOL =3D NULL; \ > +} > + > +/* The nfs localio code needs to call into nfsd to map filehandle -> str= uct nfsd_file */ > +extern struct nfs_localio_ctx * > +nfsd_open_local_fh(struct net *, struct auth_domain *, struct rpc_clnt *= , > + const struct cred *, const struct nfs_fh *, const fmode_t); > +DEFINE_NFS_TO_NFSD_SYMBOL(nfsd_open_local_fh); > + > +/* The nfs localio code needs to call into nfsd to acquire the nfsd_file= */ > +extern struct nfsd_file *nfsd_file_get(struct nfsd_file *nf); > +DEFINE_NFS_TO_NFSD_SYMBOL(nfsd_file_get); > + > +/* The nfs localio code needs to call into nfsd to release the nfsd_file= */ > +extern void nfsd_file_put(struct nfsd_file *nf); > +DEFINE_NFS_TO_NFSD_SYMBOL(nfsd_file_put); > + > +/* The nfs localio code needs to call into nfsd to access the nf->nf_fil= e */ > +extern struct file * nfsd_file_file(struct nfsd_file *nf); > +DEFINE_NFS_TO_NFSD_SYMBOL(nfsd_file_file); > + > +/* The nfs localio code needs to call into nfsd to release nn->nfsd_serv= */ > +extern void nfsd_serv_put(struct nfsd_net *nn); > +DEFINE_NFS_TO_NFSD_SYMBOL(nfsd_serv_put); > +#undef DEFINE_NFS_TO_NFSD_SYMBOL > + I have the same concerns as Neil did with this patch in v13. An ops structure that nfsd registers with nfs_common and that has pointers to all of these functions would be a lot cleaner. I think it'll end up being less code too. In fact, for that I'd probably break my usual guideline of not introducing new interfaces without callers, and just do a separate patch that adds the ops structure and sets up the handling of the pointer to it in nfs_common. > +static struct kmem_cache *nfs_localio_ctx_cache; > + > +struct nfs_localio_ctx *nfs_localio_ctx_alloc(void) > +{ > + return kmem_cache_alloc(nfs_localio_ctx_cache, > + GFP_KERNEL | __GFP_ZERO); > +} > +EXPORT_SYMBOL_GPL(nfs_localio_ctx_alloc); > + > +void nfs_localio_ctx_free(struct nfs_localio_ctx *localio) > +{ > + if (localio->nf) > + nfs_to.nfsd_file_put(localio->nf); > + if (localio->nn) > + nfs_to.nfsd_serv_put(localio->nn); > + kmem_cache_free(nfs_localio_ctx_cache, localio); > +} > +EXPORT_SYMBOL_GPL(nfs_localio_ctx_free); > + > +bool get_nfs_to_nfsd_symbols(void) > +{ > + spin_lock(&nfs_to_nfsd_lock); > + > + /* Only get symbols on first reference */ > + if (refcount_read(&nfs_to.ref) =3D=3D 0) > + refcount_set(&nfs_to.ref, 1); > + else { > + refcount_inc(&nfs_to.ref); > + spin_unlock(&nfs_to_nfsd_lock); > + return true; > + } > + > + nfs_to.nfsd_open_local_fh =3D get_nfsd_open_local_fh(); > + if (!nfs_to.nfsd_open_local_fh) > + goto out_nfsd_open_local_fh; > + > + nfs_to.nfsd_file_get =3D get_nfsd_file_get(); > + if (!nfs_to.nfsd_file_get) > + goto out_nfsd_file_get; > + > + nfs_to.nfsd_file_put =3D get_nfsd_file_put(); > + if (!nfs_to.nfsd_file_put) > + goto out_nfsd_file_put; > + > + nfs_to.nfsd_file_file =3D get_nfsd_file_file(); > + if (!nfs_to.nfsd_file_file) > + goto out_nfsd_file_file; > + > + nfs_to.nfsd_serv_put =3D get_nfsd_serv_put(); > + if (!nfs_to.nfsd_serv_put) > + goto out_nfsd_serv_put; > + > + spin_unlock(&nfs_to_nfsd_lock); > + return true; > + > +out_nfsd_serv_put: > + put_nfsd_file_file(); > +out_nfsd_file_file: > + put_nfsd_file_put(); > +out_nfsd_file_put: > + put_nfsd_file_get(); > +out_nfsd_file_get: > + put_nfsd_open_local_fh(); > +out_nfsd_open_local_fh: > + spin_unlock(&nfs_to_nfsd_lock); > + return false; > +} > +EXPORT_SYMBOL_GPL(get_nfs_to_nfsd_symbols); > + > +void put_nfs_to_nfsd_symbols(void) > +{ > + spin_lock(&nfs_to_nfsd_lock); > + > + if (!refcount_dec_and_test(&nfs_to.ref)) > + goto out; > + > + put_nfsd_open_local_fh(); > + put_nfsd_file_get(); > + put_nfsd_file_put(); > + put_nfsd_file_file(); > + put_nfsd_serv_put(); > +out: > + spin_unlock(&nfs_to_nfsd_lock); > +} > +EXPORT_SYMBOL_GPL(put_nfs_to_nfsd_symbols); > + > +static int __init nfslocalio_init(void) > +{ > + refcount_set(&nfs_to.ref, 0); > + > + nfs_to.nfsd_open_local_fh =3D NULL; > + nfs_to.nfsd_file_get =3D NULL; > + nfs_to.nfsd_file_put =3D NULL; > + nfs_to.nfsd_file_file =3D NULL; > + nfs_to.nfsd_serv_put =3D NULL; > + > + nfs_localio_ctx_cache =3D KMEM_CACHE(nfs_localio_ctx, 0); > + if (!nfs_localio_ctx_cache) > + return -ENOMEM; > + > + return 0; > +} > + > +static void __exit nfslocalio_exit(void) > +{ > + kmem_cache_destroy(nfs_localio_ctx_cache); > +} > + > +module_init(nfslocalio_init); > +module_exit(nfslocalio_exit); > diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c > index 2dc72de31f61..a83d469bca6b 100644 > --- a/fs/nfsd/filecache.c > +++ b/fs/nfsd/filecache.c > @@ -39,6 +39,7 @@ > #include > #include > #include > +#include > =20 > #include "vfs.h" > #include "nfsd.h" > @@ -345,6 +346,10 @@ nfsd_file_get(struct nfsd_file *nf) > return nf; > return NULL; > } > +EXPORT_SYMBOL_GPL(nfsd_file_get); > + > +/* Compile time type checking, not used by anything */ > +static nfs_to_nfsd_file_get_t __maybe_unused nfsd_file_get_typecheck =3D= nfsd_file_get; > =20 > /** > * nfsd_file_put - put the reference to a nfsd_file > @@ -389,6 +394,26 @@ nfsd_file_put(struct nfsd_file *nf) > if (refcount_dec_and_test(&nf->nf_ref)) > nfsd_file_free(nf); > } > +EXPORT_SYMBOL_GPL(nfsd_file_put); > + > +/* Compile time type checking, not used by anything */ > +static nfs_to_nfsd_file_put_t __maybe_unused nfsd_file_put_typecheck =3D= nfsd_file_put; > + > +/** > + * nfsd_file_file - get the backing file of an nfsd_file > + * @nf: nfsd_file of which to access the backing file. > + * > + * Return backing file for @nf. > + */ > +struct file * > +nfsd_file_file(struct nfsd_file *nf) > +{ > + return nf->nf_file; > +} > +EXPORT_SYMBOL_GPL(nfsd_file_file); > + > +/* Compile time type checking, not used by anything */ > +static nfs_to_nfsd_file_file_t __maybe_unused nfsd_file_file_typecheck = =3D nfsd_file_file; > =20 > static void > nfsd_file_dispose_list(struct list_head *dispose) > diff --git a/fs/nfsd/filecache.h b/fs/nfsd/filecache.h > index 26ada78b8c1e..6fbbb2e32e95 100644 > --- a/fs/nfsd/filecache.h > +++ b/fs/nfsd/filecache.h > @@ -56,6 +56,7 @@ int nfsd_file_cache_start_net(struct net *net); > void nfsd_file_cache_shutdown_net(struct net *net); > void nfsd_file_put(struct nfsd_file *nf); > struct nfsd_file *nfsd_file_get(struct nfsd_file *nf); > +struct file *nfsd_file_file(struct nfsd_file *nf); > void nfsd_file_close_inode_sync(struct inode *inode); > void nfsd_file_net_dispose(struct nfsd_net *nn); > bool nfsd_file_is_cached(struct inode *inode); > diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c > index c639fbe4d8c2..13c69aa40d1c 100644 > --- a/fs/nfsd/nfssvc.c > +++ b/fs/nfsd/nfssvc.c > @@ -19,6 +19,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -201,6 +202,10 @@ void nfsd_serv_put(struct nfsd_net *nn) > { > percpu_ref_put(&nn->nfsd_serv_ref); > } > +EXPORT_SYMBOL_GPL(nfsd_serv_put); > + > +/* Compile time type checking, not used by anything */ > +static nfs_to_nfsd_serv_put_t __maybe_unused nfsd_serv_put_typecheck =3D= nfsd_serv_put; > =20 > static void nfsd_serv_done(struct percpu_ref *ref) > { > diff --git a/include/linux/nfslocalio.h b/include/linux/nfslocalio.h > index 9735ae8d3e5e..68f5b39f1940 100644 > --- a/include/linux/nfslocalio.h > +++ b/include/linux/nfslocalio.h > @@ -7,6 +7,8 @@ > =20 > #include > #include > +#include > +#include > #include > #include > #include > @@ -28,4 +30,40 @@ void nfs_uuid_begin(nfs_uuid_t *); > void nfs_uuid_end(nfs_uuid_t *); > bool nfs_uuid_is_local(const uuid_t *, struct net *, struct auth_domain = *); > =20 > +struct nfsd_file; > +struct nfsd_net; > + > +struct nfs_localio_ctx { > + struct nfsd_file *nf; > + struct nfsd_net *nn; > +}; > + > +typedef struct nfs_localio_ctx * > +(*nfs_to_nfsd_open_local_fh_t)(struct net *, struct auth_domain *, > + struct rpc_clnt *, const struct cred *, > + const struct nfs_fh *, const fmode_t); > +typedef struct nfsd_file * (*nfs_to_nfsd_file_get_t)(struct nfsd_file *)= ; > +typedef void (*nfs_to_nfsd_file_put_t)(struct nfsd_file *); > +typedef struct file * (*nfs_to_nfsd_file_file_t)(struct nfsd_file *); > +typedef unsigned int (*nfs_to_nfsd_net_id_value_t)(void); > +typedef void (*nfs_to_nfsd_serv_put_t)(struct nfsd_net *); > + > +typedef struct { > + refcount_t ref; > + nfs_to_nfsd_open_local_fh_t nfsd_open_local_fh; > + nfs_to_nfsd_file_get_t nfsd_file_get; > + nfs_to_nfsd_file_put_t nfsd_file_put; > + nfs_to_nfsd_file_file_t nfsd_file_file; > + nfs_to_nfsd_net_id_value_t nfsd_net_id_value; > + nfs_to_nfsd_serv_put_t nfsd_serv_put; > +} nfs_to_nfsd_t; > + > +extern nfs_to_nfsd_t nfs_to; > + > +bool get_nfs_to_nfsd_symbols(void); > +void put_nfs_to_nfsd_symbols(void); > + > +struct nfs_localio_ctx *nfs_localio_ctx_alloc(void); > +void nfs_localio_ctx_free(struct nfs_localio_ctx *); > + > #endif /* __LINUX_NFSLOCALIO_H */ --=20 Jeff Layton