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Message-ID: <812b96cfa4414592f77c18a3d5fb354ccc2ff15d.camel@kernel.org>
Subject: Re: [PATCH v3 2/3] NFS: Configure support for netfs when NFS
 fscache is configured
From:   Jeff Layton <jlayton@kernel.org>
To:     Dave Wysochanski <dwysocha@redhat.com>,
        Anna Schumaker <anna.schumaker@netapp.com>,
        Trond Myklebust <trond.myklebust@hammerspace.com>,
        David Howells <dhowells@redhat.com>
Cc:     linux-nfs@vger.kernel.org, linux-cachefs@redhat.com,
        Benjamin Maynard <benmaynard@google.com>,
        Daire Byrne <daire.byrne@gmail.com>
Date:   Wed, 31 Aug 2022 12:43:53 -0400
In-Reply-To: <20220831005053.1287363-3-dwysocha@redhat.com>
References: <20220831005053.1287363-1-dwysocha@redhat.com>
         <20220831005053.1287363-3-dwysocha@redhat.com>
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On Tue, 2022-08-30 at 20:50 -0400, Dave Wysochanski wrote:
> As first steps for support of the netfs library when NFS_FSCACHE is
> configured, add NETFS_SUPPORT to Kconfig and add the required netfs_inode
> into struct nfs_inode.
>=20
> Using netfs requires we move the VFS inode structure to be stored
> inside struct netfs_inode, along with the fscache_cookie.
> Thus, create a new helper, NFSI_TO_INODE(), which is defined
> differently depending on whether NFS_FSCACHE is configured.
> In addition, use the netfs_inode() and netfs_i_cookie() helpers,
> and remove our own helper, nfs_i_fscache().
>=20
> Later patches will convert NFS fscache to fully use netfs.
>=20
> Link: https://lore.kernel.org/linux-nfs/da9200f1bded9b8b078a7aef227fd6b92=
eb028fb.camel@hammerspace.com/
>=20
> Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
> ---
>  fs/nfs/Kconfig         |  1 +
>  fs/nfs/delegation.c    |  2 +-
>  fs/nfs/dir.c           |  2 +-
>  fs/nfs/fscache.c       | 20 +++++++++-----------
>  fs/nfs/fscache.h       | 15 ++++++---------
>  fs/nfs/inode.c         |  6 +++---
>  fs/nfs/internal.h      |  2 +-
>  fs/nfs/pnfs.c          | 12 ++++++------
>  fs/nfs/write.c         |  2 +-
>  include/linux/nfs_fs.h | 36 ++++++++++++++++++++++++------------
>  10 files changed, 53 insertions(+), 45 deletions(-)
>=20
> diff --git a/fs/nfs/Kconfig b/fs/nfs/Kconfig
> index 14a72224b657..8fbb6caf3481 100644
> --- a/fs/nfs/Kconfig
> +++ b/fs/nfs/Kconfig
> @@ -171,6 +171,7 @@ config ROOT_NFS
>  config NFS_FSCACHE
>  	bool "Provide NFS client caching support"
>  	depends on NFS_FS=3Dm && FSCACHE || NFS_FS=3Dy && FSCACHE=3Dy
> +	select NETFS_SUPPORT
>  	help
>  	  Say Y here if you want NFS data to be cached locally on disc through
>  	  the general filesystem cache manager
> diff --git a/fs/nfs/delegation.c b/fs/nfs/delegation.c
> index 5c97cad741a7..41a2c5176783 100644
> --- a/fs/nfs/delegation.c
> +++ b/fs/nfs/delegation.c
> @@ -306,7 +306,7 @@ nfs_start_delegation_return_locked(struct nfs_inode *=
nfsi)
>  	}
>  	spin_unlock(&delegation->lock);
>  	if (ret)
> -		nfs_clear_verifier_delegated(&nfsi->vfs_inode);
> +		nfs_clear_verifier_delegated(NFSI_TO_INODE(nfsi));
>  out:
>  	return ret;
>  }
> diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
> index 5d6c2ddc7ea6..72de1b8791e9 100644
> --- a/fs/nfs/dir.c
> +++ b/fs/nfs/dir.c
> @@ -2799,7 +2799,7 @@ nfs_do_access_cache_scan(unsigned int nr_to_scan)
> =20
>  		if (nr_to_scan-- =3D=3D 0)
>  			break;
> -		inode =3D &nfsi->vfs_inode;
> +		inode =3D NFSI_TO_INODE(nfsi);
>  		spin_lock(&inode->i_lock);
>  		if (list_empty(&nfsi->access_cache_entry_lru))
>  			goto remove_lru_entry;
> diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
> index e861d7bae305..a6fc1c8b6644 100644
> --- a/fs/nfs/fscache.c
> +++ b/fs/nfs/fscache.c
> @@ -163,13 +163,14 @@ void nfs_fscache_init_inode(struct inode *inode)
>  	struct nfs_server *nfss =3D NFS_SERVER(inode);
>  	struct nfs_inode *nfsi =3D NFS_I(inode);
> =20
> -	nfsi->fscache =3D NULL;
> +	netfs_inode(inode)->cache =3D NULL;
>  	if (!(nfss->fscache && S_ISREG(inode->i_mode)))
>  		return;
> =20
>  	nfs_fscache_update_auxdata(&auxdata, inode);
> =20
> -	nfsi->fscache =3D fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache,
> +	netfs_inode(inode)->cache =3D fscache_acquire_cookie(
> +					       nfss->fscache,
>  					       0,
>  					       nfsi->fh.data, /* index_key */
>  					       nfsi->fh.size,
> @@ -183,11 +184,8 @@ void nfs_fscache_init_inode(struct inode *inode)
>   */
>  void nfs_fscache_clear_inode(struct inode *inode)
>  {
> -	struct nfs_inode *nfsi =3D NFS_I(inode);
> -	struct fscache_cookie *cookie =3D nfs_i_fscache(inode);
> -
> -	fscache_relinquish_cookie(cookie, false);
> -	nfsi->fscache =3D NULL;
> +	fscache_relinquish_cookie(netfs_i_cookie(&NFS_I(inode)->netfs), false);
> +	netfs_inode(inode)->cache =3D NULL;
>  }
> =20
>  /*
> @@ -212,7 +210,7 @@ void nfs_fscache_clear_inode(struct inode *inode)
>  void nfs_fscache_open_file(struct inode *inode, struct file *filp)
>  {
>  	struct nfs_fscache_inode_auxdata auxdata;
> -	struct fscache_cookie *cookie =3D nfs_i_fscache(inode);
> +	struct fscache_cookie *cookie =3D netfs_i_cookie(&NFS_I(inode)->netfs);
>  	bool open_for_write =3D inode_is_open_for_write(inode);
> =20
>  	if (!fscache_cookie_valid(cookie))
> @@ -230,7 +228,7 @@ EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
>  void nfs_fscache_release_file(struct inode *inode, struct file *filp)
>  {
>  	struct nfs_fscache_inode_auxdata auxdata;
> -	struct fscache_cookie *cookie =3D nfs_i_fscache(inode);
> +	struct fscache_cookie *cookie =3D netfs_i_cookie(&NFS_I(inode)->netfs);
>  	loff_t i_size =3D i_size_read(inode);
> =20
>  	nfs_fscache_update_auxdata(&auxdata, inode);
> @@ -243,7 +241,7 @@ void nfs_fscache_release_file(struct inode *inode, st=
ruct file *filp)
>  static int fscache_fallback_read_page(struct inode *inode, struct page *=
page)
>  {
>  	struct netfs_cache_resources cres;
> -	struct fscache_cookie *cookie =3D nfs_i_fscache(inode);
> +	struct fscache_cookie *cookie =3D netfs_i_cookie(&NFS_I(inode)->netfs);
>  	struct iov_iter iter;
>  	struct bio_vec bvec[1];
>  	int ret;
> @@ -271,7 +269,7 @@ static int fscache_fallback_write_page(struct inode *=
inode, struct page *page,
>  				       bool no_space_allocated_yet)
>  {
>  	struct netfs_cache_resources cres;
> -	struct fscache_cookie *cookie =3D nfs_i_fscache(inode);
> +	struct fscache_cookie *cookie =3D netfs_i_cookie(&NFS_I(inode)->netfs);
>  	struct iov_iter iter;
>  	struct bio_vec bvec[1];
>  	loff_t start =3D page_offset(page);
> diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
> index 2a37af880978..38614ed8f951 100644
> --- a/fs/nfs/fscache.h
> +++ b/fs/nfs/fscache.h
> @@ -54,7 +54,7 @@ static inline bool nfs_fscache_release_folio(struct fol=
io *folio, gfp_t gfp)
>  		if (current_is_kswapd() || !(gfp & __GFP_FS))
>  			return false;
>  		folio_wait_fscache(folio);
> -		fscache_note_page_release(nfs_i_fscache(folio->mapping->host));
> +		fscache_note_page_release(netfs_i_cookie(&NFS_I(folio->mapping->host)-=
>netfs));
>  		nfs_inc_fscache_stats(folio->mapping->host,
>  				      NFSIOS_FSCACHE_PAGES_UNCACHED);
>  	}
> @@ -66,7 +66,7 @@ static inline bool nfs_fscache_release_folio(struct fol=
io *folio, gfp_t gfp)
>   */
>  static inline int nfs_fscache_read_page(struct inode *inode, struct page=
 *page)
>  {
> -	if (nfs_i_fscache(inode))
> +	if (netfs_inode(inode)->cache)
>  		return __nfs_fscache_read_page(inode, page);
>  	return -ENOBUFS;
>  }
> @@ -78,7 +78,7 @@ static inline int nfs_fscache_read_page(struct inode *i=
node, struct page *page)
>  static inline void nfs_fscache_write_page(struct inode *inode,
>  					   struct page *page)
>  {
> -	if (nfs_i_fscache(inode))
> +	if (netfs_inode(inode)->cache)
>  		__nfs_fscache_write_page(inode, page);
>  }
> =20
> @@ -101,13 +101,10 @@ static inline void nfs_fscache_update_auxdata(struc=
t nfs_fscache_inode_auxdata *
>  static inline void nfs_fscache_invalidate(struct inode *inode, int flags=
)
>  {
>  	struct nfs_fscache_inode_auxdata auxdata;
> -	struct nfs_inode *nfsi =3D NFS_I(inode);
> +	struct fscache_cookie *cookie =3D  netfs_i_cookie(&NFS_I(inode)->netfs)=
;
> =20
> -	if (nfsi->fscache) {
> -		nfs_fscache_update_auxdata(&auxdata, inode);
> -		fscache_invalidate(nfsi->fscache, &auxdata,
> -				   i_size_read(inode), flags);
> -	}
> +	nfs_fscache_update_auxdata(&auxdata, inode);
> +	fscache_invalidate(cookie, &auxdata, i_size_read(inode), flags);
>  }
> =20
>  /*
> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> index bea7c005119c..7d1b9e39863c 100644
> --- a/fs/nfs/inode.c
> +++ b/fs/nfs/inode.c
> @@ -1411,7 +1411,7 @@ int nfs_revalidate_mapping(struct inode *inode, str=
uct address_space *mapping)
> =20
>  static bool nfs_file_has_writers(struct nfs_inode *nfsi)
>  {
> -	struct inode *inode =3D &nfsi->vfs_inode;
> +	struct inode *inode =3D NFSI_TO_INODE(nfsi);
> =20
>  	if (!S_ISREG(inode->i_mode))
>  		return false;
> @@ -2249,7 +2249,7 @@ struct inode *nfs_alloc_inode(struct super_block *s=
b)
>  #ifdef CONFIG_NFS_V4_2
>  	nfsi->xattr_cache =3D NULL;
>  #endif
> -	return &nfsi->vfs_inode;
> +	return NFSI_TO_INODE(nfsi);
>  }
>  EXPORT_SYMBOL_GPL(nfs_alloc_inode);
> =20
> @@ -2273,7 +2273,7 @@ static void init_once(void *foo)
>  {
>  	struct nfs_inode *nfsi =3D (struct nfs_inode *) foo;
> =20
> -	inode_init_once(&nfsi->vfs_inode);
> +	inode_init_once(NFSI_TO_INODE(nfsi));
>  	INIT_LIST_HEAD(&nfsi->open_files);
>  	INIT_LIST_HEAD(&nfsi->access_cache_entry_lru);
>  	INIT_LIST_HEAD(&nfsi->access_cache_inode_lru);
> diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
> index 27c720d71b4e..78d945f5f97f 100644
> --- a/fs/nfs/internal.h
> +++ b/fs/nfs/internal.h
> @@ -355,7 +355,7 @@ nfs4_label_copy(struct nfs4_label *dst, struct nfs4_l=
abel *src)
> =20
>  static inline void nfs_zap_label_cache_locked(struct nfs_inode *nfsi)
>  {
> -	if (nfs_server_capable(&nfsi->vfs_inode, NFS_CAP_SECURITY_LABEL))
> +	if (nfs_server_capable(NFSI_TO_INODE(nfsi), NFS_CAP_SECURITY_LABEL))
>  		nfsi->cache_validity |=3D NFS_INO_INVALID_LABEL;
>  }
>  #else
> diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
> index 2613b7e36eb9..e44b9934349c 100644
> --- a/fs/nfs/pnfs.c
> +++ b/fs/nfs/pnfs.c
> @@ -763,19 +763,19 @@ static struct pnfs_layout_hdr *__pnfs_destroy_layou=
t(struct nfs_inode *nfsi)
>  	struct pnfs_layout_hdr *lo;
>  	LIST_HEAD(tmp_list);
> =20
> -	spin_lock(&nfsi->vfs_inode.i_lock);
> +	spin_lock(&NFSI_TO_INODE(nfsi)->i_lock);
>  	lo =3D nfsi->layout;
>  	if (lo) {
>  		pnfs_get_layout_hdr(lo);
>  		pnfs_mark_layout_stateid_invalid(lo, &tmp_list);
>  		pnfs_layout_clear_fail_bit(lo, NFS_LAYOUT_RO_FAILED);
>  		pnfs_layout_clear_fail_bit(lo, NFS_LAYOUT_RW_FAILED);
> -		spin_unlock(&nfsi->vfs_inode.i_lock);
> +		spin_unlock(&NFSI_TO_INODE(nfsi)->i_lock);
>  		pnfs_free_lseg_list(&tmp_list);
> -		nfs_commit_inode(&nfsi->vfs_inode, 0);
> +		nfs_commit_inode(NFSI_TO_INODE(nfsi), 0);
>  		pnfs_put_layout_hdr(lo);
>  	} else
> -		spin_unlock(&nfsi->vfs_inode.i_lock);
> +		spin_unlock(&NFSI_TO_INODE(nfsi)->i_lock);
>  	return lo;
>  }
> =20
> @@ -790,9 +790,9 @@ static bool pnfs_layout_removed(struct nfs_inode *nfs=
i,
>  {
>  	bool ret;
> =20
> -	spin_lock(&nfsi->vfs_inode.i_lock);
> +	spin_lock(&NFSI_TO_INODE(nfsi)->i_lock);
>  	ret =3D nfsi->layout !=3D lo;
> -	spin_unlock(&nfsi->vfs_inode.i_lock);
> +	spin_unlock(&NFSI_TO_INODE(nfsi)->i_lock);
>  	return ret;
>  }
> =20
> diff --git a/fs/nfs/write.c b/fs/nfs/write.c
> index 1843fa235d9b..451da6336e12 100644
> --- a/fs/nfs/write.c
> +++ b/fs/nfs/write.c
> @@ -828,7 +828,7 @@ nfs_page_search_commits_for_head_request_locked(struc=
t nfs_inode *nfsi,
>  {
>  	struct nfs_page *freq, *t;
>  	struct nfs_commit_info cinfo;
> -	struct inode *inode =3D &nfsi->vfs_inode;
> +	struct inode *inode =3D NFSI_TO_INODE(nfsi);
> =20
>  	nfs_init_cinfo_from_inode(&cinfo, inode);
> =20
> diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
> index 7931fa472561..5a451caa38a4 100644
> --- a/include/linux/nfs_fs.h
> +++ b/include/linux/nfs_fs.h
> @@ -31,6 +31,10 @@
>  #include <linux/sunrpc/auth.h>
>  #include <linux/sunrpc/clnt.h>
> =20
> +#ifdef CONFIG_NFS_FSCACHE
> +#include <linux/netfs.h>
> +#endif
> +
>  #include <linux/nfs.h>
>  #include <linux/nfs2.h>
>  #include <linux/nfs3.h>
> @@ -121,6 +125,10 @@ struct nfs4_xattr_cache;
>   * nfs fs inode data in memory
>   */
>  struct nfs_inode {
> +#ifdef CONFIG_NFS_FSCACHE
> +	struct netfs_inode netfs; /* Netfslib context and inode */
> +#endif
> +
>  	/*
>  	 * The 64bit 'inode number'
>  	 */
> @@ -203,10 +211,10 @@ struct nfs_inode {
>  	/* how many bytes have been written/read and how many bytes queued up *=
/
>  	__u64 write_io;
>  	__u64 read_io;
> -#ifdef CONFIG_NFS_FSCACHE
> -	struct fscache_cookie	*fscache;
> +#ifndef CONFIG_NFS_FSCACHE
> +	/* fscache uses netfs, and netfs_inode contains the inode */
> +	struct inode	vfs_inode;
>  #endif
> -	struct inode		vfs_inode;
> =20
>  #ifdef CONFIG_NFS_V4_2
>  	struct nfs4_xattr_cache *xattr_cache;
> @@ -281,9 +289,22 @@ struct nfs4_copy_state {
>  #define NFS_INO_LAYOUTSTATS	(11)		/* layoutstats inflight */
>  #define NFS_INO_ODIRECT		(12)		/* I/O setting is O_DIRECT */
> =20
> +static inline struct inode *NFSI_TO_INODE(struct nfs_inode *nfsi)

Not crazy about the name here. Maybe VFS_I() ? ntfs and xfs have private
helpers named VFS_I that do something similar, so it seems more
idiomatic.

> +{
> +#ifdef CONFIG_NFS_FSCACHE
> +	return &nfsi->netfs.inode;
> +#else
> +	return &nfsi->vfs_inode;
> +#endif
> +}
> +

These are hard to read (and reason about) defined this way. I think I'd
rather see less #ifdef-ery here. Instead if having the #ifdef's inside
the functions, do:

#ifdef CONFIG_NFS_FSCACHE

/* define all static inlines here for fscache case */

#else

/* and here for the !fscache case */

#endif

>  static inline struct nfs_inode *NFS_I(const struct inode *inode)
>  {
> +#ifdef CONFIG_NFS_FSCACHE
> +	return container_of(inode, struct nfs_inode, netfs.inode);
> +#else
>  	return container_of(inode, struct nfs_inode, vfs_inode);
> +#endif
>  }
> =20
>  static inline struct nfs_server *NFS_SB(const struct super_block *s)
> @@ -328,15 +349,6 @@ static inline int NFS_STALE(const struct inode *inod=
e)
>  	return test_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
>  }
> =20
> -static inline struct fscache_cookie *nfs_i_fscache(struct inode *inode)
> -{
> -#ifdef CONFIG_NFS_FSCACHE
> -	return NFS_I(inode)->fscache;
> -#else
> -	return NULL;
> -#endif
> -}
> -
>  static inline __u64 NFS_FILEID(const struct inode *inode)
>  {
>  	return NFS_I(inode)->fileid;

--=20
Jeff Layton <jlayton@kernel.org>