NFS: Configure support for netfs when NFS fscache is configured

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.

Using netfs requires we move the VFS inode structure to be stored
inside struct netfs_inode, along with the fscache_cookie.
Thus, if NFS_FSCACHE is configured, place netfs_inode inside an
anonymous union so the vfs_inode memory is the same and we do
not need to modify other non-fscache areas of NFS.
In addition, inside the NFS fscache code, use the new helpers,
netfs_inode() and netfs_i_cookie() helpers, and remove our own
helper, nfs_i_fscache().

Later patches will convert NFS fscache to fully use netfs.
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Tested-by: Daire Byrne <daire@dneg.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/Kconfig

@@ -170,6 +170,7 @@ config ROOT_NFS
 config NFS_FSCACHE
 	bool "Provide NFS client caching support"
 	depends on NFS_FS=m && FSCACHE || NFS_FS=y && FSCACHE=y
+	select NETFS_SUPPORT
 	help
 	  Say Y here if you want NFS data to be cached locally on disc through
 	  the general filesystem cache manager

fs/nfs/fscache.c

@@ -163,13 +163,14 @@ void nfs_fscache_init_inode(struct inode *inode)
 	struct nfs_server *nfss = NFS_SERVER(inode);
 	struct nfs_inode *nfsi = NFS_I(inode);
 
-	nfsi->fscache = NULL;
+	netfs_inode(inode)->cache = NULL;
 	if (!(nfss->fscache && S_ISREG(inode->i_mode)))
 		return;
 
 	nfs_fscache_update_auxdata(&auxdata, inode);
 
-	nfsi->fscache = fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache,
+	netfs_inode(inode)->cache = 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 = NFS_I(inode);
-	struct fscache_cookie *cookie = nfs_i_fscache(inode);
-
-	fscache_relinquish_cookie(cookie, false);
-	nfsi->fscache = NULL;
+	fscache_relinquish_cookie(netfs_i_cookie(netfs_inode(inode)), false);
+	netfs_inode(inode)->cache = NULL;
 }
 
 /*
@@ -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 = nfs_i_fscache(inode);
+	struct fscache_cookie *cookie = netfs_i_cookie(netfs_inode(inode));
 	bool open_for_write = inode_is_open_for_write(inode);
 
 	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 = nfs_i_fscache(inode);
+	struct fscache_cookie *cookie = netfs_i_cookie(netfs_inode(inode));
 	loff_t i_size = i_size_read(inode);
 
 	nfs_fscache_update_auxdata(&auxdata, inode);
@@ -243,7 +241,7 @@ void nfs_fscache_release_file(struct inode *inode, struct file *filp)
 static int fscache_fallback_read_page(struct inode *inode, struct page *page)
 {
 	struct netfs_cache_resources cres;
-	struct fscache_cookie *cookie = nfs_i_fscache(inode);
+	struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
 	struct iov_iter iter;
 	struct bio_vec bvec;
 	int ret;
@@ -269,7 +267,7 @@ 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 = nfs_i_fscache(inode);
+	struct fscache_cookie *cookie = netfs_i_cookie(&NFS_I(inode)->netfs);
 	struct iov_iter iter;
 	struct bio_vec bvec;
 	loff_t start = page_offset(page);

fs/nfs/fscache.h

@@ -54,7 +54,7 @@ static inline bool nfs_fscache_release_folio(struct folio *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 folio *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 *inode, 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);
 }
 
@@ -101,13 +101,10 @@ static inline void nfs_fscache_update_auxdata(struct 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 = NFS_I(inode);
+	struct fscache_cookie *cookie =  netfs_i_cookie(&NFS_I(inode)->netfs);
 
-	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);
 }
 
 /*

include/linux/nfs_fs.h

@@ -31,6 +31,10 @@
 #include <linux/sunrpc/auth.h>
 #include <linux/sunrpc/clnt.h>
 
+#ifdef CONFIG_NFS_FSCACHE
+#include <linux/netfs.h>
+#endif
+
 #include <linux/nfs.h>
 #include <linux/nfs2.h>
 #include <linux/nfs3.h>
@@ -204,14 +208,15 @@ 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;
-#endif
-	struct inode		vfs_inode;
-
 #ifdef CONFIG_NFS_V4_2
 	struct nfs4_xattr_cache *xattr_cache;
 #endif
+	union {
+		struct inode		vfs_inode;
+#ifdef CONFIG_NFS_FSCACHE
+		struct netfs_inode	netfs; /* netfs context and VFS inode */
+#endif
+	};
 };
 
 struct nfs4_copy_state {
@@ -329,15 +334,6 @@ static inline int NFS_STALE(const struct inode *inode)
 	return test_bit(NFS_INO_STALE, &NFS_I(inode)->flags);
 }
 
-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;