nfs: Convert to new fscache volume/cookie API

Change the nfs filesystem to support fscache's indexing rewrite and
reenable caching in nfs.

The following changes have been made:

(1) The fscache_netfs struct is no more, and there's no need to register
the filesystem as a whole.

(2) The session cookie is now an fscache_volume cookie, allocated with
fscache_acquire_volume(). That takes three parameters: a string
representing the "volume" in the index, a string naming the cache to
use (or NULL) and a u64 that conveys coherency metadata for the
volume.

For nfs, I've made it render the volume name string as:

"nfs,<ver>,<family>,<address>,<port>,<fsidH>,<fsidL>*<,param>[,<uniq>]"

(3) The fscache_cookie_def is no more and needed information is passed
directly to fscache_acquire_cookie(). The cache no longer calls back
into the filesystem, but rather metadata changes are indicated at
other times.

fscache_acquire_cookie() is passed the same keying and coherency
information as before.

(4) fscache_enable/disable_cookie() have been removed.

Call fscache_use_cookie() and fscache_unuse_cookie() when a file is
opened or closed to prevent a cache file from being culled and to keep
resources to hand that are needed to do I/O.

If a file is opened for writing, we invalidate it with
FSCACHE_INVAL_DIO_WRITE in lieu of doing writeback to the cache,
thereby making it cease caching until all currently open files are
closed. This should give the same behaviour as the uptream code.
Making the cache store local modifications isn't straightforward for
NFS, so that's left for future patches.

(5) fscache_invalidate() now needs to be given uptodate auxiliary data and
a file size. It also takes a flag to indicate if this was due to a
DIO write.

(6) Call nfs_fscache_invalidate() with FSCACHE_INVAL_DIO_WRITE on a file
to which a DIO write is made.

(7) Call fscache_note_page_release() from nfs_release_page().

(8) Use a killable wait in nfs_vm_page_mkwrite() when waiting for
PG_fscache to be cleared.

(9) The functions to read and write data to/from the cache are stubbed out
pending a conversion to use netfslib.

Changes
=======
ver #3:
- Added missing =n fallback for nfs_fscache_release_file()[1][2].

ver #2:
- Use gfpflags_allow_blocking() rather than using flag directly.
- fscache_acquire_volume() now returns errors.
- Remove NFS_INO_FSCACHE as it's no longer used.
- Need to unuse a cookie on file-release, not inode-clear.

Signed-off-by: Dave Wysochanski <[e-mail]>
Co-developed-by: David Howells <[e-mail]>
Signed-off-by: David Howells <[e-mail]>
Tested-by: Dave Wysochanski <[e-mail]>
Acked-by: Jeff Layton <[e-mail]>
cc: Trond Myklebust <[e-mail]>
cc: Anna Schumaker <[e-mail]>
cc: [e-mail]
cc: [e-mail]
Link: https://lore.kernel.org/r/[e-mail]/ [1]
Link: https://lore.kernel.org/r/[e-mail]/ [2]
Link: https://lore.kernel.org/r/[e-mail]/ # v1
Link: https://lore.kernel.org/r/[e-mail]/ # v2
Link: https://lore.kernel.org/r/[e-mail]/ # v3
Link: https://lore.kernel.org/r/[e-mail]/ # v4

fs/nfs/Kconfig

···
 
 config NFS_FSCACHE
 	bool "Provide NFS client caching support"
-	depends on NFS_FS=m && FSCACHE_OLD_API || NFS_FS=y && FSCACHE_OLD_API=y
+	depends on NFS_FS=m && FSCACHE || NFS_FS=y && FSCACHE=y
 	help
 	  Say Y here if you want NFS data to be cached locally on disc through
 	  the general filesystem cache manager

fs/nfs/Makefile

···
 			   export.o sysfs.o fs_context.o
 nfs-$(CONFIG_ROOT_NFS)	+= nfsroot.o
 nfs-$(CONFIG_SYSCTL)	+= sysctl.o
-nfs-$(CONFIG_NFS_FSCACHE) += fscache.o fscache-index.o
+nfs-$(CONFIG_NFS_FSCACHE) += fscache.o
 
 obj-$(CONFIG_NFS_V2) += nfsv2.o
 nfsv2-y := nfs2super.o proc.o nfs2xdr.o

fs/nfs/client.c

···
 	clp->cl_net = get_net(cl_init->net);
 
 	clp->cl_principal = "*";
-	nfs_fscache_get_client_cookie(clp);
-
 	return clp;
 
 error_cleanup:
···
  */
 void nfs_free_client(struct nfs_client *clp)
 {
-	nfs_fscache_release_client_cookie(clp);
-
 	/* -EIO all pending I/O */
 	if (!IS_ERR(clp->cl_rpcclient))
 		rpc_shutdown_client(clp->cl_rpcclient);

fs/nfs/direct.c

···
 #include "internal.h"
 #include "iostat.h"
 #include "pnfs.h"
+#include "fscache.h"
 
 #define NFSDBG_FACILITY		NFSDBG_VFS
 
···
 	} else {
 		result = requested;
 	}
+	nfs_fscache_invalidate(inode, FSCACHE_INVAL_DIO_WRITE);
 out_release:
 	nfs_direct_req_release(dreq);
 out:

fs/nfs/file.c

···
 
 	nfs_inc_stats(inode, NFSIOS_VFSRELEASE);
 	nfs_file_clear_open_context(filp);
+	nfs_fscache_release_file(inode, filp);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(nfs_file_release);
···
 		return;
 	/* Cancel any unstarted writes on this page */
 	nfs_wb_page_cancel(page_file_mapping(page)->host, page);
-
-	nfs_fscache_invalidate_page(page, page->mapping->host);
+	wait_on_page_fscache(page);
 }
 
 /*
···
 static int nfs_launder_page(struct page *page)
 {
 	struct inode *inode = page_file_mapping(page)->host;
-	struct nfs_inode *nfsi = NFS_I(inode);
 
 	dfprintk(PAGECACHE, "NFS: launder_page(%ld, %llu)\n",
 		inode->i_ino, (long long)page_offset(page));
 
-	nfs_fscache_wait_on_page_write(nfsi, page);
+	wait_on_page_fscache(page);
 	return nfs_wb_page(inode, page);
 }
 
···
 	sb_start_pagefault(inode->i_sb);
 
 	/* make sure the cache has finished storing the page */
-	nfs_fscache_wait_on_page_write(NFS_I(inode), page);
+	if (PageFsCache(page) &&
+	    wait_on_page_fscache_killable(vmf->page) < 0) {
+		ret = VM_FAULT_RETRY;
+		goto out;
+	}
 
 	wait_on_bit_action(&NFS_I(inode)->flags, NFS_INO_INVALIDATING,
 			nfs_wait_bit_killable, TASK_KILLABLE);

fs/nfs/fscache-index.c

···
-// SPDX-License-Identifier: GPL-2.0-or-later
-/* NFS FS-Cache index structure definition
- *
- * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells ([e-mail])
- */
-
-#include <linux/init.h>
-#include <linux/kernel.h>
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/nfs_fs.h>
-#include <linux/nfs_fs_sb.h>
-#include <linux/in6.h>
-#include <linux/iversion.h>
-
-#include "internal.h"
-#include "fscache.h"
-
-#define NFSDBG_FACILITY		NFSDBG_FSCACHE
-
-/*
- * Define the NFS filesystem for FS-Cache.  Upon registration FS-Cache sticks
- * the cookie for the top-level index object for NFS into here.  The top-level
- * index can than have other cache objects inserted into it.
- */
-struct fscache_netfs nfs_fscache_netfs = {
-	.name		= "nfs",
-	.version	= 0,
-};
-
-/*
- * Register NFS for caching
- */
-int nfs_fscache_register(void)
-{
-	return fscache_register_netfs(&nfs_fscache_netfs);
-}
-
-/*
- * Unregister NFS for caching
- */
-void nfs_fscache_unregister(void)
-{
-	fscache_unregister_netfs(&nfs_fscache_netfs);
-}
-
-/*
- * Define the server object for FS-Cache.  This is used to describe a server
- * object to fscache_acquire_cookie().  It is keyed by the NFS protocol and
- * server address parameters.
- */
-const struct fscache_cookie_def nfs_fscache_server_index_def = {
-	.name		= "NFS.server",
-	.type 		= FSCACHE_COOKIE_TYPE_INDEX,
-};
-
-/*
- * Define the superblock object for FS-Cache.  This is used to describe a
- * superblock object to fscache_acquire_cookie().  It is keyed by all the NFS
- * parameters that might cause a separate superblock.
- */
-const struct fscache_cookie_def nfs_fscache_super_index_def = {
-	.name		= "NFS.super",
-	.type 		= FSCACHE_COOKIE_TYPE_INDEX,
-};
-
-/*
- * Consult the netfs about the state of an object
- * - This function can be absent if the index carries no state data
- * - The netfs data from the cookie being used as the target is
- *   presented, as is the auxiliary data
- */
-static
-enum fscache_checkaux nfs_fscache_inode_check_aux(void *cookie_netfs_data,
-						  const void *data,
-						  uint16_t datalen,
-						  loff_t object_size)
-{
-	struct nfs_fscache_inode_auxdata auxdata;
-	struct nfs_inode *nfsi = cookie_netfs_data;
-
-	if (datalen != sizeof(auxdata))
-		return FSCACHE_CHECKAUX_OBSOLETE;
-
-	memset(&auxdata, 0, sizeof(auxdata));
-	auxdata.mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
-	auxdata.mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
-	auxdata.ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
-	auxdata.ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
-
-	if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
-		auxdata.change_attr = inode_peek_iversion_raw(&nfsi->vfs_inode);
-
-	if (memcmp(data, &auxdata, datalen) != 0)
-		return FSCACHE_CHECKAUX_OBSOLETE;
-
-	return FSCACHE_CHECKAUX_OKAY;
-}
-
-/*
- * Get an extra reference on a read context.
- * - This function can be absent if the completion function doesn't require a
- *   context.
- * - The read context is passed back to NFS in the event that a data read on the
- *   cache fails with EIO - in which case the server must be contacted to
- *   retrieve the data, which requires the read context for security.
- */
-static void nfs_fh_get_context(void *cookie_netfs_data, void *context)
-{
-	get_nfs_open_context(context);
-}
-
-/*
- * Release an extra reference on a read context.
- * - This function can be absent if the completion function doesn't require a
- *   context.
- */
-static void nfs_fh_put_context(void *cookie_netfs_data, void *context)
-{
-	if (context)
-		put_nfs_open_context(context);
-}
-
-/*
- * Define the inode object for FS-Cache.  This is used to describe an inode
- * object to fscache_acquire_cookie().  It is keyed by the NFS file handle for
- * an inode.
- *
- * Coherency is managed by comparing the copies of i_size, i_mtime and i_ctime
- * held in the cache auxiliary data for the data storage object with those in
- * the inode struct in memory.
- */
-const struct fscache_cookie_def nfs_fscache_inode_object_def = {
-	.name		= "NFS.fh",
-	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,
-	.check_aux	= nfs_fscache_inode_check_aux,
-	.get_context	= nfs_fh_get_context,
-	.put_context	= nfs_fh_put_context,
-};

fs/nfs/fscache.c

···
 
 #define NFSDBG_FACILITY		NFSDBG_FSCACHE
 
-static struct rb_root nfs_fscache_keys = RB_ROOT;
-static DEFINE_SPINLOCK(nfs_fscache_keys_lock);
+#define NFS_MAX_KEY_LEN 1000
 
-/*
- * Layout of the key for an NFS server cache object.
- */
-struct nfs_server_key {
-	struct {
-		uint16_t	nfsversion;		/* NFS protocol version */
-		uint32_t	minorversion;		/* NFSv4 minor version */
-		uint16_t	family;			/* address family */
-		__be16		port;			/* IP port */
-	} hdr;
-	union {
-		struct in_addr	ipv4_addr;	/* IPv4 address */
-		struct in6_addr ipv6_addr;	/* IPv6 address */
-	};
-} __packed;
+static bool nfs_append_int(char *key, int *_len, unsigned long long x)
+{
+	if (*_len > NFS_MAX_KEY_LEN)
+		return false;
+	if (x == 0)
+		key[(*_len)++] = ',';
+	else
+		*_len += sprintf(key + *_len, ",%llx", x);
+	return true;
+}
 
 /*
  * Get the per-client index cookie for an NFS client if the appropriate mount
···
  * - We always try and get an index cookie for the client, but get filehandle
  *   cookies on a per-superblock basis, depending on the mount flags
  */
-void nfs_fscache_get_client_cookie(struct nfs_client *clp)
+static bool nfs_fscache_get_client_key(struct nfs_client *clp,
+				       char *key, int *_len)
 {
 	const struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) &clp->cl_addr;
 	const struct sockaddr_in *sin = (struct sockaddr_in *) &clp->cl_addr;
-	struct nfs_server_key key;
-	uint16_t len = sizeof(key.hdr);
 
-	memset(&key, 0, sizeof(key));
-	key.hdr.nfsversion = clp->rpc_ops->version;
-	key.hdr.minorversion = clp->cl_minorversion;
-	key.hdr.family = clp->cl_addr.ss_family;
+	*_len += snprintf(key + *_len, NFS_MAX_KEY_LEN - *_len,
+			  ",%u.%u,%x",
+			  clp->rpc_ops->version,
+			  clp->cl_minorversion,
+			  clp->cl_addr.ss_family);
 
 	switch (clp->cl_addr.ss_family) {
 	case AF_INET:
-		key.hdr.port = sin->sin_port;
-		key.ipv4_addr = sin->sin_addr;
-		len += sizeof(key.ipv4_addr);
-		break;
+		if (!nfs_append_int(key, _len, sin->sin_port) ||
+		    !nfs_append_int(key, _len, sin->sin_addr.s_addr))
+			return false;
+		return true;
 
 	case AF_INET6:
-		key.hdr.port = sin6->sin6_port;
-		key.ipv6_addr = sin6->sin6_addr;
-		len += sizeof(key.ipv6_addr);
-		break;
+		if (!nfs_append_int(key, _len, sin6->sin6_port) ||
+		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[0]) ||
+		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[1]) ||
+		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[2]) ||
+		    !nfs_append_int(key, _len, sin6->sin6_addr.s6_addr32[3]))
+			return false;
+		return true;
 
 	default:
 		printk(KERN_WARNING "NFS: Unknown network family '%d'\n",
 		       clp->cl_addr.ss_family);
-		clp->fscache = NULL;
-		return;
+		return false;
 	}
-
-	/* create a cache index for looking up filehandles */
-	clp->fscache = fscache_acquire_cookie(nfs_fscache_netfs.primary_index,
-					      &nfs_fscache_server_index_def,
-					      &key, len,
-					      NULL, 0,
-					      clp, 0, true);
-	dfprintk(FSCACHE, "NFS: get client cookie (0x%p/0x%p)\n",
-		 clp, clp->fscache);
 }
 
 /*
- * Dispose of a per-client cookie
- */
-void nfs_fscache_release_client_cookie(struct nfs_client *clp)
-{
-	dfprintk(FSCACHE, "NFS: releasing client cookie (0x%p/0x%p)\n",
-		 clp, clp->fscache);
-
-	fscache_relinquish_cookie(clp->fscache, NULL, false);
-	clp->fscache = NULL;
-}
-
-/*
- * Get the cache cookie for an NFS superblock.  We have to handle
- * uniquification here because the cache doesn't do it for us.
+ * Get the cache cookie for an NFS superblock.
  *
  * The default uniquifier is just an empty string, but it may be overridden
  * either by the 'fsc=xxx' option to mount, or by inheriting it from the parent
  * superblock across an automount point of some nature.
  */
-void nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq, int ulen)
+int nfs_fscache_get_super_cookie(struct super_block *sb, const char *uniq, int ulen)
 {
-	struct nfs_fscache_key *key, *xkey;
+	struct fscache_volume *vcookie;
 	struct nfs_server *nfss = NFS_SB(sb);
-	struct rb_node **p, *parent;
-	int diff;
+	unsigned int len = 3;
+	char *key;
 
-	nfss->fscache_key = NULL;
-	nfss->fscache = NULL;
-	if (!uniq) {
-		uniq = "";
-		ulen = 1;
+	if (uniq) {
+		nfss->fscache_uniq = kmemdup_nul(uniq, ulen, GFP_KERNEL);
+		if (!nfss->fscache_uniq)
+			return -ENOMEM;
 	}
 
-	key = kzalloc(sizeof(*key) + ulen, GFP_KERNEL);
+	key = kmalloc(NFS_MAX_KEY_LEN + 24, GFP_KERNEL);
 	if (!key)
-		return;
+		return -ENOMEM;
 
-	key->nfs_client = nfss->nfs_client;
-	key->key.super.s_flags = sb->s_flags & NFS_SB_MASK;
-	key->key.nfs_server.flags = nfss->flags;
-	key->key.nfs_server.rsize = nfss->rsize;
-	key->key.nfs_server.wsize = nfss->wsize;
-	key->key.nfs_server.acregmin = nfss->acregmin;
-	key->key.nfs_server.acregmax = nfss->acregmax;
-	key->key.nfs_server.acdirmin = nfss->acdirmin;
-	key->key.nfs_server.acdirmax = nfss->acdirmax;
-	key->key.nfs_server.fsid = nfss->fsid;
-	key->key.rpc_auth.au_flavor = nfss->client->cl_auth->au_flavor;
+	memcpy(key, "nfs", 3);
+	if (!nfs_fscache_get_client_key(nfss->nfs_client, key, &len) ||
+	    !nfs_append_int(key, &len, nfss->fsid.major) ||
+	    !nfs_append_int(key, &len, nfss->fsid.minor) ||
+	    !nfs_append_int(key, &len, sb->s_flags & NFS_SB_MASK) ||
+	    !nfs_append_int(key, &len, nfss->flags) ||
+	    !nfs_append_int(key, &len, nfss->rsize) ||
+	    !nfs_append_int(key, &len, nfss->wsize) ||
+	    !nfs_append_int(key, &len, nfss->acregmin) ||
+	    !nfs_append_int(key, &len, nfss->acregmax) ||
+	    !nfs_append_int(key, &len, nfss->acdirmin) ||
+	    !nfs_append_int(key, &len, nfss->acdirmax) ||
+	    !nfs_append_int(key, &len, nfss->client->cl_auth->au_flavor))
+		goto out;
 
-	key->key.uniq_len = ulen;
-	memcpy(key->key.uniquifier, uniq, ulen);
-
-	spin_lock(&nfs_fscache_keys_lock);
-	p = &nfs_fscache_keys.rb_node;
-	parent = NULL;
-	while (*p) {
-		parent = *p;
-		xkey = rb_entry(parent, struct nfs_fscache_key, node);
-
-		if (key->nfs_client < xkey->nfs_client)
-			goto go_left;
-		if (key->nfs_client > xkey->nfs_client)
-			goto go_right;
-
-		diff = memcmp(&key->key, &xkey->key, sizeof(key->key));
-		if (diff < 0)
-			goto go_left;
-		if (diff > 0)
-			goto go_right;
-
-		if (key->key.uniq_len == 0)
-			goto non_unique;
-		diff = memcmp(key->key.uniquifier,
-			      xkey->key.uniquifier,
-			      key->key.uniq_len);
-		if (diff < 0)
-			goto go_left;
-		if (diff > 0)
-			goto go_right;
-		goto non_unique;
-
-	go_left:
-		p = &(*p)->rb_left;
-		continue;
-	go_right:
-		p = &(*p)->rb_right;
+	if (ulen > 0) {
+		if (ulen > NFS_MAX_KEY_LEN - len)
+			goto out;
+		key[len++] = ',';
+		memcpy(key + len, uniq, ulen);
+		len += ulen;
 	}
-
-	rb_link_node(&key->node, parent, p);
-	rb_insert_color(&key->node, &nfs_fscache_keys);
-	spin_unlock(&nfs_fscache_keys_lock);
-	nfss->fscache_key = key;
+	key[len] = 0;
 
 	/* create a cache index for looking up filehandles */
-	nfss->fscache = fscache_acquire_cookie(nfss->nfs_client->fscache,
-					       &nfs_fscache_super_index_def,
-					       &key->key,
-					       sizeof(key->key) + ulen,
-					       NULL, 0,
-					       nfss, 0, true);
+	vcookie = fscache_acquire_volume(key,
+					 NULL, /* preferred_cache */
+					 NULL, 0 /* coherency_data */);
 	dfprintk(FSCACHE, "NFS: get superblock cookie (0x%p/0x%p)\n",
-		 nfss, nfss->fscache);
-	return;
+		 nfss, vcookie);
+	if (IS_ERR(vcookie)) {
+		if (vcookie != ERR_PTR(-EBUSY)) {
+			kfree(key);
+			return PTR_ERR(vcookie);
+		}
+		pr_err("NFS: Cache volume key already in use (%s)\n", key);
+		vcookie = NULL;
+	}
+	nfss->fscache = vcookie;
 
-non_unique:
-	spin_unlock(&nfs_fscache_keys_lock);
+out:
 	kfree(key);
-	nfss->fscache_key = NULL;
-	nfss->fscache = NULL;
-	printk(KERN_WARNING "NFS:"
-	       " Cache request denied due to non-unique superblock keys\n");
+	return 0;
 }
 
 /*
···
 	dfprintk(FSCACHE, "NFS: releasing superblock cookie (0x%p/0x%p)\n",
 		 nfss, nfss->fscache);
 
-	fscache_relinquish_cookie(nfss->fscache, NULL, false);
+	fscache_relinquish_volume(nfss->fscache, NULL, false);
 	nfss->fscache = NULL;
-
-	if (nfss->fscache_key) {
-		spin_lock(&nfs_fscache_keys_lock);
-		rb_erase(&nfss->fscache_key->node, &nfs_fscache_keys);
-		spin_unlock(&nfs_fscache_keys_lock);
-		kfree(nfss->fscache_key);
-		nfss->fscache_key = NULL;
-	}
-}
-
-static void nfs_fscache_update_auxdata(struct nfs_fscache_inode_auxdata *auxdata,
-				  struct nfs_inode *nfsi)
-{
-	memset(auxdata, 0, sizeof(*auxdata));
-	auxdata->mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
-	auxdata->mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
-	auxdata->ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
-	auxdata->ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
-
-	if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
-		auxdata->change_attr = inode_peek_iversion_raw(&nfsi->vfs_inode);
+	kfree(nfss->fscache_uniq);
 }
 
 /*
···
 	nfs_fscache_update_auxdata(&auxdata, nfsi);
 
 	nfsi->fscache = fscache_acquire_cookie(NFS_SB(inode->i_sb)->fscache,
-					       &nfs_fscache_inode_object_def,
-					       nfsi->fh.data, nfsi->fh.size,
-					       &auxdata, sizeof(auxdata),
-					       nfsi, nfsi->vfs_inode.i_size, false);
+					       0,
+					       nfsi->fh.data, /* index_key */
+					       nfsi->fh.size,
+					       &auxdata,      /* aux_data */
+					       sizeof(auxdata),
+					       i_size_read(&nfsi->vfs_inode));
 }
 
 /*
···
  */
 void nfs_fscache_clear_inode(struct inode *inode)
 {
-	struct nfs_fscache_inode_auxdata auxdata;
 	struct nfs_inode *nfsi = NFS_I(inode);
 	struct fscache_cookie *cookie = nfs_i_fscache(inode);
 
 	dfprintk(FSCACHE, "NFS: clear cookie (0x%p/0x%p)\n", nfsi, cookie);
 
-	nfs_fscache_update_auxdata(&auxdata, nfsi);
-	fscache_relinquish_cookie(cookie, &auxdata, false);
+	fscache_relinquish_cookie(cookie, false);
 	nfsi->fscache = NULL;
-}
-
-static bool nfs_fscache_can_enable(void *data)
-{
-	struct inode *inode = data;
-
-	return !inode_is_open_for_write(inode);
 }
 
 /*
···
 	struct nfs_fscache_inode_auxdata auxdata;
 	struct nfs_inode *nfsi = NFS_I(inode);
 	struct fscache_cookie *cookie = nfs_i_fscache(inode);
+	bool open_for_write = inode_is_open_for_write(inode);
 
 	if (!fscache_cookie_valid(cookie))
 		return;
 
-	nfs_fscache_update_auxdata(&auxdata, nfsi);
-
-	if (inode_is_open_for_write(inode)) {
+	fscache_use_cookie(cookie, open_for_write);
+	if (open_for_write) {
 		dfprintk(FSCACHE, "NFS: nfsi 0x%p disabling cache\n", nfsi);
-		clear_bit(NFS_INO_FSCACHE, &nfsi->flags);
-		fscache_disable_cookie(cookie, &auxdata, true);
-		fscache_uncache_all_inode_pages(cookie, inode);
-	} else {
-		dfprintk(FSCACHE, "NFS: nfsi 0x%p enabling cache\n", nfsi);
-		fscache_enable_cookie(cookie, &auxdata, nfsi->vfs_inode.i_size,
-				      nfs_fscache_can_enable, inode);
-		if (fscache_cookie_enabled(cookie))
-			set_bit(NFS_INO_FSCACHE, &NFS_I(inode)->flags);
+		nfs_fscache_update_auxdata(&auxdata, nfsi);
+		fscache_invalidate(cookie, &auxdata, i_size_read(inode),
+				   FSCACHE_INVAL_DIO_WRITE);
 	}
 }
 EXPORT_SYMBOL_GPL(nfs_fscache_open_file);
 
-/*
- * Release the caching state associated with a page, if the page isn't busy
- * interacting with the cache.
- * - Returns true (can release page) or false (page busy).
- */
-int nfs_fscache_release_page(struct page *page, gfp_t gfp)
+void nfs_fscache_release_file(struct inode *inode, struct file *filp)
 {
-	if (PageFsCache(page)) {
-		struct fscache_cookie *cookie = nfs_i_fscache(page->mapping->host);
-
-		BUG_ON(!cookie);
-		dfprintk(FSCACHE, "NFS: fscache releasepage (0x%p/0x%p/0x%p)\n",
-			 cookie, page, NFS_I(page->mapping->host));
-
-		if (!fscache_maybe_release_page(cookie, page, gfp))
-			return 0;
-
-		nfs_inc_fscache_stats(page->mapping->host,
-				      NFSIOS_FSCACHE_PAGES_UNCACHED);
-	}
-
-	return 1;
-}
-
-/*
- * Release the caching state associated with a page if undergoing complete page
- * invalidation.
- */
-void __nfs_fscache_invalidate_page(struct page *page, struct inode *inode)
-{
+	struct nfs_fscache_inode_auxdata auxdata;
+	struct nfs_inode *nfsi = NFS_I(inode);
 	struct fscache_cookie *cookie = nfs_i_fscache(inode);
 
-	BUG_ON(!cookie);
-
-	dfprintk(FSCACHE, "NFS: fscache invalidatepage (0x%p/0x%p/0x%p)\n",
-		 cookie, page, NFS_I(inode));
-
-	fscache_wait_on_page_write(cookie, page);
-
-	BUG_ON(!PageLocked(page));
-	fscache_uncache_page(cookie, page);
-	nfs_inc_fscache_stats(page->mapping->host,
-			      NFSIOS_FSCACHE_PAGES_UNCACHED);
-}
-
-/*
- * Handle completion of a page being read from the cache.
- * - Called in process (keventd) context.
- */
-static void nfs_readpage_from_fscache_complete(struct page *page,
-					       void *context,
-					       int error)
-{
-	dfprintk(FSCACHE,
-		 "NFS: readpage_from_fscache_complete (0x%p/0x%p/%d)\n",
-		 page, context, error);
-
-	/*
-	 * If the read completes with an error, mark the page with PG_checked,
-	 * unlock the page, and let the VM reissue the readpage.
-	 */
-	if (!error)
-		SetPageUptodate(page);
-	else
-		SetPageChecked(page);
-	unlock_page(page);
+	if (fscache_cookie_valid(cookie)) {
+		nfs_fscache_update_auxdata(&auxdata, nfsi);
+		fscache_unuse_cookie(cookie, &auxdata, NULL);
+	}
 }
 
 /*
···
 int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
 				struct inode *inode, struct page *page)
 {
-	int ret;
-
 	dfprintk(FSCACHE,
 		 "NFS: readpage_from_fscache(fsc:%p/p:%p(i:%lx f:%lx)/0x%p)\n",
 		 nfs_i_fscache(inode), page, page->index, page->flags, inode);
···
 		return 1;
 	}
 
-	ret = fscache_read_or_alloc_page(nfs_i_fscache(inode),
-					 page,
-					 nfs_readpage_from_fscache_complete,
-					 ctx,
-					 GFP_KERNEL);
-
-	switch (ret) {
-	case 0: /* read BIO submitted (page in fscache) */
-		dfprintk(FSCACHE,
-			 "NFS:    readpage_from_fscache: BIO submitted\n");
-		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
-		return ret;
-
-	case -ENOBUFS: /* inode not in cache */
-	case -ENODATA: /* page not in cache */
-		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
-		dfprintk(FSCACHE,
-			 "NFS:    readpage_from_fscache %d\n", ret);
-		return 1;
-
-	default:
-		dfprintk(FSCACHE, "NFS:    readpage_from_fscache %d\n", ret);
-		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
-	}
-	return ret;
+	return -ENOBUFS; // TODO: Use netfslib
 }
 
 /*
···
 				 struct list_head *pages,
 				 unsigned *nr_pages)
 {
-	unsigned npages = *nr_pages;
-	int ret;
-
 	dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
-		 nfs_i_fscache(inode), npages, inode);
+		 nfs_i_fscache(inode), *nr_pages, inode);
 
-	ret = fscache_read_or_alloc_pages(nfs_i_fscache(inode),
-					  mapping, pages, nr_pages,
-					  nfs_readpage_from_fscache_complete,
-					  ctx,
-					  mapping_gfp_mask(mapping));
-	if (*nr_pages < npages)
-		nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK,
-				      npages);
-	if (*nr_pages > 0)
-		nfs_add_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL,
-				      *nr_pages);
-
-	switch (ret) {
-	case 0: /* read submitted to the cache for all pages */
-		BUG_ON(!list_empty(pages));
-		BUG_ON(*nr_pages != 0);
-		dfprintk(FSCACHE,
-			 "NFS: nfs_getpages_from_fscache: submitted\n");
-
-		return ret;
-
-	case -ENOBUFS: /* some pages aren't cached and can't be */
-	case -ENODATA: /* some pages aren't cached */
-		dfprintk(FSCACHE,
-			 "NFS: nfs_getpages_from_fscache: no page: %d\n", ret);
-		return 1;
-
-	default:
-		dfprintk(FSCACHE,
-			 "NFS: nfs_getpages_from_fscache: ret  %d\n", ret);
-	}
-
-	return ret;
+	return -ENOBUFS; // TODO: Use netfslib
 }
 
 /*
···
  */
 void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
 {
-	int ret;
-
 	dfprintk(FSCACHE,
 		 "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx)/%d)\n",
 		 nfs_i_fscache(inode), page, page->index, page->flags, sync);
 
-	ret = fscache_write_page(nfs_i_fscache(inode), page,
-				 inode->i_size, GFP_KERNEL);
-	dfprintk(FSCACHE,
-		 "NFS:     readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
-		 page, page->index, page->flags, ret);
-
-	if (ret != 0) {
-		fscache_uncache_page(nfs_i_fscache(inode), page);
-		nfs_inc_fscache_stats(inode,
-				      NFSIOS_FSCACHE_PAGES_WRITTEN_FAIL);
-		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_UNCACHED);
-	} else {
-		nfs_inc_fscache_stats(inode,
-				      NFSIOS_FSCACHE_PAGES_WRITTEN_OK);
-	}
+	return; // TODO: Use netfslib
 }

fs/nfs/fscache.h

···
 #include <linux/nfs_mount.h>
 #include <linux/nfs4_mount.h>
 #include <linux/fscache.h>
+#include <linux/iversion.h>
 
 #ifdef CONFIG_NFS_FSCACHE
-
-/*
- * set of NFS FS-Cache objects that form a superblock key
- */
-struct nfs_fscache_key {
-	struct rb_node		node;
-	struct nfs_client	*nfs_client;	/* the server */
-
-	/* the elements of the unique key - as used by nfs_compare_super() and
-	 * nfs_compare_mount_options() to distinguish superblocks */
-	struct {
-		struct {
-			unsigned long	s_flags;	/* various flags
-							 * (& NFS_MS_MASK) */
-		} super;
-
-		struct {
-			struct nfs_fsid fsid;
-			int		flags;
-			unsigned int	rsize;		/* read size */
-			unsigned int	wsize;		/* write size */
-			unsigned int	acregmin;	/* attr cache timeouts */
-			unsigned int	acregmax;
-			unsigned int	acdirmin;
-			unsigned int	acdirmax;
-		} nfs_server;
-
-		struct {
-			rpc_authflavor_t au_flavor;
-		} rpc_auth;
-
-		/* uniquifier - can be used if nfs_server.flags includes
-		 * NFS_MOUNT_UNSHARED  */
-		u8 uniq_len;
-		char uniquifier[0];
-	} key;
-};
 
 /*
  * Definition of the auxiliary data attached to NFS inode storage objects
···
 };
 
 /*
- * fscache-index.c
- */
-extern struct fscache_netfs nfs_fscache_netfs;
-extern const struct fscache_cookie_def nfs_fscache_server_index_def;
-extern const struct fscache_cookie_def nfs_fscache_super_index_def;
-extern const struct fscache_cookie_def nfs_fscache_inode_object_def;
-
-extern int nfs_fscache_register(void);
-extern void nfs_fscache_unregister(void);
-
-/*
  * fscache.c
  */
-extern void nfs_fscache_get_client_cookie(struct nfs_client *);
-extern void nfs_fscache_release_client_cookie(struct nfs_client *);
-
-extern void nfs_fscache_get_super_cookie(struct super_block *, const char *, int);
+extern int nfs_fscache_get_super_cookie(struct super_block *, const char *, int);
 extern void nfs_fscache_release_super_cookie(struct super_block *);
 
 extern void nfs_fscache_init_inode(struct inode *);
 extern void nfs_fscache_clear_inode(struct inode *);
 extern void nfs_fscache_open_file(struct inode *, struct file *);
+extern void nfs_fscache_release_file(struct inode *, struct file *);
 
 extern void __nfs_fscache_invalidate_page(struct page *, struct inode *);
-extern int nfs_fscache_release_page(struct page *, gfp_t);
 
 extern int __nfs_readpage_from_fscache(struct nfs_open_context *,
 				       struct inode *, struct page *);
···
 					struct list_head *, unsigned *);
 extern void __nfs_readpage_to_fscache(struct inode *, struct page *, int);
 
-/*
- * wait for a page to complete writing to the cache
- */
-static inline void nfs_fscache_wait_on_page_write(struct nfs_inode *nfsi,
-						  struct page *page)
+static inline int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 {
-	if (PageFsCache(page))
-		fscache_wait_on_page_write(nfsi->fscache, page);
-}
-
-/*
- * release the caching state associated with a page if undergoing complete page
- * invalidation
- */
-static inline void nfs_fscache_invalidate_page(struct page *page,
-					       struct inode *inode)
-{
-	if (PageFsCache(page))
-		__nfs_fscache_invalidate_page(page, inode);
+	if (PageFsCache(page)) {
+		if (!gfpflags_allow_blocking(gfp) || !(gfp & __GFP_FS))
+			return false;
+		wait_on_page_fscache(page);
+		fscache_note_page_release(nfs_i_fscache(page->mapping->host));
+		nfs_inc_fscache_stats(page->mapping->host,
+				      NFSIOS_FSCACHE_PAGES_UNCACHED);
+	}
+	return true;
 }
 
 /*
···
 		__nfs_readpage_to_fscache(inode, page, sync);
 }
 
-/*
- * Invalidate the contents of fscache for this inode.  This will not sleep.
- */
-static inline void nfs_fscache_invalidate(struct inode *inode)
+static inline void nfs_fscache_update_auxdata(struct nfs_fscache_inode_auxdata *auxdata,
+					      struct nfs_inode *nfsi)
 {
-	fscache_invalidate(NFS_I(inode)->fscache);
+	memset(auxdata, 0, sizeof(*auxdata));
+	auxdata->mtime_sec  = nfsi->vfs_inode.i_mtime.tv_sec;
+	auxdata->mtime_nsec = nfsi->vfs_inode.i_mtime.tv_nsec;
+	auxdata->ctime_sec  = nfsi->vfs_inode.i_ctime.tv_sec;
+	auxdata->ctime_nsec = nfsi->vfs_inode.i_ctime.tv_nsec;
+
+	if (NFS_SERVER(&nfsi->vfs_inode)->nfs_client->rpc_ops->version == 4)
+		auxdata->change_attr = inode_peek_iversion_raw(&nfsi->vfs_inode);
 }
 
 /*
- * Wait for an object to finish being invalidated.
+ * Invalidate the contents of fscache for this inode.  This will not sleep.
  */
-static inline void nfs_fscache_wait_on_invalidate(struct inode *inode)
+static inline void nfs_fscache_invalidate(struct inode *inode, int flags)
 {
-	fscache_wait_on_invalidate(NFS_I(inode)->fscache);
+	struct nfs_fscache_inode_auxdata auxdata;
+	struct nfs_inode *nfsi = NFS_I(inode);
+
+	if (nfsi->fscache) {
+		nfs_fscache_update_auxdata(&auxdata, nfsi);
+		fscache_invalidate(nfsi->fscache, &auxdata,
+				   i_size_read(&nfsi->vfs_inode), flags);
+	}
 }
 
 /*
···
 }
 
 #else /* CONFIG_NFS_FSCACHE */
-static inline int nfs_fscache_register(void) { return 0; }
-static inline void nfs_fscache_unregister(void) {}
-
-static inline void nfs_fscache_get_client_cookie(struct nfs_client *clp) {}
-static inline void nfs_fscache_release_client_cookie(struct nfs_client *clp) {}
-
 static inline void nfs_fscache_release_super_cookie(struct super_block *sb) {}
 
 static inline void nfs_fscache_init_inode(struct inode *inode) {}
 static inline void nfs_fscache_clear_inode(struct inode *inode) {}
 static inline void nfs_fscache_open_file(struct inode *inode,
 					 struct file *filp) {}
+static inline void nfs_fscache_release_file(struct inode *inode, struct file *file) {}
 
 static inline int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 {
 	return 1; /* True: may release page */
 }
-static inline void nfs_fscache_invalidate_page(struct page *page,
-					       struct inode *inode) {}
-static inline void nfs_fscache_wait_on_page_write(struct nfs_inode *nfsi,
-						  struct page *page) {}
-
 static inline int nfs_readpage_from_fscache(struct nfs_open_context *ctx,
 					    struct inode *inode,
 					    struct page *page)
···
 					   struct page *page, int sync) {}
 
 
-static inline void nfs_fscache_invalidate(struct inode *inode) {}
-static inline void nfs_fscache_wait_on_invalidate(struct inode *inode) {}
+static inline void nfs_fscache_invalidate(struct inode *inode, int flags) {}
 
 static inline const char *nfs_server_fscache_state(struct nfs_server *server)
 {

fs/nfs/inode.c

···
 	if (!nfs_has_xattr_cache(nfsi))
 		flags &= ~NFS_INO_INVALID_XATTR;
 	if (flags & NFS_INO_INVALID_DATA)
-		nfs_fscache_invalidate(inode);
+		nfs_fscache_invalidate(inode, 0);
 	flags &= ~(NFS_INO_REVAL_PAGECACHE | NFS_INO_REVAL_FORCED);
 
 	nfsi->cache_validity |= flags;
···
 {
 	int ret;
 
+	nfs_fscache_invalidate(inode, 0);
 	if (mapping->nrpages != 0) {
 		if (S_ISREG(inode->i_mode)) {
 			ret = nfs_sync_mapping(mapping);
···
 			return ret;
 	}
 	nfs_inc_stats(inode, NFSIOS_DATAINVALIDATE);
-	nfs_fscache_wait_on_invalidate(inode);
 
 	dfprintk(PAGECACHE, "NFS: (%s/%Lu) data cache invalidated\n",
 			inode->i_sb->s_id,
···
 	if (err < 0)
 		goto out9;
 
-	err = nfs_fscache_register();
-	if (err < 0)
-		goto out8;
-
 	err = nfsiod_start();
 	if (err)
 		goto out7;
···
 out6:
 	nfsiod_stop();
 out7:
-	nfs_fscache_unregister();
-out8:
 	unregister_pernet_subsys(&nfs_net_ops);
 out9:
 	nfs_sysfs_exit();
···
 	nfs_destroy_readpagecache();
 	nfs_destroy_inodecache();
 	nfs_destroy_nfspagecache();
-	nfs_fscache_unregister();
 	unregister_pernet_subsys(&nfs_net_ops);
 	rpc_proc_unregister(&init_net, "nfs");
 	unregister_nfs_fs();

fs/nfs/nfstrace.h

···
 			{ BIT(NFS_INO_ACL_LRU_SET), "ACL_LRU_SET" }, \
 			{ BIT(NFS_INO_INVALIDATING), "INVALIDATING" }, \
 			{ BIT(NFS_INO_FSCACHE), "FSCACHE" }, \
-			{ BIT(NFS_INO_FSCACHE_LOCK), "FSCACHE_LOCK" }, \
 			{ BIT(NFS_INO_LAYOUTCOMMIT), "NEED_LAYOUTCOMMIT" }, \
 			{ BIT(NFS_INO_LAYOUTCOMMITTING), "LAYOUTCOMMIT" }, \
 			{ BIT(NFS_INO_LAYOUTSTATS), "LAYOUTSTATS" }, \

fs/nfs/super.c

···
 }
 
 #ifdef CONFIG_NFS_FSCACHE
-static void nfs_get_cache_cookie(struct super_block *sb,
-				 struct nfs_fs_context *ctx)
+static int nfs_get_cache_cookie(struct super_block *sb,
+				struct nfs_fs_context *ctx)
 {
 	struct nfs_server *nfss = NFS_SB(sb);
 	char *uniq = NULL;
 	int ulen = 0;
 
-	nfss->fscache_key = NULL;
 	nfss->fscache = NULL;
 
 	if (!ctx)
-		return;
+		return 0;
 
 	if (ctx->clone_data.sb) {
 		struct nfs_server *mnt_s = NFS_SB(ctx->clone_data.sb);
 		if (!(mnt_s->options & NFS_OPTION_FSCACHE))
-			return;
-		if (mnt_s->fscache_key) {
-			uniq = mnt_s->fscache_key->key.uniquifier;
-			ulen = mnt_s->fscache_key->key.uniq_len;
+			return 0;
+		if (mnt_s->fscache_uniq) {
+			uniq = mnt_s->fscache_uniq;
+			ulen = strlen(uniq);
 		}
 	} else {
 		if (!(ctx->options & NFS_OPTION_FSCACHE))
-			return;
+			return 0;
 		if (ctx->fscache_uniq) {
 			uniq = ctx->fscache_uniq;
 			ulen = strlen(ctx->fscache_uniq);
 		}
 	}
 
-	nfs_fscache_get_super_cookie(sb, uniq, ulen);
+	return nfs_fscache_get_super_cookie(sb, uniq, ulen);
 }
 #else
-static void nfs_get_cache_cookie(struct super_block *sb,
-				 struct nfs_fs_context *ctx)
+static int nfs_get_cache_cookie(struct super_block *sb,
+				struct nfs_fs_context *ctx)
 {
+	return 0;
 }
 #endif
 
···
 			s->s_blocksize_bits = bsize;
 			s->s_blocksize = 1U << bsize;
 		}
-		nfs_get_cache_cookie(s, ctx);
+		error = nfs_get_cache_cookie(s, ctx);
+		if (error < 0)
+			goto error_splat_super;
 	}
 
 	error = nfs_get_root(s, fc);

fs/nfs/write.c

···
 	nfs_inc_stats(inode, NFSIOS_EXTENDWRITE);
 out:
 	spin_unlock(&inode->i_lock);
+	nfs_fscache_invalidate(inode, 0);
 }
 
 /* A writeback failed: mark the page as bad, and invalidate the page cache */

include/linux/nfs_fs.h

···
 #define NFS_INO_ACL_LRU_SET	(2)		/* Inode is on the LRU list */
 #define NFS_INO_INVALIDATING	(3)		/* inode is being invalidated */
 #define NFS_INO_FSCACHE		(5)		/* inode can be cached by FS-Cache */
-#define NFS_INO_FSCACHE_LOCK	(6)		/* FS-Cache cookie management lock */
 #define NFS_INO_FORCE_READDIR	(7)		/* force readdirplus */
 #define NFS_INO_LAYOUTCOMMIT	(9)		/* layoutcommit required */
 #define NFS_INO_LAYOUTCOMMITTING (10)		/* layoutcommit inflight */

include/linux/nfs_fs_sb.h

···
 	 * This is used to generate the mv0 callback address.
 	 */
 	char			cl_ipaddr[48];
-
-#ifdef CONFIG_NFS_FSCACHE
-	struct fscache_cookie	*fscache;	/* client index cache cookie */
-#endif
-
 	struct net		*cl_net;
 	struct list_head	pending_cb_stateids;
 };
···
 	struct nfs_auth_info	auth_info;	/* parsed auth flavors */
 
 #ifdef CONFIG_NFS_FSCACHE
-	struct nfs_fscache_key	*fscache_key;	/* unique key for superblock */
-	struct fscache_cookie	*fscache;	/* superblock cookie */
+	struct fscache_volume	*fscache;	/* superblock cookie */
+	char			*fscache_uniq;	/* Uniquifier (or NULL) */
 #endif
 
 	u32			pnfs_blksize;	/* layout_blksize attr */