afs: Convert afs to use the new fscache API

Change the afs filesystem to support the new afs driver.

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. There's also no longer a cell cookie.

(2) The volume cookie is now an fscache_volume cookie, allocated with
fscache_acquire_volume(). This function 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 afs, I've made it render the volume name string as:

"afs,<cell>,<volume_id>"

and the coherency data is currently 0.

(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, except that these are now stored in big endian
form instead of cpu endian. This makes the cache more copyable.

(4) fscache_use_cookie() and fscache_unuse_cookie() are called 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.

fscache_use_cookie() is given an indication if the cache is likely to
be modified locally (e.g. the file is open for writing).

fscache_unuse_cookie() is given a coherency update if we had the file
open for writing and will update that.

(5) fscache_invalidate() is now given uptodate auxiliary data and a file
size. It can also take a flag to indicate if this was due to a DIO
write. This is wrapped into afs_fscache_invalidate() now for
convenience.

(6) fscache_resize() now gets called from the finalisation of
afs_setattr(), and afs_setattr() does use/unuse of the cookie around
the call to support this.

(7) fscache_note_page_release() is called from afs_release_page().

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

Render the parts of the cookie key for an afs inode cookie as big endian.

Changes
=======
ver #2:
- Use gfpflags_allow_blocking() rather than using flag directly.
- fscache_acquire_volume() now returns errors.

Signed-off-by: David Howells <[e-mail]>
Acked-by: Jeff Layton <[e-mail]>
Tested-by: [e-mail]
cc: Marc Dionne <[e-mail]>
cc: [e-mail]
cc: [e-mail]
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/afs/Kconfig

···
 
 config AFS_FSCACHE
 	bool "Provide AFS client caching support"
-	depends on AFS_FS=m && FSCACHE_OLD_API || AFS_FS=y && FSCACHE_OLD_API=y
+	depends on AFS_FS=m && FSCACHE || AFS_FS=y && FSCACHE=y
 	help
 	  Say Y here if you want AFS data to be cached locally on disk through
 	  the generic filesystem cache manager

fs/afs/Makefile

···
 # Makefile for Red Hat Linux AFS client.
 #
 
-afs-cache-$(CONFIG_AFS_FSCACHE) := cache.o
-
 kafs-y := \
-	$(afs-cache-y) \
 	addr_list.o \
 	callback.o \
 	cell.o \

fs/afs/cache.c

···
-// SPDX-License-Identifier: GPL-2.0-or-later
-/* AFS caching stuff
- *
- * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved.
- * Written by David Howells ([e-mail])
- */
-
-#include <linux/sched.h>
-#include "internal.h"
-
-static enum fscache_checkaux afs_vnode_cache_check_aux(void *cookie_netfs_data,
-						       const void *buffer,
-						       uint16_t buflen,
-						       loff_t object_size);
-
-struct fscache_netfs afs_cache_netfs = {
-	.name			= "afs",
-	.version		= 2,
-};
-
-struct fscache_cookie_def afs_cell_cache_index_def = {
-	.name		= "AFS.cell",
-	.type		= FSCACHE_COOKIE_TYPE_INDEX,
-};
-
-struct fscache_cookie_def afs_volume_cache_index_def = {
-	.name		= "AFS.volume",
-	.type		= FSCACHE_COOKIE_TYPE_INDEX,
-};
-
-struct fscache_cookie_def afs_vnode_cache_index_def = {
-	.name		= "AFS.vnode",
-	.type		= FSCACHE_COOKIE_TYPE_DATAFILE,
-	.check_aux	= afs_vnode_cache_check_aux,
-};
-
-/*
- * check that the auxiliary data indicates that the entry is still valid
- */
-static enum fscache_checkaux afs_vnode_cache_check_aux(void *cookie_netfs_data,
-						       const void *buffer,
-						       uint16_t buflen,
-						       loff_t object_size)
-{
-	struct afs_vnode *vnode = cookie_netfs_data;
-	struct afs_vnode_cache_aux aux;
-
-	_enter("{%llx,%x,%llx},%p,%u",
-	       vnode->fid.vnode, vnode->fid.unique, vnode->status.data_version,
-	       buffer, buflen);
-
-	memcpy(&aux, buffer, sizeof(aux));
-
-	/* check the size of the data is what we're expecting */
-	if (buflen != sizeof(aux)) {
-		_leave(" = OBSOLETE [len %hx != %zx]", buflen, sizeof(aux));
-		return FSCACHE_CHECKAUX_OBSOLETE;
-	}
-
-	if (vnode->status.data_version != aux.data_version) {
-		_leave(" = OBSOLETE [vers %llx != %llx]",
-		       aux.data_version, vnode->status.data_version);
-		return FSCACHE_CHECKAUX_OBSOLETE;
-	}
-
-	_leave(" = SUCCESS");
-	return FSCACHE_CHECKAUX_OKAY;
-}

fs/afs/cell.c

···
 			return ret;
 	}
 
-#ifdef CONFIG_AFS_FSCACHE
-	cell->cache = fscache_acquire_cookie(afs_cache_netfs.primary_index,
-					     &afs_cell_cache_index_def,
-					     cell->name, strlen(cell->name),
-					     NULL, 0,
-					     cell, 0, true);
-#endif
 	ret = afs_proc_cell_setup(cell);
 	if (ret < 0)
 		return ret;
···
 	hlist_del_rcu(&cell->proc_link);
 	afs_dynroot_rmdir(net, cell);
 	mutex_unlock(&net->proc_cells_lock);
-
-#ifdef CONFIG_AFS_FSCACHE
-	fscache_relinquish_cookie(cell->cache, NULL, false);
-	cell->cache = NULL;
-#endif
 
 	_leave("");
 }

fs/afs/file.c

···
 
 	if (file->f_flags & O_TRUNC)
 		set_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
-	
+
+	fscache_use_cookie(afs_vnode_cache(vnode), file->f_mode & FMODE_WRITE);
+
 	file->private_data = af;
 	_leave(" = 0");
 	return 0;
···
  */
 int afs_release(struct inode *inode, struct file *file)
 {
+	struct afs_vnode_cache_aux aux;
 	struct afs_vnode *vnode = AFS_FS_I(inode);
 	struct afs_file *af = file->private_data;
+	loff_t i_size;
 	int ret = 0;
 
 	_enter("{%llx:%llu},", vnode->fid.vid, vnode->fid.vnode);
···
 	file->private_data = NULL;
 	if (af->wb)
 		afs_put_wb_key(af->wb);
+
+	if ((file->f_mode & FMODE_WRITE)) {
+		i_size = i_size_read(&vnode->vfs_inode);
+		afs_set_cache_aux(vnode, &aux);
+		fscache_unuse_cookie(afs_vnode_cache(vnode), &aux, &i_size);
+	} else {
+		fscache_unuse_cookie(afs_vnode_cache(vnode), NULL, NULL);
+	}
+
 	key_put(af->key);
 	kfree(af);
 	afs_prune_wb_keys(vnode);
···
 
 static bool afs_is_cache_enabled(struct inode *inode)
 {
-	return fscache_cookie_enabled(afs_vnode_cache(AFS_FS_I(inode)));
+	struct fscache_cookie *cookie = afs_vnode_cache(AFS_FS_I(inode));
+
+	return fscache_cookie_enabled(cookie) && cookie->cache_priv;
 }
 
 static int afs_begin_cache_operation(struct netfs_read_request *rreq)
···
 #ifdef CONFIG_AFS_FSCACHE
 	struct afs_vnode *vnode = AFS_FS_I(rreq->inode);
 
-	return fscache_begin_read_operation(rreq, afs_vnode_cache(vnode));
+	return fscache_begin_read_operation(&rreq->cache_resources,
+					    afs_vnode_cache(vnode));
 #else
 	return -ENOBUFS;
 #endif
···
  * release a page and clean up its private state if it's not busy
  * - return true if the page can now be released, false if not
  */
-static int afs_releasepage(struct page *page, gfp_t gfp_flags)
+static int afs_releasepage(struct page *page, gfp_t gfp)
 {
 	struct folio *folio = page_folio(page);
 	struct afs_vnode *vnode = AFS_FS_I(folio_inode(folio));
 
 	_enter("{{%llx:%llu}[%lu],%lx},%x",
 	       vnode->fid.vid, vnode->fid.vnode, folio_index(folio), folio->flags,
-	       gfp_flags);
+	       gfp);
 
 	/* deny if page is being written to the cache and the caller hasn't
 	 * elected to wait */
 #ifdef CONFIG_AFS_FSCACHE
 	if (folio_test_fscache(folio)) {
-		if (!(gfp_flags & __GFP_DIRECT_RECLAIM) || !(gfp_flags & __GFP_FS))
+		if (!gfpflags_allow_blocking(gfp) || !(gfp & __GFP_FS))
 			return false;
 		folio_wait_fscache(folio);
 	}
+	fscache_note_page_release(afs_vnode_cache(vnode));
 #endif
 
 	if (folio_test_private(folio)) {

fs/afs/inode.c

···
 {
 #ifdef CONFIG_AFS_FSCACHE
 	struct {
-		u32 vnode_id;
-		u32 unique;
-		u32 vnode_id_ext[2];	/* Allow for a 96-bit key */
+		__be32 vnode_id;
+		__be32 unique;
+		__be32 vnode_id_ext[2];	/* Allow for a 96-bit key */
 	} __packed key;
 	struct afs_vnode_cache_aux aux;
 
···
 		return;
 	}
 
-	key.vnode_id		= vnode->fid.vnode;
-	key.unique		= vnode->fid.unique;
-	key.vnode_id_ext[0]	= vnode->fid.vnode >> 32;
-	key.vnode_id_ext[1]	= vnode->fid.vnode_hi;
-	aux.data_version	= vnode->status.data_version;
+	key.vnode_id		= htonl(vnode->fid.vnode);
+	key.unique		= htonl(vnode->fid.unique);
+	key.vnode_id_ext[0]	= htonl(vnode->fid.vnode >> 32);
+	key.vnode_id_ext[1]	= htonl(vnode->fid.vnode_hi);
+	afs_set_cache_aux(vnode, &aux);
 
-	vnode->cache = fscache_acquire_cookie(vnode->volume->cache,
-					      &afs_vnode_cache_index_def,
-					      &key, sizeof(key),
-					      &aux, sizeof(aux),
-					      vnode, vnode->status.size, true);
+	vnode->cache = fscache_acquire_cookie(
+		vnode->volume->cache,
+		vnode->status.type == AFS_FTYPE_FILE ? 0 : FSCACHE_ADV_SINGLE_CHUNK,
+		&key, sizeof(key),
+		&aux, sizeof(aux),
+		vnode->status.size);
 #endif
 }
 
···
 {
 	_enter("{%llx:%llu}", vnode->fid.vid, vnode->fid.vnode);
 
-#ifdef CONFIG_AFS_FSCACHE
-	fscache_invalidate(vnode->cache);
-#endif
+	afs_invalidate_cache(vnode, 0);
 
 	/* nuke all the non-dirty pages that aren't locked, mapped or being
 	 * written back in a regular file and completely discard the pages in a
···
 	}
 
 #ifdef CONFIG_AFS_FSCACHE
-	{
-		struct afs_vnode_cache_aux aux;
-
-		aux.data_version = vnode->status.data_version;
-		fscache_relinquish_cookie(vnode->cache, &aux,
-					  test_bit(AFS_VNODE_DELETED, &vnode->flags));
-		vnode->cache = NULL;
-	}
+	fscache_relinquish_cookie(vnode->cache,
+				  test_bit(AFS_VNODE_DELETED, &vnode->flags));
+	vnode->cache = NULL;
 #endif
 
 	afs_prune_wb_keys(vnode);
···
 
 		if (size < i_size)
 			truncate_pagecache(inode, size);
+		if (size != i_size)
+			fscache_resize_cookie(afs_vnode_cache(vp->vnode),
+					      vp->scb.status.size);
 	}
 }
 
···
 			attr->ia_valid &= ~ATTR_SIZE;
 	}
 
+	fscache_use_cookie(afs_vnode_cache(vnode), true);
+
 	/* flush any dirty data outstanding on a regular file */
 	if (S_ISREG(vnode->vfs_inode.i_mode))
 		filemap_write_and_wait(vnode->vfs_inode.i_mapping);
···
 
 out_unlock:
 	up_write(&vnode->validate_lock);
+	fscache_unuse_cookie(afs_vnode_cache(vnode), NULL, NULL);
 	_leave(" = %d", ret);
 	return ret;
 }

fs/afs/internal.h

···
 #include <linux/key.h>
 #include <linux/workqueue.h>
 #include <linux/sched.h>
-#define FSCACHE_USE_NEW_IO_API
 #include <linux/fscache.h>
 #include <linux/backing-dev.h>
 #include <linux/uuid.h>
···
 	struct key		*anonymous_key;	/* anonymous user key for this cell */
 	struct work_struct	manager;	/* Manager for init/deinit/dns */
 	struct hlist_node	proc_link;	/* /proc cell list link */
-#ifdef CONFIG_AFS_FSCACHE
-	struct fscache_cookie	*cache;		/* caching cookie */
-#endif
 	time64_t		dns_expiry;	/* Time AFSDB/SRV record expires */
 	time64_t		last_inactive;	/* Time of last drop of usage count */
 	atomic_t		ref;		/* Struct refcount */
···
 #define AFS_VOLUME_BUSY		5	/* - T if volume busy notice given */
 #define AFS_VOLUME_MAYBE_NO_IBULK 6	/* - T if some servers don't have InlineBulkStatus */
 #ifdef CONFIG_AFS_FSCACHE
-	struct fscache_cookie	*cache;		/* caching cookie */
+	struct fscache_volume	*cache;		/* Caching cookie */
 #endif
 	struct afs_server_list __rcu *servers;	/* List of servers on which volume resides */
 	rwlock_t		servers_lock;	/* Lock for ->servers */
···
  * Cache auxiliary data.
  */
 struct afs_vnode_cache_aux {
-	u64			data_version;
+	__be64			data_version;
 } __packed;
+
+static inline void afs_set_cache_aux(struct afs_vnode *vnode,
+				     struct afs_vnode_cache_aux *aux)
+{
+	aux->data_version = cpu_to_be64(vnode->status.data_version);
+}
+
+static inline void afs_invalidate_cache(struct afs_vnode *vnode, unsigned int flags)
+{
+	struct afs_vnode_cache_aux aux;
+
+	afs_set_cache_aux(vnode, &aux);
+	fscache_invalidate(afs_vnode_cache(vnode), &aux,
+			   i_size_read(&vnode->vfs_inode), flags);
+}
 
 /*
  * We use folio->private to hold the amount of the folio that we've written to,
···
  */
 #ifdef CONFIG_AFS_FSCACHE
 extern struct fscache_netfs afs_cache_netfs;
-extern struct fscache_cookie_def afs_cell_cache_index_def;
-extern struct fscache_cookie_def afs_volume_cache_index_def;
-extern struct fscache_cookie_def afs_vnode_cache_index_def;
-#else
-#define afs_cell_cache_index_def	(*(struct fscache_cookie_def *) NULL)
-#define afs_volume_cache_index_def	(*(struct fscache_cookie_def *) NULL)
-#define afs_vnode_cache_index_def	(*(struct fscache_cookie_def *) NULL)
 #endif
 
 /*
···
  * volume.c
  */
 extern struct afs_volume *afs_create_volume(struct afs_fs_context *);
-extern void afs_activate_volume(struct afs_volume *);
+extern int afs_activate_volume(struct afs_volume *);
 extern void afs_deactivate_volume(struct afs_volume *);
 extern struct afs_volume *afs_get_volume(struct afs_volume *, enum afs_volume_trace);
 extern void afs_put_volume(struct afs_net *, struct afs_volume *, enum afs_volume_trace);

fs/afs/main.c

···
 	if (!afs_lock_manager)
 		goto error_lockmgr;
 
-#ifdef CONFIG_AFS_FSCACHE
-	/* we want to be able to cache */
-	ret = fscache_register_netfs(&afs_cache_netfs);
-	if (ret < 0)
-		goto error_cache;
-#endif
-
 	ret = register_pernet_device(&afs_net_ops);
 	if (ret < 0)
 		goto error_net;
···
 error_fs:
 	unregister_pernet_device(&afs_net_ops);
 error_net:
-#ifdef CONFIG_AFS_FSCACHE
-	fscache_unregister_netfs(&afs_cache_netfs);
-error_cache:
-#endif
 	destroy_workqueue(afs_lock_manager);
 error_lockmgr:
 	destroy_workqueue(afs_async_calls);
···
 	proc_remove(afs_proc_symlink);
 	afs_fs_exit();
 	unregister_pernet_device(&afs_net_ops);
-#ifdef CONFIG_AFS_FSCACHE
-	fscache_unregister_netfs(&afs_cache_netfs);
-#endif
 	destroy_workqueue(afs_lock_manager);
 	destroy_workqueue(afs_async_calls);
 	destroy_workqueue(afs_wq);

fs/afs/volume.c

···
 /*
  * Activate a volume.
  */
-void afs_activate_volume(struct afs_volume *volume)
+int afs_activate_volume(struct afs_volume *volume)
 {
 #ifdef CONFIG_AFS_FSCACHE
-	volume->cache = fscache_acquire_cookie(volume->cell->cache,
-					       &afs_volume_cache_index_def,
-					       &volume->vid, sizeof(volume->vid),
-					       NULL, 0,
-					       volume, 0, true);
+	struct fscache_volume *vcookie;
+	char *name;
+
+	name = kasprintf(GFP_KERNEL, "afs,%s,%llx",
+			 volume->cell->name, volume->vid);
+	if (!name)
+		return -ENOMEM;
+
+	vcookie = fscache_acquire_volume(name, NULL, NULL, 0);
+	if (IS_ERR(vcookie)) {
+		if (vcookie != ERR_PTR(-EBUSY)) {
+			kfree(name);
+			return PTR_ERR(vcookie);
+		}
+		pr_err("AFS: Cache volume key already in use (%s)\n", name);
+		vcookie = NULL;
+	}
+	volume->cache = vcookie;
+	kfree(name);
 #endif
+	return 0;
 }
 
 /*
···
 	_enter("%s", volume->name);
 
 #ifdef CONFIG_AFS_FSCACHE
-	fscache_relinquish_cookie(volume->cache, NULL,
+	fscache_relinquish_volume(volume->cache, NULL,
 				  test_bit(AFS_VOLUME_DELETED, &volume->flags));
 	volume->cache = NULL;
 #endif

fs/afs/write.c

···
 #include <linux/writeback.h>
 #include <linux/pagevec.h>
 #include <linux/netfs.h>
-#include <linux/fscache.h>
 #include "internal.h"
 
 /*