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 <dwysocha@redhat.com>
Co-developed-by: David Howells <dhowells@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Dave Wysochanski <dwysocha@redhat.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
cc: Trond Myklebust <trond.myklebust@hammerspace.com>
cc: Anna Schumaker <anna.schumaker@netapp.com>
cc: linux-nfs@vger.kernel.org
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/202112100804.nksO8K4u-lkp@intel.com/ [1]
Link: https://lore.kernel.org/r/202112100957.2oEDT20W-lkp@intel.com/ [2]
Link: https://lore.kernel.org/r/163819668938.215744.14448852181937731615.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906979003.143852.2601189243864854724.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967182112.1823006.7791504655391213379.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021575950.640689.12069642327533368467.stgit@warthog.procyon.org.uk/ # v4

1 files changed, 35 insertions, 92 deletions

diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
index 6754c8607230..0fa267243d26 100644
--- a/fs/nfs/fscache.h
+++ b/fs/nfs/fscache.h
@@ -12,47 +12,11 @@
 #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
  * within the cache.
  *
@@ -70,31 +34,17 @@ struct nfs_fscache_inode_auxdata {
 };
 
 /*
- * 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 *);
@@ -103,25 +53,17 @@ extern int __nfs_readpages_from_fscache(struct nfs_open_context *,
 					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)
-{
-	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)
+static inline int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 {
-	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;
 }
 
 /*
@@ -163,20 +105,32 @@ static inline void nfs_readpage_to_fscache(struct inode *inode,
 		__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);
+	}
 }
 
 /*
@@ -190,28 +144,18 @@ static inline const char *nfs_server_fscache_state(struct nfs_server *server)
 }
 
 #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)
@@ -230,8 +174,7 @@ static inline void nfs_readpage_to_fscache(struct inode *inode,
 					   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)
 {