6 files changed, 163 insertions, 83 deletions

diff --git a/fs/fscache/io.c b/fs/fscache/io.c
index bed7628a5a9d..7a769ea57720 100644
--- a/fs/fscache/io.c
+++ b/fs/fscache/io.c
@@ -150,6 +150,14 @@ int __fscache_begin_read_operation(struct netfs_cache_resources *cres,
 }
 EXPORT_SYMBOL(__fscache_begin_read_operation);
 
+int __fscache_begin_write_operation(struct netfs_cache_resources *cres,
+				    struct fscache_cookie *cookie)
+{
+	return fscache_begin_operation(cres, cookie, FSCACHE_WANT_PARAMS,
+				       fscache_access_io_write);
+}
+EXPORT_SYMBOL(__fscache_begin_write_operation);
+
 /**
  * fscache_set_page_dirty - Mark page dirty and pin a cache object for writeback
  * @page: The page being dirtied
diff --git a/fs/nfs/fscache.c b/fs/nfs/fscache.c
index fac6438477a0..cfe901650ab0 100644
--- a/fs/nfs/fscache.c
+++ b/fs/nfs/fscache.c
@@ -249,48 +249,128 @@ void nfs_fscache_release_file(struct inode *inode, struct file *filp)
 	}
 }
 
+static inline void fscache_end_operation(struct netfs_cache_resources *cres)
+{
+	const struct netfs_cache_ops *ops = fscache_operation_valid(cres);
+
+	if (ops)
+		ops->end_operation(cres);
+}
+
+/*
+ * Fallback page reading interface.
+ */
+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 iov_iter iter;
+	struct bio_vec bvec[1];
+	int ret;
+
+	memset(&cres, 0, sizeof(cres));
+	bvec[0].bv_page		= page;
+	bvec[0].bv_offset	= 0;
+	bvec[0].bv_len		= PAGE_SIZE;
+	iov_iter_bvec(&iter, READ, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
+
+	ret = fscache_begin_read_operation(&cres, cookie);
+	if (ret < 0)
+		return ret;
+
+	ret = fscache_read(&cres, page_offset(page), &iter, NETFS_READ_HOLE_FAIL,
+			   NULL, NULL);
+	fscache_end_operation(&cres);
+	return ret;
+}
+
+/*
+ * Fallback page writing interface.
+ */
+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 iov_iter iter;
+	struct bio_vec bvec[1];
+	loff_t start = page_offset(page);
+	size_t len = PAGE_SIZE;
+	int ret;
+
+	memset(&cres, 0, sizeof(cres));
+	bvec[0].bv_page		= page;
+	bvec[0].bv_offset	= 0;
+	bvec[0].bv_len		= PAGE_SIZE;
+	iov_iter_bvec(&iter, WRITE, bvec, ARRAY_SIZE(bvec), PAGE_SIZE);
+
+	ret = fscache_begin_write_operation(&cres, cookie);
+	if (ret < 0)
+		return ret;
+
+	ret = cres.ops->prepare_write(&cres, &start, &len, i_size_read(inode),
+				      no_space_allocated_yet);
+	if (ret == 0)
+		ret = fscache_write(&cres, page_offset(page), &iter, NULL, NULL);
+	fscache_end_operation(&cres);
+	return ret;
+}
+
 /*
  * Retrieve a page from fscache
  */
-int __nfs_readpage_from_fscache(struct nfs_open_context *ctx,
-				struct inode *inode, struct page *page)
+int __nfs_readpage_from_fscache(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);
 
 	if (PageChecked(page)) {
+		dfprintk(FSCACHE, "NFS:    readpage_from_fscache: PageChecked\n");
 		ClearPageChecked(page);
 		return 1;
 	}
 
-	return -ENOBUFS; // TODO: Use netfslib
-}
-
-/*
- * Retrieve a set of pages from fscache
- */
-int __nfs_readpages_from_fscache(struct nfs_open_context *ctx,
-				 struct inode *inode,
-				 struct address_space *mapping,
-				 struct list_head *pages,
-				 unsigned *nr_pages)
-{
-	dfprintk(FSCACHE, "NFS: nfs_getpages_from_fscache (0x%p/%u/0x%p)\n",
-		 nfs_i_fscache(inode), *nr_pages, inode);
+	ret = fscache_fallback_read_page(inode, page);
+	if (ret < 0) {
+		nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_FAIL);
+		dfprintk(FSCACHE,
+			 "NFS:    readpage_from_fscache failed %d\n", ret);
+		SetPageChecked(page);
+		return ret;
+	}
 
-	return -ENOBUFS; // TODO: Use netfslib
+	/* Read completed synchronously */
+	dfprintk(FSCACHE, "NFS:    readpage_from_fscache: read successful\n");
+	nfs_inc_fscache_stats(inode, NFSIOS_FSCACHE_PAGES_READ_OK);
+	SetPageUptodate(page);
+	return 0;
 }
 
 /*
- * Store a newly fetched page in fscache
- * - PG_fscache must be set on the page
+ * Store a newly fetched page in fscache.  We can be certain there's no page
+ * stored in the cache as yet otherwise we would've read it from there.
  */
-void __nfs_readpage_to_fscache(struct inode *inode, struct page *page, int sync)
+void __nfs_readpage_to_fscache(struct inode *inode, struct page *page)
 {
+	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);
+		 "NFS: readpage_to_fscache(fsc:%p/p:%p(i:%lx f:%lx))\n",
+		 nfs_i_fscache(inode), page, page->index, page->flags);
 
-	return; // TODO: Use netfslib
+	ret = fscache_fallback_write_page(inode, page, true);
+
+	dfprintk(FSCACHE,
+		 "NFS:     readpage_to_fscache: p:%p(i:%lu f:%lx) ret %d\n",
+		 page, page->index, page->flags, ret);
+
+	if (ret != 0) {
+		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);
+	}
 }
diff --git a/fs/nfs/fscache.h b/fs/nfs/fscache.h
index 0fa267243d26..e0220fc40366 100644
--- a/fs/nfs/fscache.h
+++ b/fs/nfs/fscache.h
@@ -44,14 +44,10 @@ 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_readpage_from_fscache(struct nfs_open_context *,
-				       struct inode *, struct page *);
-extern int __nfs_readpages_from_fscache(struct nfs_open_context *,
-					struct inode *, struct address_space *,
-					struct list_head *, unsigned *);
-extern void __nfs_readpage_to_fscache(struct inode *, struct page *, int);
+extern int __nfs_readpage_from_fscache(struct inode *, struct page *);
+extern void __nfs_read_completion_to_fscache(struct nfs_pgio_header *hdr,
+					     unsigned long bytes);
+extern void __nfs_readpage_to_fscache(struct inode *, struct page *);
 
 static inline int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 {
@@ -69,27 +65,11 @@ static inline int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 /*
  * Retrieve a page from an inode data storage object.
  */
-static inline int nfs_readpage_from_fscache(struct nfs_open_context *ctx,
-					    struct inode *inode,
+static inline int nfs_readpage_from_fscache(struct inode *inode,
 					    struct page *page)
 {
 	if (NFS_I(inode)->fscache)
-		return __nfs_readpage_from_fscache(ctx, inode, page);
-	return -ENOBUFS;
-}
-
-/*
- * Retrieve a set of pages from an inode data storage object.
- */
-static inline int nfs_readpages_from_fscache(struct nfs_open_context *ctx,
-					     struct inode *inode,
-					     struct address_space *mapping,
-					     struct list_head *pages,
-					     unsigned *nr_pages)
-{
-	if (NFS_I(inode)->fscache)
-		return __nfs_readpages_from_fscache(ctx, inode, mapping, pages,
-						    nr_pages);
+		return __nfs_readpage_from_fscache(inode, page);
 	return -ENOBUFS;
 }
 
@@ -98,11 +78,10 @@ static inline int nfs_readpages_from_fscache(struct nfs_open_context *ctx,
  * in the cache.
  */
 static inline void nfs_readpage_to_fscache(struct inode *inode,
-					   struct page *page,
-					   int sync)
+					   struct page *page)
 {
-	if (PageFsCache(page))
-		__nfs_readpage_to_fscache(inode, page, sync);
+	if (NFS_I(inode)->fscache)
+		__nfs_readpage_to_fscache(inode, page);
 }
 
 static inline void nfs_fscache_update_auxdata(struct nfs_fscache_inode_auxdata *auxdata,
@@ -156,22 +135,13 @@ static inline int nfs_fscache_release_page(struct page *page, gfp_t gfp)
 {
 	return 1; /* True: may release page */
 }
-static inline int nfs_readpage_from_fscache(struct nfs_open_context *ctx,
-					    struct inode *inode,
+static inline int nfs_readpage_from_fscache(struct inode *inode,
 					    struct page *page)
 {
 	return -ENOBUFS;
 }
-static inline int nfs_readpages_from_fscache(struct nfs_open_context *ctx,
-					     struct inode *inode,
-					     struct address_space *mapping,
-					     struct list_head *pages,
-					     unsigned *nr_pages)
-{
-	return -ENOBUFS;
-}
 static inline void nfs_readpage_to_fscache(struct inode *inode,
-					   struct page *page, int sync) {}
+					   struct page *page) {}
 
 
 static inline void nfs_fscache_invalidate(struct inode *inode, int flags) {}
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index d11af2a9299c..eb00229c1a50 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -123,7 +123,7 @@ static void nfs_readpage_release(struct nfs_page *req, int error)
 		struct address_space *mapping = page_file_mapping(page);
 
 		if (PageUptodate(page))
-			nfs_readpage_to_fscache(inode, page, 0);
+			nfs_readpage_to_fscache(inode, page);
 		else if (!PageError(page) && !PagePrivate(page))
 			generic_error_remove_page(mapping, page);
 		unlock_page(page);
@@ -305,6 +305,12 @@ readpage_async_filler(void *data, struct page *page)
 
 	aligned_len = min_t(unsigned int, ALIGN(len, rsize), PAGE_SIZE);
 
+	if (!IS_SYNC(page->mapping->host)) {
+		error = nfs_readpage_from_fscache(page->mapping->host, page);
+		if (error == 0)
+			goto out_unlock;
+	}
+
 	new = nfs_create_request(desc->ctx, page, 0, aligned_len);
 	if (IS_ERR(new))
 		goto out_error;
@@ -320,6 +326,7 @@ readpage_async_filler(void *data, struct page *page)
 	return 0;
 out_error:
 	error = PTR_ERR(new);
+out_unlock:
 	unlock_page(page);
 out:
 	return error;
@@ -366,12 +373,6 @@ int nfs_readpage(struct file *file, struct page *page)
 		desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
 
 	xchg(&desc.ctx->error, 0);
-	if (!IS_SYNC(inode)) {
-		ret = nfs_readpage_from_fscache(desc.ctx, inode, page);
-		if (ret == 0)
-			goto out_wait;
-	}
-
 	nfs_pageio_init_read(&desc.pgio, inode, false,
 			     &nfs_async_read_completion_ops);
 
@@ -381,7 +382,6 @@ int nfs_readpage(struct file *file, struct page *page)
 
 	nfs_pageio_complete_read(&desc.pgio);
 	ret = desc.pgio.pg_error < 0 ? desc.pgio.pg_error : 0;
-out_wait:
 	if (!ret) {
 		ret = wait_on_page_locked_killable(page);
 		if (!PageUptodate(page) && !ret)
@@ -419,14 +419,6 @@ int nfs_readpages(struct file *file, struct address_space *mapping,
 	} else
 		desc.ctx = get_nfs_open_context(nfs_file_open_context(file));
 
-	/* attempt to read as many of the pages as possible from the cache
-	 * - this returns -ENOBUFS immediately if the cookie is negative
-	 */
-	ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping,
-					 pages, &nr_pages);
-	if (ret == 0)
-		goto read_complete; /* all pages were read */
-
 	nfs_pageio_init_read(&desc.pgio, inode, false,
 			     &nfs_async_read_completion_ops);
 
@@ -434,7 +426,6 @@ int nfs_readpages(struct file *file, struct address_space *mapping,
 
 	nfs_pageio_complete_read(&desc.pgio);
 
-read_complete:
 	put_nfs_open_context(desc.ctx);
 out:
 	trace_nfs_aop_readahead_done(inode, nr_pages, ret);
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 2b322170372a..987a187bd39a 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -2126,8 +2126,11 @@ int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
 	if (PagePrivate(page))
 		return -EBUSY;
 
-	if (!nfs_fscache_release_page(page, GFP_KERNEL))
-		return -EBUSY;
+	if (PageFsCache(page)) {
+		if (mode == MIGRATE_ASYNC)
+			return -EBUSY;
+		wait_on_page_fscache(page);
+	}
 
 	return migrate_page(mapping, newpage, page, mode);
 }
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index 7bd35f60d19a..ede50406bcb0 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -168,6 +168,7 @@ extern void __fscache_relinquish_cookie(struct fscache_cookie *, bool);
 extern void __fscache_resize_cookie(struct fscache_cookie *, loff_t);
 extern void __fscache_invalidate(struct fscache_cookie *, const void *, loff_t, unsigned int);
 extern int __fscache_begin_read_operation(struct netfs_cache_resources *, struct fscache_cookie *);
+extern int __fscache_begin_write_operation(struct netfs_cache_resources *, struct fscache_cookie *);
 
 extern void __fscache_write_to_cache(struct fscache_cookie *, struct address_space *,
 				     loff_t, size_t, loff_t, netfs_io_terminated_t, void *,
@@ -500,6 +501,33 @@ int fscache_read(struct netfs_cache_resources *cres,
 }
 
 /**
+ * fscache_begin_write_operation - Begin a write operation for the netfs lib
+ * @cres: The cache resources for the write being performed
+ * @cookie: The cookie representing the cache object
+ *
+ * Begin a write operation on behalf of the netfs helper library.  @cres
+ * indicates the cache resources to which the operation state should be
+ * attached; @cookie indicates the cache object that will be accessed.
+ *
+ * @cres->inval_counter is set from @cookie->inval_counter for comparison at
+ * the end of the operation.  This allows invalidation during the operation to
+ * be detected by the caller.
+ *
+ * Returns:
+ * * 0		- Success
+ * * -ENOBUFS	- No caching available
+ * * Other error code from the cache, such as -ENOMEM.
+ */
+static inline
+int fscache_begin_write_operation(struct netfs_cache_resources *cres,
+				  struct fscache_cookie *cookie)
+{
+	if (fscache_cookie_enabled(cookie))
+		return __fscache_begin_write_operation(cres, cookie);
+	return -ENOBUFS;
+}
+
+/**
  * fscache_write - Start a write to the cache.
  * @cres: The cache resources to use
  * @start_pos: The beginning file offset in the cache file