NFS: Support larger readdir buffers

Support readdir buffers of up to 1MB in size so that we can read
large directories using few RPC calls.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Tested-by: Benjamin Coddington <bcodding@redhat.com>
Tested-by: Dave Wysochanski <dwysocha@redhat.com>

Author: Trond Myklebust

fs/nfs/client.c

@@ -781,8 +781,8 @@ static void nfs_server_set_fsinfo(struct nfs_server *server,
 	server->wtmult = nfs_block_bits(fsinfo->wtmult, NULL);
 
 	server->dtsize = nfs_block_size(fsinfo->dtpref, NULL);
-	if (server->dtsize > PAGE_SIZE * NFS_MAX_READDIR_PAGES)
-		server->dtsize = PAGE_SIZE * NFS_MAX_READDIR_PAGES;
+	if (server->dtsize > NFS_MAX_FILE_IO_SIZE)
+		server->dtsize = NFS_MAX_FILE_IO_SIZE;
 	if (server->dtsize > server->rsize)
 		server->dtsize = server->rsize;
 

fs/nfs/dir.c

@@ -727,44 +727,47 @@ static int nfs_readdir_page_filler(struct nfs_readdir_descriptor *desc,
 	return status;
 }
 
-static
-void nfs_readdir_free_pages(struct page **pages, unsigned int npages)
+static void nfs_readdir_free_pages(struct page **pages, size_t npages)
 {
-	unsigned int i;
-	for (i = 0; i < npages; i++)
-		put_page(pages[i]);
+	while (npages--)
+		put_page(pages[npages]);
+	kfree(pages);
 }
 
 /*
  * nfs_readdir_alloc_pages() will allocate pages that must be freed with a call
  * to nfs_readdir_free_pages()
  */
-static
-int nfs_readdir_alloc_pages(struct page **pages, unsigned int npages)
+static struct page **nfs_readdir_alloc_pages(size_t npages)
 {
-	unsigned int i;
+	struct page **pages;
+	size_t i;
 
+	pages = kmalloc_array(npages, sizeof(*pages), GFP_KERNEL);
+	if (!pages)
+		return NULL;
 	for (i = 0; i < npages; i++) {
 		struct page *page = alloc_page(GFP_KERNEL);
 		if (page == NULL)
 			goto out_freepages;
 		pages[i] = page;
 	}
-	return 0;
+	return pages;
 
 out_freepages:
 	nfs_readdir_free_pages(pages, i);
-	return -ENOMEM;
+	return NULL;
 }
 
 static
 int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page, struct inode *inode)
 {
-	struct page *pages[NFS_MAX_READDIR_PAGES];
+	struct page **pages;
 	struct nfs_entry entry;
 	struct file	*file = desc->file;
+	size_t array_size;
+	size_t dtsize = NFS_SERVER(inode)->dtsize;
 	int status = -ENOMEM;
-	unsigned int array_size = ARRAY_SIZE(pages);
 
 	entry.prev_cookie = 0;
 	entry.cookie = nfs_readdir_page_last_cookie(page);
@@ -781,9 +784,11 @@ int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page,
 		goto out;
 	}
 
-	status = nfs_readdir_alloc_pages(pages, array_size);
-	if (status < 0)
+	array_size = (dtsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	pages = nfs_readdir_alloc_pages(array_size);
+	if (!pages)
 		goto out_release_label;
+
 	do {
 		unsigned int pglen;
 		status = nfs_readdir_xdr_filler(pages, desc, &entry, file, inode);

fs/nfs/internal.h

@@ -56,12 +56,6 @@ static inline bool nfs_lookup_is_soft_revalidate(const struct dentry *dentry)
 #define NFS_UNSPEC_RETRANS	(UINT_MAX)
 #define NFS_UNSPEC_TIMEO	(UINT_MAX)
 
-/*
- * Maximum number of pages that readdir can use for creating
- * a vmapped array of pages.
- */
-#define NFS_MAX_READDIR_PAGES 8
-
 struct nfs_client_initdata {
 	unsigned long init_flags;
 	const char *hostname;			/* Hostname of the server */