NFS: Improve handling of directory verifiers

If the server insists on using the readdir verifiers in order to allow
cookies to expire, then we should ensure that we cache the verifier
with the cookie, so that we can return an error if the application
tries to use the expired cookie.

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>

1 files changed, 23 insertions, 12 deletions

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 3b44bef3a1b4..454377228167 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -155,6 +155,7 @@ struct nfs_readdir_descriptor {
 	loff_t		current_index;
 	loff_t		prev_index;
 
+	__be32		verf[NFS_DIR_VERIFIER_SIZE];
 	unsigned long	dir_verifier;
 	unsigned long	timestamp;
 	unsigned long	gencount;
@@ -466,15 +467,15 @@ static int nfs_readdir_search_array(struct nfs_readdir_descriptor *desc)
 
 /* Fill a page with xdr information before transferring to the cache page */
 static int nfs_readdir_xdr_filler(struct nfs_readdir_descriptor *desc,
-				  u64 cookie, struct page **pages,
-				  size_t bufsize)
+				  __be32 *verf, u64 cookie,
+				  struct page **pages, size_t bufsize,
+				  __be32 *verf_res)
 {
 	struct inode *inode = file_inode(desc->file);
-	__be32 verf_res[2];
 	struct nfs_readdir_arg arg = {
 		.dentry = file_dentry(desc->file),
 		.cred = desc->file->f_cred,
-		.verf = NFS_I(inode)->cookieverf,
+		.verf = verf,
 		.cookie = cookie,
 		.pages = pages,
 		.page_len = bufsize,
@@ -503,8 +504,6 @@ static int nfs_readdir_xdr_filler(struct nfs_readdir_descriptor *desc,
 	}
 	desc->timestamp = timestamp;
 	desc->gencount = gencount;
-	memcpy(NFS_I(inode)->cookieverf, res.verf,
-	       sizeof(NFS_I(inode)->cookieverf));
 error:
 	return error;
 }
@@ -770,11 +769,13 @@ out_freepages:
 }
 
 static int nfs_readdir_xdr_to_array(struct nfs_readdir_descriptor *desc,
-				    struct page *page, struct inode *inode)
+				    struct page *page, __be32 *verf_arg,
+				    __be32 *verf_res)
 {
 	struct page **pages;
 	struct nfs_entry *entry;
 	size_t array_size;
+	struct inode *inode = file_inode(desc->file);
 	size_t dtsize = NFS_SERVER(inode)->dtsize;
 	int status = -ENOMEM;
 
@@ -801,8 +802,9 @@ static int nfs_readdir_xdr_to_array(struct nfs_readdir_descriptor *desc,
 
 	do {
 		unsigned int pglen;
-		status = nfs_readdir_xdr_filler(desc, entry->cookie,
-						pages, dtsize);
+		status = nfs_readdir_xdr_filler(desc, verf_arg, entry->cookie,
+						pages, dtsize,
+						verf_res);
 		if (status < 0)
 			break;
 
@@ -854,13 +856,15 @@ static int find_and_lock_cache_page(struct nfs_readdir_descriptor *desc)
 {
 	struct inode *inode = file_inode(desc->file);
 	struct nfs_inode *nfsi = NFS_I(inode);
+	__be32 verf[NFS_DIR_VERIFIER_SIZE];
 	int res;
 
 	desc->page = nfs_readdir_page_get_cached(desc);
 	if (!desc->page)
 		return -ENOMEM;
 	if (nfs_readdir_page_needs_filling(desc->page)) {
-		res = nfs_readdir_xdr_to_array(desc, desc->page, inode);
+		res = nfs_readdir_xdr_to_array(desc, desc->page,
+					       nfsi->cookieverf, verf);
 		if (res < 0) {
 			nfs_readdir_page_unlock_and_put_cached(desc);
 			if (res == -EBADCOOKIE || res == -ENOTSYNC) {
@@ -870,6 +874,7 @@ static int find_and_lock_cache_page(struct nfs_readdir_descriptor *desc)
 			}
 			return res;
 		}
+		memcpy(nfsi->cookieverf, verf, sizeof(nfsi->cookieverf));
 	}
 	res = nfs_readdir_search_array(desc);
 	if (res == 0) {
@@ -902,6 +907,7 @@ static int readdir_search_pagecache(struct nfs_readdir_descriptor *desc)
 static void nfs_do_filldir(struct nfs_readdir_descriptor *desc)
 {
 	struct file	*file = desc->file;
+	struct nfs_inode *nfsi = NFS_I(file_inode(file));
 	struct nfs_cache_array *array;
 	unsigned int i = 0;
 
@@ -915,6 +921,7 @@ static void nfs_do_filldir(struct nfs_readdir_descriptor *desc)
 			desc->eof = true;
 			break;
 		}
+		memcpy(desc->verf, nfsi->cookieverf, sizeof(desc->verf));
 		if (i < (array->size-1))
 			desc->dir_cookie = array->array[i+1].cookie;
 		else
@@ -949,8 +956,8 @@ static void nfs_do_filldir(struct nfs_readdir_descriptor *desc)
 static int uncached_readdir(struct nfs_readdir_descriptor *desc)
 {
 	struct page	*page = NULL;
+	__be32		verf[NFS_DIR_VERIFIER_SIZE];
 	int		status;
-	struct inode *inode = file_inode(desc->file);
 
 	dfprintk(DIRCACHE, "NFS: uncached_readdir() searching for cookie %Lu\n",
 			(unsigned long long)desc->dir_cookie);
@@ -967,7 +974,7 @@ static int uncached_readdir(struct nfs_readdir_descriptor *desc)
 	desc->duped = 0;
 
 	nfs_readdir_page_init_array(page, desc->dir_cookie);
-	status = nfs_readdir_xdr_to_array(desc, page, inode);
+	status = nfs_readdir_xdr_to_array(desc, page, desc->verf, verf);
 	if (status < 0)
 		goto out_release;
 
@@ -1023,6 +1030,7 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
 	desc->dup_cookie = dir_ctx->dup_cookie;
 	desc->duped = dir_ctx->duped;
 	desc->attr_gencount = dir_ctx->attr_gencount;
+	memcpy(desc->verf, dir_ctx->verf, sizeof(desc->verf));
 	spin_unlock(&file->f_lock);
 
 	do {
@@ -1061,6 +1069,7 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx)
 	dir_ctx->dup_cookie = desc->dup_cookie;
 	dir_ctx->duped = desc->duped;
 	dir_ctx->attr_gencount = desc->attr_gencount;
+	memcpy(dir_ctx->verf, desc->verf, sizeof(dir_ctx->verf));
 	spin_unlock(&file->f_lock);
 
 	kfree(desc);
@@ -1101,6 +1110,8 @@ static loff_t nfs_llseek_dir(struct file *filp, loff_t offset, int whence)
 			dir_ctx->dir_cookie = offset;
 		else
 			dir_ctx->dir_cookie = 0;
+		if (offset == 0)
+			memset(dir_ctx->verf, 0, sizeof(dir_ctx->verf));
 		dir_ctx->duped = 0;
 	}
 	spin_unlock(&filp->f_lock);