Return-Path: Received: from fieldses.org ([174.143.236.118]:49330 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753635Ab1CWSZZ (ORCPT ); Wed, 23 Mar 2011 14:25:25 -0400 Date: Wed, 23 Mar 2011 14:25:24 -0400 To: Bryan Schumaker Cc: "Trond >> Myklebust, Trond" , "linux-nfs@vger.kernel.org" Subject: Re: [PATCH 3/3] NFS: Detect loops in a readdir due to bad cookies Message-ID: <20110323182524.GB25284@fieldses.org> References: <4D8A3060.807@netapp.com> Content-Type: text/plain; charset=us-ascii In-Reply-To: <4D8A3060.807@netapp.com> From: "J. Bruce Fields" Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 On Wed, Mar 23, 2011 at 01:39:44PM -0400, Bryan Schumaker wrote: > Some filesystems (such as ext4) can return the same cookie value for multiple Do the ext4 people know about this? (And what's the easiest way to reproduce it?) --b. > files. If we try to start a readdir with one of these cookies, the server will > return the first file found with a cookie of the same value. This can cause > the client to enter an infinite loop. > > Signed-off-by: Bryan Schumaker > --- > fs/nfs/dir.c | 23 ++++++++++++++++++++++- > include/linux/nfs_fs.h | 2 ++ > 2 files changed, 24 insertions(+), 1 deletions(-) > > diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c > index b503791..dc475a7 100644 > --- a/fs/nfs/dir.c > +++ b/fs/nfs/dir.c > @@ -139,7 +139,9 @@ static struct nfs_open_dir_context *alloc_nfs_open_dir_context(struct rpc_cred * > struct nfs_open_dir_context *ctx; > ctx = kmalloc(sizeof(*ctx), GFP_KERNEL); > if (ctx != NULL) { > + ctx->duped = 0; > ctx->dir_cookie = 0; > + ctx->dup_cookie = 0; > ctx->cred = get_rpccred(cred); > } > return ctx; > @@ -342,11 +344,18 @@ static > int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_descriptor_t *desc) > { > int i; > + int new_pos; > int status = -EAGAIN; > + struct nfs_open_dir_context *ctx = desc->file->private_data; > > for (i = 0; i < array->size; i++) { > if (array->array[i].cookie == *desc->dir_cookie) { > - desc->file->f_pos = desc->current_index + i; > + new_pos = desc->current_index + i; > + if (new_pos < desc->file->f_pos) { > + ctx->dup_cookie = *desc->dir_cookie; > + ctx->duped = 1; > + } > + desc->file->f_pos = new_pos; > desc->cache_entry_index = i; > return 0; > } > @@ -731,6 +740,18 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc, void *dirent, > int i = 0; > int res = 0; > struct nfs_cache_array *array = NULL; > + struct nfs_open_dir_context *ctx = file->private_data; > + > + if (ctx->duped == 1 && ctx->dup_cookie == *desc->dir_cookie) { > + if (printk_ratelimit()) { > + pr_notice("NFS: directory %s/%s contains a readdir loop. " > + "Please contact your server vendor.", > + file->f_dentry->d_parent->d_name.name, > + file->f_dentry->d_name.name); > + } > + res = -ELOOP; > + goto out; > + } > > array = nfs_readdir_get_array(desc->page); > if (IS_ERR(array)) { > diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h > index 4b87c00..bbb812b 100644 > --- a/include/linux/nfs_fs.h > +++ b/include/linux/nfs_fs.h > @@ -97,7 +97,9 @@ struct nfs_open_context { > > struct nfs_open_dir_context { > struct rpc_cred *cred; > + int duped; > __u64 dir_cookie; > + __u64 dup_cookie; > }; > > /* > -- > 1.7.4.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html