From: Jeff Layton Subject: [PATCH 1/3] NFS: clean up short packet handling for NFSv2 readdir Date: Fri, 22 Feb 2008 14:49:59 -0500 Message-ID: <1203709801-20055-2-git-send-email-jlayton@redhat.com> References: <1203709801-20055-1-git-send-email-jlayton@redhat.com> Cc: linux-nfs@vger.kernel.org, nfsv4@linux-nfs.org To: Trond Myklebust Return-path: Received: from mx1.redhat.com ([66.187.233.31]:43166 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758565AbYBVTuY (ORCPT ); Fri, 22 Feb 2008 14:50:24 -0500 In-Reply-To: <1203709801-20055-1-git-send-email-jlayton@redhat.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: Currently, the NFS readdir decoders have a workaround for buggy servers that send an empty readdir response with the EOF bit unset. If the server sends a malformed response in some cases, this workaround kicks in and just returns an empty response rather than returning a proper error to the caller. This patch does 3 things: 1) have malformed responses with no entries return error (-EIO) 2) preserve existing workaround for servers that send empty responses with the EOF marker unset. 3) Add some comments to clarify the logic in nfs_xdr_readdirres(). Signed-off-by: Jeff Layton --- fs/nfs/nfs2xdr.c | 37 ++++++++++++++++++++++++++++--------- 1 files changed, 28 insertions(+), 9 deletions(-) diff --git a/fs/nfs/nfs2xdr.c b/fs/nfs/nfs2xdr.c index 1f7ea67..86a80b3 100644 --- a/fs/nfs/nfs2xdr.c +++ b/fs/nfs/nfs2xdr.c @@ -428,7 +428,7 @@ nfs_xdr_readdirres(struct rpc_rqst *req, __be32 *p, void *dummy) size_t hdrlen; unsigned int pglen, recvd; u32 len; - int status, nr; + int status, nr = 0; __be32 *end, *entry, *kaddr; if ((status = ntohl(*p++))) @@ -452,7 +452,12 @@ nfs_xdr_readdirres(struct rpc_rqst *req, __be32 *p, void *dummy) kaddr = p = kmap_atomic(*page, KM_USER0); end = (__be32 *)((char *)p + pglen); entry = p; - for (nr = 0; *p++; nr++) { + + /* Make sure the packet actually has a value_follows and EOF entry */ + if ((entry + 1) > end) + goto short_pkt; + + for (; *p++; nr++) { if (p + 2 > end) goto short_pkt; p++; /* fileid */ @@ -467,18 +472,32 @@ nfs_xdr_readdirres(struct rpc_rqst *req, __be32 *p, void *dummy) goto short_pkt; entry = p; } - if (!nr && (entry[0] != 0 || entry[1] == 0)) - goto short_pkt; + + /* + * Apparently some server sends responses that are a valid size, but + * contain no entries, and have value_follows==0 and EOF==0. For + * those, just set the EOF marker. + */ + if (!nr && entry[1] == 0) { + dprintk("NFS: readdir reply truncated!\n"); + entry[1] = 1; + } out: kunmap_atomic(kaddr, KM_USER0); return nr; short_pkt: + /* + * When we get a short packet there are 2 possibilities. We can + * return an error, or fix up the response to look like a valid + * response and return what we have so far. If there are no + * entries and the packet was short, then return -EIO. If there + * are valid entries in the response, return them and pretend that + * the call was successful, but incomplete. The caller can retry the + * readdir starting at the last cookie. + */ entry[0] = entry[1] = 0; - /* truncate listing ? */ - if (!nr) { - dprintk("NFS: readdir reply truncated!\n"); - entry[1] = 1; - } + if (!nr) + nr = -errno_NFSERR_IO; goto out; err_unmap: nr = -errno_NFSERR_IO; -- 1.5.4.1