On Fri, 22 Feb 2008 16:11:12 -0500
Chuck Lever <[EMAIL PROTECTED]> wrote:
> Hi Jeff-
>
> For NFSv3, is the READDIRPLUS decoder affected as well?
>
Yes. READDIR and READDIRPLUS use the same decoder routine, so this patch
should also make short READDIRPLUS packets return an error using the
same set of rules.
> Jeff Layton wrote:
> > 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 nfs3_xdr_readdirres().
> >
> > Signed-off-by: Jeff Layton <[EMAIL PROTECTED]>
> > ---
> > fs/nfs/nfs3xdr.c | 37 ++++++++++++++++++++++++++++---------
> > 1 files changed, 28 insertions(+), 9 deletions(-)
> >
> > diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
> > index 3917e2f..fb03048 100644
> > --- a/fs/nfs/nfs3xdr.c
> > +++ b/fs/nfs/nfs3xdr.c
> > @@ -508,7 +508,7 @@ nfs3_xdr_readdirres(struct rpc_rqst *req, __be32 *p,
> > struct nfs3_readdirres *res
> > struct page **page;
> > size_t hdrlen;
> > u32 len, recvd, pglen;
> > - int status, nr;
> > + int status, nr = 0;
> > __be32 *entry, *end, *kaddr;
> >
> > status = ntohl(*p++);
> > @@ -542,7 +542,12 @@ nfs3_xdr_readdirres(struct rpc_rqst *req, __be32 *p,
> > struct nfs3_readdirres *res
> > 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 + 3 > end)
> > goto short_pkt;
> > p += 2; /* inode # */
> > @@ -581,18 +586,32 @@ nfs3_xdr_readdirres(struct rpc_rqst *req, __be32 *p,
> > struct nfs3_readdirres *res
> > 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;
--
Jeff Layton <[EMAIL PROTECTED]>
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