Commit 643f8111 authored by Jeff Layton's avatar Jeff Layton Committed by Trond Myklebust
Browse files

NFS: clean up short packet handling for NFSv3 readdir 



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: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent caa02bd5

fs/nfs/nfs3xdr.c

+28 −9
Original line number Diff line number Diff line
@@ -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;

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