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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: Jeff Layton <jlayton@redhat.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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parent
caa02bd540
commit
643f81115b
1 changed files with 28 additions and 9 deletions
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@ -508,7 +508,7 @@ nfs3_xdr_readdirres(struct rpc_rqst *req, __be32 *p, struct nfs3_readdirres *res
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struct page **page;
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size_t hdrlen;
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u32 len, recvd, pglen;
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int status, nr;
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int status, nr = 0;
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__be32 *entry, *end, *kaddr;
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status = ntohl(*p++);
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@ -542,7 +542,12 @@ nfs3_xdr_readdirres(struct rpc_rqst *req, __be32 *p, struct nfs3_readdirres *res
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kaddr = p = kmap_atomic(*page, KM_USER0);
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end = (__be32 *)((char *)p + pglen);
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entry = p;
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for (nr = 0; *p++; nr++) {
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/* Make sure the packet actually has a value_follows and EOF entry */
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if ((entry + 1) > end)
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goto short_pkt;
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for (; *p++; nr++) {
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if (p + 3 > end)
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goto short_pkt;
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p += 2; /* inode # */
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@ -581,18 +586,32 @@ nfs3_xdr_readdirres(struct rpc_rqst *req, __be32 *p, struct nfs3_readdirres *res
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goto short_pkt;
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entry = p;
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}
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if (!nr && (entry[0] != 0 || entry[1] == 0))
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goto short_pkt;
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/*
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* Apparently some server sends responses that are a valid size, but
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* contain no entries, and have value_follows==0 and EOF==0. For
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* those, just set the EOF marker.
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*/
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if (!nr && entry[1] == 0) {
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dprintk("NFS: readdir reply truncated!\n");
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entry[1] = 1;
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}
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out:
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kunmap_atomic(kaddr, KM_USER0);
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return nr;
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short_pkt:
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/*
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* When we get a short packet there are 2 possibilities. We can
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* return an error, or fix up the response to look like a valid
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* response and return what we have so far. If there are no
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* entries and the packet was short, then return -EIO. If there
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* are valid entries in the response, return them and pretend that
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* the call was successful, but incomplete. The caller can retry the
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* readdir starting at the last cookie.
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*/
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entry[0] = entry[1] = 0;
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/* truncate listing ? */
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if (!nr) {
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dprintk("NFS: readdir reply truncated!\n");
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entry[1] = 1;
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}
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if (!nr)
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nr = -errno_NFSERR_IO;
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goto out;
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err_unmap:
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nr = -errno_NFSERR_IO;
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