nfsd4: don't treat readlink like a zero-copy operation
There's no advantage to this zero-copy-style readlink encoding, and it unnecessarily limits the kinds of compounds we can handle. (In practice I can't see why a client would want e.g. multiple readlink calls in a comound, but it's probably a spec violation for us not to handle it.) Signed-off-by: J. Bruce Fields <bfields@redhat.com>
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@ -3160,8 +3160,9 @@ static __be32
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nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_readlink *readlink)
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{
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int maxcount;
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__be32 wire_count;
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int zero = 0;
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struct xdr_stream *xdr = &resp->xdr;
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char *page;
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int length_offset = xdr->buf->len;
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__be32 *p;
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@ -3171,26 +3172,19 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd
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p = xdr_reserve_space(xdr, 4);
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if (!p)
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return nfserr_resource;
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if (resp->xdr.buf->page_len)
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return nfserr_resource;
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if (!*resp->rqstp->rq_next_page)
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return nfserr_resource;
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page = page_address(*(resp->rqstp->rq_next_page++));
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maxcount = PAGE_SIZE;
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if (xdr->end - xdr->p < 1)
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p = xdr_reserve_space(xdr, maxcount);
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if (!p)
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return nfserr_resource;
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/*
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* XXX: By default, the ->readlink() VFS op will truncate symlinks
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* if they would overflow the buffer. Is this kosher in NFSv4? If
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* not, one easy fix is: if ->readlink() precisely fills the buffer,
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* assume that truncation occurred, and return NFS4ERR_RESOURCE.
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*/
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nfserr = nfsd_readlink(readlink->rl_rqstp, readlink->rl_fhp, page, &maxcount);
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nfserr = nfsd_readlink(readlink->rl_rqstp, readlink->rl_fhp,
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(char *)p, &maxcount);
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if (nfserr == nfserr_isdir)
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nfserr = nfserr_inval;
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if (nfserr) {
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@ -3198,24 +3192,12 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd
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return nfserr;
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}
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WRITE32(maxcount);
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resp->xdr.buf->head[0].iov_len = (char *)p
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- (char *)resp->xdr.buf->head[0].iov_base;
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resp->xdr.buf->page_len = maxcount;
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xdr->buf->len += maxcount;
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xdr->page_ptr += 1;
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xdr->buf->buflen -= PAGE_SIZE;
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xdr->iov = xdr->buf->tail;
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/* Use rest of head for padding and remaining ops: */
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resp->xdr.buf->tail[0].iov_base = p;
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resp->xdr.buf->tail[0].iov_len = 0;
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if (maxcount&3) {
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p = xdr_reserve_space(xdr, 4);
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WRITE32(0);
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resp->xdr.buf->tail[0].iov_base += maxcount&3;
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resp->xdr.buf->tail[0].iov_len = 4 - (maxcount&3);
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}
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wire_count = htonl(maxcount);
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write_bytes_to_xdr_buf(xdr->buf, length_offset, &wire_count, 4);
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xdr_truncate_encode(xdr, length_offset + 4 + maxcount);
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if (maxcount & 3)
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write_bytes_to_xdr_buf(xdr->buf, length_offset + 4 + maxcount,
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&zero, 4 - (maxcount&3));
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return 0;
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}
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