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Commit b0420980 authored by J. Bruce Fields's avatar J. Bruce Fields
Browse files

nfsd4: allow exotic read compounds 



I'm not sure why a client would want to stuff multiple reads in a
single compound rpc, but it's legal for them to do it, and we should
really support it.

Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent fec25fa4

Documentation/filesystems/nfs/nfs41-server.txt

+0 −2
Original line number Diff line number Diff line
@@ -176,7 +176,5 @@ Nonstandard compound limitations: 
  ca_maxrequestsize request and a ca_maxresponsesize reply, so we may

  fail to live up to the promise we made in CREATE_SESSION fore channel

  negotiation.

* No more than one read-like operation allowed per compound; encoding

  replies that cross page boundaries (except for read data) not handled.



See also http://wiki.linux-nfs.org/wiki/index.php/Server_4.0_and_4.1_issues.

fs/nfsd/nfs4xdr.c

+25 −36
Original line number Diff line number Diff line
@@ -3139,28 +3139,34 @@ static __be32 nfsd4_encode_readv(struct nfsd4_compoundres *resp, 
	struct xdr_stream *xdr = &resp->xdr;

	u32 eof;

	int v;

	struct page *page;

	int starting_len = xdr->buf->len - 8;

	int space_left;

	long len;

	int thislen;

	__be32 nfserr;

	__be32 tmp;

	__be32 *p;

	u32 zzz = 0;

	int pad;



	len = maxcount;

	v = 0;

	while (len) {

		int thislen;



		page = *(resp->rqstp->rq_next_page);

		if (!page) { /* ran out of pages */

			maxcount -= len;

			break;

		}

	thislen = (void *)xdr->end - (void *)xdr->p;

	if (len < thislen)

		thislen = len;

	p = xdr_reserve_space(xdr, (thislen+3)&~3);

	WARN_ON_ONCE(!p);

	resp->rqstp->rq_vec[v].iov_base = p;

	resp->rqstp->rq_vec[v].iov_len = thislen;

	v++;

	len -= thislen;



	while (len) {

		thislen = min_t(long, len, PAGE_SIZE);

		resp->rqstp->rq_vec[v].iov_base = page_address(page);

		p = xdr_reserve_space(xdr, (thislen+3)&~3);

		WARN_ON_ONCE(!p);

		resp->rqstp->rq_vec[v].iov_base = p;

		resp->rqstp->rq_vec[v].iov_len = thislen;

		resp->rqstp->rq_next_page++;

		v++;

		len -= thislen;

	}
@@ -3170,6 +3176,7 @@ static __be32 nfsd4_encode_readv(struct nfsd4_compoundres *resp, 
			read->rd_vlen, &maxcount);

	if (nfserr)

		return nfserr;

	xdr_truncate_encode(xdr, starting_len + 8 + ((maxcount+3)&~3));



	eof = (read->rd_offset + maxcount >=

	       read->rd_fhp->fh_dentry->d_inode->i_size);
@@ -3179,27 +3186,9 @@ static __be32 nfsd4_encode_readv(struct nfsd4_compoundres *resp, 
	tmp = htonl(maxcount);

	write_bytes_to_xdr_buf(xdr->buf, starting_len + 4, &tmp, 4);



	resp->xdr.buf->page_len = maxcount;

	xdr->buf->len += maxcount;

	xdr->page_ptr += v;

	xdr->iov = xdr->buf->tail;



	/* Use rest of head for padding and remaining ops: */

	resp->xdr.buf->tail[0].iov_base = xdr->p;

	resp->xdr.buf->tail[0].iov_len = 0;

	if (maxcount&3) {

		p = xdr_reserve_space(xdr, 4);

		WRITE32(0);

		resp->xdr.buf->tail[0].iov_base += maxcount&3;

		resp->xdr.buf->tail[0].iov_len = 4 - (maxcount&3);

		xdr->buf->len -= (maxcount&3);

	}



	space_left = min_t(int, (void *)xdr->end - (void *)xdr->p,

				xdr->buf->buflen - xdr->buf->len);

	xdr->buf->buflen = xdr->buf->len + space_left;

	xdr->end = (__be32 *)((void *)xdr->end + space_left);



	pad = (maxcount&3) ? 4 - (maxcount&3) : 0;

	write_bytes_to_xdr_buf(xdr->buf, starting_len + 8 + maxcount,

								&zzz, pad);

	return 0;



}
@@ -3224,15 +3213,15 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr, 
		WARN_ON_ONCE(resp->rqstp->rq_splice_ok);

		return nfserr_resource;

	}



	if (resp->xdr.buf->page_len) {

		WARN_ON_ONCE(resp->rqstp->rq_splice_ok);

	if (resp->xdr.buf->page_len && resp->rqstp->rq_splice_ok) {

		WARN_ON_ONCE(1);

		return nfserr_resource;

	}



	xdr_commit_encode(xdr);



	maxcount = svc_max_payload(resp->rqstp);

	if (maxcount > xdr->buf->buflen - xdr->buf->len)

		maxcount = xdr->buf->buflen - xdr->buf->len;

	if (maxcount > read->rd_length)

		maxcount = read->rd_length;