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Commit 476a7b1f authored by J. Bruce Fields's avatar J. Bruce Fields
Browse files

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: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 3b299709

fs/nfsd/nfs4xdr.c

+12 −30
Original line number Diff line number Diff line
@@ -3160,8 +3160,9 @@ static __be32 
nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4_readlink *readlink)

{

	int maxcount;

	__be32 wire_count;

	int zero = 0;

	struct xdr_stream *xdr = &resp->xdr;

	char *page;

	int length_offset = xdr->buf->len;

	__be32 *p;
@@ -3171,26 +3172,19 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd 
	p = xdr_reserve_space(xdr, 4);

	if (!p)

		return nfserr_resource;



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

		return nfserr_resource;

	if (!*resp->rqstp->rq_next_page)

		return nfserr_resource;



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



	maxcount = PAGE_SIZE;



	if (xdr->end - xdr->p < 1)

	p = xdr_reserve_space(xdr, maxcount);

	if (!p)

		return nfserr_resource;



	/*

	 * XXX: By default, the ->readlink() VFS op will truncate symlinks

	 * if they would overflow the buffer.  Is this kosher in NFSv4?  If

	 * not, one easy fix is: if ->readlink() precisely fills the buffer,

	 * assume that truncation occurred, and return NFS4ERR_RESOURCE.

	 */

	nfserr = nfsd_readlink(readlink->rl_rqstp, readlink->rl_fhp, page, &maxcount);

	nfserr = nfsd_readlink(readlink->rl_rqstp, readlink->rl_fhp,

						(char *)p, &maxcount);

	if (nfserr == nfserr_isdir)

		nfserr = nfserr_inval;

	if (nfserr) {
@@ -3198,24 +3192,12 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd 
		return nfserr;

	}



	WRITE32(maxcount);

	resp->xdr.buf->head[0].iov_len = (char *)p

				- (char *)resp->xdr.buf->head[0].iov_base;

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

	xdr->buf->len += maxcount;

	xdr->page_ptr += 1;

	xdr->buf->buflen -= PAGE_SIZE;

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



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

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

	}

	wire_count = htonl(maxcount);

	write_bytes_to_xdr_buf(xdr->buf, length_offset, &wire_count, 4);

	xdr_truncate_encode(xdr, length_offset + 4 + maxcount);

	if (maxcount & 3)

		write_bytes_to_xdr_buf(xdr->buf, length_offset + 4 + maxcount,

						&zero, 4 - (maxcount&3));

	return 0;

}