From 476a7b1f4b2c9c38255653fa55157565be8b14be Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Mon, 20 Jan 2014 17:08:27 -0500 Subject: [PATCH] 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 --- fs/nfsd/nfs4xdr.c | 42 ++++++++++++------------------------------ 1 file changed, 12 insertions(+), 30 deletions(-) diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c index 3f2a52ccb9d1..cda6226bda91 100644 --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -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; } -- 2.20.1