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Commit 4e21ac4b authored by J. Bruce Fields's avatar J. Bruce Fields
Browse files

nfsd4: reserve space before inlining 0-copy pages 



Once we've included page-cache pages in the encoding it's difficult to
remove them and restart encoding.  (xdr_truncate_encode doesn't handle
that case.)  So, make sure we'll have adequate space to finish the
operation first.

For now COMPOUND_SLACK_SPACE checks should prevent this case happening,
but we want to remove those checks.

Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent d0a381dd

fs/nfsd/nfs4xdr.c

+7 −4
Original line number Diff line number Diff line
@@ -3071,6 +3071,10 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr, 
	if (!p)

		return nfserr_resource;



	/* Make sure there will be room for padding if needed: */

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

		return nfserr_resource;



	maxcount = svc_max_payload(resp->rqstp);

	if (maxcount > read->rd_length)

		maxcount = read->rd_length;
@@ -3122,8 +3126,6 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, __be32 nfserr, 
	resp->xdr.buf->tail[0].iov_len = 0;

	if (maxcount&3) {

		p = xdr_reserve_space(xdr, 4);

		if (!p)

			return nfserr_resource;

		WRITE32(0);

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

		resp->xdr.buf->tail[0].iov_len = 4 - (maxcount&3);
@@ -3156,6 +3158,9 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd 
	if (!p)

		return nfserr_resource;



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

		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
@@ -3182,8 +3187,6 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd 
	resp->xdr.buf->tail[0].iov_len = 0;

	if (maxcount&3) {

		p = xdr_reserve_space(xdr, 4);

		if  (!p)

			return nfserr_resource;

		WRITE32(0);

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

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