Commit 4163ee71 authored by Chuck Lever's avatar Chuck Lever
Browse files

NFSD: Insulate nfsd4_encode_fattr4() from page boundaries in the encode buffer 



Commit ab04de60 ("NFSD: Optimize nfsd4_encode_fattr()") replaced
the use of write_bytes_to_xdr_buf() because it's expensive and the
data items to be encoded are already properly aligned.

However, there's no guarantee that the pointer returned from
xdr_reserve_space() will still point to the correct reserved space
in the encode buffer after one or more intervening calls to
xdr_reserve_space(). It just happens to work with the current
implementation of xdr_reserve_space().

This commit effectively reverts the optimization.

Reviewed-by: default avatarNeilBrown <neilb@suse.de>
Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent b786caa6

fs/nfsd/nfs4xdr.c

+5 −5
Original line number Diff line number Diff line
@@ -3507,8 +3507,8 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct xdr_stream *xdr, 
	struct nfsd4_fattr_args args;

	struct svc_fh *tempfh = NULL;

	int starting_len = xdr->buf->len;

	__be32 *attrlen_p, status;

	int attrlen_offset;

	unsigned int attrlen_offset;

	__be32 attrlen, status;

	u32 attrmask[3];

	int err;

	struct nfsd4_compoundres *resp = rqstp->rq_resp;
@@ -3629,8 +3629,7 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct xdr_stream *xdr, 


	/* attr_vals */

	attrlen_offset = xdr->buf->len;

	attrlen_p = xdr_reserve_space(xdr, XDR_UNIT);

	if (!attrlen_p)

	if (unlikely(!xdr_reserve_space(xdr, XDR_UNIT)))

		goto out_resource;

	bitmap_from_arr32(attr_bitmap, attrmask,

			  ARRAY_SIZE(nfsd4_enc_fattr4_encode_ops));
@@ -3640,7 +3639,8 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct xdr_stream *xdr, 
		if (status != nfs_ok)

			goto out;

	}

	*attrlen_p = cpu_to_be32(xdr->buf->len - attrlen_offset - XDR_UNIT);

	attrlen = cpu_to_be32(xdr->buf->len - attrlen_offset - XDR_UNIT);

	write_bytes_to_xdr_buf(xdr->buf, attrlen_offset, &attrlen, XDR_UNIT);

	status = nfs_ok;



out: