Commit eeadcb75 authored by Anna Schumaker's avatar Anna Schumaker Committed by Chuck Lever
Browse files

NFSD: Simplify READ_PLUS 



Chuck had suggested reverting READ_PLUS so it returns a single DATA
segment covering the requested read range. This prepares the server for
a future "sparse read" function so support can easily be added without
needing to rip out the old READ_PLUS code at the same time.

Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent b7b275e6

fs/nfsd/nfs4xdr.c

+32 −107
Original line number Diff line number Diff line
@@ -4767,79 +4767,37 @@ nfsd4_encode_offload_status(struct nfsd4_compoundres *resp, __be32 nfserr, 


static __be32

nfsd4_encode_read_plus_data(struct nfsd4_compoundres *resp,

			    struct nfsd4_read *read,

			    unsigned long *maxcount, u32 *eof,

			    loff_t *pos)

			    struct nfsd4_read *read)

{

	struct xdr_stream *xdr = resp->xdr;

	bool splice_ok = test_bit(RQ_SPLICE_OK, &resp->rqstp->rq_flags);

	struct file *file = read->rd_nf->nf_file;

	int starting_len = xdr->buf->len;

	loff_t hole_pos;

	__be32 nfserr;

	__be32 *p, tmp;

	__be64 tmp64;



	hole_pos = pos ? *pos : vfs_llseek(file, read->rd_offset, SEEK_HOLE);

	if (hole_pos > read->rd_offset)

		*maxcount = min_t(unsigned long, *maxcount, hole_pos - read->rd_offset);

	*maxcount = min_t(unsigned long, *maxcount, (xdr->buf->buflen - xdr->buf->len));

	struct xdr_stream *xdr = resp->xdr;

	unsigned long maxcount;

	__be32 nfserr, *p;



	/* Content type, offset, byte count */

	p = xdr_reserve_space(xdr, 4 + 8 + 4);

	if (!p)

		return nfserr_resource;

		return nfserr_io;

	if (resp->xdr->buf->page_len && splice_ok) {

		WARN_ON_ONCE(splice_ok);

		return nfserr_serverfault;

	}



	read->rd_vlen = xdr_reserve_space_vec(xdr, resp->rqstp->rq_vec, *maxcount);

	if (read->rd_vlen < 0)

		return nfserr_resource;

	maxcount = min_t(unsigned long, read->rd_length,

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



	nfserr = nfsd_readv(resp->rqstp, read->rd_fhp, file, read->rd_offset,

			    resp->rqstp->rq_vec, read->rd_vlen, maxcount, eof);

	if (file->f_op->splice_read && splice_ok)

		nfserr = nfsd4_encode_splice_read(resp, read, file, maxcount);

	else

		nfserr = nfsd4_encode_readv(resp, read, file, maxcount);

	if (nfserr)

		return nfserr;

	xdr_truncate_encode(xdr, starting_len + 16 + xdr_align_size(*maxcount));



	tmp = htonl(NFS4_CONTENT_DATA);

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

	tmp64 = cpu_to_be64(read->rd_offset);

	write_bytes_to_xdr_buf(xdr->buf, starting_len + 4,  &tmp64, 8);

	tmp = htonl(*maxcount);

	write_bytes_to_xdr_buf(xdr->buf, starting_len + 12, &tmp,   4);



	tmp = xdr_zero;

	write_bytes_to_xdr_buf(xdr->buf, starting_len + 16 + *maxcount, &tmp,

			       xdr_pad_size(*maxcount));

	return nfs_ok;

}



static __be32

nfsd4_encode_read_plus_hole(struct nfsd4_compoundres *resp,

			    struct nfsd4_read *read,

			    unsigned long *maxcount, u32 *eof)

{

	struct file *file = read->rd_nf->nf_file;

	loff_t data_pos = vfs_llseek(file, read->rd_offset, SEEK_DATA);

	loff_t f_size = i_size_read(file_inode(file));

	unsigned long count;

	__be32 *p;



	if (data_pos == -ENXIO)

		data_pos = f_size;

	else if (data_pos <= read->rd_offset || (data_pos < f_size && data_pos % PAGE_SIZE))

		return nfsd4_encode_read_plus_data(resp, read, maxcount, eof, &f_size);

	count = data_pos - read->rd_offset;



	/* Content type, offset, byte count */

	p = xdr_reserve_space(resp->xdr, 4 + 8 + 8);

	if (!p)

		return nfserr_resource;



	*p++ = htonl(NFS4_CONTENT_HOLE);

	*p++ = cpu_to_be32(NFS4_CONTENT_DATA);

	p = xdr_encode_hyper(p, read->rd_offset);

	p = xdr_encode_hyper(p, count);

	*p = cpu_to_be32(read->rd_length);



	*eof = (read->rd_offset + count) >= f_size;

	*maxcount = min_t(unsigned long, count, *maxcount);

	return nfs_ok;

}
@@ -4847,69 +4805,36 @@ static __be32 
nfsd4_encode_read_plus(struct nfsd4_compoundres *resp, __be32 nfserr,

		       struct nfsd4_read *read)

{

	unsigned long maxcount, count;

	struct file *file = read->rd_nf->nf_file;

	struct xdr_stream *xdr = resp->xdr;

	struct file *file;

	int starting_len = xdr->buf->len;

	int last_segment = xdr->buf->len;

	int segments = 0;

	__be32 *p, tmp;

	bool is_data;

	loff_t pos;

	u32 eof;

	u32 segments = 0;

	__be32 *p;



	if (nfserr)

		return nfserr;

	file = read->rd_nf->nf_file;



	/* eof flag, segment count */

	p = xdr_reserve_space(xdr, 4 + 4);

	if (!p)

		return nfserr_resource;

		return nfserr_io;

	xdr_commit_encode(xdr);



	maxcount = min_t(unsigned long, read->rd_length,

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

	count    = maxcount;



	eof = read->rd_offset >= i_size_read(file_inode(file));

	if (eof)

	read->rd_eof = read->rd_offset >= i_size_read(file_inode(file));

	if (read->rd_eof)

		goto out;



	pos = vfs_llseek(file, read->rd_offset, SEEK_HOLE);

	is_data = pos > read->rd_offset;

	nfserr = nfsd4_encode_read_plus_data(resp, read);

	if (nfserr) {

		xdr_truncate_encode(xdr, starting_len);

		return nfserr;

	}



	while (count > 0 && !eof) {

		maxcount = count;

		if (is_data)

			nfserr = nfsd4_encode_read_plus_data(resp, read, &maxcount, &eof,

						segments == 0 ? &pos : NULL);

		else

			nfserr = nfsd4_encode_read_plus_hole(resp, read, &maxcount, &eof);

		if (nfserr)

			goto out;

		count -= maxcount;

		read->rd_offset += maxcount;

		is_data = !is_data;

		last_segment = xdr->buf->len;

	segments++;

	}



out:

	if (nfserr && segments == 0)

		xdr_truncate_encode(xdr, starting_len);

	else {

		if (nfserr) {

			xdr_truncate_encode(xdr, last_segment);

			nfserr = nfs_ok;

			eof = 0;

		}

		tmp = htonl(eof);

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

		tmp = htonl(segments);

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

	}



	p = xdr_encode_bool(p, read->rd_eof);

	*p = cpu_to_be32(segments);

	return nfserr;

}