Commit 703d7521 authored by Chuck Lever's avatar Chuck Lever
Browse files

NFSD: Hoist rq_vec preparation into nfsd_read() [step two] 



Now that the preparation of an rq_vec has been removed from the
generic read path, nfsd_splice_read() no longer needs to reset
rq_next_page.

nfsd4_encode_read() calls nfsd_splice_read() directly. As far as I
can ascertain, resetting rq_next_page for NFSv4 splice reads is
unnecessary because rq_next_page is already set correctly.

Moreover, resetting it might even be incorrect if previous
operations in the COMPOUND have already consumed at least a page of
the send buffer. I would expect that the result would be encoding
the READ payload over previously-encoded results.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 507df40e

fs/nfsd/nfs4xdr.c

+5 −5
Original line number Diff line number Diff line
@@ -4103,12 +4103,12 @@ static __be32 nfsd4_encode_readv(struct nfsd4_compoundres *resp, 
	__be32 zero = xdr_zero;

	__be32 nfserr;



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

	if (read->rd_vlen < 0)

	if (xdr_reserve_space_vec(xdr, maxcount) < 0)

		return nfserr_resource;



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

			    resp->rqstp->rq_vec, read->rd_vlen, &maxcount,

	nfserr = nfsd_iter_read(resp->rqstp, read->rd_fhp, file,

				read->rd_offset, &maxcount,

				xdr->buf->page_len & ~PAGE_MASK,

				&read->rd_eof);

	read->rd_length = maxcount;

	if (nfserr)

fs/nfsd/vfs.c

+12 −1
Original line number Diff line number Diff line
@@ -1003,6 +1003,18 @@ static __be32 nfsd_finish_read(struct svc_rqst *rqstp, struct svc_fh *fhp, 
	}

}



/**

 * nfsd_splice_read - Perform a VFS read using a splice pipe

 * @rqstp: RPC transaction context

 * @fhp: file handle of file to be read

 * @file: opened struct file of file to be read

 * @offset: starting byte offset

 * @count: IN: requested number of bytes; OUT: number of bytes read

 * @eof: OUT: set non-zero if operation reached the end of the file

 *

 * Returns nfs_ok on success, otherwise an nfserr stat value is

 * returned.

 */

__be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp,

			struct file *file, loff_t offset, unsigned long *count,

			u32 *eof)
@@ -1016,7 +1028,6 @@ __be32 nfsd_splice_read(struct svc_rqst *rqstp, struct svc_fh *fhp, 
	ssize_t host_err;



	trace_nfsd_read_splice(rqstp, fhp, offset, *count);

	rqstp->rq_next_page = rqstp->rq_respages + 1;

	host_err = splice_direct_to_actor(file, &sd, nfsd_direct_splice_actor);

	return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err);

}

include/linux/sunrpc/xdr.h

+1 −2
Original line number Diff line number Diff line
@@ -242,8 +242,7 @@ extern void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, 
extern void xdr_init_encode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,

			   struct page **pages, struct rpc_rqst *rqst);

extern __be32 *xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes);

extern int xdr_reserve_space_vec(struct xdr_stream *xdr, struct kvec *vec,

		size_t nbytes);

extern int xdr_reserve_space_vec(struct xdr_stream *xdr, size_t nbytes);

extern void __xdr_commit_encode(struct xdr_stream *xdr);

extern void xdr_truncate_encode(struct xdr_stream *xdr, size_t len);

extern void xdr_truncate_decode(struct xdr_stream *xdr, size_t len);

net/sunrpc/xdr.c

+12 −14
Original line number Diff line number Diff line
@@ -1070,22 +1070,22 @@ __be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes) 
}

EXPORT_SYMBOL_GPL(xdr_reserve_space);





/**

 * xdr_reserve_space_vec - Reserves a large amount of buffer space for sending

 * @xdr: pointer to xdr_stream

 * @vec: pointer to a kvec array

 * @nbytes: number of bytes to reserve

 *

 * Reserves enough buffer space to encode 'nbytes' of data and stores the

 * pointers in 'vec'. The size argument passed to xdr_reserve_space() is

 * determined based on the number of bytes remaining in the current page to

 * avoid invalidating iov_base pointers when xdr_commit_encode() is called.

 * The size argument passed to xdr_reserve_space() is determined based

 * on the number of bytes remaining in the current page to avoid

 * invalidating iov_base pointers when xdr_commit_encode() is called.

 *

 * Return values:

 *   %0: success

 *   %-EMSGSIZE: not enough space is available in @xdr

 */

int xdr_reserve_space_vec(struct xdr_stream *xdr, struct kvec *vec, size_t nbytes)

int xdr_reserve_space_vec(struct xdr_stream *xdr, size_t nbytes)

{

	int thislen;

	int v = 0;

	size_t thislen;

	__be32 *p;



	/*
@@ -1097,21 +1097,19 @@ int xdr_reserve_space_vec(struct xdr_stream *xdr, struct kvec *vec, size_t nbyte 
		xdr->end = xdr->p;

	}



	/* XXX: Let's find a way to make this more efficient */

	while (nbytes) {

		thislen = xdr->buf->page_len % PAGE_SIZE;

		thislen = min_t(size_t, nbytes, PAGE_SIZE - thislen);



		p = xdr_reserve_space(xdr, thislen);

		if (!p)

			return -EIO;

			return -EMSGSIZE;



		vec[v].iov_base = p;

		vec[v].iov_len = thislen;

		v++;

		nbytes -= thislen;

	}



	return v;

	return 0;

}

EXPORT_SYMBOL_GPL(xdr_reserve_space_vec);