[PATCH v1 5/6] NFSD: Hoist rq_vec preparation into nfsd_read() [step two]
From: Chuck Lever <cel@kernel.org>
Date: 2023-05-18 17:46:35
Subsystem:
filesystems (vfs and infrastructure), kernel nfsd, sunrpc, and lockd servers, networking [general], nfs, sunrpc, and lockd clients, the rest · Maintainers:
Alexander Viro, Christian Brauner, Chuck Lever, Jeff Layton, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Trond Myklebust, Anna Schumaker, Linus Torvalds
From: Chuck Lever <chuck.lever@oracle.com> 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: Chuck Lever <chuck.lever@oracle.com> --- fs/nfsd/nfs4xdr.c | 10 +++++----- fs/nfsd/vfs.c | 13 ++++++++++++- include/linux/sunrpc/xdr.h | 3 +-- net/sunrpc/xdr.c | 26 ++++++++++++-------------- 4 files changed, 30 insertions(+), 22 deletions(-)
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 23dd09c4b2cd..b83954fc57e3 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c@@ -4104,13 +4104,13 @@ 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, - &read->rd_eof); + 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) return nfserr;
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 054d58d01299..13ccd385b308 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c@@ -995,6 +995,18 @@ 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)
@@ -1008,7 +1020,6 @@ __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); }
diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index 72014c9216fc..f89ec4b5ea16 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h@@ -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);
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 36835b2f5446..2a22e78af116 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c@@ -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);