[PATCH v2 1/5] SUNRPC: Add a function for directly setting the xdr page len
From: Anna Schumaker <anna@kernel.org>
Date: 2022-07-13 19:09:11
Subsystem:
kernel nfsd, sunrpc, and lockd servers, networking [general], nfs, sunrpc, and lockd clients, the rest · Maintainers:
Chuck Lever, Jeff Layton, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Trond Myklebust, Anna Schumaker, Linus Torvalds
From: Anna Schumaker <redacted> We need to do this step during READ_PLUS decoding so that we know pages are the right length and any extra data has been preserved in the tail. Signed-off-by: Anna Schumaker <redacted> --- include/linux/sunrpc/xdr.h | 1 + net/sunrpc/xdr.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 31 insertions(+)
diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index 79824fea4529..b8f3011e109b 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h@@ -262,6 +262,7 @@ extern __be32 *xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes); extern unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len); extern void xdr_enter_page(struct xdr_stream *xdr, unsigned int len); extern int xdr_process_buf(const struct xdr_buf *buf, unsigned int offset, unsigned int len, int (*actor)(struct scatterlist *, void *), void *data); +extern void xdr_set_pagelen(struct xdr_stream *, unsigned int len); extern unsigned int xdr_align_data(struct xdr_stream *, unsigned int offset, unsigned int length); extern unsigned int xdr_expand_hole(struct xdr_stream *, unsigned int offset, unsigned int length); extern bool xdr_stream_subsegment(struct xdr_stream *xdr, struct xdr_buf *subbuf,
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index ea734b14af0f..9d7c93645f01 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c@@ -1518,6 +1518,36 @@ unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len) } EXPORT_SYMBOL_GPL(xdr_read_pages); +/** + * xdr_set_pagelen - Sets the length of the XDR pages + * @xdr: pointer to xdr_stream struct + * @len: new length of the XDR page data + * + * Either grows or shrinks the length of the xdr pages by setting pagelen to + * @len bytes. When shrinking, any extra data is moved into buf->tail, whereas + * when growing any data beyond the current pointer is moved into the tail. + * + * Returns True if the operation was successful, and False otherwise. + */ +void xdr_set_pagelen(struct xdr_stream *xdr, unsigned int len) +{ + struct xdr_buf *buf = xdr->buf; + size_t remaining = xdr_stream_remaining(xdr); + size_t base = 0; + + if (len < buf->page_len) { + base = buf->page_len - len; + xdr_shrink_pagelen(buf, len); + } else { + xdr_buf_head_shift_right(buf, xdr_stream_pos(xdr), + buf->page_len, remaining); + if (len > buf->page_len) + xdr_buf_try_expand(buf, len - buf->page_len); + } + xdr_set_tail_base(xdr, base, remaining); +} +EXPORT_SYMBOL_GPL(xdr_set_pagelen); + unsigned int xdr_align_data(struct xdr_stream *xdr, unsigned int offset, unsigned int length) {
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2.37.0