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[v6,02/10] SUNRPC: Implement a xdr_page_pos() function

Message ID 20200928170919.707641-3-Anna.Schumaker@Netapp.com (mailing list archive)
State New
Headers show
Series NFS: Add support for the v4.2 READ_PLUS operation | expand

Commit Message

Anna Schumaker Sept. 28, 2020, 5:09 p.m. UTC
From: Anna Schumaker <Anna.Schumaker@Netapp.com>

I'll need this for READ_PLUS to help figure out the offset where page
data is stored at, but it might also be useful for other things.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
 include/linux/sunrpc/xdr.h |  1 +
 net/sunrpc/xdr.c           | 13 +++++++++++++
 2 files changed, 14 insertions(+)
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diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index 6613d96a3029..026edbd041d5 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h
@@ -242,6 +242,7 @@  extern int xdr_restrict_buflen(struct xdr_stream *xdr, int newbuflen);
 extern void xdr_write_pages(struct xdr_stream *xdr, struct page **pages,
 		unsigned int base, unsigned int len);
 extern unsigned int xdr_stream_pos(const struct xdr_stream *xdr);
+extern unsigned int xdr_page_pos(const struct xdr_stream *xdr);
 extern void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf,
 			    __be32 *p, struct rpc_rqst *rqst);
 extern void xdr_init_decode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index c62b0882c0d8..8d29450fdce5 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -505,6 +505,19 @@  unsigned int xdr_stream_pos(const struct xdr_stream *xdr)
+ * xdr_page_pos - Return the current offset from the start of the xdr pages
+ * @xdr: pointer to struct xdr_stream
+ */
+unsigned int xdr_page_pos(const struct xdr_stream *xdr)
+	unsigned int pos = xdr_stream_pos(xdr);
+	WARN_ON(pos < xdr->buf->head[0].iov_len);
+	return pos - xdr->buf->head[0].iov_len;
  * xdr_init_encode - Initialize a struct xdr_stream for sending data.
  * @xdr: pointer to xdr_stream struct