From: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
This patch adds the ability to "read a hole" into a set of XDR data
pages by taking the following steps:
1) Shift all data after the current xdr->p to the right, possibly into
the tail,
2) Zero the specified range, and
3) Update xdr->p to point beyond the hole.
Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
---
include/linux/sunrpc/xdr.h | 1 +
net/sunrpc/xdr.c | 100 +++++++++++++++++++++++++++++++++++++
2 files changed, 101 insertions(+)
diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index b41f34977995..81a79099ed3b 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h
@@ -263,6 +263,7 @@ 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(struct xdr_buf *buf, unsigned int offset, unsigned int len, int (*actor)(struct scatterlist *, void *), void *data);
+extern size_t xdr_expand_hole(struct xdr_stream *, size_t, uint64_t);
/**
* xdr_stream_remaining - Return the number of bytes remaining in the stream
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 8bed0ec21563..bc9b9b0945f5 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -266,6 +266,40 @@ _shift_data_right_pages(struct page **pages, size_t pgto_base,
} while ((len -= copy) != 0);
}
+static void
+_shift_data_right_tail(struct xdr_buf *buf, size_t pgfrom_base, size_t len)
+{
+ struct kvec *tail = buf->tail;
+
+ /* Make room for new data. */
+ if (tail->iov_len > 0)
+ memmove((char *)tail->iov_base + len, tail->iov_base, len);
+
+ _copy_from_pages((char *)tail->iov_base,
+ buf->pages,
+ buf->page_base + pgfrom_base,
+ len);
+
+ tail->iov_len += len;
+}
+
+static void
+_shift_data_right(struct xdr_buf *buf, size_t to, size_t from, size_t len)
+{
+ size_t shift = len;
+
+ if ((to + len) > buf->page_len) {
+ shift = (to + len) - buf->page_len;
+ _shift_data_right_tail(buf, (from + len) - shift, shift);
+ shift = len - shift;
+ }
+
+ _shift_data_right_pages(buf->pages,
+ buf->page_base + to,
+ buf->page_base + from,
+ shift);
+}
+
/**
* _copy_to_pages
* @pages: array of pages
@@ -350,6 +384,33 @@ _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
}
EXPORT_SYMBOL_GPL(_copy_from_pages);
+/**
+ * _zero_data_pages
+ * @pages: array of pages
+ * @pgbase: beginning page vector address
+ * @len: length
+ */
+static void
+_zero_data_pages(struct page **pages, size_t pgbase, size_t len)
+{
+ struct page **page;
+ size_t zero;
+
+ page = pages + (pgbase >> PAGE_SHIFT);
+ pgbase &= ~PAGE_MASK;
+
+ do {
+ zero = len;
+ if (pgbase + zero > PAGE_SIZE)
+ zero = PAGE_SIZE - pgbase;
+
+ zero_user_segment(*page, pgbase, pgbase + zero);
+ page++;
+ pgbase = 0;
+
+ } while ((len -= zero) != 0);
+}
+
/**
* xdr_shrink_bufhead
* @buf: xdr_buf
@@ -505,6 +566,24 @@ unsigned int xdr_stream_pos(const struct xdr_stream *xdr)
}
EXPORT_SYMBOL_GPL(xdr_stream_pos);
+/**
+ * xdr_page_pos - Return the current offset from the start of the xdr->buf->pages
+ * @xdr: pointer to struct xdr_stream
+ */
+static size_t xdr_page_pos(const struct xdr_stream *xdr)
+{
+ unsigned int offset;
+ unsigned int base = xdr->buf->page_len;
+ void *kaddr = xdr->buf->tail->iov_base;;
+
+ if (xdr->page_ptr) {
+ base = (xdr->page_ptr - xdr->buf->pages) * PAGE_SIZE;
+ kaddr = page_address(*xdr->page_ptr);
+ }
+ offset = xdr->p - (__be32 *)kaddr;
+ return base + (offset * sizeof(__be32));
+}
+
/**
* xdr_init_encode - Initialize a struct xdr_stream for sending data.
* @xdr: pointer to xdr_stream struct
@@ -1062,6 +1141,27 @@ unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
}
EXPORT_SYMBOL_GPL(xdr_read_pages);
+size_t xdr_expand_hole(struct xdr_stream *xdr, size_t offset, uint64_t length)
+{
+ struct xdr_buf *buf = xdr->buf;
+ size_t from = 0;
+
+ if ((offset + length) < offset ||
+ (offset + length) > buf->page_len)
+ length = buf->page_len - offset;
+
+ if (offset == 0)
+ xdr_align_pages(xdr, xdr->nwords << 2);
+ else
+ from = xdr_page_pos(xdr);
+
+ _shift_data_right(buf, offset + length, from, xdr->nwords << 2);
+ _zero_data_pages(buf->pages, buf->page_base + offset, length);
+ xdr_set_page(xdr, offset + length);
+ return length;
+}
+EXPORT_SYMBOL_GPL(xdr_expand_hole);
+
/**
* xdr_enter_page - decode data from the XDR page
* @xdr: pointer to xdr_stream struct
--
2.24.1
