From: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
For now, this function simply aligns the data at the beginning of the
pages. This can eventually be expanded to shift data to the correct
offsets when we're ready.
Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
---
include/linux/sunrpc/xdr.h | 1 +
net/sunrpc/xdr.c | 121 +++++++++++++++++++++++++++++++++++++
2 files changed, 122 insertions(+)
diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index 36a81c29542e..9548d075e06d 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h
@@ -252,6 +252,7 @@ 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 uint64_t xdr_align_data(struct xdr_stream *, uint64_t, uint32_t);
extern uint64_t xdr_expand_hole(struct xdr_stream *, uint64_t, uint64_t);
/**
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 3a168bd54c87..eedb6d7300d2 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -19,6 +19,9 @@
#include <linux/bvec.h>
#include <trace/events/sunrpc.h>
+static void _copy_to_pages(struct page **, size_t, const char *, size_t);
+
+
/*
* XDR functions for basic NFS types
*/
@@ -201,6 +204,88 @@ EXPORT_SYMBOL_GPL(xdr_inline_pages);
* Helper routines for doing 'memmove' like operations on a struct xdr_buf
*/
+/**
+ * _shift_data_left_pages
+ * @pages: vector of pages containing both the source and dest memory area.
+ * @pgto_base: page vector address of destination
+ * @pgfrom_base: page vector address of source
+ * @len: number of bytes to copy
+ *
+ * Note: the addresses pgto_base and pgfrom_base are both calculated in
+ * the same way:
+ * if a memory area starts at byte 'base' in page 'pages[i]',
+ * then its address is given as (i << PAGE_CACHE_SHIFT) + base
+ * Alse note: pgto_base must be < pgfrom_base, but the memory areas
+ * they point to may overlap.
+ */
+static void
+_shift_data_left_pages(struct page **pages, size_t pgto_base,
+ size_t pgfrom_base, size_t len)
+{
+ struct page **pgfrom, **pgto;
+ char *vfrom, *vto;
+ size_t copy;
+
+ BUG_ON(pgfrom_base <= pgto_base);
+
+ pgto = pages + (pgto_base >> PAGE_SHIFT);
+ pgfrom = pages + (pgfrom_base >> PAGE_SHIFT);
+
+ pgto_base &= ~PAGE_MASK;
+ pgfrom_base &= ~PAGE_MASK;
+
+ do {
+ if (pgto_base >= PAGE_SIZE) {
+ pgto_base = 0;
+ pgto++;
+ }
+ if (pgfrom_base >= PAGE_SIZE){
+ pgfrom_base = 0;
+ pgfrom++;
+ }
+
+ copy = len;
+ if (copy > (PAGE_SIZE - pgto_base))
+ copy = PAGE_SIZE - pgto_base;
+ if (copy > (PAGE_SIZE - pgfrom_base))
+ copy = PAGE_SIZE - pgfrom_base;
+
+ vto = kmap_atomic(*pgto);
+ if (*pgto != *pgfrom) {
+ vfrom = kmap_atomic(*pgfrom);
+ memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
+ kunmap_atomic(vfrom);
+ } else
+ memmove(vto + pgto_base, vto + pgfrom_base, copy);
+ flush_dcache_page(*pgto);
+ kunmap_atomic(vto);
+
+ pgto_base += copy;
+ pgfrom_base += copy;
+
+ } while ((len -= copy) != 0);
+}
+
+static void
+_shift_data_left_tail(struct xdr_buf *buf, unsigned int pgto, size_t len)
+{
+ struct kvec *tail = buf->tail;
+
+ if (len > tail->iov_len)
+ len = tail->iov_len;
+
+ _copy_to_pages(buf->pages,
+ buf->page_base + pgto,
+ (char *)tail->iov_base,
+ len);
+ tail->iov_len -= len;
+
+ if (tail->iov_len > 0)
+ memmove((char *)tail->iov_base,
+ tail->iov_base + len,
+ tail->iov_len);
+}
+
/**
* _shift_data_right_pages
* @pages: vector of pages containing both the source and dest memory area.
@@ -1173,6 +1258,42 @@ unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
}
EXPORT_SYMBOL_GPL(xdr_read_pages);
+uint64_t xdr_align_data(struct xdr_stream *xdr, uint64_t offset, uint32_t length)
+{
+ struct xdr_buf *buf = xdr->buf;
+ unsigned int from, bytes;
+ unsigned int shift = 0;
+
+ if ((offset + length) < offset ||
+ (offset + length) > buf->page_len)
+ length = buf->page_len - offset;
+
+ xdr_realign_pages(xdr);
+ from = xdr_page_pos(xdr);
+ bytes = xdr->nwords << 2;
+ if (length < bytes)
+ bytes = length;
+
+ /* Move page data to the left */
+ if (from > offset) {
+ shift = min_t(unsigned int, bytes, buf->page_len - from);
+ _shift_data_left_pages(buf->pages,
+ buf->page_base + offset,
+ buf->page_base + from,
+ shift);
+ bytes -= shift;
+
+ /* Move tail data into the pages, if necessary */
+ if (bytes > 0)
+ _shift_data_left_tail(buf, offset + shift, bytes);
+ }
+
+ xdr->nwords -= XDR_QUADLEN(length);
+ xdr_set_page(xdr, from + length, PAGE_SIZE);
+ return length;
+}
+EXPORT_SYMBOL_GPL(xdr_align_data);
+
uint64_t xdr_expand_hole(struct xdr_stream *xdr, uint64_t offset, uint64_t length)
{
struct xdr_buf *buf = xdr->buf;
--
2.28.0
