From: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
Expanding holes tends to put the data content a few bytes to the right
of where we want it. This patch implements a left-shift operation to
line everything up properly.
Signed-off-by: Anna Schumaker <Anna.Schumaker@xxxxxxxxxx>
---
include/linux/sunrpc/xdr.h | 1 +
net/sunrpc/xdr.c | 135 +++++++++++++++++++++++++++++++++++++
2 files changed, 136 insertions(+)
diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index 81a79099ed3b..90abf732c8ee 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h
@@ -264,6 +264,7 @@ 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);
+extern uint64_t xdr_align_data(struct xdr_stream *, uint64_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 bc9b9b0945f5..a857c2308ee1 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
*/
@@ -300,6 +303,117 @@ _shift_data_right(struct xdr_buf *buf, size_t to, size_t from, size_t len)
shift);
}
+
+/**
+ * _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 = pgto_base % PAGE_SIZE;
+ pgfrom_base = pgfrom_base % PAGE_SIZE;
+
+ 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;
+
+ if (pgto_base == 131056)
+ break;
+
+ 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, size_t pgto_base,
+ size_t tail_from, size_t len)
+{
+ struct kvec *tail = buf->tail;
+ size_t shift = len;
+
+ if (len == 0)
+ return;
+ if (pgto_base + len > buf->page_len)
+ shift = buf->page_len - pgto_base;
+
+ _copy_to_pages(buf->pages,
+ buf->page_base + pgto_base,
+ (char *)(tail->iov_base + tail_from),
+ shift);
+
+ memmove((char *)tail->iov_base, tail->iov_base + tail_from + shift, shift);
+ tail->iov_len -= (tail_from + shift);
+}
+
+static void
+_shift_data_left(struct xdr_buf *buf, size_t to, size_t from, size_t len)
+{
+ size_t shift = len;
+
+ if (from < buf->page_len) {
+ shift = min(len, buf->page_len - from);
+ _shift_data_left_pages(buf->pages,
+ buf->page_base + to,
+ buf->page_base + from,
+ shift);
+ to += shift;
+ from += shift;
+ shift = len - shift;
+ }
+
+ if (shift == 0)
+ return;
+ if (from >= buf->page_len)
+ from -= buf->page_len;
+
+ _shift_data_left_tail(buf, to, from, shift);
+}
+
/**
* _copy_to_pages
* @pages: array of pages
@@ -1162,6 +1276,27 @@ size_t xdr_expand_hole(struct xdr_stream *xdr, size_t offset, uint64_t length)
}
EXPORT_SYMBOL_GPL(xdr_expand_hole);
+uint64_t xdr_align_data(struct xdr_stream *xdr, uint64_t offset, uint64_t length)
+{
+ struct xdr_buf *buf = xdr->buf;
+ size_t from = offset;
+
+ if (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_left(buf, offset, from, length);
+ }
+
+ xdr->nwords -= XDR_QUADLEN(length);
+ xdr_set_page(xdr, from + length);
+ return length;
+}
+EXPORT_SYMBOL_GPL(xdr_align_data);
+
/**
* xdr_enter_page - decode data from the XDR page
* @xdr: pointer to xdr_stream struct
--
2.24.1
