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authorAnna Schumaker <Anna.Schumaker@Netapp.com>2014-05-28 21:38:53 +0400
committerAnna Schumaker <Anna.Schumaker@Netapp.com>2020-10-07 21:28:39 +0300
commit84ce182ab85b8ad5002fb1125ba572df99dd0d1c (patch)
tree36f05b537b1100e12933283fa9d445f193e86d81 /net/sunrpc/xdr.c
parent43f0f0816cdbe7361dd17db3b4c1033446033ba6 (diff)
downloadlinux-84ce182ab85b8ad5002fb1125ba572df99dd0d1c.tar.xz
SUNRPC: Add the ability to expand holes in data pages
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@Netapp.com>
Diffstat (limited to 'net/sunrpc/xdr.c')
-rw-r--r--net/sunrpc/xdr.c69
1 files changed, 69 insertions, 0 deletions
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 10a88a67206a..1052ccdb4e99 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -391,6 +391,38 @@ _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
EXPORT_SYMBOL_GPL(_copy_from_pages);
/**
+ * _zero_pages
+ * @pages: array of pages
+ * @pgbase: beginning page vector address
+ * @len: length
+ */
+static void
+_zero_pages(struct page **pages, size_t pgbase, size_t len)
+{
+ struct page **page;
+ char *vpage;
+ size_t zero;
+
+ page = pages + (pgbase >> PAGE_SHIFT);
+ pgbase &= ~PAGE_MASK;
+
+ do {
+ zero = PAGE_SIZE - pgbase;
+ if (zero > len)
+ zero = len;
+
+ vpage = kmap_atomic(*page);
+ memset(vpage + pgbase, 0, zero);
+ kunmap_atomic(vpage);
+
+ flush_dcache_page(*page);
+ pgbase = 0;
+ page++;
+
+ } while ((len -= zero) != 0);
+}
+
+/**
* xdr_shrink_bufhead
* @buf: xdr_buf
* @len: bytes to remove from buf->head[0]
@@ -1096,6 +1128,43 @@ unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
}
EXPORT_SYMBOL_GPL(xdr_read_pages);
+uint64_t xdr_expand_hole(struct xdr_stream *xdr, uint64_t offset, uint64_t length)
+{
+ struct xdr_buf *buf = xdr->buf;
+ unsigned int bytes;
+ unsigned int from;
+ unsigned int truncated = 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 (offset + length + bytes > buf->page_len) {
+ unsigned int shift = (offset + length + bytes) - buf->page_len;
+ unsigned int res = _shift_data_right_tail(buf, from + bytes - shift, shift);
+ truncated = shift - res;
+ xdr->nwords -= XDR_QUADLEN(truncated);
+ bytes -= shift;
+ }
+
+ /* Now move the page data over and zero pages */
+ if (bytes > 0)
+ _shift_data_right_pages(buf->pages,
+ buf->page_base + offset + length,
+ buf->page_base + from,
+ bytes);
+ _zero_pages(buf->pages, buf->page_base + offset, length);
+
+ buf->len += length - (from - offset) - truncated;
+ xdr_set_page(xdr, offset + length, PAGE_SIZE);
+ return length;
+}
+EXPORT_SYMBOL_GPL(xdr_expand_hole);
+
/**
* xdr_enter_page - decode data from the XDR page
* @xdr: pointer to xdr_stream struct