rpc: move process_xdr_buf

Since process_xdr_buf() is useful outside of the kerberos-specific code, we
move it to net/sunrpc/xdr.c, export it, and rename it in keeping with xdr_*
naming convention of xdr.c.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 68 insertions, 0 deletions

diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 5a6485946f3c..a0af250ca319 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -1021,3 +1021,71 @@ xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
 
         return xdr_xcode_array2(buf, base, desc, 1);
 }
+
+int
+xdr_process_buf(struct xdr_buf *buf, unsigned int offset, unsigned int len,
+                int (*actor)(struct scatterlist *, void *), void *data)
+{
+        int i, ret = 0;
+        unsigned page_len, thislen, page_offset;
+        struct scatterlist      sg[1];
+
+        if (offset >= buf->head[0].iov_len) {
+                offset -= buf->head[0].iov_len;
+        } else {
+                thislen = buf->head[0].iov_len - offset;
+                if (thislen > len)
+                        thislen = len;
+                sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
+                ret = actor(sg, data);
+                if (ret)
+                        goto out;
+                offset = 0;
+                len -= thislen;
+        }
+        if (len == 0)
+                goto out;
+
+        if (offset >= buf->page_len) {
+                offset -= buf->page_len;
+        } else {
+                page_len = buf->page_len - offset;
+                if (page_len > len)
+                        page_len = len;
+                len -= page_len;
+                page_offset = (offset + buf->page_base) & (PAGE_CACHE_SIZE - 1);
+                i = (offset + buf->page_base) >> PAGE_CACHE_SHIFT;
+                thislen = PAGE_CACHE_SIZE - page_offset;
+                do {
+                        if (thislen > page_len)
+                                thislen = page_len;
+                        sg->page = buf->pages[i];
+                        sg->offset = page_offset;
+                        sg->length = thislen;
+                        ret = actor(sg, data);
+                        if (ret)
+                                goto out;
+                        page_len -= thislen;
+                        i++;
+                        page_offset = 0;
+                        thislen = PAGE_CACHE_SIZE;
+                } while (page_len != 0);
+                offset = 0;
+        }
+        if (len == 0)
+                goto out;
+        if (offset < buf->tail[0].iov_len) {
+                thislen = buf->tail[0].iov_len - offset;
+                if (thislen > len)
+                        thislen = len;
+                sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
+                ret = actor(sg, data);
+                len -= thislen;
+        }
+        if (len != 0)
+                ret = -EINVAL;
+out:
+        return ret;
+}
+EXPORT_SYMBOL(xdr_process_buf);
+