@@ -1633,7 +1633,7 @@ EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
* Sets up @subbuf to represent a portion of @xdr. The portion
* starts at the current offset in @xdr, and extends for a length
* of @nbytes. If this is successful, @xdr is advanced to the next
- * position following that portion.
+ * XDR data item following that portion.
*
* Return values:
* %true: @subbuf has been initialized, and @xdr has been advanced.
@@ -1642,29 +1642,31 @@ EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
bool xdr_stream_subsegment(struct xdr_stream *xdr, struct xdr_buf *subbuf,
unsigned int nbytes)
{
- unsigned int remaining, offset, len;
+ unsigned int start = xdr_stream_pos(xdr);
+ unsigned int remaining, len;
- if (xdr_buf_subsegment(xdr->buf, subbuf, xdr_stream_pos(xdr), nbytes))
+ /* Extract @subbuf and bounds-check the fn arguments */
+ if (xdr_buf_subsegment(xdr->buf, subbuf, start, nbytes))
return false;
- if (subbuf->head[0].iov_len)
- if (!__xdr_inline_decode(xdr, subbuf->head[0].iov_len))
- return false;
-
- remaining = subbuf->page_len;
- offset = subbuf->page_base;
- while (remaining) {
- len = min_t(unsigned int, remaining, PAGE_SIZE) - offset;
-
+ /* Advance @xdr by @nbytes */
+ for (remaining = nbytes; remaining;) {
if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
return false;
- if (!__xdr_inline_decode(xdr, len))
- return false;
+ len = (char *)xdr->end - (char *)xdr->p;
+ if (remaining <= len) {
+ xdr->p = (__be32 *)((char *)xdr->p +
+ (remaining + xdr_pad_size(nbytes)));
+ break;
+ }
+
+ xdr->p = (__be32 *)((char *)xdr->p + len);
+ xdr->end = xdr->p;
remaining -= len;
- offset = 0;
}
+ xdr_stream_set_pos(xdr, start + nbytes);
return true;
}
EXPORT_SYMBOL_GPL(xdr_stream_subsegment);
xdr_stream_subsegment() was introduced in commit c1346a1216ab ("NFSD: Replace the internals of the READ_BUF() macro"). There are two call sites for xdr_stream_subsegment(). One is nfsd4_decode_write(), and the other is nfsd4_decode_setxattr(). Currently neither of these call sites calls this API when xdr_buf::page_base is a non-zero value. However, I'm about to add a case where page_base will sometimes not be zero when nfsd4_decode_write() invokes this API. Replace the logic in xdr_stream_subsegment() that advances to the next data item in the xdr_stream with something more generic in order to handle this new use case. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> --- net/sunrpc/xdr.c | 32 +++++++++++++++++--------------- 1 file changed, 17 insertions(+), 15 deletions(-)