diff options
Diffstat (limited to 'net/sunrpc/xdr.c')
| -rw-r--r-- | net/sunrpc/xdr.c | 168 |
1 files changed, 107 insertions, 61 deletions
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c index 5d2b3e6979fb..482586c23fdd 100644 --- a/net/sunrpc/xdr.c +++ b/net/sunrpc/xdr.c @@ -775,6 +775,34 @@ static void xdr_buf_pages_shift_left(const struct xdr_buf *buf, xdr_buf_tail_copy_left(buf, 0, len - buf->page_len, shift); } +static void xdr_buf_head_shift_left(const struct xdr_buf *buf, + unsigned int base, unsigned int len, + unsigned int shift) +{ + const struct kvec *head = buf->head; + unsigned int bytes; + + if (!shift || !len) + return; + + if (shift > base) { + bytes = (shift - base); + if (bytes >= len) + return; + base += bytes; + len -= bytes; + } + + if (base < head->iov_len) { + bytes = min_t(unsigned int, len, head->iov_len - base); + memmove(head->iov_base + (base - shift), + head->iov_base + base, bytes); + base += bytes; + len -= bytes; + } + xdr_buf_pages_shift_left(buf, base - head->iov_len, len, shift); +} + /** * xdr_shrink_bufhead * @buf: xdr_buf @@ -1472,71 +1500,35 @@ unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len) } EXPORT_SYMBOL_GPL(xdr_read_pages); -unsigned int xdr_align_data(struct xdr_stream *xdr, unsigned int offset, - unsigned int length) -{ - struct xdr_buf *buf = xdr->buf; - unsigned int from, bytes, len; - unsigned int shift; - - xdr_realign_pages(xdr); - from = xdr_page_pos(xdr); - - if (from >= buf->page_len + buf->tail->iov_len) - return 0; - if (from + buf->head->iov_len >= buf->len) - return 0; - - len = buf->len - buf->head->iov_len; - - /* We only shift data left! */ - if (WARN_ONCE(from < offset, "SUNRPC: misaligned data src=%u dst=%u\n", - from, offset)) - return 0; - if (WARN_ONCE(offset > buf->page_len, - "SUNRPC: buffer overflow. offset=%u, page_len=%u\n", - offset, buf->page_len)) - return 0; - - /* Move page data to the left */ - shift = from - offset; - xdr_buf_pages_shift_left(buf, from, len, shift); - - bytes = xdr_stream_remaining(xdr); - if (length > bytes) - length = bytes; - bytes -= length; - - xdr->buf->len -= shift; - xdr_set_page(xdr, offset + length, bytes); - return length; -} -EXPORT_SYMBOL_GPL(xdr_align_data); - -unsigned int xdr_expand_hole(struct xdr_stream *xdr, unsigned int offset, - unsigned int length) +/** + * xdr_set_pagelen - Sets the length of the XDR pages + * @xdr: pointer to xdr_stream struct + * @len: new length of the XDR page data + * + * Either grows or shrinks the length of the xdr pages by setting pagelen to + * @len bytes. When shrinking, any extra data is moved into buf->tail, whereas + * when growing any data beyond the current pointer is moved into the tail. + * + * Returns True if the operation was successful, and False otherwise. + */ +void xdr_set_pagelen(struct xdr_stream *xdr, unsigned int len) { struct xdr_buf *buf = xdr->buf; - unsigned int from, to, shift; - - xdr_realign_pages(xdr); - from = xdr_page_pos(xdr); - to = xdr_align_size(offset + length); - - /* Could the hole be behind us? */ - if (to > from) { - unsigned int buflen = buf->len - buf->head->iov_len; - shift = to - from; - xdr_buf_try_expand(buf, shift); - xdr_buf_pages_shift_right(buf, from, buflen, shift); - xdr_set_page(xdr, to, xdr_stream_remaining(xdr)); - } else if (to != from) - xdr_align_data(xdr, to, 0); - xdr_buf_pages_zero(buf, offset, length); + size_t remaining = xdr_stream_remaining(xdr); + size_t base = 0; - return length; + if (len < buf->page_len) { + base = buf->page_len - len; + xdr_shrink_pagelen(buf, len); + } else { + xdr_buf_head_shift_right(buf, xdr_stream_pos(xdr), + buf->page_len, remaining); + if (len > buf->page_len) + xdr_buf_try_expand(buf, len - buf->page_len); + } + xdr_set_tail_base(xdr, base, remaining); } -EXPORT_SYMBOL_GPL(xdr_expand_hole); +EXPORT_SYMBOL_GPL(xdr_set_pagelen); /** * xdr_enter_page - decode data from the XDR page @@ -1681,6 +1673,60 @@ bool xdr_stream_subsegment(struct xdr_stream *xdr, struct xdr_buf *subbuf, EXPORT_SYMBOL_GPL(xdr_stream_subsegment); /** + * xdr_stream_move_subsegment - Move part of a stream to another position + * @xdr: the source xdr_stream + * @offset: the source offset of the segment + * @target: the target offset of the segment + * @length: the number of bytes to move + * + * Moves @length bytes from @offset to @target in the xdr_stream, overwriting + * anything in its space. Returns the number of bytes in the segment. + */ +unsigned int xdr_stream_move_subsegment(struct xdr_stream *xdr, unsigned int offset, + unsigned int target, unsigned int length) +{ + struct xdr_buf buf; + unsigned int shift; + + if (offset < target) { + shift = target - offset; + if (xdr_buf_subsegment(xdr->buf, &buf, offset, shift + length) < 0) + return 0; + xdr_buf_head_shift_right(&buf, 0, length, shift); + } else if (offset > target) { + shift = offset - target; + if (xdr_buf_subsegment(xdr->buf, &buf, target, shift + length) < 0) + return 0; + xdr_buf_head_shift_left(&buf, shift, length, shift); + } + return length; +} +EXPORT_SYMBOL_GPL(xdr_stream_move_subsegment); + +/** + * xdr_stream_zero - zero out a portion of an xdr_stream + * @xdr: an xdr_stream to zero out + * @offset: the starting point in the stream + * @length: the number of bytes to zero + */ +unsigned int xdr_stream_zero(struct xdr_stream *xdr, unsigned int offset, + unsigned int length) +{ + struct xdr_buf buf; + + if (xdr_buf_subsegment(xdr->buf, &buf, offset, length) < 0) + return 0; + if (buf.head[0].iov_len) + xdr_buf_iov_zero(buf.head, 0, buf.head[0].iov_len); + if (buf.page_len > 0) + xdr_buf_pages_zero(&buf, 0, buf.page_len); + if (buf.tail[0].iov_len) + xdr_buf_iov_zero(buf.tail, 0, buf.tail[0].iov_len); + return length; +} +EXPORT_SYMBOL_GPL(xdr_stream_zero); + +/** * xdr_buf_trim - lop at most "len" bytes off the end of "buf" * @buf: buf to be trimmed * @len: number of bytes to reduce "buf" by |