From c4f2f591f02c392ea7de018d2733748bf4c7b5f5 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Fri, 4 Dec 2020 17:15:09 -0500 Subject: SUNRPC: Fix xdr_expand_hole() We do want to try to grow the buffer if possible, but if that attempt fails, we still want to move the data and truncate the XDR message. Signed-off-by: Trond Myklebust --- net/sunrpc/xdr.c | 274 ++++++++++++++++++++++++++++++++++++------------------- 1 file changed, 179 insertions(+), 95 deletions(-) (limited to 'net/sunrpc') diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c index c474339ba9ac..e0906ed24374 100644 --- a/net/sunrpc/xdr.c +++ b/net/sunrpc/xdr.c @@ -334,46 +334,6 @@ _shift_data_right_pages(struct page **pages, size_t pgto_base, } while ((len -= copy) != 0); } -static unsigned int -_shift_data_right_tail(struct xdr_buf *buf, unsigned int pgfrom, size_t len) -{ - struct kvec *tail = buf->tail; - unsigned int tailbuf_len; - unsigned int result = 0; - size_t copy; - - tailbuf_len = buf->buflen - buf->head->iov_len - buf->page_len; - - /* Shift the tail first */ - if (tailbuf_len != 0) { - unsigned int free_space = tailbuf_len - tail->iov_len; - - if (len < free_space) - free_space = len; - if (len > free_space) - len = free_space; - - tail->iov_len += free_space; - copy = len; - - if (tail->iov_len > len) { - char *p = (char *)tail->iov_base + len; - memmove(p, tail->iov_base, tail->iov_len - free_space); - result += tail->iov_len - free_space; - } else - copy = tail->iov_len; - - /* Copy from the inlined pages into the tail */ - _copy_from_pages((char *)tail->iov_base, - buf->pages, - buf->page_base + pgfrom, - copy); - result += copy; - } - - return result; -} - /** * _copy_to_pages * @pages: array of pages @@ -464,18 +424,42 @@ _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len) } EXPORT_SYMBOL_GPL(_copy_from_pages); +static void xdr_buf_iov_zero(const struct kvec *iov, unsigned int base, + unsigned int len) +{ + if (base >= iov->iov_len) + return; + if (len > iov->iov_len - base) + len = iov->iov_len - base; + memset(iov->iov_base + base, 0, len); +} + /** - * _zero_pages - * @pages: array of pages - * @pgbase: beginning page vector address + * xdr_buf_pages_zero + * @buf: xdr_buf + * @pgbase: beginning offset * @len: length */ -static void -_zero_pages(struct page **pages, size_t pgbase, size_t len) +static void xdr_buf_pages_zero(const struct xdr_buf *buf, unsigned int pgbase, + unsigned int len) { + struct page **pages = buf->pages; struct page **page; char *vpage; - size_t zero; + unsigned int zero; + + if (!len) + return; + if (pgbase >= buf->page_len) { + xdr_buf_iov_zero(buf->tail, pgbase - buf->page_len, len); + return; + } + if (pgbase + len > buf->page_len) { + xdr_buf_iov_zero(buf->tail, 0, pgbase + len - buf->page_len); + len = buf->page_len - pgbase; + } + + pgbase += buf->page_base; page = pages + (pgbase >> PAGE_SHIFT); pgbase &= ~PAGE_MASK; @@ -496,6 +480,103 @@ _zero_pages(struct page **pages, size_t pgbase, size_t len) } while ((len -= zero) != 0); } +static void xdr_buf_try_expand(struct xdr_buf *buf, unsigned int len) +{ + struct kvec *head = buf->head; + struct kvec *tail = buf->tail; + unsigned int sum = head->iov_len + buf->page_len + tail->iov_len; + unsigned int free_space; + + if (sum > buf->len) { + free_space = min_t(unsigned int, sum - buf->len, len); + buf->len += free_space; + len -= free_space; + if (!len) + return; + } + + if (buf->buflen > sum) { + /* Expand the tail buffer */ + free_space = min_t(unsigned int, buf->buflen - sum, len); + tail->iov_len += free_space; + buf->len += free_space; + } +} + +static void xdr_buf_tail_copy_right(const struct xdr_buf *buf, + unsigned int base, unsigned int len, + unsigned int shift) +{ + const struct kvec *tail = buf->tail; + unsigned int to = base + shift; + + if (to >= tail->iov_len) + return; + if (len + to > tail->iov_len) + len = tail->iov_len - to; + memmove(tail->iov_base + to, tail->iov_base + base, len); +} + +static void xdr_buf_pages_copy_right(const struct xdr_buf *buf, + unsigned int base, unsigned int len, + unsigned int shift) +{ + const struct kvec *tail = buf->tail; + unsigned int to = base + shift; + unsigned int pglen = 0; + unsigned int talen = 0, tato = 0; + + if (base >= buf->page_len) + return; + if (len > buf->page_len - base) + len = buf->page_len - base; + if (to >= buf->page_len) { + tato = to - buf->page_len; + if (tail->iov_len >= len + tato) + talen = len; + else if (tail->iov_len > tato) + talen = tail->iov_len - tato; + } else if (len + to >= buf->page_len) { + pglen = buf->page_len - to; + talen = len - pglen; + if (talen > tail->iov_len) + talen = tail->iov_len; + } else + pglen = len; + + _copy_from_pages(tail->iov_base + tato, buf->pages, + buf->page_base + base + pglen, talen); + _shift_data_right_pages(buf->pages, buf->page_base + to, + buf->page_base + base, pglen); +} + +static void xdr_buf_tail_shift_right(const struct xdr_buf *buf, + unsigned int base, unsigned int len, + unsigned int shift) +{ + const struct kvec *tail = buf->tail; + + if (base >= tail->iov_len || !shift || !len) + return; + xdr_buf_tail_copy_right(buf, base, len, shift); +} + +static void xdr_buf_pages_shift_right(const struct xdr_buf *buf, + unsigned int base, unsigned int len, + unsigned int shift) +{ + if (!shift || !len) + return; + if (base >= buf->page_len) { + xdr_buf_tail_shift_right(buf, base - buf->page_len, len, shift); + return; + } + if (base + len > buf->page_len) + xdr_buf_tail_shift_right(buf, 0, base + len - buf->page_len, + shift); + xdr_buf_pages_copy_right(buf, base, len, shift); +} + static void xdr_buf_tail_copy_left(const struct xdr_buf *buf, unsigned int base, unsigned int len, unsigned int shift) { @@ -685,30 +766,33 @@ xdr_shrink_bufhead(struct xdr_buf *buf, size_t len) } /** - * xdr_shrink_pagelen - shrinks buf->pages by up to @len bytes + * xdr_shrink_pagelen - shrinks buf->pages to @len bytes * @buf: xdr_buf - * @len: bytes to remove from buf->pages + * @len: new page buffer length * * The extra data is not lost, but is instead moved into buf->tail. * Returns the actual number of bytes moved. */ -static unsigned int -xdr_shrink_pagelen(struct xdr_buf *buf, size_t len) +static unsigned int xdr_shrink_pagelen(struct xdr_buf *buf, unsigned int len) { - unsigned int pglen = buf->page_len; - unsigned int result; - - if (len > buf->page_len) - len = buf-> page_len; - - result = _shift_data_right_tail(buf, pglen - len, len); - buf->page_len -= len; - buf->buflen -= len; - /* Have we truncated the message? */ - if (buf->len > buf->buflen) - buf->len = buf->buflen; + unsigned int shift, buflen = buf->len - buf->head->iov_len; - return result; + WARN_ON_ONCE(len > buf->page_len); + if (buf->head->iov_len >= buf->len || len > buflen) + buflen = len; + if (buf->page_len > buflen) { + buf->buflen -= buf->page_len - buflen; + buf->page_len = buflen; + } + if (len >= buf->page_len) + return 0; + shift = buf->page_len - len; + xdr_buf_try_expand(buf, shift); + xdr_buf_pages_shift_right(buf, len, buflen - len, shift); + buf->page_len = len; + buf->len -= shift; + buf->buflen -= shift; + return shift; } void @@ -728,6 +812,18 @@ unsigned int xdr_stream_pos(const struct xdr_stream *xdr) } EXPORT_SYMBOL_GPL(xdr_stream_pos); +static void xdr_stream_set_pos(struct xdr_stream *xdr, unsigned int pos) +{ + unsigned int blen = xdr->buf->len; + + xdr->nwords = blen > pos ? XDR_QUADLEN(blen) - XDR_QUADLEN(pos) : 0; +} + +static void xdr_stream_page_set_pos(struct xdr_stream *xdr, unsigned int pos) +{ + xdr_stream_set_pos(xdr, pos + xdr->buf->head[0].iov_len); +} + /** * xdr_page_pos - Return the current offset from the start of the xdr pages * @xdr: pointer to struct xdr_stream @@ -1291,7 +1387,7 @@ static unsigned int xdr_align_pages(struct xdr_stream *xdr, unsigned int len) struct xdr_buf *buf = xdr->buf; unsigned int nwords = XDR_QUADLEN(len); unsigned int cur = xdr_stream_pos(xdr); - unsigned int copied, offset; + unsigned int copied; if (xdr->nwords == 0) return 0; @@ -1305,9 +1401,8 @@ static unsigned int xdr_align_pages(struct xdr_stream *xdr, unsigned int len) len = buf->page_len; else if (nwords < xdr->nwords) { /* Truncate page data and move it into the tail */ - offset = buf->page_len - len; - copied = xdr_shrink_pagelen(buf, offset); - trace_rpc_xdr_alignment(xdr, offset, copied); + copied = xdr_shrink_pagelen(buf, len); + trace_rpc_xdr_alignment(xdr, len, copied); xdr->nwords = XDR_QUADLEN(buf->len - cur); } return len; @@ -1387,39 +1482,28 @@ unsigned int xdr_align_data(struct xdr_stream *xdr, unsigned int offset, } EXPORT_SYMBOL_GPL(xdr_align_data); -uint64_t xdr_expand_hole(struct xdr_stream *xdr, uint64_t offset, uint64_t length) +unsigned int xdr_expand_hole(struct xdr_stream *xdr, unsigned int offset, + unsigned int 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; + unsigned int from, to, shift; xdr_realign_pages(xdr); from = xdr_page_pos(xdr); - bytes = xdr_stream_remaining(xdr); - - 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, xdr_stream_remaining(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_stream_page_set_pos(xdr, to); + } else if (to != from) + xdr_align_data(xdr, to, 0); + xdr_buf_pages_zero(buf, offset, length); + + xdr_set_page(xdr, to, xdr_stream_remaining(xdr)); return length; } EXPORT_SYMBOL_GPL(xdr_expand_hole); -- cgit v1.2.3