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SUNRPC: Fix xdr_expand_hole()

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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 <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2020-12-04 17:15:09 -05:00
parent 9a20f6f4e6
commit c4f2f591f0
2 changed files with 178 additions and 94 deletions
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2
include/linux/sunrpc/xdr.h
View File

@ -253,7 +253,7 @@ extern unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len);
extern void xdr_enter_page(struct xdr_stream *xdr, unsigned int len);
extern int xdr_process_buf(struct xdr_buf *buf, unsigned int offset, unsigned int len, int (*actor)(struct scatterlist *, void *), void *data);
extern unsigned int xdr_align_data(struct xdr_stream *, unsigned int offset, unsigned int length);
extern uint64_t xdr_expand_hole(struct xdr_stream *, uint64_t, uint64_t);
extern unsigned int xdr_expand_hole(struct xdr_stream *, unsigned int offset, unsigned int length);
/**
* xdr_stream_remaining - Return the number of bytes remaining in the stream

270
net/sunrpc/xdr.c
View File

@ -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;
unsigned int shift, buflen = buf->len - buf->head->iov_len;
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;
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);
to = xdr_align_size(offset + length);
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;
}
/* 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);
/* 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));
xdr_set_page(xdr, to, xdr_stream_remaining(xdr));
return length;
}
EXPORT_SYMBOL_GPL(xdr_expand_hole);