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SUNRPC: When expanding the buffer, we may need grow the sparse pages

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If we're shifting the page data to the right, and this happens to be a
sparse page array, then we may need to allocate new pages in order to
receive the data.

Reported-by: "Mkrtchyan, Tigran" <tigran.mkrtchyan@desy.de>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2020-12-10 08:55:35 -05:00
parent f8d0e60f10
commit 5802f7c2a6
1 changed files with 33 additions and 2 deletions
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35
net/sunrpc/xdr.c
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@ -478,16 +478,47 @@ static void xdr_buf_pages_zero(const struct xdr_buf *buf, unsigned int pgbase,
} while ((len -= zero) != 0);
}
static unsigned int xdr_buf_pages_fill_sparse(const struct xdr_buf *buf,
unsigned int buflen, gfp_t gfp)
{
unsigned int i, npages, pagelen;
if (!(buf->flags & XDRBUF_SPARSE_PAGES))
return buflen;
if (buflen <= buf->head->iov_len)
return buflen;
pagelen = buflen - buf->head->iov_len;
if (pagelen > buf->page_len)
pagelen = buf->page_len;
npages = (pagelen + buf->page_base + PAGE_SIZE - 1) >> PAGE_SHIFT;
for (i = 0; i < npages; i++) {
if (!buf->pages[i])
continue;
buf->pages[i] = alloc_page(gfp);
if (likely(buf->pages[i]))
continue;
buflen -= pagelen;
pagelen = i << PAGE_SHIFT;
if (pagelen > buf->page_base)
buflen += pagelen - buf->page_base;
break;
}
return buflen;
}
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;
unsigned int free_space, newlen;
if (sum > buf->len) {
free_space = min_t(unsigned int, sum - buf->len, len);
buf->len += free_space;
newlen = xdr_buf_pages_fill_sparse(buf, buf->len + free_space,
GFP_KERNEL);
free_space = newlen - buf->len;
buf->len = newlen;
len -= free_space;
if (!len)
return;