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SUNRPC: Clean up helpers xdr_set_iov() and xdr_set_page_base() 

Allow xdr_set_iov() to set a base so that we can use it to set the
cursor to a specific position in the kvec buffer.

If the new base overflows the kvec/pages buffer in either xdr_set_iov()
or xdr_set_page_base(), then truncate it so that we point to the end of
the buffer.

Finally, change both function to return the number of bytes remaining to
read in their buffers.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2020-11-21 14:50:43 -05:00
parent 2b1f83d108
commit 8d86e373b0
1 changed files with 19 additions and 17 deletions
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36
net/sunrpc/xdr.c
View File

@ -970,19 +970,22 @@ void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int b
}
EXPORT_SYMBOL_GPL(xdr_write_pages);
static void xdr_set_iov(struct xdr_stream *xdr, struct kvec *iov,
unsigned int len)
static unsigned int xdr_set_iov(struct xdr_stream *xdr, struct kvec *iov,
unsigned int base, unsigned int len)
{
if (len > iov->iov_len)
len = iov->iov_len;
xdr->p = (__be32*)iov->iov_base;
if (unlikely(base > len))
base = len;
xdr->p = (__be32*)(iov->iov_base + base);
xdr->end = (__be32*)(iov->iov_base + len);
xdr->iov = iov;
xdr->page_ptr = NULL;
return len - base;
}
static int xdr_set_page_base(struct xdr_stream *xdr,
unsigned int base, unsigned int len)
static unsigned int xdr_set_page_base(struct xdr_stream *xdr,
unsigned int base, unsigned int len)
{
unsigned int pgnr;
unsigned int maxlen;
@ -991,9 +994,11 @@ static int xdr_set_page_base(struct xdr_stream *xdr,
void *kaddr;
maxlen = xdr->buf->page_len;
if (base >= maxlen)
return -EINVAL;
maxlen -= base;
if (base >= maxlen) {
base = maxlen;
maxlen = 0;
} else
maxlen -= base;
if (len > maxlen)
len = maxlen;
@ -1011,14 +1016,14 @@ static int xdr_set_page_base(struct xdr_stream *xdr,
pgend = PAGE_SIZE;
xdr->end = (__be32*)(kaddr + pgend);
xdr->iov = NULL;
return 0;
return len;
}
static void xdr_set_page(struct xdr_stream *xdr, unsigned int base,
unsigned int len)
{
if (xdr_set_page_base(xdr, base, len) < 0)
xdr_set_iov(xdr, xdr->buf->tail, xdr->nwords << 2);
if (xdr_set_page_base(xdr, base, len) == 0)
xdr_set_iov(xdr, xdr->buf->tail, 0, xdr_stream_remaining(xdr));
}
static void xdr_set_next_page(struct xdr_stream *xdr)
@ -1055,12 +1060,9 @@ void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p,
xdr->scratch.iov_base = NULL;
xdr->scratch.iov_len = 0;
xdr->nwords = XDR_QUADLEN(buf->len);
if (buf->head[0].iov_len != 0)
xdr_set_iov(xdr, buf->head, buf->len);
else if (buf->page_len != 0)
xdr_set_page_base(xdr, 0, buf->len);
else
xdr_set_iov(xdr, buf->tail, buf->len);
if (xdr_set_iov(xdr, buf->head, 0, buf->len) == 0 &&
xdr_set_page_base(xdr, 0, buf->len) == 0)
xdr_set_iov(xdr, buf->tail, 0, buf->len);
if (p != NULL && p > xdr->p && xdr->end >= p) {
xdr->nwords -= p - xdr->p;
xdr->p = p;