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Subject[sunrpc] remove xdr_kmap()
I was auditing nfs for missing flush_dcache_page() calls. They appear
to be done almost nowhere in nfs and so likely nowhere near enough, and
that makes nfs one of the primary suspects for breaking various machines
I have.

In this process, I stumbled over a blatant kmap() deadlock in
xdr_kmap(), which fortunately is never called.

This patch removes these dangerous nowhere-called functions.
vs. 2.6.10-bk1


-- wli


Index: wli-2.6.10-bk1/include/linux/sunrpc/xdr.h
===================================================================
--- wli-2.6.10-bk1.orig/include/linux/sunrpc/xdr.h 2004-08-13 22:38:10.000000000 -0700
+++ wli-2.6.10-bk1/include/linux/sunrpc/xdr.h 2004-12-28 14:27:16.000000000 -0800
@@ -145,8 +145,6 @@
/*
* XDR buffer helper functions
*/
-extern int xdr_kmap(struct kvec *, struct xdr_buf *, size_t);
-extern void xdr_kunmap(struct xdr_buf *, size_t);
extern void xdr_shift_buf(struct xdr_buf *, size_t);
extern void _copy_from_pages(char *, struct page **, size_t, size_t);
extern void xdr_buf_from_iov(struct kvec *, struct xdr_buf *);
Index: wli-2.6.10-bk1/net/sunrpc/xdr.c
===================================================================
--- wli-2.6.10-bk1.orig/net/sunrpc/xdr.c 2004-08-13 22:37:26.000000000 -0700
+++ wli-2.6.10-bk1/net/sunrpc/xdr.c 2004-12-28 14:27:16.000000000 -0800
@@ -216,93 +216,6 @@
}
}

-/*
- * Map a struct xdr_buf into an kvec array.
- */
-int xdr_kmap(struct kvec *iov_base, struct xdr_buf *xdr, size_t base)
-{
- struct kvec *iov = iov_base;
- struct page **ppage = xdr->pages;
- unsigned int len, pglen = xdr->page_len;
-
- len = xdr->head[0].iov_len;
- if (base < len) {
- iov->iov_len = len - base;
- iov->iov_base = (char *)xdr->head[0].iov_base + base;
- iov++;
- base = 0;
- } else
- base -= len;
-
- if (pglen == 0)
- goto map_tail;
- if (base >= pglen) {
- base -= pglen;
- goto map_tail;
- }
- if (base || xdr->page_base) {
- pglen -= base;
- base += xdr->page_base;
- ppage += base >> PAGE_CACHE_SHIFT;
- base &= ~PAGE_CACHE_MASK;
- }
- do {
- len = PAGE_CACHE_SIZE;
- iov->iov_base = kmap(*ppage);
- if (base) {
- iov->iov_base += base;
- len -= base;
- base = 0;
- }
- if (pglen < len)
- len = pglen;
- iov->iov_len = len;
- iov++;
- ppage++;
- } while ((pglen -= len) != 0);
-map_tail:
- if (xdr->tail[0].iov_len) {
- iov->iov_len = xdr->tail[0].iov_len - base;
- iov->iov_base = (char *)xdr->tail[0].iov_base + base;
- iov++;
- }
- return (iov - iov_base);
-}
-
-void xdr_kunmap(struct xdr_buf *xdr, size_t base)
-{
- struct page **ppage = xdr->pages;
- unsigned int pglen = xdr->page_len;
-
- if (!pglen)
- return;
- if (base > xdr->head[0].iov_len)
- base -= xdr->head[0].iov_len;
- else
- base = 0;
-
- if (base >= pglen)
- return;
- if (base || xdr->page_base) {
- pglen -= base;
- base += xdr->page_base;
- ppage += base >> PAGE_CACHE_SHIFT;
- /* Note: The offset means that the length of the first
- * page is really (PAGE_CACHE_SIZE - (base & ~PAGE_CACHE_MASK)).
- * In order to avoid an extra test inside the loop,
- * we bump pglen here, and just subtract PAGE_CACHE_SIZE... */
- pglen += base & ~PAGE_CACHE_MASK;
- }
- for (;;) {
- flush_dcache_page(*ppage);
- kunmap(*ppage);
- if (pglen <= PAGE_CACHE_SIZE)
- break;
- pglen -= PAGE_CACHE_SIZE;
- ppage++;
- }
-}
-
void
xdr_partial_copy_from_skb(struct xdr_buf *xdr, unsigned int base,
skb_reader_t *desc,
-
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