Commit b307d465 authored Jul 21, 2011 by Jan Beulich Committed by Linus Torvalds Jul 21, 2011

FS-Cache: Fix __fscache_uncache_all_inode_pages()'s outer loop



The compiler, at least for ix86 and m68k, validly warns that the
comparison:

	next <= (loff_t)-1

is always true (and it's always true also for x86-64 and probably all
other arches - as long as pgoff_t isn't wider than loff_t).  The
intention appears to be to avoid wrapping of "next", so rather than
eliminating the pointless comparison, fix the loop to indeed get exited
when "next" would otherwise wrap.

On m68k the following warning is observed:

  fs/fscache/page.c: In function '__fscache_uncache_all_inode_pages':
  fs/fscache/page.c:979: warning: comparison is always false due to limited range of data type

Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reported-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Jan Beulich <jbeulich@novell.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Suresh Jayaraman <sjayaraman@suse.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent cf6ace16

fs/fscache/page.c

+5 −9

Original line number	Original line	Diff line number	Diff line
	@@ -976,16 +976,12 @@ void __fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,

	pagevec_init(&pvec, 0);		pagevec_init(&pvec, 0);
	next = 0;		next = 0;
	while (next <= (loff_t)-1 &&		do {
	pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)		if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE))
	) {		break;
	for (i = 0; i < pagevec_count(&pvec); i++) {		for (i = 0; i < pagevec_count(&pvec); i++) {
	struct page *page = pvec.pages[i];		struct page *page = pvec.pages[i];
	pgoff_t page_index = page->index;		next = page->index;

	ASSERTCMP(page_index, >=, next);
	next = page_index + 1;

	if (PageFsCache(page)) {		if (PageFsCache(page)) {
	__fscache_wait_on_page_write(cookie, page);		__fscache_wait_on_page_write(cookie, page);
	__fscache_uncache_page(cookie, page);		__fscache_uncache_page(cookie, page);
	@@ -993,7 +989,7 @@ void __fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,
	}		}
	pagevec_release(&pvec);		pagevec_release(&pvec);
	cond_resched();		cond_resched();
	}		} while (++next);

	_leave("");		_leave("");
	}		}