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>

diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index 2f343b4d7a7d87b6792aad379b91ebffee9e15bc..3f7a59bfa7ada5cf1f8da1d7a391c36322004fba 100644 (file)
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -976,16 +976,12 @@ void __fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,
 
        pagevec_init(&pvec, 0);
        next = 0;
-       while (next <= (loff_t)-1 &&
-              pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)
-              ) {
+       do {
+               if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE))
+                       break;
                for (i = 0; i < pagevec_count(&pvec); i++) {
                        struct page *page = pvec.pages[i];
-                       pgoff_t page_index = page->index;
-
-                       ASSERTCMP(page_index, >=, next);
-                       next = page_index + 1;
-
+                       next = page->index;
                        if (PageFsCache(page)) {
                                __fscache_wait_on_page_write(cookie, page);
                                __fscache_uncache_page(cookie, page);
@@ -993,7 +989,7 @@ void __fscache_uncache_all_inode_pages(struct fscache_cookie *cookie,
                }
                pagevec_release(&pvec);
                cond_resched();
-       }
+       } while (++next);
 
        _leave("");
 }