-/*
- * Page Region interfaces.
- *
- * For pages in filesystems where the blocksize is smaller than the
- * pagesize, we use the page->private field (long) to hold a bitmap
- * of uptodate regions within the page.
- *
- * Each such region is "bytes per page / bits per long" bytes long.
- *
- * NBPPR == number-of-bytes-per-page-region
- * BTOPR == bytes-to-page-region (rounded up)
- * BTOPRT == bytes-to-page-region-truncated (rounded down)
- */
-#if (BITS_PER_LONG == 32)
-#define PRSHIFT (PAGE_CACHE_SHIFT - 5) /* (32 == 1<<5) */
-#elif (BITS_PER_LONG == 64)
-#define PRSHIFT (PAGE_CACHE_SHIFT - 6) /* (64 == 1<<6) */
-#else
-#error BITS_PER_LONG must be 32 or 64
-#endif
-#define NBPPR (PAGE_CACHE_SIZE/BITS_PER_LONG)
-#define BTOPR(b) (((unsigned int)(b) + (NBPPR - 1)) >> PRSHIFT)
-#define BTOPRT(b) (((unsigned int)(b) >> PRSHIFT))
-
-STATIC unsigned long
-page_region_mask(
- size_t offset,
- size_t length)
-{
- unsigned long mask;
- int first, final;
-
- first = BTOPR(offset);
- final = BTOPRT(offset + length - 1);
- first = min(first, final);
-
- mask = ~0UL;
- mask <<= BITS_PER_LONG - (final - first);
- mask >>= BITS_PER_LONG - (final);
-
- ASSERT(offset + length <= PAGE_CACHE_SIZE);
- ASSERT((final - first) < BITS_PER_LONG && (final - first) >= 0);
-
- return mask;
-}
-
-STATIC void
-set_page_region(
- struct page *page,
- size_t offset,
- size_t length)
-{
- set_page_private(page,
- page_private(page) | page_region_mask(offset, length));
- if (page_private(page) == ~0UL)
- SetPageUptodate(page);
-}
-
-STATIC int
-test_page_region(
- struct page *page,
- size_t offset,
- size_t length)
-{
- unsigned long mask = page_region_mask(offset, length);
-
- return (mask && (page_private(page) & mask) == mask);
-}
-