[PATCH 004 of 8] md/bitmap: Use set_bit etc for bitmap page attributes.

NeilBrown
2006-05-12T06:10:18Z

In particular, this means that we use 4 bits per page instead of a
whole unsigned long.

Signed-off-by: Neil Brown <neilb@suse.de>

### Diffstat output
./drivers/md/bitmap.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)

diff ./drivers/md/bitmap.c~current~ ./drivers/md/bitmap.c
--- ./drivers/md/bitmap.c~current~ 2006-05-12 15:56:51.000000000 +1000
+++ ./drivers/md/bitmap.c 2006-05-12 15:58:22.000000000 +1000
@@ -700,27 +700,27 @@ static void bitmap_file_kick(struct bitm
}

enum bitmap_page_attr {
- BITMAP_PAGE_DIRTY = 1, // there are set bits that need to be synced
- BITMAP_PAGE_CLEAN = 2, // there are bits that might need to be cleared
- BITMAP_PAGE_NEEDWRITE=4, // there are cleared bits that need to be synced
+ BITMAP_PAGE_DIRTY = 0, // there are set bits that need to be synced
+ BITMAP_PAGE_CLEAN = 1, // there are bits that might need to be cleared
+ BITMAP_PAGE_NEEDWRITE=2, // there are cleared bits that need to be synced
};

static inline void set_page_attr(struct bitmap *bitmap, struct page *page,
enum bitmap_page_attr attr)
{
- bitmap->filemap_attr[page->index] |= attr;
+ __set_bit((page->index<<2) + attr, bitmap->filemap_attr);
}

static inline void clear_page_attr(struct bitmap *bitmap, struct page *page,
enum bitmap_page_attr attr)
{
- bitmap->filemap_attr[page->index] &= ~attr;
+ __clear_bit((page->index<<2) + attr, bitmap->filemap_attr);
}

static inline unsigned long test_page_attr(struct bitmap *bitmap, struct page *page,
enum bitmap_page_attr attr)
{
- return bitmap->filemap_attr[page->index] & attr;
+ return test_bit((page->index<<2) + attr, bitmap->filemap_attr);
}

/*
@@ -872,7 +872,12 @@ static int bitmap_init_from_disk(struct
if (!bitmap->filemap)
goto out;

- bitmap->filemap_attr = kzalloc(sizeof(long) * num_pages, GFP_KERNEL);
+ /* We need 4 bits per page, rounded up to a multiple of sizeof(unsigned long) */
+ bitmap->filemap_attr = kzalloc(
+ (((num_pages*4/8)+sizeof(unsigned long)-1)
+ /sizeof(unsigned long))
+ *sizeof(unsigned long),
+ GFP_KERNEL);
if (!bitmap->filemap_attr)
goto out;