From 993e6525bfcc67ba48fe55bd64ec043a4b721e1d Mon Sep 17 00:00:00 2001 From: Eric Blake Date: Mon, 25 Sep 2017 09:55:13 -0500 Subject: dirty-bitmap: Track bitmap size by bytes We are still using an internal hbitmap that tracks a size in sectors, with the granularity scaled down accordingly, because it lets us use a shortcut for our iterators which are currently sector-based. But there's no reason we can't track the dirty bitmap size in bytes, since it is (mostly) an internal-only variable (remember, the size is how many bytes are covered by the bitmap, not how many bytes the bitmap occupies). A later cleanup will convert dirty bitmap internals to be entirely byte-based, eliminating the intermediate sector rounding added here; and technically, since bdrv_getlength() already rounds up to sectors, our use of DIV_ROUND_UP is more for theoretical completeness than for any actual rounding. Use is_power_of_2() while at it, instead of open-coding that. Signed-off-by: Eric Blake Reviewed-by: John Snow Reviewed-by: Kevin Wolf Reviewed-by: Fam Zheng Signed-off-by: Kevin Wolf --- block/dirty-bitmap.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) (limited to 'block/dirty-bitmap.c') diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c index 755555af32..6d32554b4e 100644 --- a/block/dirty-bitmap.c +++ b/block/dirty-bitmap.c @@ -42,7 +42,7 @@ struct BdrvDirtyBitmap { HBitmap *meta; /* Meta dirty bitmap */ BdrvDirtyBitmap *successor; /* Anonymous child; implies frozen status */ char *name; /* Optional non-empty unique ID */ - int64_t size; /* Size of the bitmap (Number of sectors) */ + int64_t size; /* Size of the bitmap, in bytes */ bool disabled; /* Bitmap is disabled. It ignores all writes to the device */ int active_iterators; /* How many iterators are active */ @@ -115,17 +115,14 @@ BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs, { int64_t bitmap_size; BdrvDirtyBitmap *bitmap; - uint32_t sector_granularity; - assert((granularity & (granularity - 1)) == 0); + assert(is_power_of_2(granularity) && granularity >= BDRV_SECTOR_SIZE); if (name && bdrv_find_dirty_bitmap(bs, name)) { error_setg(errp, "Bitmap already exists: %s", name); return NULL; } - sector_granularity = granularity >> BDRV_SECTOR_BITS; - assert(sector_granularity); - bitmap_size = bdrv_nb_sectors(bs); + bitmap_size = bdrv_getlength(bs); if (bitmap_size < 0) { error_setg_errno(errp, -bitmap_size, "could not get length of device"); errno = -bitmap_size; @@ -133,7 +130,12 @@ BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs, } bitmap = g_new0(BdrvDirtyBitmap, 1); bitmap->mutex = &bs->dirty_bitmap_mutex; - bitmap->bitmap = hbitmap_alloc(bitmap_size, ctz32(sector_granularity)); + /* + * TODO - let hbitmap track full granularity. For now, it is tracking + * only sector granularity, as a shortcut for our iterators. + */ + bitmap->bitmap = hbitmap_alloc(DIV_ROUND_UP(bitmap_size, BDRV_SECTOR_SIZE), + ctz32(granularity) - BDRV_SECTOR_BITS); bitmap->size = bitmap_size; bitmap->name = g_strdup(name); bitmap->disabled = false; @@ -175,7 +177,7 @@ void bdrv_release_meta_dirty_bitmap(BdrvDirtyBitmap *bitmap) int64_t bdrv_dirty_bitmap_size(const BdrvDirtyBitmap *bitmap) { - return bitmap->size * BDRV_SECTOR_SIZE; + return bitmap->size; } const char *bdrv_dirty_bitmap_name(const BdrvDirtyBitmap *bitmap) @@ -305,14 +307,13 @@ BdrvDirtyBitmap *bdrv_reclaim_dirty_bitmap(BlockDriverState *bs, void bdrv_dirty_bitmap_truncate(BlockDriverState *bs, int64_t bytes) { BdrvDirtyBitmap *bitmap; - int64_t size = DIV_ROUND_UP(bytes, BDRV_SECTOR_SIZE); bdrv_dirty_bitmaps_lock(bs); QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) { assert(!bdrv_dirty_bitmap_frozen(bitmap)); assert(!bitmap->active_iterators); - hbitmap_truncate(bitmap->bitmap, size); - bitmap->size = size; + hbitmap_truncate(bitmap->bitmap, DIV_ROUND_UP(bytes, BDRV_SECTOR_SIZE)); + bitmap->size = bytes; } bdrv_dirty_bitmaps_unlock(bs); } @@ -549,7 +550,8 @@ void bdrv_clear_dirty_bitmap(BdrvDirtyBitmap *bitmap, HBitmap **out) hbitmap_reset_all(bitmap->bitmap); } else { HBitmap *backup = bitmap->bitmap; - bitmap->bitmap = hbitmap_alloc(bitmap->size, + bitmap->bitmap = hbitmap_alloc(DIV_ROUND_UP(bitmap->size, + BDRV_SECTOR_SIZE), hbitmap_granularity(backup)); *out = backup; } -- cgit v1.2.3