block: implement dirty bitmap using HBitmap

This actually uses the dirty bitmap in the block layer, and converts
mirroring to use an HBitmapIter.

Reviewed-by: Laszlo Ersek <lersek@redhat.com> (except block/mirror.c parts)
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 16 insertions, 80 deletions

diff --git a/block.c b/block.c
index 6fa7c90144..e0ff736403 100644
--- a/block.c
+++ b/block.c
@@ -1286,7 +1286,6 @@ static void bdrv_move_feature_fields(BlockDriverState *bs_dest,
     bs_dest->iostatus           = bs_src->iostatus;
 
     /* dirty bitmap */
-    bs_dest->dirty_count        = bs_src->dirty_count;
     bs_dest->dirty_bitmap       = bs_src->dirty_bitmap;
 
     /* job */
@@ -2035,36 +2034,6 @@ int bdrv_read_unthrottled(BlockDriverState *bs, int64_t sector_num,
     return ret;
 }
 
-#define BITS_PER_LONG  (sizeof(unsigned long) * 8)
-
-static void set_dirty_bitmap(BlockDriverState *bs, int64_t sector_num,
-                             int nb_sectors, int dirty)
-{
-    int64_t start, end;
-    unsigned long val, idx, bit;
-
-    start = sector_num / BDRV_SECTORS_PER_DIRTY_CHUNK;
-    end = (sector_num + nb_sectors - 1) / BDRV_SECTORS_PER_DIRTY_CHUNK;
-
-    for (; start <= end; start++) {
-        idx = start / BITS_PER_LONG;
-        bit = start % BITS_PER_LONG;
-        val = bs->dirty_bitmap[idx];
-        if (dirty) {
-            if (!(val & (1UL << bit))) {
-                bs->dirty_count++;
-                val |= 1UL << bit;
-            }
-        } else {
-            if (val & (1UL << bit)) {
-                bs->dirty_count--;
-                val &= ~(1UL << bit);
-            }
-        }
-        bs->dirty_bitmap[idx] = val;
-    }
-}
-
 /* Return < 0 if error. Important errors are:
   -EIO         generic I/O error (may happen for all errors)
   -ENOMEDIUM   No media inserted.
@@ -4173,7 +4142,7 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
     }
 
     if (bs->dirty_bitmap) {
-        set_dirty_bitmap(bs, sector_num, nb_sectors, 0);
+        bdrv_reset_dirty(bs, sector_num, nb_sectors);
     }
 
     if (bs->drv->bdrv_co_discard) {
@@ -4335,18 +4304,15 @@ void bdrv_set_dirty_tracking(BlockDriverState *bs, int enable)
 {
     int64_t bitmap_size;
 
-    bs->dirty_count = 0;
     if (enable) {
         if (!bs->dirty_bitmap) {
-            bitmap_size = (bdrv_getlength(bs) >> BDRV_SECTOR_BITS) +
-                    BDRV_SECTORS_PER_DIRTY_CHUNK * BITS_PER_LONG - 1;
-            bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * BITS_PER_LONG;
-
-            bs->dirty_bitmap = g_new0(unsigned long, bitmap_size);
+            bitmap_size = (bdrv_getlength(bs) >> BDRV_SECTOR_BITS);
+            bs->dirty_bitmap = hbitmap_alloc(bitmap_size,
+                                             BDRV_LOG_SECTORS_PER_DIRTY_CHUNK);
         }
     } else {
         if (bs->dirty_bitmap) {
-            g_free(bs->dirty_bitmap);
+            hbitmap_free(bs->dirty_bitmap);
             bs->dirty_bitmap = NULL;
         }
     }
@@ -4354,67 +4320,37 @@ void bdrv_set_dirty_tracking(BlockDriverState *bs, int enable)
 
 int bdrv_get_dirty(BlockDriverState *bs, int64_t sector)
 {
-    int64_t chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;
-
-    if (bs->dirty_bitmap &&
-        (sector << BDRV_SECTOR_BITS) < bdrv_getlength(bs)) {
-        return !!(bs->dirty_bitmap[chunk / BITS_PER_LONG] &
-            (1UL << (chunk % BITS_PER_LONG)));
+    if (bs->dirty_bitmap) {
+        return hbitmap_get(bs->dirty_bitmap, sector);
     } else {
         return 0;
     }
 }
 
-int64_t bdrv_get_next_dirty(BlockDriverState *bs, int64_t sector)
+void bdrv_dirty_iter_init(BlockDriverState *bs, HBitmapIter *hbi)
 {
-    int64_t chunk;
-    int bit, elem;
-
-    /* Avoid an infinite loop.  */
-    assert(bs->dirty_count > 0);
-
-    sector = (sector | (BDRV_SECTORS_PER_DIRTY_CHUNK - 1)) + 1;
-    chunk = sector / (int64_t)BDRV_SECTORS_PER_DIRTY_CHUNK;
-
-    QEMU_BUILD_BUG_ON(sizeof(bs->dirty_bitmap[0]) * 8 != BITS_PER_LONG);
-    elem = chunk / BITS_PER_LONG;
-    bit = chunk % BITS_PER_LONG;
-    for (;;) {
-        if (sector >= bs->total_sectors) {
-            sector = 0;
-            bit = elem = 0;
-        }
-        if (bit == 0 && bs->dirty_bitmap[elem] == 0) {
-            sector += BDRV_SECTORS_PER_DIRTY_CHUNK * BITS_PER_LONG;
-            elem++;
-        } else {
-            if (bs->dirty_bitmap[elem] & (1UL << bit)) {
-                return sector;
-            }
-            sector += BDRV_SECTORS_PER_DIRTY_CHUNK;
-            if (++bit == BITS_PER_LONG) {
-                bit = 0;
-                elem++;
-            }
-        }
-    }
+    hbitmap_iter_init(hbi, bs->dirty_bitmap, 0);
 }
 
 void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
                     int nr_sectors)
 {
-    set_dirty_bitmap(bs, cur_sector, nr_sectors, 1);
+    hbitmap_set(bs->dirty_bitmap, cur_sector, nr_sectors);
 }
 
 void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
                       int nr_sectors)
 {
-    set_dirty_bitmap(bs, cur_sector, nr_sectors, 0);
+    hbitmap_reset(bs->dirty_bitmap, cur_sector, nr_sectors);
 }
 
 int64_t bdrv_get_dirty_count(BlockDriverState *bs)
 {
-    return bs->dirty_count;
+    if (bs->dirty_bitmap) {
+        return hbitmap_count(bs->dirty_bitmap) >> BDRV_LOG_SECTORS_PER_DIRTY_CHUNK;
+    } else {
+        return 0;
+    }
 }
 
 void bdrv_set_in_use(BlockDriverState *bs, int in_use)