[Qemu-devel] [PATCH 3/4] Count dirty blocks and expose an API to get dirty count

[Liran Schour <lirans@il.ibm.com>]

This will manage dirty counter for each device and will allow to get the
dirty counter from above.

Signed-off-by: Liran Schour <lirans@il.ibm.com>
---
 block.c     |   20 ++++++++++++++++----
 block.h     |    1 +
 block_int.h |    1 +
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/block.c b/block.c
index 853f025..ecfcba4 100644
--- a/block.c
+++ b/block.c
@@ -652,9 +652,15 @@ static void set_dirty_bitmap(BlockDriverState *bs, int64_t sector_num,
         bit = start % (sizeof(unsigned long) * 8);
         val = bs->dirty_bitmap[idx];
         if (dirty) {
-            val |= 1 << bit;
+            if (!(val & (1 << bit))) {
+                bs->dirty_count++;
+                val |= 1 << bit;
+            }
         } else {
-            val &= ~(1 << bit);
+            if (val & (1 << bit)) {
+                bs->dirty_count--;
+                val &= ~(1 << bit);
+            }
         }
         bs->dirty_bitmap[idx] = val;
     }
@@ -1972,14 +1978,15 @@ void *qemu_blockalign(BlockDriverState *bs, size_t size)
 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 * 8 - 1;
             bitmap_size /= BDRV_SECTORS_PER_DIRTY_CHUNK * 8;
 
-            bs->dirty_bitmap = qemu_mallocz(bitmap_size);
+            bs->dirty_bitmap = qemu_mallocz(bitmap_size);  
         }
     } else {
         if (bs->dirty_bitmap) {
@@ -2007,3 +2014,8 @@ void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
 {
     set_dirty_bitmap(bs, cur_sector, nr_sectors, 0);
 }
+
+int64_t bdrv_get_dirty_count(BlockDriverState *bs)
+{
+    return bs->dirty_count;
+}
diff --git a/block.h b/block.h
index 4a8b628..bf489d0 100644
--- a/block.h
+++ b/block.h
@@ -198,4 +198,5 @@ void bdrv_set_dirty_tracking(BlockDriverState *bs, int enable);
 int bdrv_get_dirty(BlockDriverState *bs, int64_t sector);
 void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
                       int nr_sectors);
+int64_t bdrv_get_dirty_count(BlockDriverState *bs);
 #endif
diff --git a/block_int.h b/block_int.h
index 9a3b2e0..8d5d9bc 100644
--- a/block_int.h
+++ b/block_int.h
@@ -172,6 +172,7 @@ struct BlockDriverState {
     int type;
     char device_name[32];
     unsigned long *dirty_bitmap;
+    int64_t dirty_count;
     BlockDriverState *next;
     void *private;
 };
-- 
1.5.2.4