[Qemu-devel] [PATCH 01/21] backup: move from done_bitmap to copy_bitmap

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

Use HBitmap copy_bitmap instead of done_bitmap. This is needed to unify
backup loop for full/incremental modes in future patches.

We reset bit of the copy_bitmap immediately after checking it in
backup_do_cow(). It is safe, because all other intersecting requests
will wait for our request finish anyway.

The other difference is that in case of error we will have zeroed bit in
copy_bitmap, when in done_bitmap we have not set bit.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/backup.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/block/backup.c b/block/backup.c
index ea38733..6b27e55 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -39,11 +39,12 @@ typedef struct BackupBlockJob {
     BlockdevOnError on_target_error;
     CoRwlock flush_rwlock;
     uint64_t sectors_read;
-    unsigned long *done_bitmap;
     int64_t cluster_size;
     bool compress;
     NotifierWithReturn before_write;
     QLIST_HEAD(, CowRequest) inflight_reqs;
+
+    HBitmap *copy_bitmap;
 } BackupBlockJob;
 
 /* Size of a cluster in sectors, instead of bytes. */
@@ -115,10 +116,11 @@ static int coroutine_fn backup_do_cow(BackupBlockJob *job,
     cow_request_begin(&cow_request, job, start, end);
 
     for (; start < end; start++) {
-        if (test_bit(start, job->done_bitmap)) {
+        if (!hbitmap_get(job->copy_bitmap, start)) {
             trace_backup_do_cow_skip(job, start);
             continue; /* already copied */
         }
+        hbitmap_reset(job->copy_bitmap, start, 1);
 
         trace_backup_do_cow_process(job, start);
 
@@ -141,6 +143,7 @@ static int coroutine_fn backup_do_cow(BackupBlockJob *job,
             if (error_is_read) {
                 *error_is_read = true;
             }
+            hbitmap_set(job->copy_bitmap, start, 1);
             goto out;
         }
 
@@ -157,11 +160,10 @@ static int coroutine_fn backup_do_cow(BackupBlockJob *job,
             if (error_is_read) {
                 *error_is_read = false;
             }
+            hbitmap_set(job->copy_bitmap, start, 1);
             goto out;
         }
 
-        set_bit(start, job->done_bitmap);
-
         /* Publish progress, guest I/O counts as progress too.  Note that the
          * offset field is an opaque progress value, it is not a disk offset.
          */
@@ -271,7 +273,7 @@ void backup_do_checkpoint(BlockJob *job, Error **errp)
     }
 
     len = DIV_ROUND_UP(backup_job->common.len, backup_job->cluster_size);
-    bitmap_zero(backup_job->done_bitmap, len);
+    hbitmap_set(backup_job->copy_bitmap, 0, len);
 }
 
 void backup_wait_for_overlapping_requests(BlockJob *job, int64_t sector_num,
@@ -450,7 +452,8 @@ static void coroutine_fn backup_run(void *opaque)
     start = 0;
     end = DIV_ROUND_UP(job->common.len, job->cluster_size);
 
-    job->done_bitmap = bitmap_new(end);
+    job->copy_bitmap = hbitmap_alloc(end, 0);
+    hbitmap_set(job->copy_bitmap, 0, end);
 
     job->before_write.notify = backup_before_write_notify;
     bdrv_add_before_write_notifier(bs, &job->before_write);
@@ -524,7 +527,7 @@ static void coroutine_fn backup_run(void *opaque)
     /* wait until pending backup_do_cow() calls have completed */
     qemu_co_rwlock_wrlock(&job->flush_rwlock);
     qemu_co_rwlock_unlock(&job->flush_rwlock);
-    g_free(job->done_bitmap);
+    hbitmap_free(job->copy_bitmap);
 
     data = g_malloc(sizeof(*data));
     data->ret = ret;
-- 
1.8.3.1