[Qemu-devel] [PULL 02/10] backup: move from done_bitmap to copy_bitmap

[Jeff Cody <jcody@redhat.com>]

From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

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

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20171012135313.227864-3-vsementsov@virtuozzo.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
---
 block/backup.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

diff --git a/block/backup.c b/block/backup.c
index 99e6bcc..5175808 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -40,11 +40,12 @@ typedef struct BackupBlockJob {
     BlockdevOnError on_target_error;
     CoRwlock flush_rwlock;
     uint64_t bytes_read;
-    unsigned long *done_bitmap;
     int64_t cluster_size;
     bool compress;
     NotifierWithReturn before_write;
     QLIST_HEAD(, CowRequest) inflight_reqs;
+
+    HBitmap *copy_bitmap;
 } BackupBlockJob;
 
 /* See if in-flight requests overlap and wait for them to complete */
@@ -109,10 +110,11 @@ static int coroutine_fn backup_do_cow(BackupBlockJob *job,
     cow_request_begin(&cow_request, job, start, end);
 
     for (; start < end; start += job->cluster_size) {
-        if (test_bit(start / job->cluster_size, job->done_bitmap)) {
+        if (!hbitmap_get(job->copy_bitmap, start / job->cluster_size)) {
             trace_backup_do_cow_skip(job, start);
             continue; /* already copied */
         }
+        hbitmap_reset(job->copy_bitmap, start / job->cluster_size, 1);
 
         trace_backup_do_cow_process(job, start);
 
@@ -132,6 +134,7 @@ static int coroutine_fn backup_do_cow(BackupBlockJob *job,
             if (error_is_read) {
                 *error_is_read = true;
             }
+            hbitmap_set(job->copy_bitmap, start / job->cluster_size, 1);
             goto out;
         }
 
@@ -148,11 +151,10 @@ static int coroutine_fn backup_do_cow(BackupBlockJob *job,
             if (error_is_read) {
                 *error_is_read = false;
             }
+            hbitmap_set(job->copy_bitmap, start / job->cluster_size, 1);
             goto out;
         }
 
-        set_bit(start / job->cluster_size, 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.
          */
@@ -260,7 +262,7 @@ 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 offset,
@@ -425,19 +427,22 @@ static void coroutine_fn backup_run(void *opaque)
     BackupBlockJob *job = opaque;
     BackupCompleteData *data;
     BlockDriverState *bs = blk_bs(job->common.blk);
-    int64_t offset;
+    int64_t offset, nb_clusters;
     int ret = 0;
 
     QLIST_INIT(&job->inflight_reqs);
     qemu_co_rwlock_init(&job->flush_rwlock);
 
-    job->done_bitmap = bitmap_new(DIV_ROUND_UP(job->common.len,
-                                               job->cluster_size));
+    nb_clusters = DIV_ROUND_UP(job->common.len, job->cluster_size);
+    job->copy_bitmap = hbitmap_alloc(nb_clusters, 0);
+    hbitmap_set(job->copy_bitmap, 0, nb_clusters);
 
     job->before_write.notify = backup_before_write_notify;
     bdrv_add_before_write_notifier(bs, &job->before_write);
 
     if (job->sync_mode == MIRROR_SYNC_MODE_NONE) {
+        /* All bits are set in copy_bitmap to allow any cluster to be copied.
+         * This does not actually require them to be copied. */
         while (!block_job_is_cancelled(&job->common)) {
             /* Yield until the job is cancelled.  We just let our before_write
              * notify callback service CoW requests. */
@@ -512,7 +517,7 @@ 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;
-- 
2.9.5