[Qemu-devel] [PATCH v7 2/5] block/backup: move to copy_bitmap with granularity

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

We are going to share this bitmap between backup and backup-top filter
driver, so let's share something more meaningful. It also simplifies
some calculations.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
---
 block/backup.c | 48 +++++++++++++++++++++++-------------------------
 1 file changed, 23 insertions(+), 25 deletions(-)

diff --git a/block/backup.c b/block/backup.c
index d9f5db18ac..510fc54f98 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -113,7 +113,8 @@ static int coroutine_fn backup_cow_with_bounce_buffer(BackupBlockJob *job,
     int read_flags = is_write_notifier ? BDRV_REQ_NO_SERIALISING : 0;
     int write_flags = job->serialize_target_writes ? BDRV_REQ_SERIALISING : 0;
 
-    hbitmap_reset(job->copy_bitmap, start / job->cluster_size, 1);
+    assert(QEMU_IS_ALIGNED(start, job->cluster_size));
+    hbitmap_reset(job->copy_bitmap, start, job->cluster_size);
     nbytes = MIN(job->cluster_size, job->len - start);
     if (!*bounce_buffer) {
         *bounce_buffer = blk_blockalign(blk, job->cluster_size);
@@ -147,7 +148,7 @@ static int coroutine_fn backup_cow_with_bounce_buffer(BackupBlockJob *job,
 
     return nbytes;
 fail:
-    hbitmap_set(job->copy_bitmap, start / job->cluster_size, 1);
+    hbitmap_set(job->copy_bitmap, start, job->cluster_size);
     return ret;
 
 }
@@ -167,16 +168,15 @@ static int coroutine_fn backup_cow_with_offload(BackupBlockJob *job,
     int write_flags = job->serialize_target_writes ? BDRV_REQ_SERIALISING : 0;
 
     assert(QEMU_IS_ALIGNED(job->copy_range_size, job->cluster_size));
+    assert(QEMU_IS_ALIGNED(start, job->cluster_size));
     nbytes = MIN(job->copy_range_size, end - start);
     nr_clusters = DIV_ROUND_UP(nbytes, job->cluster_size);
-    hbitmap_reset(job->copy_bitmap, start / job->cluster_size,
-                  nr_clusters);
+    hbitmap_reset(job->copy_bitmap, start, job->cluster_size * nr_clusters);
     ret = blk_co_copy_range(blk, start, job->target, start, nbytes,
                             read_flags, write_flags);
     if (ret < 0) {
         trace_backup_do_cow_copy_range_fail(job, start, ret);
-        hbitmap_set(job->copy_bitmap, start / job->cluster_size,
-                    nr_clusters);
+        hbitmap_set(job->copy_bitmap, start, job->cluster_size * nr_clusters);
         return ret;
     }
 
@@ -204,7 +204,7 @@ static int coroutine_fn backup_do_cow(BackupBlockJob *job,
     cow_request_begin(&cow_request, job, start, end);
 
     while (start < end) {
-        if (!hbitmap_get(job->copy_bitmap, start / job->cluster_size)) {
+        if (!hbitmap_get(job->copy_bitmap, start)) {
             trace_backup_do_cow_skip(job, start);
             start += job->cluster_size;
             continue; /* already copied */
@@ -300,6 +300,11 @@ static void backup_clean(Job *job)
     assert(s->target);
     blk_unref(s->target);
     s->target = NULL;
+
+    if (s->copy_bitmap) {
+        hbitmap_free(s->copy_bitmap);
+        s->copy_bitmap = NULL;
+    }
 }
 
 static void backup_attached_aio_context(BlockJob *job, AioContext *aio_context)
@@ -312,7 +317,6 @@ static void backup_attached_aio_context(BlockJob *job, AioContext *aio_context)
 void backup_do_checkpoint(BlockJob *job, Error **errp)
 {
     BackupBlockJob *backup_job = container_of(job, BackupBlockJob, common);
-    int64_t len;
 
     assert(block_job_driver(job) == &backup_job_driver);
 
@@ -322,8 +326,7 @@ void backup_do_checkpoint(BlockJob *job, Error **errp)
         return;
     }
 
-    len = DIV_ROUND_UP(backup_job->len, backup_job->cluster_size);
-    hbitmap_set(backup_job->copy_bitmap, 0, len);
+    hbitmap_set(backup_job->copy_bitmap, 0, backup_job->len);
 }
 
 static void backup_drain(BlockJob *job)
@@ -378,16 +381,16 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
 {
     int ret;
     bool error_is_read;
-    int64_t cluster;
+    int64_t offset;
     HBitmapIter hbi;
 
     hbitmap_iter_init(&hbi, job->copy_bitmap, 0);
-    while ((cluster = hbitmap_iter_next(&hbi)) != -1) {
+    while ((offset = hbitmap_iter_next(&hbi)) != -1) {
         do {
             if (yield_and_check(job)) {
                 return 0;
             }
-            ret = backup_do_cow(job, cluster * job->cluster_size,
+            ret = backup_do_cow(job, offset,
                                 job->cluster_size, &error_is_read, false);
             if (ret < 0 && backup_error_action(job, error_is_read, -ret) ==
                            BLOCK_ERROR_ACTION_REPORT)
@@ -409,12 +412,9 @@ static void backup_incremental_init_copy_bitmap(BackupBlockJob *job)
     while (bdrv_dirty_bitmap_next_dirty_area(job->sync_bitmap,
                                              &offset, &bytes))
     {
-        uint64_t cluster = offset / job->cluster_size;
-        uint64_t end_cluster = DIV_ROUND_UP(offset + bytes, job->cluster_size);
+        hbitmap_set(job->copy_bitmap, offset, bytes);
 
-        hbitmap_set(job->copy_bitmap, cluster, end_cluster - cluster);
-
-        offset = end_cluster * job->cluster_size;
+        offset += bytes;
         if (offset >= job->len) {
             break;
         }
@@ -423,30 +423,27 @@ static void backup_incremental_init_copy_bitmap(BackupBlockJob *job)
 
     /* TODO job_progress_set_remaining() would make more sense */
     job_progress_update(&job->common.job,
-        job->len - hbitmap_count(job->copy_bitmap) * job->cluster_size);
+        job->len - hbitmap_count(job->copy_bitmap));
 }
 
 static int coroutine_fn backup_run(Job *job, Error **errp)
 {
     BackupBlockJob *s = container_of(job, BackupBlockJob, common.job);
     BlockDriverState *bs = blk_bs(s->common.blk);
-    int64_t offset, nb_clusters;
+    int64_t offset;
     int ret = 0;
 
     QLIST_INIT(&s->inflight_reqs);
     qemu_co_rwlock_init(&s->flush_rwlock);
 
-    nb_clusters = DIV_ROUND_UP(s->len, s->cluster_size);
     job_progress_set_remaining(job, s->len);
 
-    s->copy_bitmap = hbitmap_alloc(nb_clusters, 0);
     if (s->sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
         backup_incremental_init_copy_bitmap(s);
     } else {
-        hbitmap_set(s->copy_bitmap, 0, nb_clusters);
+        hbitmap_set(s->copy_bitmap, 0, s->len);
     }
 
-
     s->before_write.notify = backup_before_write_notify;
     bdrv_add_before_write_notifier(bs, &s->before_write);
 
@@ -527,7 +524,6 @@ static int coroutine_fn backup_run(Job *job, Error **errp)
     /* wait until pending backup_do_cow() calls have completed */
     qemu_co_rwlock_wrlock(&s->flush_rwlock);
     qemu_co_rwlock_unlock(&s->flush_rwlock);
-    hbitmap_free(s->copy_bitmap);
 
     return ret;
 }
@@ -678,6 +674,8 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs,
     } else {
         job->cluster_size = MAX(BACKUP_CLUSTER_SIZE_DEFAULT, bdi.cluster_size);
     }
+
+    job->copy_bitmap = hbitmap_alloc(len, ctz32(job->cluster_size));
     job->use_copy_range = true;
     job->copy_range_size = MIN_NON_ZERO(blk_get_max_transfer(job->common.blk),
                                         blk_get_max_transfer(job->target));
-- 
2.18.0