[PATCH v5 19/22] parallels: Remove unnecessary data_end field

[Alexander Ivanov <alexander.ivanov@virtuozzo.com>]

Since we have used bitmap, field data_end in BDRVParallelsState is
redundant and can be removed.

Add parallels_data_end() helper and remove data_end handling.

Note: bdrv_pwrite_zeroes() was removed from the branch where we reallocate
clusters. It's redundant - bdrv_pwrite_zeroes() was already called for all
such clusters.

Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
---
 block/parallels.c | 45 +++++++++++++--------------------------------
 block/parallels.h |  1 -
 2 files changed, 13 insertions(+), 33 deletions(-)

diff --git a/block/parallels.c b/block/parallels.c
index fd80179642..11b6f97454 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -268,6 +268,13 @@ static void parallels_free_used_bitmap(BlockDriverState *bs)
     s->used_bmap = NULL;
 }
 
+static int64_t parallels_data_end(BDRVParallelsState *s)
+{
+    int64_t data_end = s->data_start * BDRV_SECTOR_SIZE;
+    data_end += s->used_bmap_size * s->cluster_size;
+    return data_end;
+}
+
 int64_t GRAPH_RDLOCK parallels_allocate_host_clusters(BlockDriverState *bs,
                                                       int64_t *clusters)
 {
@@ -279,7 +286,7 @@ int64_t GRAPH_RDLOCK parallels_allocate_host_clusters(BlockDriverState *bs,
 
     first_free = find_first_zero_bit(s->used_bmap, s->used_bmap_size);
     if (first_free == s->used_bmap_size) {
-        host_off = s->data_end * BDRV_SECTOR_SIZE;
+        host_off = parallels_data_end(s);
         prealloc_clusters = *clusters + s->prealloc_size / s->tracks;
         bytes = *clusters * s->cluster_size;
         prealloc_bytes = prealloc_clusters * s->cluster_size;
@@ -307,31 +314,14 @@ int64_t GRAPH_RDLOCK parallels_allocate_host_clusters(BlockDriverState *bs,
         s->used_bmap = bitmap_zero_extend(s->used_bmap, s->used_bmap_size,
                                           new_usedsize);
         s->used_bmap_size = new_usedsize;
-        if (host_off + bytes > s->data_end * BDRV_SECTOR_SIZE) {
-            s->data_end = (host_off + bytes) / BDRV_SECTOR_SIZE;
-        }
     } else {
         next_used = find_next_bit(s->used_bmap, s->used_bmap_size, first_free);
 
         /* Not enough continuous clusters in the middle, adjust the size */
         *clusters = MIN(*clusters, next_used - first_free);
-        bytes = *clusters * s->cluster_size;
 
         host_off = s->data_start * BDRV_SECTOR_SIZE;
         host_off += first_free * s->cluster_size;
-
-        /*
-         * No need to preallocate if we are using tail area from the above
-         * branch. In the other case we are likely re-using hole. Preallocate
-         * the space if required by the prealloc_mode.
-         */
-        if (s->prealloc_mode == PRL_PREALLOC_MODE_FALLOCATE &&
-                host_off < s->data_end * BDRV_SECTOR_SIZE) {
-            ret = bdrv_pwrite_zeroes(bs->file, host_off, bytes, 0);
-            if (ret < 0) {
-                return ret;
-            }
-        }
     }
 
     ret = parallels_mark_used(bs, s->used_bmap, s->used_bmap_size,
@@ -763,13 +753,7 @@ parallels_check_outside_image(BlockDriverState *bs, BdrvCheckResult *res,
         }
     }
 
-    if (high_off == 0) {
-        res->image_end_offset = s->data_end << BDRV_SECTOR_BITS;
-    } else {
-        res->image_end_offset = high_off + s->cluster_size;
-        s->data_end = res->image_end_offset >> BDRV_SECTOR_BITS;
-    }
-
+    res->image_end_offset = parallels_data_end(s);
     return 0;
 }
 
@@ -808,8 +792,6 @@ parallels_check_unused_clusters(BlockDriverState *bs, bool truncate)
         return ret;
     }
 
-    s->data_end = end_off / BDRV_SECTOR_SIZE;
-
     return leak;
 }
 
@@ -1401,8 +1383,7 @@ static int parallels_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     s->data_start = data_start;
-    s->data_end = s->data_start;
-    if (s->data_end < (s->header_size >> BDRV_SECTOR_BITS)) {
+    if (s->data_start < (s->header_size >> BDRV_SECTOR_BITS)) {
         /*
          * There is not enough unused space to fit to block align between BAT
          * and actual data. We can't avoid read-modify-write...
@@ -1435,11 +1416,11 @@ static int parallels_open(BlockDriverState *bs, QDict *options, int flags,
 
     for (i = 0; i < s->bat_size; i++) {
         sector = bat2sect(s, i);
-        if (sector + s->tracks > s->data_end) {
-            s->data_end = sector + s->tracks;
+        if (sector + s->tracks > file_nb_sectors) {
+            need_check = true;
+            break;
         }
     }
-    need_check = need_check || s->data_end > file_nb_sectors;
 
     ret = parallels_fill_used_bitmap(bs);
     if (ret == -ENOMEM) {
diff --git a/block/parallels.h b/block/parallels.h
index d1e46dcfa8..1d41a59b6f 100644
--- a/block/parallels.h
+++ b/block/parallels.h
@@ -79,7 +79,6 @@ typedef struct BDRVParallelsState {
     unsigned int bat_size;
 
     int64_t  data_start;
-    int64_t  data_end;
     uint64_t prealloc_size;
     ParallelsPreallocMode prealloc_mode;
 
-- 
2.40.1