[Qemu-devel] [PATCH v4 1/8] block: Add "base" option to bdrv_get_block_status

[Fam Zheng <famz@redhat.com>]

Now this function follows the backing chain until seeing BDRV_BLOCK_ALLOCATED.
Base is not included, and it can be NULL just like bdrv_is_allocated_above().

Existing callers pass in bs->backing_hd to keep the old behavior.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/io.c            | 39 ++++++++++++++++++++++++++++++++-------
 include/block/block.h |  3 ++-
 qemu-img.c            |  6 ++++--
 3 files changed, 38 insertions(+), 10 deletions(-)

diff --git a/block/io.c b/block/io.c
index 1ce62c4..36a4007 100644
--- a/block/io.c
+++ b/block/io.c
@@ -673,7 +673,8 @@ int bdrv_make_zero(BlockDriverState *bs, BdrvRequestFlags flags)
         if (nb_sectors <= 0) {
             return 0;
         }
-        ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &n);
+        ret = bdrv_get_block_status(bs, bs->backing_hd, sector_num,
+                                    nb_sectors, &n);
         if (ret < 0) {
             error_report("error getting block status at sector %" PRId64 ": %s",
                          sector_num, strerror(-ret));
@@ -1450,7 +1451,8 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
 
     if (ret & BDRV_BLOCK_RAW) {
         assert(ret & BDRV_BLOCK_OFFSET_VALID);
-        return bdrv_get_block_status(bs->file, ret >> BDRV_SECTOR_BITS,
+        return bdrv_get_block_status(bs->file, bs->file->backing_hd,
+                                     ret >> BDRV_SECTOR_BITS,
                                      *pnum, pnum);
     }
 
@@ -1497,14 +1499,34 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
     return ret;
 }
 
+static int64_t coroutine_fn bdrv_co_get_block_status_above(BlockDriverState *bs,
+        BlockDriverState *base,
+        int64_t sector_num,
+        int nb_sectors,
+        int *pnum)
+{
+    BlockDriverState *p;
+    int64_t ret;
+
+    assert(bs != base);
+    for (p = bs; p != base; p = p->backing_hd) {
+        ret = bdrv_co_get_block_status(p, sector_num, nb_sectors, pnum);
+        if (ret < 0 || ret & BDRV_BLOCK_ALLOCATED) {
+            break;
+        }
+    }
+    return ret;
+}
+
 /* Coroutine wrapper for bdrv_get_block_status() */
 static void coroutine_fn bdrv_get_block_status_co_entry(void *opaque)
 {
     BdrvCoGetBlockStatusData *data = opaque;
-    BlockDriverState *bs = data->bs;
 
-    data->ret = bdrv_co_get_block_status(bs, data->sector_num, data->nb_sectors,
-                                         data->pnum);
+    data->ret = bdrv_co_get_block_status_above(data->bs, data->base,
+                                               data->sector_num,
+                                               data->nb_sectors,
+                                               data->pnum);
     data->done = true;
 }
 
@@ -1513,12 +1535,14 @@ static void coroutine_fn bdrv_get_block_status_co_entry(void *opaque)
  *
  * See bdrv_co_get_block_status() for details.
  */
-int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num,
+int64_t bdrv_get_block_status(BlockDriverState *bs, BlockDriverState *base,
+                              int64_t sector_num,
                               int nb_sectors, int *pnum)
 {
     Coroutine *co;
     BdrvCoGetBlockStatusData data = {
         .bs = bs,
+        .base = base,
         .sector_num = sector_num,
         .nb_sectors = nb_sectors,
         .pnum = pnum,
@@ -1543,7 +1567,8 @@ int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num,
 int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num,
                                    int nb_sectors, int *pnum)
 {
-    int64_t ret = bdrv_get_block_status(bs, sector_num, nb_sectors, pnum);
+    int64_t ret = bdrv_get_block_status(bs, bs->backing_hd,
+                                        sector_num, nb_sectors, pnum);
     if (ret < 0) {
         return ret;
     }
diff --git a/include/block/block.h b/include/block/block.h
index 7d1a717..e1d408c 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -359,7 +359,8 @@ int bdrv_has_zero_init_1(BlockDriverState *bs);
 int bdrv_has_zero_init(BlockDriverState *bs);
 bool bdrv_unallocated_blocks_are_zero(BlockDriverState *bs);
 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs);
-int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num,
+int64_t bdrv_get_block_status(BlockDriverState *bs, BlockDriverState *base,
+                              int64_t sector_num,
                               int nb_sectors, int *pnum);
 int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
                       int *pnum);
diff --git a/qemu-img.c b/qemu-img.c
index 8d30e43..723d8a6 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -1350,7 +1350,8 @@ static int convert_iteration_sectors(ImgConvertState *s, int64_t sector_num)
     n = MIN(s->total_sectors - sector_num, BDRV_REQUEST_MAX_SECTORS);
 
     if (s->sector_next_status <= sector_num) {
-        ret = bdrv_get_block_status(blk_bs(s->src[s->src_cur]),
+        BlockDriverState *bs = blk_bs(s->src[s->src_cur]);
+        ret = bdrv_get_block_status(bs, bs->backing_hd,
                                     sector_num - s->src_cur_offset,
                                     n, &n);
         if (ret < 0) {
@@ -2287,7 +2288,8 @@ static int get_block_status(BlockDriverState *bs, int64_t sector_num,
 
     depth = 0;
     for (;;) {
-        ret = bdrv_get_block_status(bs, sector_num, nb_sectors, &nb_sectors);
+        ret = bdrv_get_block_status(bs, bs->backing_hd, sector_num,
+                                    nb_sectors, &nb_sectors);
         if (ret < 0) {
             return ret;
         }
-- 
2.4.1