[Qemu-devel] [PATCH] qcow2: Support BDRV_REQ_MAY_UNMAP

[Fam Zheng]

Handling this is similar to what is done to the L2 entry in the case of
compressed clusters.

Signed-off-by: Fam Zheng <address@hidden>
---
 block/qcow2-cluster.c | 9 +++++----
 block/qcow2.c         | 3 ++-
 block/qcow2.h         | 3 ++-
 3 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 61d1ffd..928c1e2 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1558,7 +1558,7 @@ fail:
  * clusters.
  */
 static int zero_single_l2(BlockDriverState *bs, uint64_t offset,
-                          uint64_t nb_clusters)
+                          uint64_t nb_clusters, int flags)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t *l2_table;
@@ -1582,7 +1582,7 @@ static int zero_single_l2(BlockDriverState *bs, uint64_t 
offset,
 
         /* Update L2 entries */
         qcow2_cache_entry_mark_dirty(bs, s->l2_table_cache, l2_table);
-        if (old_offset & QCOW_OFLAG_COMPRESSED) {
+        if (old_offset & QCOW_OFLAG_COMPRESSED || flags & BDRV_REQ_MAY_UNMAP) {
             l2_table[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
             qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);
         } else {
@@ -1595,7 +1595,8 @@ static int zero_single_l2(BlockDriverState *bs, uint64_t 
offset,
     return nb_clusters;
 }
 
-int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors)
+int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors,
+                        int flags)
 {
     BDRVQcow2State *s = bs->opaque;
     uint64_t nb_clusters;
@@ -1612,7 +1613,7 @@ int qcow2_zero_clusters(BlockDriverState *bs, uint64_t 
offset, int nb_sectors)
     s->cache_discards = true;
 
     while (nb_clusters > 0) {
-        ret = zero_single_l2(bs, offset, nb_clusters);
+        ret = zero_single_l2(bs, offset, nb_clusters, flags);
         if (ret < 0) {
             goto fail;
         }
diff --git a/block/qcow2.c b/block/qcow2.c
index 0e53a4d..474f244 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1154,6 +1154,7 @@ static int qcow2_open(BlockDriverState *bs, QDict 
*options, int flags,
 
     /* Initialise locks */
     qemu_co_mutex_init(&s->lock);
+    bs->supported_zero_flags = BDRV_REQ_MAY_UNMAP;
 
     /* Repair image if dirty */
     if (!(flags & (BDRV_O_CHECK | BDRV_O_INACTIVE)) && !bs->read_only &&
@@ -2476,7 +2477,7 @@ static coroutine_fn int 
qcow2_co_pwrite_zeroes(BlockDriverState *bs,
     trace_qcow2_pwrite_zeroes(qemu_coroutine_self(), offset, count);
 
     /* Whatever is left can use real zero clusters */
-    ret = qcow2_zero_clusters(bs, offset, count >> BDRV_SECTOR_BITS);
+    ret = qcow2_zero_clusters(bs, offset, count >> BDRV_SECTOR_BITS, flags);
     qemu_co_mutex_unlock(&s->lock);
 
     return ret;
diff --git a/block/qcow2.h b/block/qcow2.h
index 9ce5a37..92203a8 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -547,7 +547,8 @@ uint64_t 
qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
 int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m);
 int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset,
     int nb_sectors, enum qcow2_discard_type type, bool full_discard);
-int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors);
+int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors,
+                        int flags);
 
 int qcow2_expand_zero_clusters(BlockDriverState *bs,
                                BlockDriverAmendStatusCB *status_cb,
-- 
2.7.4