[PATCH v4 2/2] quorum: Implement bdrv_co_pwrite_zeroes()

[Alberto Garcia <berto@igalia.com>]

This simply calls bdrv_co_pwrite_zeroes() in all children.

bs->supported_zero_flags is also set to the flags that are supported
by all children.

Signed-off-by: Alberto Garcia <berto@igalia.com>
---
 block/quorum.c             | 36 ++++++++++++++++++++++++++++++++++--
 tests/qemu-iotests/312     | 11 +++++++++++
 tests/qemu-iotests/312.out |  8 ++++++++
 3 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/block/quorum.c b/block/quorum.c
index 9691a9bee9..b70d365ba9 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -692,8 +692,13 @@ static void write_quorum_entry(void *opaque)
     QuorumChildRequest *sacb = &acb->qcrs[i];
 
     sacb->bs = s->children[i]->bs;
-    sacb->ret = bdrv_co_pwritev(s->children[i], acb->offset, acb->bytes,
-                                acb->qiov, acb->flags);
+    if (acb->flags & BDRV_REQ_ZERO_WRITE) {
+        sacb->ret = bdrv_co_pwrite_zeroes(s->children[i], acb->offset,
+                                          acb->bytes, acb->flags);
+    } else {
+        sacb->ret = bdrv_co_pwritev(s->children[i], acb->offset, acb->bytes,
+                                    acb->qiov, acb->flags);
+    }
     if (sacb->ret == 0) {
         acb->success_count++;
     } else {
@@ -739,6 +744,14 @@ static int quorum_co_pwritev(BlockDriverState *bs, uint64_t offset,
     return ret;
 }
 
+static int quorum_co_pwrite_zeroes(BlockDriverState *bs, int64_t offset,
+                                   int bytes, BdrvRequestFlags flags)
+
+{
+    return quorum_co_pwritev(bs, offset, bytes, NULL,
+                             flags | BDRV_REQ_ZERO_WRITE);
+}
+
 static int64_t quorum_getlength(BlockDriverState *bs)
 {
     BDRVQuorumState *s = bs->opaque;
@@ -897,6 +910,21 @@ static QemuOptsList quorum_runtime_opts = {
     },
 };
 
+static void quorum_refresh_flags(BlockDriverState *bs)
+{
+    BDRVQuorumState *s = bs->opaque;
+    int i;
+
+    bs->supported_zero_flags =
+        BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK;
+
+    for (i = 0; i < s->num_children; i++) {
+        bs->supported_zero_flags &= s->children[i]->bs->supported_zero_flags;
+    }
+
+    bs->supported_zero_flags |= BDRV_REQ_WRITE_UNCHANGED;
+}
+
 static int quorum_open(BlockDriverState *bs, QDict *options, int flags,
                        Error **errp)
 {
@@ -991,6 +1019,7 @@ static int quorum_open(BlockDriverState *bs, QDict *options, int flags,
     s->next_child_index = s->num_children;
 
     bs->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED;
+    quorum_refresh_flags(bs);
 
     g_free(opened);
     goto exit;
@@ -1062,6 +1091,7 @@ static void quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs,
     }
     s->children = g_renew(BdrvChild *, s->children, s->num_children + 1);
     s->children[s->num_children++] = child;
+    quorum_refresh_flags(bs);
 
 out:
     bdrv_drained_end(bs);
@@ -1106,6 +1136,7 @@ static void quorum_del_child(BlockDriverState *bs, BdrvChild *child,
     s->children = g_renew(BdrvChild *, s->children, --s->num_children);
     bdrv_unref_child(bs, child);
 
+    quorum_refresh_flags(bs);
     bdrv_drained_end(bs);
 }
 
@@ -1251,6 +1282,7 @@ static BlockDriver bdrv_quorum = {
 
     .bdrv_co_preadv                     = quorum_co_preadv,
     .bdrv_co_pwritev                    = quorum_co_pwritev,
+    .bdrv_co_pwrite_zeroes              = quorum_co_pwrite_zeroes,
 
     .bdrv_add_child                     = quorum_add_child,
     .bdrv_del_child                     = quorum_del_child,
diff --git a/tests/qemu-iotests/312 b/tests/qemu-iotests/312
index 1b08f1552f..41340494b0 100755
--- a/tests/qemu-iotests/312
+++ b/tests/qemu-iotests/312
@@ -114,6 +114,17 @@ $QEMU_IO -c "write -P 0 $((0x200000)) $((0x10000))" "$TEST_IMG.0" | _filter_qemu
 $QEMU_IO -c "write -z   $((0x200000)) $((0x30000))" "$TEST_IMG.1" | _filter_qemu_io
 $QEMU_IO -c "write -P 0 $((0x200000)) $((0x20000))" "$TEST_IMG.2" | _filter_qemu_io
 
+# Test 5: write data to a region and then zeroize it, doing it
+# directly on the quorum device instead of the individual images.
+# This has no effect on the end result but proves that the quorum driver
+# supports 'write -z'.
+$QEMU_IO -c "open -o $quorum" -c "write -P 1 $((0x250000)) $((0x10000))" | _filter_qemu_io
+# Verify the data that we just wrote
+$QEMU_IO -c "open -o $quorum" -c "read -P 1 $((0x250000)) $((0x10000))" | _filter_qemu_io
+$QEMU_IO -c "open -o $quorum" -c "write -z $((0x250000)) $((0x10000))" | _filter_qemu_io
+# Now it should read back as zeroes
+$QEMU_IO -c "open -o $quorum" -c "read -P 0 $((0x250000)) $((0x10000))" | _filter_qemu_io
+
 echo
 echo '### Launch the drive-mirror job'
 echo
diff --git a/tests/qemu-iotests/312.out b/tests/qemu-iotests/312.out
index 4ae749175b..cdd5c40e08 100644
--- a/tests/qemu-iotests/312.out
+++ b/tests/qemu-iotests/312.out
@@ -39,6 +39,14 @@ wrote 196608/196608 bytes at offset 2097152
 192 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 wrote 131072/131072 bytes at offset 2097152
 128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 65536/65536 bytes at offset 2424832
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 65536/65536 bytes at offset 2424832
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 65536/65536 bytes at offset 2424832
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 65536/65536 bytes at offset 2424832
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
 ### Launch the drive-mirror job
 
-- 
2.20.1