From: Max Reitz <mreitz@redhat.com>
To: qemu-block@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
Alberto Garcia <berto@igalia.com>,
qemu-devel@nongnu.org, Max Reitz <mreitz@redhat.com>
Subject: [PATCH for-5.0 v2 10/23] quorum: Implement .bdrv_recurse_can_replace()
Date: Mon, 11 Nov 2019 17:02:03 +0100 [thread overview]
Message-ID: <20191111160216.197086-11-mreitz@redhat.com> (raw)
In-Reply-To: <20191111160216.197086-1-mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
block/quorum.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 62 insertions(+)
diff --git a/block/quorum.c b/block/quorum.c
index 3a824e77e3..8ee03e9baf 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -825,6 +825,67 @@ static bool quorum_recurse_is_first_non_filter(BlockDriverState *bs,
return false;
}
+static bool quorum_recurse_can_replace(BlockDriverState *bs,
+ BlockDriverState *to_replace)
+{
+ BDRVQuorumState *s = bs->opaque;
+ int i;
+
+ for (i = 0; i < s->num_children; i++) {
+ /*
+ * We have no idea whether our children show the same data as
+ * this node (@bs). It is actually highly likely that
+ * @to_replace does not, because replacing a broken child is
+ * one of the main use cases here.
+ *
+ * We do know that the new BDS will match @bs, so replacing
+ * any of our children by it will be safe. It cannot change
+ * the data this quorum node presents to its parents.
+ *
+ * However, replacing @to_replace by @bs in any of our
+ * children's chains may change visible data somewhere in
+ * there. We therefore cannot recurse down those chains with
+ * bdrv_recurse_can_replace().
+ * (More formally, bdrv_recurse_can_replace() requires that
+ * @to_replace will be replaced by something matching the @bs
+ * passed to it. We cannot guarantee that.)
+ *
+ * Thus, we can only check whether any of our immediate
+ * children matches @to_replace.
+ *
+ * (In the future, we might add a function to recurse down a
+ * chain that checks that nothing there cares about a change
+ * in data from the respective child in question. For
+ * example, most filters do not care when their child's data
+ * suddenly changes, as long as their parents do not care.)
+ */
+ if (s->children[i].child->bs == to_replace) {
+ Error *local_err = NULL;
+
+ /*
+ * We now have to ensure that there is no other parent
+ * that cares about replacing this child by a node with
+ * potentially different data.
+ */
+ s->children[i].to_be_replaced = true;
+ bdrv_child_refresh_perms(bs, s->children[i].child, &local_err);
+
+ /* Revert permissions */
+ s->children[i].to_be_replaced = false;
+ bdrv_child_refresh_perms(bs, s->children[i].child, &error_abort);
+
+ if (local_err) {
+ error_free(local_err);
+ return false;
+ }
+
+ return true;
+ }
+ }
+
+ return false;
+}
+
static int quorum_valid_threshold(int threshold, int num_children, Error **errp)
{
@@ -1195,6 +1256,7 @@ static BlockDriver bdrv_quorum = {
.is_filter = true,
.bdrv_recurse_is_first_non_filter = quorum_recurse_is_first_non_filter,
+ .bdrv_recurse_can_replace = quorum_recurse_can_replace,
.strong_runtime_opts = quorum_strong_runtime_opts,
};
--
2.23.0
next prev parent reply other threads:[~2019-11-11 16:06 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-11 16:01 [PATCH for-5.0 v2 00/23] block: Fix check_to_replace_node() Max Reitz
2019-11-11 16:01 ` [PATCH for-5.0 v2 01/23] blockdev: Allow external snapshots everywhere Max Reitz
2019-11-11 16:01 ` [PATCH for-5.0 v2 02/23] blockdev: Allow resizing everywhere Max Reitz
2019-12-06 14:04 ` Alberto Garcia
2019-12-09 13:56 ` Max Reitz
2019-11-11 16:01 ` [PATCH for-5.0 v2 03/23] block: Drop bdrv_is_first_non_filter() Max Reitz
2019-11-11 16:01 ` [PATCH for-5.0 v2 04/23] iotests: Let 041 use -blockdev for quorum children Max Reitz
2019-11-11 16:01 ` [PATCH for-5.0 v2 05/23] quorum: Fix child permissions Max Reitz
2019-11-29 9:14 ` Vladimir Sementsov-Ogievskiy
2019-11-11 16:01 ` [PATCH for-5.0 v2 06/23] block: Add bdrv_recurse_can_replace() Max Reitz
2019-11-29 9:34 ` Vladimir Sementsov-Ogievskiy
2019-11-29 10:23 ` Max Reitz
2019-11-29 11:04 ` Vladimir Sementsov-Ogievskiy
2019-11-11 16:02 ` [PATCH for-5.0 v2 07/23] blkverify: Implement .bdrv_recurse_can_replace() Max Reitz
2019-11-29 9:41 ` Vladimir Sementsov-Ogievskiy
2019-11-11 16:02 ` [PATCH for-5.0 v2 08/23] quorum: Store children in own structure Max Reitz
2019-11-29 9:46 ` Vladimir Sementsov-Ogievskiy
2019-11-11 16:02 ` [PATCH for-5.0 v2 09/23] quorum: Add QuorumChild.to_be_replaced Max Reitz
2019-11-29 9:59 ` Vladimir Sementsov-Ogievskiy
2019-11-11 16:02 ` Max Reitz [this message]
2019-11-29 10:18 ` [PATCH for-5.0 v2 10/23] quorum: Implement .bdrv_recurse_can_replace() Vladimir Sementsov-Ogievskiy
2019-11-29 12:50 ` Max Reitz
2020-02-05 15:55 ` Kevin Wolf
2020-02-05 16:03 ` Kevin Wolf
2020-02-06 10:21 ` Max Reitz
2020-02-06 14:42 ` Kevin Wolf
2020-02-06 15:19 ` Max Reitz
2020-02-06 15:42 ` Kevin Wolf
2020-02-06 16:44 ` Max Reitz
2019-11-11 16:02 ` [PATCH for-5.0 v2 11/23] block: Use bdrv_recurse_can_replace() Max Reitz
2019-11-29 11:07 ` Vladimir Sementsov-Ogievskiy
2020-02-05 15:57 ` Kevin Wolf
2019-11-11 16:02 ` [PATCH for-5.0 v2 12/23] block: Remove bdrv_recurse_is_first_non_filter() Max Reitz
2019-11-11 16:02 ` [PATCH for-5.0 v2 13/23] mirror: Double-check immediately before replacing Max Reitz
2019-11-29 11:18 ` Vladimir Sementsov-Ogievskiy
2019-11-11 16:02 ` [PATCH for-5.0 v2 14/23] quorum: Stop marking it as a filter Max Reitz
2019-11-11 16:02 ` [PATCH for-5.0 v2 15/23] mirror: Prevent loops Max Reitz
2019-11-29 12:01 ` Vladimir Sementsov-Ogievskiy
2019-11-29 13:46 ` Max Reitz
2019-11-29 13:55 ` Vladimir Sementsov-Ogievskiy
2019-11-29 14:17 ` Max Reitz
2019-11-29 14:26 ` Vladimir Sementsov-Ogievskiy
2019-11-29 14:38 ` Max Reitz
2019-12-02 12:12 ` Vladimir Sementsov-Ogievskiy
2019-12-09 14:43 ` Max Reitz
2019-12-13 11:18 ` Vladimir Sementsov-Ogievskiy
2019-12-20 11:39 ` Max Reitz
2019-12-20 11:55 ` Vladimir Sementsov-Ogievskiy
2019-12-20 12:10 ` Max Reitz
2019-11-11 16:02 ` [PATCH for-5.0 v2 16/23] iotests: Use complete_and_wait() in 155 Max Reitz
2019-11-11 16:02 ` [PATCH for-5.0 v2 17/23] iotests: Use skip_if_unsupported decorator in 041 Max Reitz
2019-12-03 12:03 ` Vladimir Sementsov-Ogievskiy
2019-11-11 16:02 ` [PATCH for-5.0 v2 18/23] iotests: Add VM.assert_block_path() Max Reitz
2019-12-03 12:59 ` Vladimir Sementsov-Ogievskiy
2019-12-09 15:10 ` Max Reitz
2019-12-13 11:26 ` Vladimir Sementsov-Ogievskiy
2019-12-13 11:27 ` Vladimir Sementsov-Ogievskiy
2019-12-20 11:42 ` Max Reitz
2019-11-11 16:02 ` [PATCH for-5.0 v2 19/23] iotests: Resolve TODOs in 041 Max Reitz
2019-12-03 13:32 ` Vladimir Sementsov-Ogievskiy
2019-12-03 13:33 ` Vladimir Sementsov-Ogievskiy
2019-12-09 15:15 ` Max Reitz
2019-12-13 11:31 ` Vladimir Sementsov-Ogievskiy
2019-11-11 16:02 ` [PATCH for-5.0 v2 20/23] iotests: Use self.image_len in TestRepairQuorum Max Reitz
2019-11-11 16:02 ` [PATCH for-5.0 v2 21/23] iotests: Add tests for invalid Quorum @replaces Max Reitz
2019-12-03 14:40 ` Vladimir Sementsov-Ogievskiy
2019-11-11 16:02 ` [PATCH for-5.0 v2 22/23] iotests: Check that @replaces can replace filters Max Reitz
2019-12-03 15:58 ` Vladimir Sementsov-Ogievskiy
2019-12-09 15:17 ` Max Reitz
2019-11-11 16:02 ` [PATCH for-5.0 v2 23/23] iotests: Mirror must not attempt to create loops Max Reitz
2019-12-03 17:03 ` Vladimir Sementsov-Ogievskiy
2019-11-29 12:24 ` [PATCH for-5.0 v2 00/23] block: Fix check_to_replace_node() Vladimir Sementsov-Ogievskiy
2019-11-29 12:49 ` Max Reitz
2019-11-29 12:55 ` Vladimir Sementsov-Ogievskiy
2019-11-29 13:08 ` Max Reitz
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