From: Lukas Straub <lukasstraub2@web.de>
To: qemu-devel <qemu-devel@nongnu.org>
Cc: Kevin Wolf <kwolf@redhat.com>,
Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>,
qemu-block <qemu-block@nongnu.org>,
Wen Congyang <wencongyang2@huawei.com>,
Xie Changlong <xiechanglong.d@gmail.com>,
Max Reitz <mreitz@redhat.com>
Subject: [PATCH v6 3/4] replication: Properly attach children
Date: Sun, 18 Jul 2021 16:48:33 +0200 [thread overview]
Message-ID: <5d0539d729afb8072d0d7cde977c5066285591b4.1626619393.git.lukasstraub2@web.de> (raw)
In-Reply-To: <cover.1626619393.git.lukasstraub2@web.de>
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The replication driver needs access to the children block-nodes of
it's child so it can issue bdrv_make_empty() and bdrv_co_pwritev()
to manage the replication. However, it does this by directly copying
the BdrvChilds, which is wrong.
Fix this by properly attaching the block-nodes with
bdrv_attach_child() and requesting the required permissions.
This ultimatively fixes a potential crash in replication_co_writev(),
because it may write to s->secondary_disk if it is in state
BLOCK_REPLICATION_FAILOVER_FAILED, without requesting write
permissions first. And now the workaround in
secondary_do_checkpoint() can be removed.
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
block/replication.c | 30 +++++++++++++++++++++++++++---
1 file changed, 27 insertions(+), 3 deletions(-)
diff --git a/block/replication.c b/block/replication.c
index 25bbdf5d4b..b74192f795 100644
--- a/block/replication.c
+++ b/block/replication.c
@@ -165,7 +165,12 @@ static void replication_child_perm(BlockDriverState *bs, BdrvChild *c,
uint64_t perm, uint64_t shared,
uint64_t *nperm, uint64_t *nshared)
{
- *nperm = BLK_PERM_CONSISTENT_READ;
+ if (role & BDRV_CHILD_PRIMARY) {
+ *nperm = BLK_PERM_CONSISTENT_READ;
+ } else {
+ *nperm = 0;
+ }
+
if ((bs->open_flags & (BDRV_O_INACTIVE | BDRV_O_RDWR)) == BDRV_O_RDWR) {
*nperm |= BLK_PERM_WRITE;
}
@@ -557,8 +562,25 @@ static void replication_start(ReplicationState *rs, ReplicationMode mode,
return;
}
- s->hidden_disk = hidden_disk;
- s->secondary_disk = secondary_disk;
+ bdrv_ref(hidden_disk->bs);
+ s->hidden_disk = bdrv_attach_child(bs, hidden_disk->bs, "hidden disk",
+ &child_of_bds, BDRV_CHILD_DATA,
+ &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ aio_context_release(aio_context);
+ return;
+ }
+
+ bdrv_ref(secondary_disk->bs);
+ s->secondary_disk = bdrv_attach_child(bs, secondary_disk->bs,
+ "secondary disk", &child_of_bds,
+ BDRV_CHILD_DATA, &local_err);
+ if (local_err) {
+ error_propagate(errp, local_err);
+ aio_context_release(aio_context);
+ return;
+ }
/* start backup job now */
error_setg(&s->blocker,
@@ -664,7 +686,9 @@ static void replication_done(void *opaque, int ret)
if (ret == 0) {
s->stage = BLOCK_REPLICATION_DONE;
+ bdrv_unref_child(bs, s->secondary_disk);
s->secondary_disk = NULL;
+ bdrv_unref_child(bs, s->hidden_disk);
s->hidden_disk = NULL;
s->error = 0;
} else {
--
2.20.1
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next prev parent reply other threads:[~2021-07-18 14:52 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-18 14:48 [PATCH v6 0/4] replication: Bugfix and properly attach children Lukas Straub
2021-07-18 14:48 ` [PATCH v6 1/4] replication: Remove s->active_disk Lukas Straub
2021-07-19 2:26 ` Zhang, Chen
2021-07-18 14:48 ` [PATCH v6 2/4] replication: Reduce usage of s->hidden_disk and s->secondary_disk Lukas Straub
2021-07-18 14:48 ` Lukas Straub [this message]
2021-07-18 14:48 ` [PATCH v6 4/4] replication: Remove workaround Lukas Straub
2021-07-20 14:25 ` [PATCH v6 0/4] replication: Bugfix and properly attach children Kevin Wolf
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