From 1e0582ad34e77a060e2067a35992979c9eae82c9 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Fri, 13 Mar 2020 12:34:31 +0000 Subject: [PATCH 11/20] block: bdrv_reopen() with backing file in different AioContext RH-Author: Kevin Wolf Message-id: <20200313123439.10548-6-kwolf@redhat.com> Patchwork-id: 94282 O-Subject: [RHEL-AV-8.2.0 qemu-kvm PATCH v2 05/13] block: bdrv_reopen() with backing file in different AioContext Bugzilla: 1790482 1805143 RH-Acked-by: John Snow RH-Acked-by: Daniel P. Berrange RH-Acked-by: Peter Krempa This patch allows bdrv_reopen() (and therefore the x-blockdev-reopen QMP command) to attach a node as the new backing file even if the node is in a different AioContext than the parent if one of both nodes can be moved to the AioContext of the other node. Signed-off-by: Kevin Wolf Tested-by: Peter Krempa Message-Id: <20200306141413.30705-3-kwolf@redhat.com> Reviewed-by: Alberto Garcia Signed-off-by: Kevin Wolf (cherry picked from commit 1de6b45fb5c1489b450df7d1a4c692bba9678ce6) Signed-off-by: Kevin Wolf Signed-off-by: Danilo C. L. de Paula --- block.c | 32 ++++++++++++++++++++++++++------ tests/qemu-iotests/245 | 8 +++----- 2 files changed, 29 insertions(+), 11 deletions(-) diff --git a/block.c b/block.c index a744bb5..39e4647 100644 --- a/block.c +++ b/block.c @@ -3749,6 +3749,29 @@ static void bdrv_reopen_perm(BlockReopenQueue *q, BlockDriverState *bs, *shared = cumulative_shared_perms; } +static bool bdrv_reopen_can_attach(BlockDriverState *parent, + BdrvChild *child, + BlockDriverState *new_child, + Error **errp) +{ + AioContext *parent_ctx = bdrv_get_aio_context(parent); + AioContext *child_ctx = bdrv_get_aio_context(new_child); + GSList *ignore; + bool ret; + + ignore = g_slist_prepend(NULL, child); + ret = bdrv_can_set_aio_context(new_child, parent_ctx, &ignore, NULL); + g_slist_free(ignore); + if (ret) { + return ret; + } + + ignore = g_slist_prepend(NULL, child); + ret = bdrv_can_set_aio_context(parent, child_ctx, &ignore, errp); + g_slist_free(ignore); + return ret; +} + /* * Take a BDRVReopenState and check if the value of 'backing' in the * reopen_state->options QDict is valid or not. @@ -3800,14 +3823,11 @@ static int bdrv_reopen_parse_backing(BDRVReopenState *reopen_state, } /* - * TODO: before removing the x- prefix from x-blockdev-reopen we - * should move the new backing file into the right AioContext - * instead of returning an error. + * Check AioContext compatibility so that the bdrv_set_backing_hd() call in + * bdrv_reopen_commit() won't fail. */ if (new_backing_bs) { - if (bdrv_get_aio_context(new_backing_bs) != bdrv_get_aio_context(bs)) { - error_setg(errp, "Cannot use a new backing file " - "with a different AioContext"); + if (!bdrv_reopen_can_attach(bs, bs->backing, new_backing_bs, errp)) { return -EINVAL; } } diff --git a/tests/qemu-iotests/245 b/tests/qemu-iotests/245 index f69c2fa..919131d 100644 --- a/tests/qemu-iotests/245 +++ b/tests/qemu-iotests/245 @@ -1013,18 +1013,16 @@ class TestBlockdevReopen(iotests.QMPTestCase): # neither of them can switch to the other AioContext def test_iothreads_error(self): self.run_test_iothreads('iothread0', 'iothread1', - "Cannot use a new backing file with a different AioContext") + "Cannot change iothread of active block backend") def test_iothreads_compatible_users(self): self.run_test_iothreads('iothread0', 'iothread0') def test_iothreads_switch_backing(self): - self.run_test_iothreads('iothread0', None, - "Cannot use a new backing file with a different AioContext") + self.run_test_iothreads('iothread0', None) def test_iothreads_switch_overlay(self): - self.run_test_iothreads(None, 'iothread0', - "Cannot use a new backing file with a different AioContext") + self.run_test_iothreads(None, 'iothread0') if __name__ == '__main__': iotests.main(supported_fmts=["qcow2"], -- 1.8.3.1