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block/export: stop using is_external in vhost-user-blk server

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vhost-user activity must be suspended during bdrv_drained_begin/end().
This prevents new requests from interfering with whatever is happening
in the drained section.

Previously this was done using aio_set_fd_handler()'s is_external
argument. In a multi-queue block layer world the aio_disable_external()
API cannot be used since multiple AioContext may be processing I/O, not
just one.

Switch to BlockDevOps->drained_begin/end() callbacks.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230516190238.8401-8-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2023-05-16 15:02:25 -04:00 • committed by Kevin Wolf
parent 8f5e9a8ee1
commit e1054cd4aa
2 changed files with 31 additions and 7 deletions
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28
block/export/vhost-user-blk-server.c
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@ -212,15 +212,21 @@ static void blk_aio_attached(AioContext *ctx, void *opaque)
{
VuBlkExport *vexp = opaque;
/*
* The actual attach will happen in vu_blk_drained_end() and we just
* restore ctx here.
*/
vexp->export.ctx = ctx;
vhost_user_server_attach_aio_context(&vexp->vu_server, ctx);
}
static void blk_aio_detach(void *opaque)
{
VuBlkExport *vexp = opaque;
vhost_user_server_detach_aio_context(&vexp->vu_server);
/*
* The actual detach already happened in vu_blk_drained_begin() but from
* this point on we must not access ctx anymore.
*/
vexp->export.ctx = NULL;
}
@ -272,6 +278,22 @@ static void vu_blk_exp_resize(void *opaque)
vu_config_change_msg(&vexp->vu_server.vu_dev);
}
/* Called with vexp->export.ctx acquired */
static void vu_blk_drained_begin(void *opaque)
{
VuBlkExport *vexp = opaque;
vhost_user_server_detach_aio_context(&vexp->vu_server);
}
/* Called with vexp->export.blk AioContext acquired */
static void vu_blk_drained_end(void *opaque)
{
VuBlkExport *vexp = opaque;
vhost_user_server_attach_aio_context(&vexp->vu_server, vexp->export.ctx);
}
/*
* Ensures that bdrv_drained_begin() waits until in-flight requests complete.
*
@ -285,6 +307,8 @@ static bool vu_blk_drained_poll(void *opaque)
}
static const BlockDevOps vu_blk_dev_ops = {
.drained_begin = vu_blk_drained_begin,
.drained_end = vu_blk_drained_end,
.drained_poll = vu_blk_drained_poll,
.resize_cb = vu_blk_exp_resize,
};