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block: Convert bdrv_is_inserted() to co_wrapper

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bdrv_is_inserted() is categorized as an I/O function, and it currently
doesn't run in a coroutine. We should let it take a graph rdlock since
it traverses the block nodes graph, which however is only possible in a
coroutine.

Therefore turn it into a co_wrapper to move the actual function into a
coroutine where the lock can be taken.

At the same time, add also blk_is_inserted as co_wrapper_mixed, since it
is called in both coroutine and non-coroutine contexts.

Because now this function creates a new coroutine and polls, we need to
take the AioContext lock where it is missing, for the only reason that
internally c_w_mixed_bdrv_rdlock calls AIO_WAIT_WHILE and it expects to
release the AioContext lock. Once the rwlock is ultimated and placed in
every place it needs to be, we will poll using AIO_WAIT_WHILE_UNLOCKED
and remove the AioContext lock.

Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-Id: <20230113204212.359076-5-kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Emanuele Giuseppe Esposito
2023-01-13 21:42:02 +01:00
committed by Kevin Wolf
parent 09d9fc97f8
commit 1e97be9156
8 changed files with 32 additions and 20 deletions
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8
blockdev.c
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@ -1024,6 +1024,7 @@ fail:
static BlockDriverState *qmp_get_root_bs(const char *name, Error **errp)
{
BlockDriverState *bs;
AioContext *aio_context;
bs = bdrv_lookup_bs(name, name, errp);
if (bs == NULL) {
@ -1035,11 +1036,16 @@ static BlockDriverState *qmp_get_root_bs(const char *name, Error **errp)
return NULL;
}
aio_context = bdrv_get_aio_context(bs);
aio_context_acquire(aio_context);
if (!bdrv_is_inserted(bs)) {
error_setg(errp, "Device has no medium");
return NULL;
bs = NULL;
}
aio_context_release(aio_context);
return bs;
}