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linux-aio: properly bubble up errors from initialization

Browse source 
laio_init() can fail for a couple of reasons, which will lead to a NULL
pointer dereference in laio_attach_aio_context().

To solve this, add a aio_setup_linux_aio() function which is called
early in raw_open_common. If this fails, propagate the error up. The
signature of aio_get_linux_aio() was not modified, because it seems
preferable to return the actual errno from the possible failing
initialization calls.

Additionally, when the AioContext changes, we need to associate a
LinuxAioState with the new AioContext. Use the bdrv_attach_aio_context
callback and call the new aio_setup_linux_aio(), which will allocate a
new AioContext if needed, and return errors on failures. If it fails for
any reason, fallback to threaded AIO with an error message, as the
device is already in-use by the guest.

Add an assert that aio_get_linux_aio() cannot return NULL.

Signed-off-by: Nishanth Aravamudan <naravamudan@digitalocean.com>
Message-id: 20180622193700.6523-1-naravamudan@digitalocean.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Nishanth Aravamudan 2018-06-22 12:37:00 -07:00 • committed by Stefan Hajnoczi
parent f18793b096
commit ed6e216171
6 changed files with 53 additions and 13 deletions
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14
util/async.c
View file

@ -323,14 +323,22 @@ ThreadPool *aio_get_thread_pool(AioContext *ctx)
}
#ifdef CONFIG_LINUX_AIO
LinuxAioState *aio_get_linux_aio(AioContext *ctx)
LinuxAioState *aio_setup_linux_aio(AioContext *ctx, Error **errp)
{
if (!ctx->linux_aio) {
ctx->linux_aio = laio_init();
laio_attach_aio_context(ctx->linux_aio, ctx);
ctx->linux_aio = laio_init(errp);
if (ctx->linux_aio) {
laio_attach_aio_context(ctx->linux_aio, ctx);
}
}
return ctx->linux_aio;
}
LinuxAioState *aio_get_linux_aio(AioContext *ctx)
{
assert(ctx->linux_aio);
return ctx->linux_aio;
}
#endif
void aio_notify(AioContext *ctx)