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![Vivek Goyal](https://secure.gravatar.com/avatar/cfad562b71aa70b8bfc25867b5d55cfa.jpg?s=96&d=mm)
Vivek Goyal committed 2b5e027657d
virtiofs: schedule blocking async replies in separate worker [ Upstream commit bb737bbe48bea9854455cb61ea1dc06e92ce586c ] In virtiofs (unlike in regular fuse) processing of async replies is serialized. This can result in a deadlock in rare corner cases when there's a circular dependency between the completion of two or more async replies. Such a deadlock can be reproduced with xfstests:generic/503 if TEST_DIR == SCRATCH_MNT (which is a misconfiguration): - Process A is waiting for page lock in worker thread context and blocked (virtio_fs_requests_done_work()). - Process B is holding page lock and waiting for pending writes to finish (fuse_wait_on_page_writeback()). - Write requests are waiting in virtqueue and can't complete because worker thread is blocked on page lock (process A). Fix this by creating a unique work_struct for each async reply that can block (O_DIRECT read). Fixes: a62a8ef9d97d ("virtio-fs: add virtiofs filesystem") Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>