Before switching between AioContexts we need to make sure that we're
fully quiesced ("nb_requests == 0" for every client) when entering the
drained section. Otherwise, coroutines may be run in the wrong context
after the switch, leading to a number of critical issues.To accomplish this, we add ".drained_poll" to BlockDevOps and use it in the NBD server, along with ".drained_being" and "drained_end", to coordinate the quiescing of the server while entering a drained section. Sergio Lopez (2): block-backend: add drained_poll nbd/server: Use drained block ops to quiesce the server block/block-backend.c | 7 ++- include/sysemu/block-backend.h | 4 ++ nbd/server.c | 99 +++++++++++++++++++++++++--------- 3 files changed, 85 insertions(+), 25 deletions(-) -- 2.26.2
