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Trond Myklebust authored
We currently have a deadlock in which the state recovery thread ends up blocking due to one of the locks which it is trying to recover holding the nfs_inode->rwsem. The situation is as follows: the state recovery thread is scheduled in order to recover from a reboot. It immediately drains the session, forcing all ordinary NFSv4.1 calls to nfs41_setup_sequence() to be put to sleep. This includes the file locking process that holds the nfs_inode->rwsem. When the thread gets to nfs4_reclaim_locks(), it tries to grab a write lock on nfs_inode->rwsem, and boom... Fix is to have the lock drop the nfs_inode->rwsem while it is doing RPC calls. We use a sequence lock in order to signal to the locking process whether or not a state recovery thread has run on that inode, in which case it should retry the lock. Reported-by:
Andy Adamson <andros@netapp.com> Signed-off-by:
Trond Myklebust <Trond.Myklebust@netapp.com>
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