NFSv4: Fix deadlock between nfs4_evict_inode() and nfs4_opendata_get_inode()
[ Upstream commit dfe1fe75 ] If the inode is being evicted, but has to return a delegation first, then it can cause a deadlock in the corner case where the server reboots before the delegreturn completes, but while the call to iget5_locked() in nfs4_opendata_get_inode() is waiting for the inode free to complete. Since the open call still holds a session slot, the reboot recovery cannot proceed. In order to break the logjam, we can turn the delegation return into a privileged operation for the case where we're evicting the inode. We know that in that case, there can be no other state recovery operation that conflicts. Reported-by: zhangxiaoxu (A) <zhangxiaoxu5@huawei.com> Fixes: 5fcdfacc ("NFSv4: Return delegations synchronously in evict_inode") Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
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