SUNRPC: Set memalloc_nofs_save() for sync tasks

SUNRPC: Set memalloc_nofs_save() for sync tasks

BugLink: https://bugs.launchpad.net/bugs/1920246
[ Upstream commit f0940f4b3284a00f38a5d42e6067c2aaa20e1f2e ]

We could recurse into NFS doing memory reclaim while sending a sync task,
which might result in a deadlock.  Set memalloc_nofs_save for sync task
execution.

Fixes: a1231fda7e94 ("SUNRPC: Set memalloc_nofs_save() on all rpciod/xprtiod jobs")
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>