When the afs module is removed, one of the things that has to be done is to
purge the cell database. afs_cell_purge() cancels the management timer and
then starts the cell manager work item to do the purging. This does a
single run through and then assumes that all cells are now purged - but
this is no longer the case.
With the introduction of alias detection, a later cell in the database can
now be holding an active count on an earlier cell (cell->alias_of). The
purge scan passes by the earlier cell first, but this can't be got rid of
until it has discarded the alias. Ordinarily, afs_unuse_cell() would
handle this by setting the management timer to trigger another pass - but
afs_set_cell_timer() doesn't do anything if the namespace is being removed
(net->live == false). rmmod then hangs in the wait on cells_outstanding in
afs_cell_purge().
Fix this by making afs_set_cell_timer() directly queue the cell manager if
net->live is false. This causes additional management passes.
Queueing the cell manager increments cells_outstanding to make sure the
wait won't complete until all cells are destroyed.
Fixes: 8a070a9648 ("afs: Detect cell aliases 1 - Cells with root volumes")
Signed-off-by: David Howells <dhowells@redhat.com>
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