Commit 286377f6 authored Oct 15, 2020 by David Howells

afs: Fix cell purging with aliases



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: 8a070a96 ("afs: Detect cell aliases 1 - Cells with root volumes")
Signed-off-by: David Howells <dhowells@redhat.com>

parent 88c853c3

fs/afs/cell.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -19,6 +19,7 @@ static unsigned __read_mostly afs_cell_gc_delay = 10;
		static unsigned __read_mostly afs_cell_min_ttl = 10 * 60;
		static unsigned __read_mostly afs_cell_max_ttl = 24 * 60 * 60;

		static void afs_queue_cell_manager(struct afs_net *);
		static void afs_manage_cell_work(struct work_struct *);

		static void afs_dec_cells_outstanding(struct afs_net *net)
		@@ -37,6 +38,8 @@ static void afs_set_cell_timer(struct afs_net *net, time64_t delay)
		atomic_inc(&net->cells_outstanding);
		if (timer_reduce(&net->cells_timer, jiffies + delay * HZ))
		afs_dec_cells_outstanding(net);
		} else {
		afs_queue_cell_manager(net);
		}
		}

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