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Commit c64e80d5 authored by Jeff Layton's avatar Jeff Layton Committed by J. Bruce Fields
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NLM: don't requeue block if it was invalidated while GRANT_MSG was in flight 



It's possible for lockd to catch a SIGKILL while a GRANT_MSG callback
is in flight. If this happens we don't want lockd to insert the block
back into the nlm_blocked list.

This helps that situation, but there's still a possible race. Fixing
that will mean adding real locking for nlm_blocked.

Signed-off-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
parent 9706501e

fs/lockd/svclock.c

+11 −0
Original line number Diff line number Diff line
@@ -795,6 +795,17 @@ static void nlmsvc_grant_callback(struct rpc_task *task, void *data) 


	dprintk("lockd: GRANT_MSG RPC callback\n");



	/* if the block is not on a list at this point then it has

	 * been invalidated. Don't try to requeue it.

	 *

	 * FIXME: it's possible that the block is removed from the list

	 * after this check but before the nlmsvc_insert_block. In that

	 * case it will be added back. Perhaps we need better locking

	 * for nlm_blocked?

	 */

	if (list_empty(&block->b_list))

		return;



	/* Technically, we should down the file semaphore here. Since we

	 * move the block towards the head of the queue only, no harm

	 * can be done, though. */