Commit 253f9fd4 authored Sep 04, 2015 by Shaohua Li Committed by NeilBrown Nov 01, 2015

raid5-cache: don't delay stripe captured in log



There is a case a stripe gets delayed forever.
1. a stripe finishes construction
2. a new bio hits the stripe
3. handle_stripe runs for the stripe. The stripe gets DELAYED bit set
since construction can't run for new bio (the stripe is locked since
step 1)

Without log, handle_stripe will call ops_run_io. After IO finishes, the
stripe gets unlocked and the stripe will restart and run construction
for the new bio. With log, ops_run_io need to run two times. If the
DELAYED bit set, the stripe can't enter into the handle_list, so the
second ops_run_io doesn't run, which leaves the stripe stalled.

Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: NeilBrown <neilb@suse.com>

parent 85f2f9a4

drivers/md/raid5-cache.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -479,6 +479,11 @@ int r5l_write_stripe(struct r5l_log log, struct stripe_head sh)
		return -EINVAL;

		set_bit(STRIPE_LOG_TRAPPED, &sh->state);
		/*
		* The stripe must enter state machine again to finish the write, so
		* don't delay.
		*/
		clear_bit(STRIPE_DELAYED, &sh->state);
		atomic_inc(&sh->count);

		mutex_lock(&log->io_mutex);

Admin message