md/r5cache: handle sync with data in write back cache
Currently, sync of raid456 array cannot make progress when hitting
data in writeback r5cache.
This patch fixes this issue by flushing cached data of the stripe
before processing the sync request. This is achived by:
1. In handle_stripe(), do not set STRIPE_SYNCING if the stripe is
in write back cache;
2. In r5c_try_caching_write(), handle the stripe in sync with write
through;
3. In do_release_stripe(), make stripe in sync write out and send
it to the state machine.
Shaohua: explictly set STRIPE_HANDLE after write out completed
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Shaohua Li <shli@fb.com>
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 0ac57a9..9c4f765 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -233,11 +233,15 @@
if (test_bit(R5_InJournal, &sh->dev[i].flags))
injournal++;
/*
- * When quiesce in r5c write back, set STRIPE_HANDLE for stripes with
- * data in journal, so they are not released to cached lists
+ * In the following cases, the stripe cannot be released to cached
+ * lists. Therefore, we make the stripe write out and set
+ * STRIPE_HANDLE:
+ * 1. when quiesce in r5c write back;
+ * 2. when resync is requested fot the stripe.
*/
- if (conf->quiesce && r5c_is_writeback(conf->log) &&
- !test_bit(STRIPE_HANDLE, &sh->state) && injournal != 0) {
+ if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) ||
+ (conf->quiesce && r5c_is_writeback(conf->log) &&
+ !test_bit(STRIPE_HANDLE, &sh->state) && injournal != 0)) {
if (test_bit(STRIPE_R5C_CACHING, &sh->state))
r5c_make_stripe_write_out(sh);
set_bit(STRIPE_HANDLE, &sh->state);
@@ -4656,8 +4660,13 @@
if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state) && !sh->batch_head) {
spin_lock(&sh->stripe_lock);
- /* Cannot process 'sync' concurrently with 'discard' */
- if (!test_bit(STRIPE_DISCARD, &sh->state) &&
+ /*
+ * Cannot process 'sync' concurrently with 'discard'.
+ * Flush data in r5cache before 'sync'.
+ */
+ if (!test_bit(STRIPE_R5C_PARTIAL_STRIPE, &sh->state) &&
+ !test_bit(STRIPE_R5C_FULL_STRIPE, &sh->state) &&
+ !test_bit(STRIPE_DISCARD, &sh->state) &&
test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
set_bit(STRIPE_SYNCING, &sh->state);
clear_bit(STRIPE_INSYNC, &sh->state);