[PATCH v2 10/11] md: add atomic mode switching when I/O completion

[tada keisuke <keisuke1.tada@xxxxxxxxxx>]

This patch depends on patch 09.

If percpu mode in softirq context, switch to atomic mode in delayed execution.
Move from softirq context to a context where RCUs are available and switch to atomic mode.
This patch completes the addition of atomic mode switching.

Signed-off-by: Keisuke TADA <keisuke1.tada@xxxxxxxxxx>
Signed-off-by: Toshifumi OHTAKE <toshifumi.ootake@xxxxxxxxxx>
---
 drivers/md/md.c | 16 ++++++++++++++++
 drivers/md/md.h |  6 ++++++
 2 files changed, 22 insertions(+)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 5f785353353d..18d0f214098b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -9606,6 +9606,7 @@ void md_check_recovery(struct mddev *mddev)
 		return;
 	if ( ! (
 		(mddev->sb_flags & ~ (1<<MD_SB_CHANGE_PENDING)) ||
+		test_bit(MD_RECOVERY_PERCPU, &mddev->recovery) ||
 		test_bit(MD_RECOVERY_NEEDED, &mddev->recovery) ||
 		test_bit(MD_RECOVERY_DONE, &mddev->recovery) ||
 		(mddev->external == 0 && mddev->safemode == 1) ||
@@ -9616,6 +9617,21 @@ void md_check_recovery(struct mddev *mddev)
 
 	if (mddev_trylock(mddev)) {
 		bool try_set_sync = mddev->safemode != 0;
+		struct md_rdev *fault_rdev;
+		bool faulty_some = false;
+
+		rdev_for_each(fault_rdev, mddev) {
+			if (fault_rdev->raid_disk >= 0 &&
+			    test_bit(Faulty, &fault_rdev->flags) &&
+			    nr_pending_is_percpu_mode(fault_rdev)) {
+				percpu_ref_switch_to_atomic_sync(&fault_rdev->nr_pending);
+				faulty_some = true;
+			}
+		}
+		if (faulty_some) {
+			clear_bit(MD_RECOVERY_PERCPU, &mddev->recovery);
+			goto unlock;
+		}
 
 		if (!mddev->external && mddev->safemode == 1)
 			mddev->safemode = 0;
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 57b09b567ffa..a3c0b5e8cf05 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -605,6 +605,7 @@ enum recovery_flags {
 	MD_RECOVERY_FROZEN,	/* User request to abort, and not restart, any action */
 	MD_RECOVERY_ERROR,	/* sync-action interrupted because io-error */
 	MD_RECOVERY_WAIT,	/* waiting for pers->start() to finish */
+	MD_RECOVERY_PERCPU,	/* nr_pending when faulty needs to be switched to atomic */
 	MD_RESYNCING_REMOTE,	/* remote node is running resync thread */
 };
 
@@ -887,6 +888,11 @@ static inline void rdev_dec_pending(struct md_rdev *rdev, struct mddev *mddev)
 	int faulty = test_bit(Faulty, &rdev->flags);
 	nr_pending_dec(rdev);
 	if (faulty) {
+		if (nr_pending_is_percpu_mode(rdev)) {
+			set_bit(MD_RECOVERY_PERCPU, &mddev->recovery);
+			md_wakeup_thread(mddev->thread);
+			return;
+		}
 		if (nr_pending_is_zero(rdev)) {
 			set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
 			md_wakeup_thread(mddev->thread);
-- 
2.34.1