md: remove special meaning of ->quiesce(.., 2)

The '2' argument means "wake up anything that is waiting".
This is an inelegant part of the design and was added
to help support management of suspend_lo/suspend_hi setting.
Now that suspend_lo/hi is managed in mddev_suspend/resume,
that need is gone.
These is still a couple of places where we call 'quiesce'
with an argument of '2', but they can safely be changed to
call ->quiesce(.., 1); ->quiesce(.., 0) which
achieve the same result at the small cost of pausing IO
briefly.

This removes a small "optimization" from suspend_{hi,lo}_store,
but it isn't clear that optimization served a useful purpose.
The code now is a lot clearer.

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

9 files changed, 37 insertions, 69 deletions

diff --git a/drivers/md/md-cluster.c b/drivers/md/md-cluster.c
index bc81ecc24c96..d0fd1bd8575c 100644
--- a/drivers/md/md-cluster.c
+++ b/drivers/md/md-cluster.c
@@ -442,10 +442,11 @@ static void __remove_suspend_info(struct md_cluster_info *cinfo, int slot)
 static void remove_suspend_info(struct mddev *mddev, int slot)
 {
         struct md_cluster_info *cinfo = mddev->cluster_info;
+        mddev->pers->quiesce(mddev, 1);
         spin_lock_irq(&cinfo->suspend_lock);
         __remove_suspend_info(cinfo, slot);
         spin_unlock_irq(&cinfo->suspend_lock);
-        mddev->pers->quiesce(mddev, 2);
+        mddev->pers->quiesce(mddev, 0);
 }
 
 
@@ -492,13 +493,12 @@ static void process_suspend_info(struct mddev *mddev,
         s->lo = lo;
         s->hi = hi;
         mddev->pers->quiesce(mddev, 1);
-        mddev->pers->quiesce(mddev, 0);
         spin_lock_irq(&cinfo->suspend_lock);
         /* Remove existing entry (if exists) before adding */
         __remove_suspend_info(cinfo, slot);
         list_add(&s->list, &cinfo->suspend_list);
         spin_unlock_irq(&cinfo->suspend_lock);
-        mddev->pers->quiesce(mddev, 2);
+        mddev->pers->quiesce(mddev, 0);
 }
 
 static void process_add_new_disk(struct mddev *mddev, struct cluster_msg *cmsg)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 9155f00dca20..d441b1d9846c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4846,7 +4846,7 @@ suspend_lo_show(struct mddev *mddev, char *page)
 static ssize_t
 suspend_lo_store(struct mddev *mddev, const char *buf, size_t len)
 {
-        unsigned long long old, new;
+        unsigned long long new;
         int err;
 
         err = kstrtoull(buf, 10, &new);
@@ -4862,17 +4862,10 @@ suspend_lo_store(struct mddev *mddev, const char *buf, size_t len)
         if (mddev->pers == NULL ||
             mddev->pers->quiesce == NULL)
                 goto unlock;
-        old = mddev->suspend_lo;
+        mddev_suspend(mddev);
         mddev->suspend_lo = new;
-        if (new >= old) {
-                /* Shrinking suspended region */
-                wake_up(&mddev->sb_wait);
-                mddev->pers->quiesce(mddev, 2);
-        } else {
-                /* Expanding suspended region - need to wait */
-                mddev_suspend(mddev);
-                mddev_resume(mddev);
-        }
+        mddev_resume(mddev);
+
         err = 0;
 unlock:
         mddev_unlock(mddev);
@@ -4890,7 +4883,7 @@ suspend_hi_show(struct mddev *mddev, char *page)
 static ssize_t
 suspend_hi_store(struct mddev *mddev, const char *buf, size_t len)
 {
-        unsigned long long old, new;
+        unsigned long long new;
         int err;
 
         err = kstrtoull(buf, 10, &new);
@@ -4903,20 +4896,13 @@ suspend_hi_store(struct mddev *mddev, const char *buf, size_t len)
         if (err)
                 return err;
         err = -EINVAL;
-        if (mddev->pers == NULL ||
-            mddev->pers->quiesce == NULL)
+        if (mddev->pers == NULL)
                 goto unlock;
-        old = mddev->suspend_hi;
+
+        mddev_suspend(mddev);
         mddev->suspend_hi = new;
-        if (new <= old) {
-                /* Shrinking suspended region */
-                wake_up(&mddev->sb_wait);
-                mddev->pers->quiesce(mddev, 2);
-        } else {
-                /* Expanding suspended region - need to wait */
-                mddev_suspend(mddev);
-                mddev_resume(mddev);
-        }
+        mddev_resume(mddev);
+
         err = 0;
 unlock:
         mddev_unlock(mddev);
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 03fc641e5da1..998b4ce1498f 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -544,12 +544,11 @@ struct md_personality
         int (*check_reshape) (struct mddev *mddev);
         int (*start_reshape) (struct mddev *mddev);
         void (*finish_reshape) (struct mddev *mddev);
-        /* quiesce moves between quiescence states
-         * 0 - fully active
-         * 1 - no new requests allowed
-         * others - reserved
+        /* quiesce suspends or resumes internal processing.
+         * 1 - stop new actions and wait for action io to complete
+         * 0 - return to normal behaviour
          */
-        void (*quiesce) (struct mddev *mddev, int state);
+        void (*quiesce) (struct mddev *mddev, int quiesce);
         /* takeover is used to transition an array from one
          * personality to another.  The new personality must be able
          * to handle the data in the current layout.
diff --git a/drivers/md/raid0.c b/drivers/md/raid0.c
index 5a00fc118470..5ecba9eef441 100644
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -768,7 +768,7 @@ static void *raid0_takeover(struct mddev *mddev)
         return ERR_PTR(-EINVAL);
 }
 
-static void raid0_quiesce(struct mddev *mddev, int state)
+static void raid0_quiesce(struct mddev *mddev, int quiesce)
 {
 }
 
diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index fb56ef79a1c3..9428dfa7e9a0 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -3273,21 +3273,14 @@ static int raid1_reshape(struct mddev *mddev)
         return 0;
 }
 
-static void raid1_quiesce(struct mddev *mddev, int state)
+static void raid1_quiesce(struct mddev *mddev, int quiesce)
 {
         struct r1conf *conf = mddev->private;
 
-        switch(state) {
-        case 2: /* wake for suspend */
-                wake_up(&conf->wait_barrier);
-                break;
-        case 1:
+        if (quiesce)
                 freeze_array(conf, 0);
-                break;
-        case 0:
+        else
                 unfreeze_array(conf);
-                break;
-        }
 }
 
 static void *raid1_takeover(struct mddev *mddev)
diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index b0de5b5ee689..615f677ceb1a 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3828,18 +3828,14 @@ static void raid10_free(struct mddev *mddev, void *priv)
         kfree(conf);
 }
 
-static void raid10_quiesce(struct mddev *mddev, int state)
+static void raid10_quiesce(struct mddev *mddev, int quiesce)
 {
         struct r10conf *conf = mddev->private;
 
-        switch(state) {
-        case 1:
+        if (quiesce)
                 raise_barrier(conf, 0);
-                break;
-        case 0:
+        else
                 lower_barrier(conf);
-                break;
-        }
 }
 
 static int raid10_resize(struct mddev *mddev, sector_t sectors)
diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 59af7cf35092..037ed274807f 100644
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -1589,21 +1589,21 @@ void r5l_wake_reclaim(struct r5l_log *log, sector_t space)
         md_wakeup_thread(log->reclaim_thread);
 }
 
-void r5l_quiesce(struct r5l_log *log, int state)
+void r5l_quiesce(struct r5l_log *log, int quiesce)
 {
         struct mddev *mddev;
-        if (!log || state == 2)
+        if (!log)
                 return;
-        if (state == 0)
-                kthread_unpark(log->reclaim_thread->tsk);
-        else if (state == 1) {
+
+        if (quiesce) {
                 /* make sure r5l_write_super_and_discard_space exits */
                 mddev = log->rdev->mddev;
                 wake_up(&mddev->sb_wait);
                 kthread_park(log->reclaim_thread->tsk);
                 r5l_wake_reclaim(log, MaxSector);
                 r5l_do_reclaim(log);
-        }
+        } else
+                kthread_unpark(log->reclaim_thread->tsk);
 }
 
 bool r5l_log_disk_error(struct r5conf *conf)
diff --git a/drivers/md/raid5-log.h b/drivers/md/raid5-log.h
index 328d67aedda4..c3596a27a5a8 100644
--- a/drivers/md/raid5-log.h
+++ b/drivers/md/raid5-log.h
@@ -8,7 +8,7 @@ extern void r5l_write_stripe_run(struct r5l_log *log);
 extern void r5l_flush_stripe_to_raid(struct r5l_log *log);
 extern void r5l_stripe_write_finished(struct stripe_head *sh);
 extern int r5l_handle_flush_request(struct r5l_log *log, struct bio *bio);
-extern void r5l_quiesce(struct r5l_log *log, int state);
+extern void r5l_quiesce(struct r5l_log *log, int quiesce);
 extern bool r5l_log_disk_error(struct r5conf *conf);
 extern bool r5c_is_writeback(struct r5l_log *log);
 extern int
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 354a969f50a6..17ffa1e44c84 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -8008,16 +8008,12 @@ static void raid5_finish_reshape(struct mddev *mddev)
         }
 }
 
-static void raid5_quiesce(struct mddev *mddev, int state)
+static void raid5_quiesce(struct mddev *mddev, int quiesce)
 {
         struct r5conf *conf = mddev->private;
 
-        switch(state) {
-        case 2: /* resume for a suspend */
-                wake_up(&conf->wait_for_overlap);
-                break;
-
-        case 1: /* stop all writes */
+        if (quiesce) {
+                /* stop all writes */
                 lock_all_device_hash_locks_irq(conf);
                 /* '2' tells resync/reshape to pause so that all
                  * active stripes can drain
@@ -8033,17 +8029,15 @@ static void raid5_quiesce(struct mddev *mddev, int state)
                 unlock_all_device_hash_locks_irq(conf);
                 /* allow reshape to continue */
                 wake_up(&conf->wait_for_overlap);
-                break;
-
-        case 0: /* re-enable writes */
+        } else {
+                /* re-enable writes */
                 lock_all_device_hash_locks_irq(conf);
                 conf->quiesce = 0;
                 wake_up(&conf->wait_for_quiescent);
                 wake_up(&conf->wait_for_overlap);
                 unlock_all_device_hash_locks_irq(conf);
-                break;
         }
-        r5l_quiesce(conf->log, state);
+        r5l_quiesce(conf->log, quiesce);
 }
 
 static void *raid45_takeover_raid0(struct mddev *mddev, int level)