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Subject[PATCH 4.14 39/61] md: remove special meaning of ->quiesce(.., 2)
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: NeilBrown <neilb@suse.com>

commit b03e0ccb5ab9df3efbe51c87843a1ffbecbafa1f upstream.

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>
Signed-off-by: Jack Wang <jinpu.wang@profitbricks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/md/md-cluster.c | 6 +++---
drivers/md/md.c | 34 ++++++++++------------------------
drivers/md/md.h | 9 ++++-----
drivers/md/raid0.c | 2 +-
drivers/md/raid1.c | 13 +++----------
drivers/md/raid10.c | 10 +++-------
drivers/md/raid5-cache.c | 12 ++++++------
drivers/md/raid5-log.h | 2 +-
drivers/md/raid5.c | 18 ++++++------------
9 files changed, 37 insertions(+), 69 deletions(-)

--- a/drivers/md/md-cluster.c
+++ b/drivers/md/md-cluster.c
@@ -442,10 +442,11 @@ static void __remove_suspend_info(struct
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
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)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4850,7 +4850,7 @@ suspend_lo_show(struct mddev *mddev, cha
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);
@@ -4866,17 +4866,10 @@ suspend_lo_store(struct mddev *mddev, co
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);
@@ -4894,7 +4887,7 @@ suspend_hi_show(struct mddev *mddev, cha
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);
@@ -4907,20 +4900,13 @@ suspend_hi_store(struct mddev *mddev, co
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);
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -546,12 +546,11 @@ 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.
--- a/drivers/md/raid0.c
+++ b/drivers/md/raid0.c
@@ -768,7 +768,7 @@ static void *raid0_takeover(struct mddev
return ERR_PTR(-EINVAL);
}

-static void raid0_quiesce(struct mddev *mddev, int state)
+static void raid0_quiesce(struct mddev *mddev, int quiesce)
{
}

--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -3276,21 +3276,14 @@ static int raid1_reshape(struct mddev *m
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)
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -3838,18 +3838,14 @@ static void raid10_free(struct mddev *md
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)
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -1589,21 +1589,21 @@ void r5l_wake_reclaim(struct r5l_log *lo
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)
--- a/drivers/md/raid5-log.h
+++ b/drivers/md/raid5-log.h
@@ -9,7 +9,7 @@ extern void r5l_write_stripe_run(struct
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
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -8003,16 +8003,12 @@ static void raid5_finish_reshape(struct
}
}

-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
@@ -8028,17 +8024,15 @@ static void raid5_quiesce(struct mddev *
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)

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