Since we have switched to sync way to handle METADATA_UPDATED
msg for md-cluster, then process_metadata_update is depended
on mddev->thread->wqueue.
With the new change, clustered raid could possible hang if
array received a METADATA_UPDATED msg after array unregistered
mddev->thread, so we need to stop clustered raid (bitmap_destroy
-> bitmap_free -> md_cluster_stop) earlier than unregister
thread (mddev_detach -> md_unregister_thread).
And this change should be safe for non-clustered raid since
all writes are stopped before the destroy. Also in md_run,
we activate the personality (pers->run()) before activating
the bitmap (bitmap_create()). So it is pleasingly symmetric
to stop the bitmap (bitmap_destroy()) before stopping the
personality (__md_stop() calls pers->free()), we achieve this
by move bitmap_destroy to the beginning of __md_stop.
But we don't want to break the codes for waiting behind IO as
Shaohua mentioned, so introduce bitmap_wait_behind_writes to
call the codes, and call the new fun in both mddev_detach and
bitmap_destroy, then we will not break original behind IO code
and also fit the new condition well.
Signed-off-by: Guoqing Jiang <gqjiang@xxxxxxxx>
---
Changes from v3:
1. move bitmap_destroy to __md_stop
2. add bitmap_wait_behind_writes to handle behind IO
drivers/md/bitmap.c | 17 +++++++++++++++++
drivers/md/bitmap.h | 1 +
drivers/md/md.c | 13 ++-----------
3 files changed, 20 insertions(+), 11 deletions(-)
diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index b6fa55a3cff8..20cad80d6e34 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -1764,6 +1764,21 @@ void bitmap_free(struct bitmap *bitmap)
}
EXPORT_SYMBOL(bitmap_free);
+void bitmap_wait_behind_writes(struct mddev *mddev)
+{
+ struct bitmap *bitmap = mddev->bitmap;
+
+ /* wait for behind writes to complete */
+ if (bitmap && atomic_read(&bitmap->behind_writes) > 0) {
+ pr_debug("md:%s: behind writes in progress - waiting to stop.\n",
+ mdname(mddev));
+ /* need to kick something here to make sure I/O goes? */
+ wait_event(bitmap->behind_wait,
+ atomic_read(&bitmap->behind_writes) == 0);
+ }
+}
+EXPORT_SYMBOL(bitmap_wait_behind_writes);
+
void bitmap_destroy(struct mddev *mddev)
{
struct bitmap *bitmap = mddev->bitmap;
@@ -1771,6 +1786,8 @@ void bitmap_destroy(struct mddev *mddev)
if (!bitmap) /* there was no bitmap */
return;
+ bitmap_wait_behind_writes(mddev);
+
mutex_lock(&mddev->bitmap_info.mutex);
spin_lock(&mddev->lock);
mddev->bitmap = NULL; /* disconnect from the md device */
diff --git a/drivers/md/bitmap.h b/drivers/md/bitmap.h
index 9f761097aab2..d15721ac07a6 100644
--- a/drivers/md/bitmap.h
+++ b/drivers/md/bitmap.h
@@ -271,6 +271,7 @@ struct bitmap *get_bitmap_from_slot(struct mddev *mddev, int slot);
int bitmap_copy_from_slot(struct mddev *mddev, int slot,
sector_t *lo, sector_t *hi, bool clear_bits);
void bitmap_free(struct bitmap *bitmap);
+void bitmap_wait_behind_writes(struct mddev *mddev);
#endif
#endif
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 79a99a1c9ce7..dc131fabfc7c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5534,15 +5534,7 @@ EXPORT_SYMBOL_GPL(md_stop_writes);
static void mddev_detach(struct mddev *mddev)
{
- struct bitmap *bitmap = mddev->bitmap;
- /* wait for behind writes to complete */
- if (bitmap && atomic_read(&bitmap->behind_writes) > 0) {
- pr_debug("md:%s: behind writes in progress - waiting to stop.\n",
- mdname(mddev));
- /* need to kick something here to make sure I/O goes? */
- wait_event(bitmap->behind_wait,
- atomic_read(&bitmap->behind_writes) == 0);
- }
+ bitmap_wait_behind_writes(mddev);
if (mddev->pers && mddev->pers->quiesce) {
mddev->pers->quiesce(mddev, 1);
mddev->pers->quiesce(mddev, 0);
@@ -5555,6 +5547,7 @@ static void mddev_detach(struct mddev *mddev)
static void __md_stop(struct mddev *mddev)
{
struct md_personality *pers = mddev->pers;
+ bitmap_destroy(mddev);
mddev_detach(mddev);
/* Ensure ->event_work is done */
flush_workqueue(md_misc_wq);
@@ -5575,7 +5568,6 @@ void md_stop(struct mddev *mddev)
* This is called from dm-raid
*/
__md_stop(mddev);
- bitmap_destroy(mddev);
if (mddev->bio_set)
bioset_free(mddev->bio_set);
}
@@ -5713,7 +5705,6 @@ static int do_md_stop(struct mddev *mddev, int mode,
if (mode == 0) {
pr_info("md: %s stopped.\n", mdname(mddev));
- bitmap_destroy(mddev);
if (mddev->bitmap_info.file) {
struct file *f = mddev->bitmap_info.file;
spin_lock(&mddev->lock);
--
2.6.2
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