md/raid5: avoid deadlock when raid5 array has unack badblocks during md_stop_writes.
When raid5 recovery hits a fresh badblock, this badblock will flagged as unack
badblock until md_update_sb() is called.
But md_stop will take reconfig lock which means raid5d can't call
md_update_sb() in md_check_recovery(), the badblock will always
be unack, so raid5d thread enters an infinite loop and md_stop_write()
can never stop sync_thread. This causes deadlock.
To solve this, when STOP_ARRAY ioctl is issued and sync_thread is
running, we need set md->recovery FROZEN and INTR flags and wait for
sync_thread to stop before we (re)take reconfig lock.
This requires that raid5 reshape_request notices MD_RECOVERY_INTR
(which it probably should have noticed anyway) and stops waiting for a
metadata update in that case.
Reported-by: Jianpeng Ma <majianpeng@gmail.com>
Reported-by: Bian Yu <bianyu@kedacom.com>
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index a74045d..47e7bc7 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5340,20 +5340,35 @@
static int md_set_readonly(struct mddev *mddev, struct block_device *bdev)
{
int err = 0;
+ int did_freeze = 0;
+
+ if (!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery)) {
+ did_freeze = 1;
+ set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+ md_wakeup_thread(mddev->thread);
+ }
+ if (mddev->sync_thread) {
+ set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+ /* Thread might be blocked waiting for metadata update
+ * which will now never happen */
+ wake_up_process(mddev->sync_thread->tsk);
+ }
+ mddev_unlock(mddev);
+ wait_event(resync_wait, mddev->sync_thread == NULL);
+ mddev_lock_nointr(mddev);
+
mutex_lock(&mddev->open_mutex);
- if (atomic_read(&mddev->openers) > !!bdev) {
+ if (atomic_read(&mddev->openers) > !!bdev ||
+ mddev->sync_thread ||
+ (bdev && !test_bit(MD_STILL_CLOSED, &mddev->flags))) {
printk("md: %s still in use.\n",mdname(mddev));
+ if (did_freeze) {
+ clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+ md_wakeup_thread(mddev->thread);
+ }
err = -EBUSY;
goto out;
}
- if (bdev && !test_bit(MD_STILL_CLOSED, &mddev->flags)) {
- /* Someone opened the device since we flushed it
- * so page cache could be dirty and it is too late
- * to flush. So abort
- */
- mutex_unlock(&mddev->open_mutex);
- return -EBUSY;
- }
if (mddev->pers) {
__md_stop_writes(mddev);
@@ -5364,7 +5379,7 @@
set_disk_ro(mddev->gendisk, 1);
clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
sysfs_notify_dirent_safe(mddev->sysfs_state);
- err = 0;
+ err = 0;
}
out:
mutex_unlock(&mddev->open_mutex);
@@ -5380,20 +5395,34 @@
{
struct gendisk *disk = mddev->gendisk;
struct md_rdev *rdev;
+ int did_freeze = 0;
+
+ if (!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery)) {
+ did_freeze = 1;
+ set_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+ md_wakeup_thread(mddev->thread);
+ }
+ if (mddev->sync_thread) {
+ set_bit(MD_RECOVERY_INTR, &mddev->recovery);
+ /* Thread might be blocked waiting for metadata update
+ * which will now never happen */
+ wake_up_process(mddev->sync_thread->tsk);
+ }
+ mddev_unlock(mddev);
+ wait_event(resync_wait, mddev->sync_thread == NULL);
+ mddev_lock_nointr(mddev);
mutex_lock(&mddev->open_mutex);
if (atomic_read(&mddev->openers) > !!bdev ||
- mddev->sysfs_active) {
+ mddev->sysfs_active ||
+ mddev->sync_thread ||
+ (bdev && !test_bit(MD_STILL_CLOSED, &mddev->flags))) {
printk("md: %s still in use.\n",mdname(mddev));
mutex_unlock(&mddev->open_mutex);
- return -EBUSY;
- }
- if (bdev && !test_bit(MD_STILL_CLOSED, &mddev->flags)) {
- /* Someone opened the device since we flushed it
- * so page cache could be dirty and it is too late
- * to flush. So abort
- */
- mutex_unlock(&mddev->open_mutex);
+ if (did_freeze) {
+ clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery);
+ md_wakeup_thread(mddev->thread);
+ }
return -EBUSY;
}
if (mddev->pers) {
@@ -7931,6 +7960,7 @@
/* resync has finished, collect result */
md_unregister_thread(&mddev->sync_thread);
+ wake_up(&resync_wait);
if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) &&
!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery)) {
/* success...*/
