It only checks openers when stopping an array. But some users still can
access mddev through sysfs interfaces. Now ->active is added once mddev
is accessed which is done in function mddev_get protected by lock
all_mddevs_lock. They are md_open, md_seq_show, md_attr_show/store and
md_notify_reboot and md_exit.
->openers is only added in md_open while mddev_get is called too. So we
can replace ->openers with ->active. This can guarantee no one access the
array once MD_CLOSING is set.
At the same time, ->open_mutex is replaced with all_mddevs_lock. Though
all_mddevs_lock is a global lock, the only place checks ->active and sets
MD_CLOSING in ioctl path. So it doesn't affect performance.
Signed-off-by: Xiao Ni <xni@xxxxxxxxxx>
---
drivers/md/md.c | 47 +++++++++++++++++------------------------------
drivers/md/md.h | 11 -----------
2 files changed, 17 insertions(+), 41 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 3cfe26359d7e..455792834e53 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -523,18 +523,27 @@ void mddev_resume(struct mddev *mddev)
EXPORT_SYMBOL_GPL(mddev_resume);
/* sync bdev before setting device to readonly or stopping raid*/
-static int mddev_set_closing_and_sync_blockdev(struct mddev *mddev, int opener_num)
+static int mddev_set_closing_and_sync_blockdev(struct mddev *mddev)
{
- mutex_lock(&mddev->open_mutex);
- if (mddev->pers && atomic_read(&mddev->openers) > opener_num) {
- mutex_unlock(&mddev->open_mutex);
+ spin_lock(&all_mddevs_lock);
+
+ /*
+ * there are two places that call this function and ->active
+ * is added before calling this function. So the array can't
+ * be stopped when ->active is bigger than 1.
+ */
+ if (mddev->pers && atomic_read(&mddev->active) > 1) {
+
+ spin_unlock(&all_mddevs_lock);
return -EBUSY;
}
+
if (test_and_set_bit(MD_CLOSING, &mddev->flags)) {
- mutex_unlock(&mddev->open_mutex);
+ spin_unlock(&all_mddevs_lock);
return -EBUSY;
}
- mutex_unlock(&mddev->open_mutex);
+
+ spin_unlock(&all_mddevs_lock);
sync_blockdev(mddev->gendisk->part0);
return 0;
@@ -663,7 +672,6 @@ int mddev_init(struct mddev *mddev)
/* We want to start with the refcount at zero */
percpu_ref_put(&mddev->writes_pending);
- mutex_init(&mddev->open_mutex);
mutex_init(&mddev->reconfig_mutex);
mutex_init(&mddev->suspend_mutex);
mutex_init(&mddev->bitmap_info.mutex);
@@ -672,7 +680,6 @@ int mddev_init(struct mddev *mddev)
INIT_LIST_HEAD(&mddev->deleting);
timer_setup(&mddev->safemode_timer, md_safemode_timeout, 0);
atomic_set(&mddev->active, 1);
- atomic_set(&mddev->openers, 0);
atomic_set(&mddev->sync_seq, 0);
spin_lock_init(&mddev->lock);
init_waitqueue_head(&mddev->sb_wait);
@@ -4421,8 +4428,7 @@ array_state_store(struct mddev *mddev, const char *buf, size_t len)
case read_auto:
if (!mddev->pers || !md_is_rdwr(mddev))
break;
- /* write sysfs will not open mddev and opener should be 0 */
- err = mddev_set_closing_and_sync_blockdev(mddev, 0);
+ err = mddev_set_closing_and_sync_blockdev(mddev);
if (err)
return err;
break;
@@ -7745,7 +7751,7 @@ static int md_ioctl(struct block_device *bdev, blk_mode_t mode,
/* Need to flush page cache, and ensure no-one else opens
* and writes
*/
- err = mddev_set_closing_and_sync_blockdev(mddev, 1);
+ err = mddev_set_closing_and_sync_blockdev(mddev);
if (err)
return err;
}
@@ -7945,7 +7951,6 @@ static int md_set_read_only(struct block_device *bdev, bool ro)
static int md_open(struct gendisk *disk, blk_mode_t mode)
{
struct mddev *mddev;
- int err;
spin_lock(&all_mddevs_lock);
mddev = mddev_get(disk->private_data);
@@ -7953,25 +7958,8 @@ static int md_open(struct gendisk *disk, blk_mode_t mode)
if (!mddev)
return -ENODEV;
- err = mutex_lock_interruptible(&mddev->open_mutex);
- if (err)
- goto out;
-
- err = -ENODEV;
- if (test_bit(MD_CLOSING, &mddev->flags))
- goto out_unlock;
-
- atomic_inc(&mddev->openers);
- mutex_unlock(&mddev->open_mutex);
-
disk_check_media_change(disk);
return 0;
-
-out_unlock:
- mutex_unlock(&mddev->open_mutex);
-out:
- mddev_put(mddev);
- return err;
}
static void md_release(struct gendisk *disk)
@@ -7979,7 +7967,6 @@ static void md_release(struct gendisk *disk)
struct mddev *mddev = disk->private_data;
BUG_ON(!mddev);
- atomic_dec(&mddev->openers);
mddev_put(mddev);
}
diff --git a/drivers/md/md.h b/drivers/md/md.h
index a9dccb3d84ed..60dc0943e05b 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -496,19 +496,8 @@ struct mddev {
int recovery_disabled;
int in_sync; /* know to not need resync */
- /* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
- * that we are never stopping an array while it is open.
- * 'reconfig_mutex' protects all other reconfiguration.
- * These locks are separate due to conflicting interactions
- * with disk->open_mutex.
- * Lock ordering is:
- * reconfig_mutex -> disk->open_mutex
- * disk->open_mutex -> open_mutex: e.g. __blkdev_get -> md_open
- */
- struct mutex open_mutex;
struct mutex reconfig_mutex;
atomic_t active; /* general refcount */
- atomic_t openers; /* number of active opens */
int changed; /* True if we might need to
* reread partition info */
--
2.32.0 (Apple Git-132)
