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authorGuoqing Jiang <gqjiang@suse.com>2015-12-21 02:51:01 +0300
committerNeilBrown <neilb@suse.com>2016-01-06 03:39:21 +0300
commite19508fa4df896b115f5321c21ce7669559b0863 (patch)
tree1deee55c3bf4081034c4c69558cf33dec302065a /drivers/md/md-cluster.c
parent8b9277c81450de9d8081ff6571ac5986e6c83f49 (diff)
downloadlinux-e19508fa4df896b115f5321c21ce7669559b0863.tar.xz
md-cluster: update comments for MD_CLUSTER_SEND_LOCKED_ALREADY
1. fix unbalanced parentheses. 2. add more description about that MD_CLUSTER_SEND_LOCKED_ALREADY will be cleared after set it in add_new_disk. Signed-off-by: Guoqing Jiang <gqjiang@suse.com> Signed-off-by: NeilBrown <neilb@suse.com>
Diffstat (limited to 'drivers/md/md-cluster.c')
-rw-r--r--drivers/md/md-cluster.c23
1 files changed, 18 insertions, 5 deletions
diff --git a/drivers/md/md-cluster.c b/drivers/md/md-cluster.c
index ad3ec7df1547..0ded8e97751d 100644
--- a/drivers/md/md-cluster.c
+++ b/drivers/md/md-cluster.c
@@ -53,11 +53,12 @@ struct resync_info {
* accomodate lock and hold. See next comment.
*/
#define MD_CLUSTER_SEND_LOCK 4
-/* If cluster operations must lock the communication channel,
- * so as to perform extra operations (and no other operation
- * is allowed on the MD, such as adding a disk. Token needs
- * to be locked and held until the operation completes with
- * a md_update_sb(), which would eventually release the lock.
+/* If cluster operations (such as adding a disk) must lock the
+ * communication channel, so as to perform extra operations
+ * (update metadata) and no other operation is allowed on the
+ * MD. Token needs to be locked and held until the operation
+ * completes witha md_update_sb(), which would eventually release
+ * the lock.
*/
#define MD_CLUSTER_SEND_LOCKED_ALREADY 5
@@ -1021,6 +1022,18 @@ static int add_new_disk(struct mddev *mddev, struct md_rdev *rdev)
unlock_comm(cinfo);
else {
dlm_lock_sync(cinfo->no_new_dev_lockres, DLM_LOCK_CR);
+ /* Since MD_CHANGE_DEVS will be set in add_bound_rdev which
+ * will run soon after add_new_disk, the below path will be
+ * invoked:
+ * md_wakeup_thread(mddev->thread)
+ * -> conf->thread (raid1d)
+ * -> md_check_recovery -> md_update_sb
+ * -> metadata_update_start/finish
+ * MD_CLUSTER_SEND_LOCKED_ALREADY will be cleared eventually.
+ *
+ * For other failure cases, metadata_update_cancel and
+ * add_new_disk_cancel also clear below bit as well.
+ * */
set_bit(MD_CLUSTER_SEND_LOCKED_ALREADY, &cinfo->state);
wake_up(&cinfo->wait);
}