[PATCH 1/1] md: Need to update superblock after changing rdev sb_flags

It doesn't update rdev superblock flags to disk after changing these flags.
This patch does this job. In the process of creating a raid, it creates per
device sysfs files and then sets value to mddev->pers. There is a interval
between the two events. If someone changes rdev flags in this interval, it
needs to record this. So it sets MD_SB_CHANGE_DEVS first. If mddev->pers is
NULL, it can update superblock after creating mddev->thread.

Signed-off-by: Xiao Ni <redacted>
---
 drivers/md/md.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 6c0c3d0..40d0f50 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c

@@ -2976,7 +2976,11 @@ state_store(struct md_rdev *rdev, const char *buf, size_t len)
         *  -write_error - clears WriteErrorSeen
         *  {,-}failfast - set/clear FailFast
         */
+
+       struct mddev *mddev = rdev->mddev;
        int err = -EINVAL;
+       bool need_update_sb = false;
+
        if (cmd_match(buf, "faulty") && rdev->mddev->pers) {
                md_error(rdev->mddev, rdev);
                if (test_bit(Faulty, &rdev->flags))

@@ -2991,7 +2995,6 @@ state_store(struct md_rdev *rdev, const char *buf, size_t len)
                if (rdev->raid_disk >= 0)
                        err = -EBUSY;
                else {
-                       struct mddev *mddev = rdev->mddev;
                        err = 0;
                        if (mddev_is_clustered(mddev))
                                err = md_cluster_ops->remove_disk(mddev, rdev);

@@ -3008,10 +3011,12 @@ state_store(struct md_rdev *rdev, const char *buf, size_t len)
        } else if (cmd_match(buf, "writemostly")) {
                set_bit(WriteMostly, &rdev->flags);
                mddev_create_serial_pool(rdev->mddev, rdev, false);
+               need_update_sb = true;
                err = 0;
        } else if (cmd_match(buf, "-writemostly")) {
                mddev_destroy_serial_pool(rdev->mddev, rdev, false);
                clear_bit(WriteMostly, &rdev->flags);
+               need_update_sb = true;
                err = 0;
        } else if (cmd_match(buf, "blocked")) {
                set_bit(Blocked, &rdev->flags);

@@ -3037,9 +3042,11 @@ state_store(struct md_rdev *rdev, const char *buf, size_t len)
                err = 0;
        } else if (cmd_match(buf, "failfast")) {
                set_bit(FailFast, &rdev->flags);
+               need_update_sb = true;
                err = 0;
        } else if (cmd_match(buf, "-failfast")) {
                clear_bit(FailFast, &rdev->flags);
+               need_update_sb = true;
                err = 0;
        } else if (cmd_match(buf, "-insync") && rdev->raid_disk >= 0 &&
                   !test_bit(Journal, &rdev->flags)) {

@@ -3118,6 +3125,11 @@ state_store(struct md_rdev *rdev, const char *buf, size_t len)
                clear_bit(ExternalBbl, &rdev->flags);
                err = 0;
        }
+       if (need_update_sb) {
+               set_bit(MD_SB_CHANGE_DEVS, &mddev->sb_flags);
+               if (mddev->pers)
+                       md_wakeup_thread(mddev->thread);
+       }
        if (!err)
                sysfs_notify_dirent_safe(rdev->sysfs_state);
        return err ? err : len;
--

2.7.5