md/r5cache: disable write back for degraded array

[mirror_ubuntu-artful-kernel.git] / drivers / md / raid5-cache.c

diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
index 3d7dda85494c86b111c94a2dbd6bc42d33e206c1..302dea3296ba5ccd07740365314f45d74df49ec2 100644 (file)
--- a/drivers/md/raid5-cache.c
+++ b/drivers/md/raid5-cache.c
@@ -162,6 +162,8 @@ struct r5l_log {
 
        /* to submit async io_units, to fulfill ordering of flush */
        struct work_struct deferred_io_work;
+       /* to disable write back during in degraded mode */
+       struct work_struct disable_writeback_work;
 };
 
 /*
@@ -611,6 +613,21 @@ static void r5l_submit_io_async(struct work_struct *work)
                r5l_do_submit_io(log, io);
 }
 
+static void r5c_disable_writeback_async(struct work_struct *work)
+{
+       struct r5l_log *log = container_of(work, struct r5l_log,
+                                          disable_writeback_work);
+       struct mddev *mddev = log->rdev->mddev;
+
+       if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH)
+               return;
+       pr_info("md/raid:%s: Disabling writeback cache for degraded array.\n",
+               mdname(mddev));
+       mddev_suspend(mddev);
+       log->r5c_journal_mode = R5C_JOURNAL_MODE_WRITE_THROUGH;
+       mddev_resume(mddev);
+}
+
 static void r5l_submit_current_io(struct r5l_log *log)
 {
        struct r5l_io_unit *io = log->current_io;
@@ -2269,6 +2286,10 @@ static ssize_t r5c_journal_mode_store(struct mddev *mddev,
            val > R5C_JOURNAL_MODE_WRITE_BACK)
                return -EINVAL;
 
+       if (raid5_calc_degraded(conf) > 0 &&
+           val == R5C_JOURNAL_MODE_WRITE_BACK)
+               return -EINVAL;
+
        mddev_suspend(mddev);
        conf->log->r5c_journal_mode = val;
        mddev_resume(mddev);
@@ -2323,6 +2344,16 @@ int r5c_try_caching_write(struct r5conf *conf,
                set_bit(STRIPE_R5C_CACHING, &sh->state);
        }
 
+       /*
+        * When run in degraded mode, array is set to write-through mode.
+        * This check helps drain pending write safely in the transition to
+        * write-through mode.
+        */
+       if (s->failed) {
+               r5c_make_stripe_write_out(sh);
+               return -EAGAIN;
+       }
+
        for (i = disks; i--; ) {
                dev = &sh->dev[i];
                /* if non-overwrite, use writing-out phase */
@@ -2579,6 +2610,19 @@ ioerr:
        return ret;
 }
 
+void r5c_update_on_rdev_error(struct mddev *mddev)
+{
+       struct r5conf *conf = mddev->private;
+       struct r5l_log *log = conf->log;
+
+       if (!log)
+               return;
+
+       if (raid5_calc_degraded(conf) > 0 &&
+           conf->log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_BACK)
+               schedule_work(&log->disable_writeback_work);
+}
+
 int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
 {
        struct request_queue *q = bdev_get_queue(rdev->bdev);
@@ -2651,6 +2695,7 @@ int r5l_init_log(struct r5conf *conf, struct md_rdev *rdev)
        spin_lock_init(&log->no_space_stripes_lock);
 
        INIT_WORK(&log->deferred_io_work, r5l_submit_io_async);
+       INIT_WORK(&log->disable_writeback_work, r5c_disable_writeback_async);
 
        log->r5c_journal_mode = R5C_JOURNAL_MODE_WRITE_THROUGH;
        INIT_LIST_HEAD(&log->stripe_in_journal_list);
@@ -2683,6 +2728,7 @@ io_kc:
 
 void r5l_exit_log(struct r5l_log *log)
 {
+       flush_work(&log->disable_writeback_work);
        md_unregister_thread(&log->reclaim_thread);
        mempool_destroy(log->meta_pool);
        bioset_free(log->bs);