md: add honouring of suspend_{lo,hi} to raid1.

This will allow us to stop writeout to portions of the array
while  they are resynced by someone else - e.g. another node in
a cluster.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index e07ce2e..35b2d86 100644 (file)
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -801,6 +801,25 @@ static int make_request(struct request_queue *q, struct bio * bio)
 
        md_write_start(mddev, bio); /* wait on superblock update early */
 
+       if (bio_data_dir(bio) == WRITE &&
+           bio->bi_sector + bio->bi_size/512 > mddev->suspend_lo &&
+           bio->bi_sector < mddev->suspend_hi) {
+               /* As the suspend_* range is controlled by
+                * userspace, we want an interruptible
+                * wait.
+                */
+               DEFINE_WAIT(w);
+               for (;;) {
+                       flush_signals(current);
+                       prepare_to_wait(&conf->wait_barrier,
+                                       &w, TASK_INTERRUPTIBLE);
+                       if (bio->bi_sector + bio->bi_size/512 <= mddev->suspend_lo ||
+                           bio->bi_sector >= mddev->suspend_hi)
+                               break;
+                       schedule();
+               }
+               finish_wait(&conf->wait_barrier, &w);
+       }
        if (unlikely(!mddev->barriers_work &&
                     bio_rw_flagged(bio, BIO_RW_BARRIER))) {
                if (rw == WRITE)
@@ -2271,6 +2290,9 @@ static void raid1_quiesce(mddev_t *mddev, int state)
        conf_t *conf = mddev->private;
 
        switch(state) {
+       case 2: /* wake for suspend */
+               wake_up(&conf->wait_barrier);
+               break;
        case 1:
                raise_barrier(conf);
                break;