--- drivers/md/raid1.c

+++ drivers/md/raid1.c

@@ -845,6 +845,15 @@ static int make_request(struct request_q

}

mirror = conf->mirrors + rdisk;

+ if (test_bit(WriteMostly, &mirror->rdev->flags) &&

+ bitmap) {

+ /* Reading from a write-mostly device must

+ * take care not to over-take any writes

+ * that are 'behind'

+ */

+ wait_event(bitmap->behind_wait,

+ atomic_read(&bitmap->behind_writes) == 0);

+ }

r1_bio->read_disk = rdisk;

read_bio = bio_clone(bio, GFP_NOIO);

@@ -922,9 +931,13 @@ static int make_request(struct request_q

set_bit(R1BIO_Degraded, &r1_bio->state);

}

- /* do behind I/O ? */

+ /* do behind I/O ?

+ * Not if there are too many, or cannot allocate memory,

+ * or a reader on WriteMostly is waiting for behind writes

+ * to flush */

if (bitmap &&

atomic_read(&bitmap->behind_writes) < bitmap->max_write_behind &&

+ !waitqueue_active(&bitmap->behind_wait) &&

(behind_pages = alloc_behind_pages(bio)) != NULL)

set_bit(R1BIO_BehindIO, &r1_bio->state);

@@ -1175,6 +1188,7 @@ static int raid1_remove_disk(mddev_t *md

* is not possible.

*/

if (!test_bit(Faulty, &rdev->flags) &&

+ !mddev->recovery_disabled &&

mddev->degraded < conf->raid_disks) {

err = -EBUSY;

goto abort;

@@ -2105,15 +2119,13 @@ static int stop(mddev_t *mddev)

{

conf_t *conf = mddev->private;

struct bitmap *bitmap = mddev->bitmap;

- int behind_wait = 0;

/* wait for behind writes to complete */

- while (bitmap && atomic_read(&bitmap->behind_writes) > 0) {

- behind_wait++;

- printk(KERN_INFO "raid1: behind writes in progress on device %s, waiting to stop (%d)\n", mdname(mddev), behind_wait);

- set_current_state(TASK_UNINTERRUPTIBLE);

- schedule_timeout(HZ); /* wait a second */

+ if (bitmap && atomic_read(&bitmap->behind_writes) > 0) {

+ printk(KERN_INFO "raid1: behind writes in progress on device %s, waiting to stop.\n", mdname(mddev));

/* need to kick something here to make sure I/O goes? */

+ wait_event(bitmap->behind_wait,

+ atomic_read(&bitmap->behind_writes) == 0);

}

raise_barrier(conf);