dm raid1: add framework to hold bios during suspend
Add framework to delay bios until a suspend and then resubmit them with
either DM_ENDIO_REQUEUE (if the suspend was noflush) or complete them
with -EIO. I/O barrier support will use this.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Takahiro Yasui <tyasui@redhat.com>
Tested-by: Takahiro Yasui <tyasui@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index 85c8704c..895cce7 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -58,6 +58,7 @@
struct bio_list reads;
struct bio_list writes;
struct bio_list failures;
+ struct bio_list holds; /* bios are waiting until suspend */
struct dm_region_hash *rh;
struct dm_kcopyd_client *kcopyd_client;
@@ -450,6 +451,27 @@
io->count = bio->bi_size >> 9;
}
+static void hold_bio(struct mirror_set *ms, struct bio *bio)
+{
+ /*
+ * If device is suspended, complete the bio.
+ */
+ if (atomic_read(&ms->suspend)) {
+ if (dm_noflush_suspending(ms->ti))
+ bio_endio(bio, DM_ENDIO_REQUEUE);
+ else
+ bio_endio(bio, -EIO);
+ return;
+ }
+
+ /*
+ * Hold bio until the suspend is complete.
+ */
+ spin_lock_irq(&ms->lock);
+ bio_list_add(&ms->holds, bio);
+ spin_unlock_irq(&ms->lock);
+}
+
/*-----------------------------------------------------------------
* Reads
*---------------------------------------------------------------*/
@@ -1225,6 +1247,9 @@
struct mirror_set *ms = (struct mirror_set *) ti->private;
struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
+ struct bio_list holds;
+ struct bio *bio;
+
atomic_set(&ms->suspend, 1);
/*
@@ -1247,6 +1272,22 @@
* we know that all of our I/O has been pushed.
*/
flush_workqueue(ms->kmirrord_wq);
+
+ /*
+ * Now set ms->suspend is set and the workqueue flushed, no more
+ * entries can be added to ms->hold list, so process it.
+ *
+ * Bios can still arrive concurrently with or after this
+ * presuspend function, but they cannot join the hold list
+ * because ms->suspend is set.
+ */
+ spin_lock_irq(&ms->lock);
+ holds = ms->holds;
+ bio_list_init(&ms->holds);
+ spin_unlock_irq(&ms->lock);
+
+ while ((bio = bio_list_pop(&holds)))
+ hold_bio(ms, bio);
}
static void mirror_postsuspend(struct dm_target *ti)