From: Yu Kuai <yukuai3@xxxxxxxxxx>
IO fast path will set bits to dirty, and those dirty bits will be cleared
by daemon after IO is done. llbitmap_barrier is used to synchronize between
IO path and daemon;
IO path:
1) try to grab a reference, if succeed, set expire time after 5s and
return;
2) if failed to grab a reference, wait for daemon to finish clearing dirty
bits;
Daemon(Daemon will be waken up every daemon_sleep seconds):
For each page:
1) check if page expired, if not skip this page; for expired page:
2) suspend the page and wait for inflight write IO to be done;
3) change dirty page to clean;
4) resume the page;
Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
drivers/md/md-llbitmap.c | 46 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/drivers/md/md-llbitmap.c b/drivers/md/md-llbitmap.c
index 315a4eb7627c..994ca0be3d17 100644
--- a/drivers/md/md-llbitmap.c
+++ b/drivers/md/md-llbitmap.c
@@ -435,6 +435,14 @@ static void llbitmap_write_page(struct llbitmap *llbitmap, int idx)
}
}
+static void active_release(struct percpu_ref *ref)
+{
+ struct llbitmap_barrier *barrier =
+ container_of(ref, struct llbitmap_barrier, active);
+
+ wake_up(&barrier->wait);
+}
+
static int llbitmap_cache_pages(struct llbitmap *llbitmap)
{
int nr_pages = (llbitmap->chunks + BITMAP_SB_SIZE + PAGE_SIZE - 1) / PAGE_SIZE;
@@ -562,3 +570,41 @@ static enum llbitmap_state llbitmap_state_machine(struct llbitmap *llbitmap,
return state;
}
+
+static void llbitmap_raise_barrier(struct llbitmap *llbitmap, int page_idx)
+{
+ struct llbitmap_barrier *barrier = &llbitmap->barrier[page_idx];
+
+retry:
+ if (likely(percpu_ref_tryget_live(&barrier->active))) {
+ WRITE_ONCE(barrier->expire, jiffies + BARRIER_IDLE * HZ);
+ return;
+ }
+
+ wait_event(barrier->wait, !percpu_ref_is_dying(&barrier->active));
+ goto retry;
+}
+
+static void llbitmap_release_barrier(struct llbitmap *llbitmap, int page_idx)
+{
+ struct llbitmap_barrier *barrier = &llbitmap->barrier[page_idx];
+
+ percpu_ref_put(&barrier->active);
+}
+
+static void llbitmap_suspend(struct llbitmap *llbitmap, int page_idx)
+{
+ struct llbitmap_barrier *barrier = &llbitmap->barrier[page_idx];
+
+ percpu_ref_kill(&barrier->active);
+ wait_event(barrier->wait, percpu_ref_is_zero(&barrier->active));
+}
+
+static void llbitmap_resume(struct llbitmap *llbitmap, int page_idx)
+{
+ struct llbitmap_barrier *barrier = &llbitmap->barrier[page_idx];
+
+ barrier->expire = LONG_MAX;
+ percpu_ref_resurrect(&barrier->active);
+ wake_up(&barrier->wait);
+}
--
2.39.2
