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 | 38 ++++++++++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)
diff --git a/drivers/md/md-llbitmap.c b/drivers/md/md-llbitmap.c
index f782f092ab5d..4d5f9a139a25 100644
--- a/drivers/md/md-llbitmap.c
+++ b/drivers/md/md-llbitmap.c
@@ -651,4 +651,42 @@ 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_page_ctl *pctl = llbitmap->pctl[page_idx];
+
+retry:
+ if (likely(percpu_ref_tryget_live(&pctl->active))) {
+ WRITE_ONCE(pctl->expire, jiffies + BARRIER_IDLE * HZ);
+ return;
+ }
+
+ wait_event(pctl->wait, !percpu_ref_is_dying(&pctl->active));
+ goto retry;
+}
+
+static void llbitmap_release_barrier(struct llbitmap *llbitmap, int page_idx)
+{
+ struct llbitmap_page_ctl *pctl = llbitmap->pctl[page_idx];
+
+ percpu_ref_put(&pctl->active);
+}
+
+static void llbitmap_suspend(struct llbitmap *llbitmap, int page_idx)
+{
+ struct llbitmap_page_ctl *pctl = llbitmap->pctl[page_idx];
+
+ percpu_ref_kill(&pctl->active);
+ wait_event(pctl->wait, percpu_ref_is_zero(&pctl->active));
+}
+
+static void llbitmap_resume(struct llbitmap *llbitmap, int page_idx)
+{
+ struct llbitmap_page_ctl *pctl = llbitmap->pctl[page_idx];
+
+ pctl->expire = LONG_MAX;
+ percpu_ref_resurrect(&pctl->active);
+ wake_up(&pctl->wait);
+}
+
#endif /* CONFIG_MD_LLBITMAP */
--
2.39.2
