blk: centralize non-request unplug handling.

Both md and umem has similar code for getting notified on an
blk_finish_plug event.
Centralize this code in block/ and allow each driver to
provide its distinctive difference.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

2 files changed, 12 insertions, 52 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 34381172a947..b493fa417387 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -498,59 +498,13 @@ void md_flush_request(struct mddev *mddev, struct bio *bio)
 }
 EXPORT_SYMBOL(md_flush_request);
 
-/* Support for plugging.
- * This mirrors the plugging support in request_queue, but does not
- * require having a whole queue or request structures.
- * We allocate an md_plug_cb for each md device and each thread it gets
- * plugged on.  This links tot the private plug_handle structure in the
- * personality data where we keep a count of the number of outstanding
- * plugs so other code can see if a plug is active.
- */
-struct md_plug_cb {
-        struct blk_plug_cb cb;
-        struct mddev *mddev;
-};
-
-static void plugger_unplug(struct blk_plug_cb *cb)
+void md_unplug(struct blk_plug_cb *cb)
 {
-        struct md_plug_cb *mdcb = container_of(cb, struct md_plug_cb, cb);
-        md_wakeup_thread(mdcb->mddev->thread);
-        kfree(mdcb);
-}
-
-/* Check that an unplug wakeup will come shortly.
- * If not, wakeup the md thread immediately
- */
-int mddev_check_plugged(struct mddev *mddev)
-{
-        struct blk_plug *plug = current->plug;
-        struct md_plug_cb *mdcb;
-
-        if (!plug)
-                return 0;
-
-        list_for_each_entry(mdcb, &plug->cb_list, cb.list) {
-                if (mdcb->cb.callback == plugger_unplug &&
-                    mdcb->mddev == mddev) {
-                        /* Already on the list, move to top */
-                        if (mdcb != list_first_entry(&plug->cb_list,
-                                                    struct md_plug_cb,
-                                                    cb.list))
-                                list_move(&mdcb->cb.list, &plug->cb_list);
-                        return 1;
-                }
-        }
-        /* Not currently on the callback list */
-        mdcb = kmalloc(sizeof(*mdcb), GFP_ATOMIC);
-        if (!mdcb)
-                return 0;
-
-        mdcb->mddev = mddev;
-        mdcb->cb.callback = plugger_unplug;
-        list_add(&mdcb->cb.list, &plug->cb_list);
-        return 1;
+        struct mddev *mddev = cb->data;
+        md_wakeup_thread(mddev->thread);
+        kfree(cb);
 }
-EXPORT_SYMBOL_GPL(mddev_check_plugged);
+EXPORT_SYMBOL(md_unplug);
 
 static inline struct mddev *mddev_get(struct mddev *mddev)
 {
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 91786c46b85c..8f998e08fb87 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -627,6 +627,12 @@ extern struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
                                    struct mddev *mddev);
 extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
                                    struct mddev *mddev);
-extern int mddev_check_plugged(struct mddev *mddev);
 extern void md_trim_bio(struct bio *bio, int offset, int size);
+
+extern void md_unplug(struct blk_plug_cb *cb);
+static inline int mddev_check_plugged(struct mddev *mddev)
+{
+        return !!blk_check_plugged(md_unplug, mddev,
+                                   sizeof(struct blk_plug_cb));
+}
 #endif /* _MD_MD_H */