drbd: split out some helper functions to drbd_al_begin_io

To make the code easier to follow,
use an explicit find_active_resync_extent(),
and add a "nonblock" parameter to _al_get().

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 28 insertions, 21 deletions

diff --git a/drivers/block/drbd/drbd_actlog.c b/drivers/block/drbd/drbd_actlog.c
index e4f1231c2ef2..ff03f9053316 100644
--- a/drivers/block/drbd/drbd_actlog.c
+++ b/drivers/block/drbd/drbd_actlog.c
@@ -222,25 +222,37 @@ int drbd_md_sync_page_io(struct drbd_conf *mdev, struct drbd_backing_dev *bdev,
         return err;
 }
 
-static struct lc_element *_al_get(struct drbd_conf *mdev, unsigned int enr)
+static struct bm_extent *find_active_resync_extent(struct drbd_conf *mdev, unsigned int enr)
 {
-        struct lc_element *al_ext;
         struct lc_element *tmp;
-        int wake;
-
-        spin_lock_irq(&mdev->al_lock);
         tmp = lc_find(mdev->resync, enr/AL_EXT_PER_BM_SECT);
         if (unlikely(tmp != NULL)) {
                 struct bm_extent  *bm_ext = lc_entry(tmp, struct bm_extent, lce);
-                if (test_bit(BME_NO_WRITES, &bm_ext->flags)) {
-                        wake = !test_and_set_bit(BME_PRIORITY, &bm_ext->flags);
-                        spin_unlock_irq(&mdev->al_lock);
-                        if (wake)
-                                wake_up(&mdev->al_wait);
-                        return NULL;
-                }
+                if (test_bit(BME_NO_WRITES, &bm_ext->flags))
+                        return bm_ext;
         }
-        al_ext = lc_get(mdev->act_log, enr);
+        return NULL;
+}
+
+static struct lc_element *_al_get(struct drbd_conf *mdev, unsigned int enr, bool nonblock)
+{
+        struct lc_element *al_ext;
+        struct bm_extent *bm_ext;
+        int wake;
+
+        spin_lock_irq(&mdev->al_lock);
+        bm_ext = find_active_resync_extent(mdev, enr);
+        if (bm_ext) {
+                wake = !test_and_set_bit(BME_PRIORITY, &bm_ext->flags);
+                spin_unlock_irq(&mdev->al_lock);
+                if (wake)
+                        wake_up(&mdev->al_wait);
+                return NULL;
+        }
+        if (nonblock)
+                al_ext = lc_try_get(mdev->act_log, enr);
+        else
+                al_ext = lc_get(mdev->act_log, enr);
         spin_unlock_irq(&mdev->al_lock);
         return al_ext;
 }
@@ -251,7 +263,6 @@ bool drbd_al_begin_io_fastpath(struct drbd_conf *mdev, struct drbd_interval *i)
          * we may need to activate two extents in one go */
         unsigned first = i->sector >> (AL_EXTENT_SHIFT-9);
         unsigned last = i->size == 0 ? first : (i->sector + (i->size >> 9) - 1) >> (AL_EXTENT_SHIFT-9);
-        bool fastpath_ok = true;
 
         D_ASSERT((unsigned)(last - first) <= 1);
         D_ASSERT(atomic_read(&mdev->local_cnt) > 0);
@@ -260,12 +271,7 @@ bool drbd_al_begin_io_fastpath(struct drbd_conf *mdev, struct drbd_interval *i)
         if (first != last)
                 return false;
 
-        spin_lock_irq(&mdev->al_lock);
-        fastpath_ok =
-                lc_find(mdev->resync, first/AL_EXT_PER_BM_SECT) == NULL &&
-                lc_try_get(mdev->act_log, first) != NULL;
-        spin_unlock_irq(&mdev->al_lock);
-        return fastpath_ok;
+        return _al_get(mdev, first, true);
 }
 
 bool drbd_al_begin_io_prepare(struct drbd_conf *mdev, struct drbd_interval *i)
@@ -282,7 +288,8 @@ bool drbd_al_begin_io_prepare(struct drbd_conf *mdev, struct drbd_interval *i)
 
         for (enr = first; enr <= last; enr++) {
                 struct lc_element *al_ext;
-                wait_event(mdev->al_wait, (al_ext = _al_get(mdev, enr)) != NULL);
+                wait_event(mdev->al_wait,
+                                (al_ext = _al_get(mdev, enr, false)) != NULL);
                 if (al_ext->lc_number != enr)
                         need_transaction = true;
         }