drbd: bitmap keep track of changes vs on-disk bitmap

When we set or clear bits in a bitmap page,
also set a flag in the page->private pointer.

This allows us to skip writes of unchanged pages.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 29 insertions, 103 deletions

diff --git a/drivers/block/drbd/drbd_actlog.c b/drivers/block/drbd/drbd_actlog.c
index e3f0f4d31d7..090fc2ce0df 100644
--- a/drivers/block/drbd/drbd_actlog.c
+++ b/drivers/block/drbd/drbd_actlog.c
@@ -262,6 +262,33 @@ void drbd_al_complete_io(struct drbd_conf *mdev, sector_t sector)
         spin_unlock_irqrestore(&mdev->al_lock, flags);
 }
 
+#if (PAGE_SHIFT + 3) < (AL_EXTENT_SHIFT - BM_BLOCK_SHIFT)
+/* Currently BM_BLOCK_SHIFT, BM_EXT_SHIFT and AL_EXTENT_SHIFT
+ * are still coupled, or assume too much about their relation.
+ * Code below will not work if this is violated.
+ * Will be cleaned up with some followup patch.
+ */
+# error FIXME
+#endif
+
+static unsigned int al_extent_to_bm_page(unsigned int al_enr)
+{
+        return al_enr >>
+                /* bit to page */
+                ((PAGE_SHIFT + 3) -
+                /* al extent number to bit */
+                 (AL_EXTENT_SHIFT - BM_BLOCK_SHIFT));
+}
+
+static unsigned int rs_extent_to_bm_page(unsigned int rs_enr)
+{
+        return rs_enr >>
+                /* bit to page */
+                ((PAGE_SHIFT + 3) -
+                /* al extent number to bit */
+                 (BM_EXT_SHIFT - BM_BLOCK_SHIFT));
+}
+
 int
 w_al_write_transaction(struct drbd_conf *mdev, struct drbd_work *w, int unused)
 {
@@ -289,7 +316,7 @@ w_al_write_transaction(struct drbd_conf *mdev, struct drbd_work *w, int unused)
          * For now, we must not write the transaction,
          * if we cannot write out the bitmap of the evicted extent. */
         if (mdev->state.conn < C_CONNECTED && evicted != LC_FREE)
-                drbd_bm_write_sect(mdev, evicted/AL_EXT_PER_BM_SECT);
+                drbd_bm_write_page(mdev, al_extent_to_bm_page(evicted));
 
         /* The bitmap write may have failed, causing a state change. */
         if (mdev->state.disk < D_INCONSISTENT) {
@@ -636,105 +663,6 @@ out_bio_put:
 }
 
 /**
- * drbd_al_to_on_disk_bm() -  * Writes bitmap parts covered by active AL extents
- * @mdev:       DRBD device.
- *
- * Called when we detach (unconfigure) local storage,
- * or when we go from R_PRIMARY to R_SECONDARY role.
- */
-void drbd_al_to_on_disk_bm(struct drbd_conf *mdev)
-{
-        int i, nr_elements;
-        unsigned int enr;
-        struct bio **bios;
-        struct drbd_atodb_wait wc;
-
-        ERR_IF (!get_ldev_if_state(mdev, D_ATTACHING))
-                return; /* sorry, I don't have any act_log etc... */
-
-        wait_event(mdev->al_wait, lc_try_lock(mdev->act_log));
-
-        nr_elements = mdev->act_log->nr_elements;
-
-        /* GFP_KERNEL, we are not in anyone's write-out path */
-        bios = kzalloc(sizeof(struct bio *) * nr_elements, GFP_KERNEL);
-        if (!bios)
-                goto submit_one_by_one;
-
-        atomic_set(&wc.count, 0);
-        init_completion(&wc.io_done);
-        wc.mdev = mdev;
-        wc.error = 0;
-
-        for (i = 0; i < nr_elements; i++) {
-                enr = lc_element_by_index(mdev->act_log, i)->lc_number;
-                if (enr == LC_FREE)
-                        continue;
-                /* next statement also does atomic_inc wc.count and local_cnt */
-                if (atodb_prepare_unless_covered(mdev, bios,
-                                                enr/AL_EXT_PER_BM_SECT,
-                                                &wc))
-                        goto free_bios_submit_one_by_one;
-        }
-
-        /* unnecessary optimization? */
-        lc_unlock(mdev->act_log);
-        wake_up(&mdev->al_wait);
-
-        /* all prepared, submit them */
-        for (i = 0; i < nr_elements; i++) {
-                if (bios[i] == NULL)
-                        break;
-                if (drbd_insert_fault(mdev, DRBD_FAULT_MD_WR)) {
-                        bios[i]->bi_rw = WRITE;
-                        bio_endio(bios[i], -EIO);
-                } else {
-                        submit_bio(WRITE, bios[i]);
-                }
-        }
-
-        /* always (try to) flush bitmap to stable storage */
-        drbd_md_flush(mdev);
-
-        /* In case we did not submit a single IO do not wait for
-         * them to complete. ( Because we would wait forever here. )
-         *
-         * In case we had IOs and they are already complete, there
-         * is not point in waiting anyways.
-         * Therefore this if () ... */
-        if (atomic_read(&wc.count))
-                wait_for_completion(&wc.io_done);
-
-        put_ldev(mdev);
-
-        kfree(bios);
-        return;
-
- free_bios_submit_one_by_one:
-        /* free everything by calling the endio callback directly. */
-        for (i = 0; i < nr_elements && bios[i]; i++)
-                bio_endio(bios[i], 0);
-
-        kfree(bios);
-
- submit_one_by_one:
-        dev_warn(DEV, "Using the slow drbd_al_to_on_disk_bm()\n");
-
-        for (i = 0; i < mdev->act_log->nr_elements; i++) {
-                enr = lc_element_by_index(mdev->act_log, i)->lc_number;
-                if (enr == LC_FREE)
-                        continue;
-                /* Really slow: if we have al-extents 16..19 active,
-                 * sector 4 will be written four times! Synchronous! */
-                drbd_bm_write_sect(mdev, enr/AL_EXT_PER_BM_SECT);
-        }
-
-        lc_unlock(mdev->act_log);
-        wake_up(&mdev->al_wait);
-        put_ldev(mdev);
-}
-
-/**
  * drbd_al_apply_to_bm() - Sets the bitmap to diry(1) where covered ba active AL extents
  * @mdev:       DRBD device.
  */
@@ -813,7 +741,7 @@ static int w_update_odbm(struct drbd_conf *mdev, struct drbd_work *w, int unused
                 return 1;
         }
 
-        drbd_bm_write_sect(mdev, udw->enr);
+        drbd_bm_write_page(mdev, rs_extent_to_bm_page(udw->enr));
         put_ldev(mdev);
 
         kfree(udw);
@@ -893,7 +821,6 @@ static void drbd_try_clear_on_disk_bm(struct drbd_conf *mdev, sector_t sector,
                                 dev_warn(DEV, "Kicking resync_lru element enr=%u "
                                      "out with rs_failed=%d\n",
                                      ext->lce.lc_number, ext->rs_failed);
-                                set_bit(WRITE_BM_AFTER_RESYNC, &mdev->flags);
                         }
                         ext->rs_left = rs_left;
                         ext->rs_failed = success ? 0 : count;
@@ -912,7 +839,6 @@ static void drbd_try_clear_on_disk_bm(struct drbd_conf *mdev, sector_t sector,
                                 drbd_queue_work_front(&mdev->data.work, &udw->w);
                         } else {
                                 dev_warn(DEV, "Could not kmalloc an udw\n");
-                                set_bit(WRITE_BM_AFTER_RESYNC, &mdev->flags);
                         }
                 }
         } else {