3 files changed, 31 insertions, 23 deletions

diff --git a/drivers/block/drbd/drbd_actlog.c b/drivers/block/drbd/drbd_actlog.c
index 4b484ac1d8cb..10459a145062 100644
--- a/drivers/block/drbd/drbd_actlog.c
+++ b/drivers/block/drbd/drbd_actlog.c
@@ -614,21 +614,24 @@ void drbd_al_shrink(struct drbd_device *device)
         wake_up(&device->al_wait);
 }
 
-int drbd_initialize_al(struct drbd_device *device, void *buffer)
+int drbd_al_initialize(struct drbd_device *device, void *buffer)
 {
         struct al_transaction_on_disk *al = buffer;
         struct drbd_md *md = &device->ldev->md;
-        sector_t al_base = md->md_offset + md->al_offset;
         int al_size_4k = md->al_stripes * md->al_stripe_size_4k;
         int i;
 
-        memset(al, 0, 4096);
-        al->magic = cpu_to_be32(DRBD_AL_MAGIC);
-        al->transaction_type = cpu_to_be16(AL_TR_INITIALIZED);
-        al->crc32c = cpu_to_be32(crc32c(0, al, 4096));
+        __al_write_transaction(device, al);
+        /* There may or may not have been a pending transaction. */
+        spin_lock_irq(&device->al_lock);
+        lc_committed(device->act_log);
+        spin_unlock_irq(&device->al_lock);
 
-        for (i = 0; i < al_size_4k; i++) {
-                int err = drbd_md_sync_page_io(device, device->ldev, al_base + i * 8, WRITE);
+        /* The rest of the transactions will have an empty "updates" list, and
+         * are written out only to provide the context, and to initialize the
+         * on-disk ring buffer. */
+        for (i = 1; i < al_size_4k; i++) {
+                int err = __al_write_transaction(device, al);
                 if (err)
                         return err;
         }
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index df3d89d5777a..b6844feb9f9b 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -1667,7 +1667,7 @@ extern int __drbd_change_sync(struct drbd_device *device, sector_t sector, int s
 #define drbd_rs_failed_io(device, sector, size) \
         __drbd_change_sync(device, sector, size, RECORD_RS_FAILED)
 extern void drbd_al_shrink(struct drbd_device *device);
-extern int drbd_initialize_al(struct drbd_device *, void *);
+extern int drbd_al_initialize(struct drbd_device *, void *);
 
 /* drbd_nl.c */
 /* state info broadcast */
diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index c7cd3df8107e..f4ca27359541 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -903,15 +903,14 @@ drbd_determine_dev_size(struct drbd_device *device, enum dds_flags flags, struct
         int md_moved, la_size_changed;
         enum determine_dev_size rv = DS_UNCHANGED;
 
-        /* race:
-         * application request passes inc_ap_bio,
-         * but then cannot get an AL-reference.
-         * this function later may wait on ap_bio_cnt == 0. -> deadlock.
+        /* We may change the on-disk offsets of our meta data below.  Lock out
+         * anything that may cause meta data IO, to avoid acting on incomplete
+         * layout changes or scribbling over meta data that is in the process
+         * of being moved.
          *
-         * to avoid that:
-         * Suspend IO right here.
-         * still lock the act_log to not trigger ASSERTs there.
-         */
+         * Move is not exactly correct, btw, currently we have all our meta
+         * data in core memory, to "move" it we just write it all out, there
+         * are no reads. */
         drbd_suspend_io(device);
         buffer = drbd_md_get_buffer(device, __func__); /* Lock meta-data IO */
         if (!buffer) {
@@ -919,9 +918,6 @@ drbd_determine_dev_size(struct drbd_device *device, enum dds_flags flags, struct
                 return DS_ERROR;
         }
 
-        /* no wait necessary anymore, actually we could assert that */
-        wait_event(device->al_wait, lc_try_lock(device->act_log));
-
         prev_first_sect = drbd_md_first_sector(device->ldev);
         prev_size = device->ldev->md.md_size_sect;
         la_size_sect = device->ldev->md.la_size_sect;
@@ -997,20 +993,29 @@ drbd_determine_dev_size(struct drbd_device *device, enum dds_flags flags, struct
                  * Clear the timer, to avoid scary "timer expired!" messages,
                  * "Superblock" is written out at least twice below, anyways. */
                 del_timer(&device->md_sync_timer);
-                drbd_al_shrink(device); /* All extents inactive. */
 
+                /* We won't change the "al-extents" setting, we just may need
+                 * to move the on-disk location of the activity log ringbuffer.
+                 * Lock for transaction is good enough, it may well be "dirty"
+                 * or even "starving". */
+                wait_event(device->al_wait, lc_try_lock_for_transaction(device->act_log));
+
+                /* mark current on-disk bitmap and activity log as unreliable */
                 prev_flags = md->flags;
-                md->flags &= ~MDF_PRIMARY_IND;
+                md->flags |= MDF_FULL_SYNC | MDF_AL_DISABLED;
                 drbd_md_write(device, buffer);
 
+                drbd_al_initialize(device, buffer);
+
                 drbd_info(device, "Writing the whole bitmap, %s\n",
                          la_size_changed && md_moved ? "size changed and md moved" :
                          la_size_changed ? "size changed" : "md moved");
                 /* next line implicitly does drbd_suspend_io()+drbd_resume_io() */
                 drbd_bitmap_io(device, md_moved ? &drbd_bm_write_all : &drbd_bm_write,
                                "size changed", BM_LOCKED_MASK);
-                drbd_initialize_al(device, buffer);
 
+                /* on-disk bitmap and activity log is authoritative again
+                 * (unless there was an IO error meanwhile...) */
                 md->flags = prev_flags;
                 drbd_md_write(device, buffer);