md/bitmap: separate out loading a bitmap from initialising the structures.

dm makes this distinction between ->ctr and ->resume, so we need to
too.

Also get the new bitmap_load to clear out the bitmap first, as this is
most consistent with the dm suspend/resume approach

Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 48 insertions, 21 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 93765261c363..1ba1e122e948 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -1681,7 +1681,6 @@ int bitmap_create(mddev_t *mddev)
         unsigned long pages;
         struct file *file = mddev->bitmap_info.file;
         int err;
-        sector_t start;
         struct sysfs_dirent *bm = NULL;
 
         BUILD_BUG_ON(sizeof(bitmap_super_t) != 256);
@@ -1763,13 +1762,40 @@ int bitmap_create(mddev_t *mddev)
         if (!bitmap->bp)
                 goto error;
 
-        /* now that we have some pages available, initialize the in-memory
-         * bitmap from the on-disk bitmap */
-        start = 0;
-        if (mddev->degraded == 0
-            || bitmap->events_cleared == mddev->events)
-                /* no need to keep dirty bits to optimise a re-add of a missing device */
-                start = mddev->recovery_cp;
+        printk(KERN_INFO "created bitmap (%lu pages) for device %s\n",
+                pages, bmname(bitmap));
+
+        mddev->bitmap = bitmap;
+
+
+        return (bitmap->flags & BITMAP_WRITE_ERROR) ? -EIO : 0;
+
+ error:
+        bitmap_free(bitmap);
+        return err;
+}
+
+int bitmap_load(mddev_t *mddev)
+{
+        int err = 0;
+        sector_t sector = 0;
+        struct bitmap *bitmap = mddev->bitmap;
+
+        if (!bitmap)
+                goto out;
+
+        /* Clear out old bitmap info first:  Either there is none, or we
+         * are resuming after someone else has possibly changed things,
+         * so we should forget old cached info.
+         * All chunks should be clean, but some might need_sync.
+         */
+        while (sector < mddev->resync_max_sectors) {
+                int blocks;
+                bitmap_start_sync(bitmap, sector, &blocks, 0);
+                sector += blocks;
+        }
+        bitmap_close_sync(bitmap);
+
         if (mddev->bitmap_info.log) {
                 unsigned long i;
                 struct dm_dirty_log *log = mddev->bitmap_info.log;
@@ -1778,29 +1804,30 @@ int bitmap_create(mddev_t *mddev)
                                 bitmap_set_memory_bits(bitmap,
                                                        (sector_t)i << CHUNK_BLOCK_SHIFT(bitmap),
                                                        1);
-                err = 0;
-        } else
-                err = bitmap_init_from_disk(bitmap, start);
+        } else {
+                sector_t start = 0;
+                if (mddev->degraded == 0
+                    || bitmap->events_cleared == mddev->events)
+                        /* no need to keep dirty bits to optimise a
+                         * re-add of a missing device */
+                        start = mddev->recovery_cp;
 
+                err = bitmap_init_from_disk(bitmap, start);
+        }
         if (err)
-                goto error;
-
-        printk(KERN_INFO "created bitmap (%lu pages) for device %s\n",
-                pages, bmname(bitmap));
-
-        mddev->bitmap = bitmap;
+                goto out;
 
         mddev->thread->timeout = mddev->bitmap_info.daemon_sleep;
         md_wakeup_thread(mddev->thread);
 
         bitmap_update_sb(bitmap);
 
-        return (bitmap->flags & BITMAP_WRITE_ERROR) ? -EIO : 0;
-
- error:
-        bitmap_free(bitmap);
+        if (bitmap->flags & BITMAP_WRITE_ERROR)
+                err = -EIO;
+out:
         return err;
 }
+EXPORT_SYMBOL_GPL(bitmap_load);
 
 static ssize_t
 location_show(mddev_t *mddev, char *page)