1 files changed, 21 insertions, 7 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 41df4cda66e2..2925219f0881 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -520,6 +520,8 @@ success:
         bitmap->daemon_sleep = daemon_sleep;
         bitmap->flags |= sb->state;
         bitmap->events_cleared = le64_to_cpu(sb->events_cleared);
+        if (sb->state & BITMAP_STALE)
+                bitmap->events_cleared = bitmap->mddev->events;
         err = 0;
 out:
         kunmap(bitmap->sb_page);
@@ -818,7 +820,7 @@ int bitmap_unplug(struct bitmap *bitmap)
         return 0;
 }
 
-static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset);
+static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed);
 /* * bitmap_init_from_disk -- called at bitmap_create time to initialize
  * the in-memory bitmap from the on-disk bitmap -- also, sets up the
  * memory mapping of the bitmap file
@@ -826,8 +828,11 @@ static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset);
  *   if there's no bitmap file, or if the bitmap file had been
  *   previously kicked from the array, we mark all the bits as
  *   1's in order to cause a full resync.
+ *
+ * We ignore all bits for sectors that end earlier than 'start'.
+ * This is used when reading an out-of-date bitmap...
  */
-static int bitmap_init_from_disk(struct bitmap *bitmap)
+static int bitmap_init_from_disk(struct bitmap *bitmap, sector_t start)
 {
         unsigned long i, chunks, index, oldindex, bit;
         struct page *page = NULL, *oldpage = NULL;
@@ -914,7 +919,7 @@ static int bitmap_init_from_disk(struct bitmap *bitmap)
                                  * whole page and write it out
                                  */
                                 memset(page_address(page) + offset, 0xff,
-                                        PAGE_SIZE - offset);
+                                       PAGE_SIZE - offset);
                                 ret = write_page(bitmap, page, 1);
                                 if (ret) {
                                         kunmap(page);
@@ -928,8 +933,11 @@ static int bitmap_init_from_disk(struct bitmap *bitmap)
                 }
                 if (test_bit(bit, page_address(page))) {
                         /* if the disk bit is set, set the memory bit */
-                        bitmap_set_memory_bits(bitmap, i << CHUNK_BLOCK_SHIFT(bitmap));
+                        bitmap_set_memory_bits(bitmap, i << CHUNK_BLOCK_SHIFT(bitmap),
+                                               ((i+1) << (CHUNK_BLOCK_SHIFT(bitmap)) >= start)
+                                );
                         bit_cnt++;
+                        set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
                 }
         }
 
@@ -1424,7 +1432,7 @@ void bitmap_close_sync(struct bitmap *bitmap)
         }
 }
 
-static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset)
+static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int needed)
 {
         /* For each chunk covered by any of these sectors, set the
          * counter to 1 and set resync_needed.  They should all
@@ -1441,7 +1449,7 @@ static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset)
         }
         if (! *bmc) {
                 struct page *page;
-                *bmc = 1 | NEEDED_MASK;
+                *bmc = 1 | (needed?NEEDED_MASK:0);
                 bitmap_count_page(bitmap, offset, 1);
                 page = filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap));
                 set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
@@ -1517,6 +1525,7 @@ int bitmap_create(mddev_t *mddev)
         unsigned long pages;
         struct file *file = mddev->bitmap_file;
         int err;
+        sector_t start;
 
         BUG_ON(sizeof(bitmap_super_t) != 256);
 
@@ -1581,7 +1590,12 @@ int bitmap_create(mddev_t *mddev)
 
         /* now that we have some pages available, initialize the in-memory
          * bitmap from the on-disk bitmap */
-        err = bitmap_init_from_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;
+        err = bitmap_init_from_disk(bitmap, start);
 
         if (err)
                 return err;