1 files changed, 21 insertions, 7 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 41df4cda66e..2925219f088 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+ * This is used when reading an out-of-date bitmap...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;