[PATCH] md: always honour md bitmap being read from disk

The code currently will ignore the bitmap if the array seem to be in-sync.
This is wrong if the array is degraded, and probably wrong anyway.  If the
bitmap says some chunks are not in in-sync, and the superblock says everything
IS in sync, then something is clearly wrong, and it is safer to trust the
bitmap.

Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 23 insertions, 29 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 70bca955e0de..09d32db06d20 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -818,8 +818,7 @@ int bitmap_unplug(struct bitmap *bitmap)
         return 0;
 }
 
-static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset,
-        unsigned long sectors, int in_sync);
+static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset);
 /* * 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
@@ -828,7 +827,7 @@ static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset,
  *   previously kicked from the array, we mark all the bits as
  *   1's in order to cause a full resync.
  */
-static int bitmap_init_from_disk(struct bitmap *bitmap, int in_sync)
+static int bitmap_init_from_disk(struct bitmap *bitmap)
 {
         unsigned long i, chunks, index, oldindex, bit;
         struct page *page = NULL, *oldpage = NULL;
@@ -929,8 +928,7 @@ static int bitmap_init_from_disk(struct bitmap *bitmap, int in_sync)
                 }
                 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), 1, in_sync);
+                        bitmap_set_memory_bits(bitmap, i << CHUNK_BLOCK_SHIFT(bitmap));
                         bit_cnt++;
                 }
         }
@@ -1426,35 +1424,30 @@ void bitmap_close_sync(struct bitmap *bitmap)
         }
 }
 
-static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset,
-                                   unsigned long sectors, int in_sync)
+static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset)
 {
         /* For each chunk covered by any of these sectors, set the
-         * counter to 1 and set resync_needed unless in_sync.  They should all
+         * counter to 1 and set resync_needed.  They should all
          * be 0 at this point
          */
-        while (sectors) {
-                int secs;
-                bitmap_counter_t *bmc;
-                spin_lock_irq(&bitmap->lock);
-                bmc = bitmap_get_counter(bitmap, offset, &secs, 1);
-                if (!bmc) {
-                        spin_unlock_irq(&bitmap->lock);
-                        return;
-                }
-                if (! *bmc) {
-                        struct page *page;
-                        *bmc = 1 | (in_sync? 0 : NEEDED_MASK);
-                        bitmap_count_page(bitmap, offset, 1);
-                        page = filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap));
-                        set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
-                }
+
+        int secs;
+        bitmap_counter_t *bmc;
+        spin_lock_irq(&bitmap->lock);
+        bmc = bitmap_get_counter(bitmap, offset, &secs, 1);
+        if (!bmc) {
                 spin_unlock_irq(&bitmap->lock);
-                if (sectors > secs)
-                        sectors -= secs;
-                else
-                        sectors = 0;
+                return;
         }
+        if (! *bmc) {
+                struct page *page;
+                *bmc = 1 | NEEDED_MASK;
+                bitmap_count_page(bitmap, offset, 1);
+                page = filemap_get_page(bitmap, offset >> CHUNK_BLOCK_SHIFT(bitmap));
+                set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
+        }
+        spin_unlock_irq(&bitmap->lock);
+
 }
 
 /*
@@ -1565,7 +1558,8 @@ 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, mddev->recovery_cp == MaxSector);
+        err = bitmap_init_from_disk(bitmap);
+
         if (err)
                 return err;