md-cluster: fix bitmap sub-offset in bitmap_read_sb

bitmap_read_sb is modifying mddev->bitmap_info.offset. This works for
the first bitmap read. However, when multiple bitmaps need to be opened
by the same node, it ends up corrupting the offset. Fix it by using a
local variable.

Also, bitmap_read_sb is not required in bitmap_copy_from_slot since
it is called in bitmap_create. Remove bitmap_read_sb().

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: NeilBrown <neilb@suse.com>

1 files changed, 4 insertions, 7 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index a4ab51350f40..1b9c2df718c6 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -559,6 +559,7 @@ static int bitmap_read_sb(struct bitmap *bitmap)
         unsigned long sectors_reserved = 0;
         int err = -EINVAL;
         struct page *sb_page;
+        loff_t offset = bitmap->mddev->bitmap_info.offset;
 
         if (!bitmap->storage.file && !bitmap->mddev->bitmap_info.offset) {
                 chunksize = 128 * 1024 * 1024;
@@ -585,9 +586,9 @@ re_read:
                 bm_blocks = ((bm_blocks+7) >> 3) + sizeof(bitmap_super_t);
                 /* to 4k blocks */
                 bm_blocks = DIV_ROUND_UP_SECTOR_T(bm_blocks, 4096);
-                bitmap->mddev->bitmap_info.offset += bitmap->cluster_slot * (bm_blocks << 3);
+                offset = bitmap->mddev->bitmap_info.offset + (bitmap->cluster_slot * (bm_blocks << 3));
                 pr_info("%s:%d bm slot: %d offset: %llu\n", __func__, __LINE__,
-                        bitmap->cluster_slot, (unsigned long long)bitmap->mddev->bitmap_info.offset);
+                        bitmap->cluster_slot, offset);
         }
 
         if (bitmap->storage.file) {
@@ -598,7 +599,7 @@ re_read:
                                 bitmap, bytes, sb_page);
         } else {
                 err = read_sb_page(bitmap->mddev,
-                                   bitmap->mddev->bitmap_info.offset,
+                                   offset,
                                    sb_page,
                                    0, sizeof(bitmap_super_t));
         }
@@ -1875,10 +1876,6 @@ int bitmap_copy_from_slot(struct mddev *mddev, int slot,
         if (IS_ERR(bitmap))
                 return PTR_ERR(bitmap);
 
-        rv = bitmap_read_sb(bitmap);
-        if (rv)
-                goto err;
-
         rv = bitmap_init_from_disk(bitmap, 0);
         if (rv)
                 goto err;