[PATCH] md: Don't remove bitmap from md array when switching to read-only

While a read-only array doesn't not really need a bitmap, we should
not remove the bitmap when switching an array to read-only because
 a/ There is no code to re-add the bitmap which switching to read-write,
 b/ There is insufficient locking - the bitmap could be accessed while it is
    being removed.

Cc: Reuben Farrelly <reuben-lkml@reub.net>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 06dee51..653d4dc 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2689,14 +2689,6 @@ static int do_md_stop(mddev_t * mddev, int ro)
                        set_disk_ro(disk, 1);
        }
 
-       bitmap_destroy(mddev);
-       if (mddev->bitmap_file) {
-               atomic_set(&mddev->bitmap_file->f_dentry->d_inode->i_writecount, 1);
-               fput(mddev->bitmap_file);
-               mddev->bitmap_file = NULL;
-       }
-       mddev->bitmap_offset = 0;
-
        /*
         * Free resources if final stop
         */
@@ -2706,6 +2698,14 @@ static int do_md_stop(mddev_t * mddev, int ro)
                struct gendisk *disk;
                printk(KERN_INFO "md: %s stopped.\n", mdname(mddev));
 
+               bitmap_destroy(mddev);
+               if (mddev->bitmap_file) {
+                       atomic_set(&mddev->bitmap_file->f_dentry->d_inode->i_writecount, 1);
+                       fput(mddev->bitmap_file);
+                       mddev->bitmap_file = NULL;
+               }
+               mddev->bitmap_offset = 0;
+
                ITERATE_RDEV(mddev,rdev,tmp)
                        if (rdev->raid_disk >= 0) {
                                char nm[20];