btrfs: fix integer overflow in calc_reclaim_items_nr

Dave Jones hit a WARN_ON(nr < 0) in btrfs_wait_ordered_roots() with
v4.12-rc6.  This was because commit 70e7af244 made it possible for
calc_reclaim_items_nr() to return a negative number.  It's not really a
bug in that commit, it just didn't go far enough down the stack to find
all the possible 64->32 bit overflows.

This switches calc_reclaim_items_nr() to return a u64 and changes everyone
that uses the results of that math to u64 as well.

Reported-by: Dave Jones <davej@codemonkey.org.uk>
Fixes: 70e7af2 ("Btrfs: fix delalloc accounting leak caused by u32 overflow")
Signed-off-by: Chris Mason <clm@fb.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 5fe1ca8abc70..bee3edeea7a3 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -388,7 +388,7 @@ int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
         if (ret)
                 btrfs_err(fs_info, "kobj add dev failed %d", ret);
 
-        btrfs_wait_ordered_roots(fs_info, -1, 0, (u64)-1);
+        btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 
         /* force writing the updated state information to disk */
         trans = btrfs_start_transaction(root, 0);
@@ -507,7 +507,7 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
                 mutex_unlock(&dev_replace->lock_finishing_cancel_unmount);
                 return ret;
         }
-        btrfs_wait_ordered_roots(fs_info, -1, 0, (u64)-1);
+        btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
 
         trans = btrfs_start_transaction(root, 0);
         if (IS_ERR(trans)) {