Fix a sign bug causing invalid memory access in the ino_paths ioctl.

To see the problem, create many hardlinks to the same file (120 should do it),
then look up paths by inode with:

  ls -i
  btrfs inspect inode-resolve -v $ino /mnt/btrfs

I noticed the memory layout of the fspath->val data had some irregularities
(some unnecessary gaps that stop appearing about halfway),
so I'm not sure there aren't any bugs left in it.

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index f3187938e081..2bcbea3f6308 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -1186,7 +1186,7 @@ static char *ref_to_path(struct btrfs_root *fs_root,
         int slot;
         u64 next_inum;
         int ret;
-        s64 bytes_left = size - 1;
+        s64 bytes_left = ((s64)size) - 1;
         struct extent_buffer *eb = eb_in;
         struct btrfs_key found_key;
         int leave_spinning = path->leave_spinning;