btrfs: convert extent_map.refs from atomic_t to refcount_t

refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index a59674c3e69e..ccfe9fe7754a 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -4196,7 +4196,7 @@ static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
                 if (em->generation <= test_gen)
                         continue;
                 /* Need a ref to keep it from getting evicted from cache */
-                atomic_inc(&em->refs);
+                refcount_inc(&em->refs);
                 set_bit(EXTENT_FLAG_LOGGING, &em->flags);
                 list_add_tail(&em->list, &extents);
                 num++;