Merge branch 'for-linus-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs

Pull btrfs fixes from Chris Mason:
 "Some fixes from Omar and Dave Sterba for our new free space tree.

  This isn't heavily used yet, but as we move toward making it the new
  default we wanted to nail down an endian bug"

* 'for-linus-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs:
  btrfs: tests: uninline member definitions in free_space_extent
  btrfs: tests: constify free space extent specs
  Btrfs: expand free space tree sanity tests to catch endianness bug
  Btrfs: fix extent buffer bitmap tests on big-endian systems
  Btrfs: catch invalid free space trees
  Btrfs: fix mount -o clear_cache,space_cache=v2
  Btrfs: fix free space tree bitmaps on big-endian systems

1 files changed, 11 insertions, 1 deletions

diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index ac5eacd3055b..db4c253f8011 100644
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -239,7 +239,17 @@ struct btrfs_ioctl_fs_info_args {
  * Used by:
  * struct btrfs_ioctl_feature_flags
  */
-#define BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE (1ULL << 0)
+#define BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE         (1ULL << 0)
+/*
+ * Older kernels (< 4.9) on big-endian systems produced broken free space tree
+ * bitmaps, and btrfs-progs also used to corrupt the free space tree (versions
+ * < 4.7.3).  If this bit is clear, then the free space tree cannot be trusted.
+ * btrfs-progs can also intentionally clear this bit to ask the kernel to
+ * rebuild the free space tree, however this might not work on older kernels
+ * that do not know about this bit. If not sure, clear the cache manually on
+ * first mount when booting older kernel versions.
+ */
+#define BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID   (1ULL << 1)
 
 #define BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF    (1ULL << 0)
 #define BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL   (1ULL << 1)