btrfs: switch inode_cache option handling to pending changes

The pending mount option(s) now share namespace and bits with the normal
options, and the existing one for (inode_cache) is unset unconditionally
at each transaction commit.

Introduce a separate namespace for pending changes and enhance the
descriptions of the intended change to use separate bits for each
action.

Signed-off-by: David Sterba <dsterba@suse.cz>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index f30b061..1c9157e 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2098,7 +2098,6 @@
 #define BTRFS_MOUNT_CHECK_INTEGRITY_INCLUDING_EXTENT_DATA (1 << 21)
 #define BTRFS_MOUNT_PANIC_ON_FATAL_ERROR	(1 << 22)
 #define BTRFS_MOUNT_RESCAN_UUID_TREE	(1 << 23)
-#define	BTRFS_MOUNT_CHANGE_INODE_CACHE	(1 << 24)
 
 #define BTRFS_DEFAULT_COMMIT_INTERVAL	(30)
 #define BTRFS_DEFAULT_MAX_INLINE	(8192)
@@ -2131,6 +2130,9 @@
  * transaction commit)
  */
 
+#define BTRFS_PENDING_SET_INODE_MAP_CACHE	(0)
+#define BTRFS_PENDING_CLEAR_INODE_MAP_CACHE	(1)
+
 #define btrfs_test_pending(info, opt)	\
 	test_bit(BTRFS_PENDING_##opt, &(info)->pending_changes)
 #define btrfs_set_pending(info, opt)	\