Additional documentation for XFS store.

lib/obuilder.ml

@@ -12,6 +12,7 @@ module Docker = Docker
 module Btrfs_store = Btrfs_store
 module Zfs_store = Zfs_store
 module Rsync_store = Rsync_store
+module Xfs_store = Xfs_store
 module Store_spec = Store_spec
 module Docker_store = Docker_store
 

lib/xfs_store.mli

@@ -1,7 +1,11 @@
-(** Store build results using rsync. *)
+(** Store builds results using {b XFS} with the reflink feature.
+
+    XFS is intended to behave consistently as it scales to large storage and many files, modern-day XFS was originally from SGI Irix. This store uses the {b reflink} feature in XFS to share blocks between files, to support fast snapshots of directory trees and deduplicate file data for more efficient use of storage hardware.
+
+    For more details on the XFS implementation see {{: https://blogs.oracle.com/linux/post/xfs-data-block-sharing-reflink} XFS - Data Block Sharing (Reflink)} and {{: https://blogs.oracle.com/linux/post/upcoming-xfs-work-in-linux-v48-v49-and-v410-by-darrick-wong} Upcoming XFS Work in Linux v4.8 v4.9 and v4.10+}. *)
 
 include S.STORE
 
 val create : path:string -> t Lwt.t
-(** [create ~path] creates a new xfs store where everything will
+(** [create ~path] creates a new XFS store where everything will
     be stored under [path]. *)