libdiskfs: Add relatime support

* doc/hurd.texi (diskfs_set_node_atime): Document relatime behavior.
* libdiskfs/diskfs.h (diskfs_set_node_atime): Likewise.
* libdiskfs/init-init.c (_diskfs_relatime): Add variable.
* libdiskfs/file-statfs.c (ST_RELATIME): Define if not defined already.
(diskfs_S_file_statfs): Report ST_RELATIME when _diskfs_relatime is set.
* libdiskfs/node-times.c (atime_should_update): New function.
(diskfs_set_node_atime): Document relatime behavior. Call
atime_should_update instead of reading _diskfs_noatime.
* libdiskfs/opts-common.c (diskfs_common_options): Add --strictatime and
-R/--relatime options.
* libdiskfs/opts-std-runtime.c (struct parse_hook): Add relatime field.
(set_opts): Set _diskfs_relatime from relatime field.
(parse_opt): Parse -R option.
* libdiskfs/opts-std-startup.c (parse_startup_opt): Parse -R option.
* libdiskfs/priv.h (_diskfs_relatime): Declare variable.
(atime_should_update): Declare function.
* libdiskfs/opts-append-std.c (diskfs_append_std_options): Add reporting
--relatime option.
* libdiskfs/conch-fetch.c (iohelp_fetch_shared_data): Call
atime_should_update instead of reading _diskfs_noatime.
* libdiskfs/rdwr-internal.c (_diskfs_rdwr_internal): Likewise.

1 files changed, 3 insertions, 1 deletions

diff --git a/doc/hurd.texi b/doc/hurd.texi
index 038d80b6..c3442c8c 100644
--- a/doc/hurd.texi
+++ b/doc/hurd.texi
@@ -3973,7 +3973,9 @@ disk allocation strategies.
 
 @deftypefun void diskfs_set_node_atime (@w{struct node *@var{np}})
 If disk is not readonly and the noatime option is not enabled, set
-@code{@var{np}->dn_set_atime}.
+@code{@var{np}->dn_set_atime}. If relatime is enabled, only set
+@code{@var{np}->dn_set_atime} if the atime has not been updated today,
+or if ctime or mtime are more recent than atime.
 @end deftypefun
 
 @deftypefun void diskfs_set_node_times (@w{struct node *@var{np}})