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, 11 insertions, 0 deletions

diff --git a/libdiskfs/priv.h b/libdiskfs/priv.h
index 5be7c2b5..420323dd 100644
--- a/libdiskfs/priv.h
+++ b/libdiskfs/priv.h
@@ -38,6 +38,10 @@ extern int _diskfs_nosuid, _diskfs_noexec;
 /* This relaxes the requirement to set `st_atim'.  */
 extern int _diskfs_noatime;
 
+/* Will set `st_atim' if it has not been updated in 24 hours or
+   if `st_ctim' or `st_mtim' are younger than `st_atim'.  */
+extern int _diskfs_relatime;
+
 /* This enables SysV style group behaviour.  New nodes inherit the GID
    of the user creating them unless the SGID bit is set of the parent
    directory.  */
@@ -98,6 +102,13 @@ void _diskfs_control_clean (void *);
    links, then request soft references to be dropped.  */
 void _diskfs_lastref (struct node *np);
 
+/* If the disk is not readonly and noatime is not set, then check relatime
+   conditions: if either `np->dn_stat.st_mtim.tv_sec' or
+   `np->dn_stat.st_ctim.tv_sec' is greater than `np->dn_stat.st_atim.tv_sec',
+   or if the atime is greater than 24 hours old, return true.
+   */
+int atime_should_update (struct node *np);
+
 /* Number of outstanding PT_CTL ports. */
 extern int _diskfs_ncontrol_ports;