ディレクトリ配下でのNOATIME
bind mountのmntオプションは多重階層マウントのMS_RECのみで、他のmntオプションでのbind mountはできず、しかもmount後の属性変更はMS_SHARED | MS_PRIVATE | MS_SLAVE | MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE MS_UNBINDABLEのみで、MS_NOATIME等の他の属性変更はremountしなければならない。
サンプル
[root@localhost north]# mount /dev/sda7 /mnt7 [root@localhost north]# mount : /dev/sda7 on /mnt7 type ext3 (rw,relatime,data=ordered) [root@localhost mnt7]# mkdir dir1 [root@localhost mnt7]# mkdir dir2 [root@localhost mnt7]# mount --bind dir1 dir1 [root@localhost mnt7]# mount -o noatime,remount dir1 [root@localhost mnt7]# touch dir1/txt [root@localhost mnt7]# touch dir2/txt [root@localhost mnt7]# stat dir1/txt Access: 2017-08-21 18:38:25.572974386 +0900 Modify: 2017-08-21 18:38:25.572974386 +0900 Change: 2017-08-21 18:38:25.572974386 +0900 [root@localhost mnt7]# stat dir2/txt Access: 2017-08-21 18:38:31.035073249 +0900 Modify: 2017-08-21 18:38:31.035073249 +0900 Change: 2017-08-21 18:38:31.035073249 +0900 [root@localhost mnt7]# echo abc > dir1/txt [root@localhost mnt7]# stat dir1/txt Access: 2017-08-21 18:38:25.572974386 +0900 Modify: 2017-08-21 18:40:46.378544394 +0900 Change: 2017-08-21 18:40:46.378544394 +0900 [root@localhost mnt7]# cat dir1/txt abc [root@localhost mnt7]# stat dir1/txt Access: 2017-08-21 18:38:25.572974386 +0900 <- atime更新されない Modify: 2017-08-21 18:40:46.378544394 +0900 Change: 2017-08-21 18:40:46.378544394 +0900 [root@localhost mnt7]# echo abc > dir2/txt [root@localhost mnt7]# stat dir2/txt Access: 2017-08-21 18:38:31.035073249 +0900 Modify: 2017-08-21 18:40:53.605680804 +0900 Change: 2017-08-21 18:40:53.605680804 +0900 [root@localhost mnt7]# cat dir2/txt abc [root@localhost mnt7]# stat dir2/txt Access: 2017-08-21 18:42:28.256467310 +0900 <- atime更新 Modify: 2017-08-21 18:40:53.605680804 +0900 Change: 2017-08-21 18:40:53.605680804 +0900
カーネル
long do_mount(const char *dev_name, const char *dir_name,
const char *type_page, unsigned long flags, void *data_page)
{
struct path path;
int retval = 0;
int mnt_flags = 0;
if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
flags &= ~MS_MGC_MSK;
if (!dir_name || !*dir_name || !memchr(dir_name, 0, PAGE_SIZE))
return -EINVAL;
if (data_page)
((char *)data_page)[PAGE_SIZE - 1] = 0;
retval = kern_path(dir_name, LOOKUP_FOLLOW, &path);
if (retval)
return retval;
retval = security_sb_mount(dev_name, &path,
type_page, flags, data_page);
if (retval)
goto dput_out;
if (!(flags & MS_NOATIME))
mnt_flags |= MNT_RELATIME;
if (flags & MS_NOSUID)
mnt_flags |= MNT_NOSUID;
if (flags & MS_NODEV)
mnt_flags |= MNT_NODEV;
if (flags & MS_NOEXEC)
mnt_flags |= MNT_NOEXEC;
if (flags & MS_NOATIME)
mnt_flags |= MNT_NOATIME;
if (flags & MS_NODIRATIME)
mnt_flags |= MNT_NODIRATIME;
if (flags & MS_STRICTATIME)
mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME);
if (flags & MS_RDONLY)
mnt_flags |= MNT_READONLY;
flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE | MS_BORN |
MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT |
MS_STRICTATIME);
if (flags & MS_REMOUNT)
retval = do_remount(&path, flags & ~MS_REMOUNT, mnt_flags,
data_page);
else if (flags & MS_BIND)
retval = do_loopback(&path, dev_name, flags & MS_REC);
else if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE))
retval = do_change_type(&path, flags);
else if (flags & MS_MOVE)
retval = do_move_mount(&path, dev_name);
else
retval = do_new_mount(&path, type_page, flags, mnt_flags,
dev_name, data_page);
dput_out:
path_put(&path);
return retval;
}
