Re: [fuse-devel] utimensat fails to update ctime

[OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>]

Eric Blake <ebb9@byu.net> writes:

> By the way, is there any reliable way, other than uname() and checking for
> a minimum kernel version, to tell if all file systems will properly
> support UTIME_OMIT?

Um... sorry, I don't know. And it might be hard to detect efficiently if
the workaround is enough efficient like one fstat() syscall (Pass fd to
kernel.  I.e. just read from cached inode).

> For coreutils 8.3, we will be inserting a workaround where instead of
> using UTIME_OMIT, we call fstatat() in advance of utimensat() and pass
> the original timestamp down.  But it would be nice to avoid the
> penalty of the extra stat if there were a reliable way to ensure that,
> regardless of file system, the use of UTIME_OMIT will be honored.
> After all, coreutils wants touch(1) to work regardless of how old the
> user's kernel and file system drivers are.

Or it would depend on coreutils policy though, personally I think it's
ok that it ignores the bug as known fs bug, otherwise coreutils would
need to collect workarounds on several filesystems of several OSes.

Thanks.
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>