On Wed, Jun 03, 2020 at 09:56:13AM +0800, Xiao Yang wrote: > On 2020/6/3 2:14, Darrick J. Wong wrote: > > On Tue, Jun 02, 2020 at 04:51:48PM +0800, Xiao Yang wrote: > > > On 2020/4/14 0:30, Darrick J. Wong wrote: > > > > This might be a good time to introduce a few new helpers: > > > > > > > > _require_scratch_dax ("Does $SCRATCH_DEV support DAX?") > > > > _require_scratch_dax_mountopt ("Does the fs support the DAX mount options?") > > > > _require_scratch_daX_iflag ("Does the fs support FS_XFLAG_DAX?") > > > Hi Darrick, > > > > > > Now, I am trying to introduce these new helpers and have some questions: > > > 1) There are five testcases related to old dax implementation, should we > > > only convert them to new dax implementation or make them compatible with old > > > and new dax implementation? > > > > What is the 'old' DAX implementation? ext2 XIP? > Hi Darrick, > > Thanks for your quick feedback. > > Right, the 'old' DAX implementation means old dax mount option(i.e. -o dax) > > Compare new and old dax mount option on ext4 and xfs, is the following logic > right? > -o dax=always == -o dax > -o dax=never == without dax > -o dax=inode == nothing No. -o dax=always is the same as -o dax. dax=inode was and still is the behavior you got with no option at all. -o dax=never is a new option. > Of course, we should uses new option if ext4/xfs supports new dax mount > option on distros. But should we fallback to use old option if ext4/xfs > doesn't support new dax mount option on some old distros? > btw: > it seems hard for testcases to use two different sets of mount options(i.e. > old and new) so do you have any suggestion? Try dax=never, it should work on any type of storage device if the kernel implements the "new" mount options at all. --D > > > > > 2) I think _require_xfs_io_command "chattr" "x" is enough to check if fs > > > supports FS_XFLAG_DAX. Is it necessary to add _require_scratch_dax_iflag()? > > > like this: > > > _require_scratch_dax_iflag() > > > { > > > _require_xfs_io_command "chattr" "x" > > > } > > > > I suggested that list based on the major control knobs that will be > > visible to userspace programs. Even if this is just a one-line helper, > > its name is useful for recognizing which of those knobs we're looking > > for. > > > > Yes, you could probably save a trivial amount of time by skipping one > > iteration of bash function calling, but now everyone has to remember > > that the xfs_io chattr "x" flag means the dax inode flag, and not > > confuse it for chmod +x or something else. > > Got it, thanks for your detailed explanation. > > Best Regards, > Xiao Yang > > > > --D > > > > > Best Regards, > > > Xiao Yang > > > > > > > > > > > > . > > > > >