On Wed, 2015-06-10 at 18:34 +0800, Dongsheng Yang wrote: > On 06/10/2015 06:25 PM, Artem Bityutskiy wrote: > > On Wed, 2015-06-10 at 18:10 +0800, Dongsheng Yang wrote: > >> On 06/10/2015 05:21 PM, Artem Bityutskiy wrote: > >>> On Wed, 2015-06-10 at 11:16 +0800, Dongsheng Yang wrote: > >>>> Therefore, I introduced a new option named as force_atime in ubifs. > >>>> That's a ubifs-dependent opiton and it works as a main switch, in > >>>> a higher level compared with atime and noatime. If force_atime, we > >>>> support the atime-related flags. Otherwise, we don't care about all of > >>>> them in flags and don't support atime anyway. > >>> > >>> How bad is it to just default to relatime like other file-systems do, > >>> comparing to what we have now? > >> > >> Ha, yes, that's a problem. I read it from wiki that the author think > >> it's bad for ubifs. But I did not do a measure about it. > > > > Since I am one of the authors, I think we were mostly looking at the > > full atime support, and did not really look at relatime. > > > >> In theory, yes, lots of writing would damage the flash. So I think > >> just make it optional to user is a flexible way to do it. Even we > >> want to make the default to relatime, I think it's better to keep > >> the compatibility for a period and provide a force_atime to user. > >> > >> When lots of users said "okey, we are mostly choosing force_atime in our > >> use cases.". I believe that's a safe way to make ubifs supporting > >> atime by default. > > > > Let me make a step back. So what I hear is that the problem is that you > > cannot find the original mount options. For example, when you see the > > MNT_RELATIME flag, you do not know whether it was specified by the user > > or it was VFS adding this flag. Is this correct? > > > > If it is correct, then I think we need to look at a VFS-level solution. > > If the above is the only problem, then I'd say that introducing a custom > > "force_atime" is a work-around for VFS limitations. > > That's correct. Yes, I really want to solve it in vfs at first. But > later, just submited this patch as a Problem-solved for us. Because I > thought the force_atime would disappear when we decide to support > atime by default in future. > > Besides a change in VFS would cause more discussion, after a trade-off, > I submitted this patch for ubifs. :) > > But yes, there is really, at leat, a TODO entry for VFS in this > scenario I think. If you think we need to do it rather than a > work-around as what this patch did. I will think a better way > in VFS for that. :) Yes, I think a custom mount option should be the last resort solution, for the case when other options failed. One way would be to push this assignment down to individual file-systems. Another way would be to have the original flags preserved and passed to the file-system. May be you can find a better way. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
