On Tue, May 23, 2017 at 4:19 PM, Chandan Rajendra <chandan@xxxxxxxxxxxxxxxxxx> wrote: > On Tuesday, May 23, 2017 6:27:42 PM IST Amir Goldstein wrote: >> On Wed, May 17, 2017 at 3:46 PM, Chandan Rajendra >> <chandan@xxxxxxxxxxxxxxxxxx> wrote: >> > On Wednesday, May 17, 2017 5:56:31 PM IST Amir Goldstein wrote: >> >> On Wed, May 17, 2017 at 2:42 PM, Chandan Rajendra >> >> >> There is actually one task that should be very simple to do and can also >> >> bring large benefit for many users. >> >> >> >> In his pull request for kernel 4.12 Miklos writes: >> >> "The biggest part of this is making st_dev/st_ino on the overlay behave like a >> >> normal filesystem ... future work will move the general case towards more sane >> >> behavior." >> >> https://marc.info/?l=linux-unionfs&m=149442365202823&w=2 >> >> >> >> The work towards constant st_dev/st_ino for the general case is not within my >> >> immediate scope of interest, but it shouldn't be hard. The basic idea was >> >> explained by Miklos here: >> >> https://marc.info/?l=linux-unionfs&m=149259338809700&w=2 >> >> >> > Amir, I will work on this task. Thanks for the guidance. >> > >> >> Hi Chandan, >> >> Were you able to figure out the scope of the task? >> Or didn't get around to it yet? > > Hi Amir, > > I spent time understanding current overlayfs code. I am now starting to > work on the problem statement. > > I should be able to post the patches to the mailing list by the end of > this week. > ... >> >> Please let me know if you intend to work on this soon, because I may be >> working on some parts of this task for a different feature. Chandan, My apologies for biting into your task, but as I wrote, I needed some parts for another feature, so implemented partial non-samefs support [1]. At least one of the 2 "relax same fs" patches was not as trivial as I indented for your task to be. You still need to implement this part: "The only extra thing needed compared to the samefs case is the allocation of dummy device numbers for lower layers." I also fixes unionmount-testsuite to check constant inode for non samefs [2]. The problem now is that all the test pass, although, as I wrote, I only implemented partial support for non samefs. This means that the test coverage for constant st_ino/st_dev is insufficient to validate the results of your task. Which is good, because it will give you an opportunity to enhance the tests :) It would be great if you could add validation to the fact that the overlay st_ino/ st_dev pair is different from the underlying inode st_ino/st_dev. That is not the case with upstream overlayfs and that is not the case with my partial work on non same fs constant st_ino. A new overlay xfstest, along the lines of overlay/017 that validates the uniqueness of st_ino/st_dev would also be a good idea. Thanks, Amir. [1] https://github.com/amir73il/linux/commits/ovl-constino [2] https://github.com/amir73il/unionmount-testsuite/commits/ovl-constino -- To unsubscribe from this list: send the line "unsubscribe linux-unionfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
