Re: xattr hash error in 4.13-rc with overlayfs over ext4

From: Miklos Szeredi
Date: Thu Jul 27 2017 - 15:36:26 EST


On Thu, Jul 27, 2017 at 9:28 PM, Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
> On Thu, Jul 27, 2017 at 8:20 PM, Tahsin Erdogan <tahsin@xxxxxxxxxx> wrote:
>> Hi Miklos,
>> I made a first attempt to reproduce the failure but did not get lucky.
>>
>>> Inode 3093, i_blocks is 16, should be 8. Fix<y>? yes
>> Does this inode correspond to foo, bar or a preexisting file?

The inode in question corresponds to the copy-up of bar into upper.

There's quite a lot overlayfs does in this apparently simple
operation, and that's probably why I've not been able to reproduce
without overlayfs (although admittedly I didn't try very hard).

It's basically the following:

- create tempfile
- copy data from lower/bar to work/index/XXX using reflink
- copy metadata
- set trusted.overlay.origin xattr
- set trusted.overlay.nlink xattr
- hardlink index file to upper/bar
- overwrite trusted.overlay.nlink with different value

And ther's also some attr and xattr setting going on for the upper directory.

Thanks,
Miklos