Re: [PATCH 3/3] ovl: redirect on rename-dir

On Sun, Nov 13, 2016 at 12:00 PM, Amir Goldstein [off-list ref] wrote:

On Fri, Nov 11, 2016 at 12:39 AM, Miklos Szeredi [off-list ref] wrote:

quoted

New version is at:

git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs.git #redirect

News:
- it actually should work in all cases
- when rename is not cross directory, just store the new name instead
of a full path, as suggested by Amir
- when redirect path is too long fall back to EXDEV (the max length
should probably be a module param)

Looks goods, except for the case of change from relative to absolute
redirect of the victim dentry. IIUC, ovl_set_redirect() will return immediately
because ovl_dentry_is_redirect() and will not get to setting the absolute
redirect.

I added some more tests to catch this problem at:
https://github.com/amir73il/unionmount-testsuite.git #ovl_rename_dir

In the new version, upper recycling is optional and you can set a bound
to the number of layers. This is needed to catch the bug because the
scenario is:
- Rename populated dir in same dir
- Move the populated dir to another dir
- Re-mount
- Populated dir is empty

The following test run demonstrates it:

$ sudo ./run --ov=0 rename-move-dir
...
TEST rename-move-dir.py:37: Rename populated dir and move into another
 ./run --rename /mnt/a/dir102 /mnt/a/dir102x
 ./run --rename /mnt/a/dir102 /mnt/a/dir102x -E ENOENT
 ./run --rename /mnt/a/dir102x /mnt/a/empty102/dir102
 ./run --rename /mnt/a/dir102x /mnt/a/empty102/dir102 -E ENOENT
 ./run --open-file /mnt/a/dir102 -r -d -E ENOENT
 ./run --open-file /mnt/a/dir102x -r -d -E ENOENT
 ./run --open-file /mnt/a/empty102/dir102 -r -d
/mnt/a/empty102/dir102/a: File is missing


Amir.