Re: PROBLEM: Attempting to create subdirectory returns error after removing parent directory with child entries using rmdir()

[Bastian Arjun Shajit <bastian-yrGDUoBaLx3QT0dZR+AlfA@public.gmane.org>]

Hi Steve,

On 22.06.2016 23:23, Shajit Bastian wrote:
> Hi Steve,
>
> On 22.06.2016 18:48, Steve French wrote:
>> Does this patch which is in recent kernels change the behavior:
>>
>> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/fs/cifs?id=897fba1172d637d344f009d700f7eb8a1fa262f1
> I think this patch might solve the problem. I will test and update asap.

I applied the patch and tested again. This solves the problem. Thanks you.

Br,
Bastian
>
> Br,
> Bastian
>> On Wed, Jun 22, 2016 at 8:35 AM, Bastian Arjun Shajit
>> <bastian-yrGDUoBaLx3QT0dZR+AlfA@public.gmane.org> wrote:
>>> Hi,
>>>
>>> We encountered the following error or unexpected behaviour when
>>> following the steps given below:
>>>
>>> 1. Mount the remote share exported by either windows or samba using the
>>> following command:
>>> sudo mount -t cifs -o
>>> port=445,vers=2.1,username=<username>,password=password,noperm,actimeo=0
>>> //<IP>/SH1 /mnt/test && cd /mnt/test
>>>
>>> 2. Run the attached program on the mounted share. You should see the
>>> following output:
>>>
>>> **bastian@gutbark-UX32VD:/mnt/test$ /KVMstorage/cifs_dir_bug
>>> ** [4428] mkdir ./parentdir 0777
>>> ** [4428] mkdir ./parentdir/sub.0 0777
>>> ** [4428] chdir ./parentdir/sub.0
>>> ** [4428] rmdir /mnt/test/parentdir
>>> !! [4428] stat() /mnt/test/parentdir Success
>>> ** [4428] mkdir /mnt/test/parentdir/sub.1
>>> !! [4428] mkdir /mnt/test/parentdir/sub.1 failed(No such file or directory)
>>>
>>> You can see from the above logs, stat of parentdir is successful but
>>> creating a new child directory under the parent fails.
>>>
>>> The attached program does the following:
>>> a. Create a parent directory
>>> b. Create a sub-directory under the parent.
>>> c. Change dir to sub-directory
>>> d. Now delete the parent directory using absolute path from the cifs
>>> client using "rmdir".
>>>
>>> The POSIX behaviour for rmdir() is that if there are entries other than
>>> "." and ".." it must return ENOTEMPTY error. But as per SMB2 protocol
>>> specification, we delete a directory by:
>>> a. Open directory with "Delete on Close" Flag set in the "CreateOptions"
>>> field of the SMB2 CREATE request.
>>> b. Close the open handle returned in the response for the previous request.
>>>
>>> As per SMB2 specification, the SMB2 close will always return NT status
>>> STATUS_SUCCESS for removing the directory even if the directory has
>>> child entries, but the server does not delete the directory itself.
>>>
>>> 4. Manually running "tree" on the mounted share shows the following:
>>> bastian@gutbark-UX32VD:/mnt/test$ tree
>>> .
>>> |__parentdir
>>> 1 directory, 0 files
>>>
>>> We clearly see above that the parent directory does not show any child
>>> directories.
>>>
>>> 5.Now we unmount and mount the remote share again
>>> bastian@gutbark-UX32VD:/mnt/test$ cd / && sudo umount /mnt/test
>>> bastian@gutbark-UX32VD:/KVMstorage/$ sudo mount -t cifs -o
>>> port=445,vers=2.1,username=<Username>,password=password,noperm,actimeo=0
>>> //<IP>/SH1 /mnt/test && cd /mnt/test
>>> bastian@gutbark-UX32VD:/mnt/test$ tree
>>> .
>>> |__parentdir
>>>              |__ sub.0
>>> 2 directories, 0 files//
>>>
>>> As you can see, remounting the remote share now displays a subdirectory
>>> which was not displayed in the earlier mount cycle.
>>>
>>> We used the following test setup for reproducing the above said issue:
>>> 1. Cifs client: Version = 2.06, Linux versions: Ubuntu, 3.19.8-ckt5 &
>>> 3.16.0-49-generic
>>> 2. Server: Windows 8.1 pro, Windows 7, Samba 4.1.6-Ubuntu.
>>> 3. Reproducible only on SMB2 protocol version.
>>>
>>> The issue was reproducible always on WIndows SMB server whereas on Samba
>>> server we were able to reproduce 1/2 times.
>>>
>>> We ran the same tests on CIFS client version: 2.08, Linux versions 4.4
>>> and 4.5 and we were unable to reproduce the issue.
>>>
>>> Br,
>>> Bastian
>>>
>>
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