[Samba] Debug file_new then open_file_ntcreate fails with doesn't exist

[Jeremy Allison]

On Tue, Jul 20, 2021 at 12:43:10PM -0700, Matthew Schumacher via samba wrote:
>On 7/16/21 2:25 PM, Jeremy Allison wrote:
>>On Fri, Jul 16, 2021 at 01:44:17PM -0700, Matthew Schumacher via 
>>samba wrote:
>>>On 7/16/21 12:12 PM, Jeremy Allison wrote:
>>>>>
>>>>>Anybody see this before or thoughts on work arounds?  I'm 
>>>>>running the latest stable samba 4.14.6 in AD mode.
>>>>
>>>>We haven't seen that, it looks strange. I take it there's no
>>>>other application running that could race and delete ?
>>>>
>>>>Can you check the recently release 4.15.rc1 to see if it's
>>>>something that got fixed ? There have been *lots* of changes
>>>>in the pathname area between 4.14.x -> 4.15.rc1.
>>><snip>
>>Oh hang on a minute. Look at that create_disposition = 0x1.
>>
>>This means:
>>
>>#define FILE_OPEN 1                  /* File exists open. File not 
>>exist fail. */
>>
>>So smbd is doing the right thing here. To create
>>a new file, create_disposition must be one of either:
>>
>>#define FILE_CREATE 2                   /* File exists fail. File 
>>not exist create. */
>>#define FILE_OPEN_IF 3                  /* File exists open. File 
>>not exist create. */
>>#define FILE_OVERWRITE_IF 5             /* File exists overwrite. 
>>File not exist create. */
>
>Hi Jermey,
>
>Thanks for looking at this.
>
>After fighting with it more, what I thought was the problem (some race 
>condition with a file being read right after creation) didn't end up 
>being the issue.  I noticed that whenever I restarted the linux server 
>it would work again which is super odd because restarting samba 
>wouldn't do anything to resolve it.  Given that the only thing that 
>really changes with a reboot is handled by the kernel, I decided to 
>upgrade the kernel from 4.19.171 to 5.10.52 thinking that the issue 
>might be in the kernel.  Sure enough, the issue goes away.
>
>Do you by chance know of any kernel issues that could cause this? I'm 
>not sure what I would be looking for in a kernel changelog that would 
>affect samba like this.

Not a clue I'm afraid. I'm glad it ended up working for you though !