Re: [RFC PATCH 0/4] 9pfs: Add 9pfs support for Windows host

[Christian Schoenebeck <qemu_oss@crudebyte.com>]

On Dienstag, 19. April 2022 13:10:40 CEST Shi, Guohuai wrote:
> Hi All,
> 
> I just finished a basic PoC for mapped-file.
> It works! I think I can also support "security_model=map-xattr" by NTFS
> ADS.

Slick!
 
> However, I got a limitation of MinGW:
> 
> https://github.com/mirror/mingw-w64/blob/master/mingw-w64-crt/misc/dirent.c#
> L290
>  
> MinGW can not handle seekdir() while the directory has changed.
> That means, if run command like "rm -rf *", MinGW may not delete all files.
> "rm -rf *" need to call readdir()(and call seekdir() in 9P) and unlink(),
> and MinGW's seekdir() may seek directory to wrong directory entry index. 
> I am considering to change 9PFS readdir() implement on Windows host, to fix
> this problem.

To avoid history repeating [1]: please do not attempt to address this in 9p.c!
That file is the controller portion of 9p server and must remain fs-agnostic.
Such kind of issue should rather be addressed on fs driver level
(e.g. 9p-local.c, 9p-util-windows.c).

I.e. don't do it like this:
[1] https://lore.kernel.org/all/20211122004913.20052-1-wwcohen@gmail.com/T/#m734f405973768e43ce3ed7550bd21809abb25813

Best regards,
Christian Schoenebeck