filesystems mounted within an SMB share and REPARSE_TAG_MOUNT_POINT

[Jeremy Allison]

On Wed, Mar 01, 2023 at 04:46:06PM -0500, Andrew Walker via samba-technical wrote:
>
>I'm still slowly investigating things related to this, but it's pretty
>clear that nesting submounts in Windows Server can cause problems for the
>Linux SMB client
>
> ```
>PS C:\SHARE> fsutil file queryFileID SUBDS/foo
>File ID is 0x00000000000000000001000000000026
>PS C:\SHARE> fsutil file queryFileID .\SUBDS3\TESTFOLDER\
>File ID is 0x00000000000000000001000000000026
>```
>
>I generated directories with duplicate file ids (SHARE\SUBDS\foo and
>SHARE\SUBDS3\TESTFOLDER) within the SMB share in Windows. The Linux SMB
>client gives them the same inode number.
>
>```
>root at truenas[/tmpcifs]# stat SUBDS/foo
>  File: SUBDS/foo
>  Size: 0         Blocks: 0          IO Block: 1048576 directory
>Device: 5eh/94d Inode: 281474976710694  Links: 2
>Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
>Access: 2023-03-01 13:13:42.425159200 -0800
>Modify: 2023-03-01 13:13:42.425159200 -0800
>Change: 2023-03-01 13:13:42.425159200 -0800
> Birth: 2023-02-22 10:49:37.331907600 -0800
>
>root at truenas[/tmpcifs]# stat SUBDS3/TESTFOLDER
>  File: SUBDS3/TESTFOLDER
>  Size: 0         Blocks: 0          IO Block: 1048576 directory
>Device: 5eh/94d Inode: 281474976710694  Links: 2
>Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
>Access: 2023-03-01 12:25:56.283589300 -0800
>Modify: 2023-03-01 12:25:56.268165700 -0800
>Change: 2023-03-01 12:25:56.268165700 -0800
> Birth: 2023-03-01 11:48:09.617084100 -0800
>```
>
>I think handling for submounts will probably need to be fixed in Linux
>clients as well.

Great catch ! Thanks for forwarding that to the Linux client lists.