Who uses the 'nodev' flag in /proc/filesystems ???

[Neil Brown]

Hi, 
 I just noticed that the FS_REQUIRES_DEV flag is used for just two
 things in the kernel.

  1/ to place the text 'nodev' at the start of the line in
       /proc/filesystems
  2/ to tell nfsd that it is reasonably OK to use the s_dev field 
     in the superblock as a stable, unique identifier for the
     filesystem.

I have a filesystem I am playing with for which I am quite happy to
lose the second aspect of FS_REQUIRES_DEV (it does use a device, but
there could well be multiple devices, and the fs can migrate from one
device to another so s_dev is even less stable than normal).  However
I would like to understand the implications of losing the first aspect
of FS_REQUIRES_DEV before deciding whether to provide the flag or not.

Hence the question in the subject:

  Who uses the 'nodev' flag in /proc/filesystems?

Are there any known users of this flag?

Thanks,
NeilBrown

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