[Bug 315782] Re: Change of capitalization in filenames on FAT32

[Jim Lieb]

It is correct that the kernel is that gating issue for making this
change.  There are technical issues that make the change difficult.  The
rename syscall is defined to be atomic to fix race and consistency
problems with the original link+unlink behavior.  Making an attempt to
fix it in userspace, such as glibc or the application(s) breaks this
requirement because the implementation would be equivalent to the
original link+unlink.  In addition, vfat requires an 8.3 alias name to
also be created for compatiblility with the even older FAT filesystem.
This makes it even more ugly.  The 8.3 alias can be hidden in the vfat
layer but it can have only one long name associated with it.  The layers
above don't know anything about this alias or the case insensitivity
because, for the multiple other filesystems, it doesn't have to.  All of
these issues are solvable problems but a correct solution would have to
invade all of the other filesystems and the upper (vfs) layer with case
sensitive/insensitive state to work.  This gets very ugly very fast.

The long and short of it is that the way UNIX/Linux handles case-
insensitive filesystems is a compromise and every compromise involves
giving up something.  Making an atomic rename work correctly and cleanly
in a pre-emptible, multi-cpu kernel where case sensitivity is the deeply
embedded rule requires some things to go over the side, the issue in
this bug being one of them.  All in all, the compromises UNIX/Linux has
had to make to accomodate these filesystems (VMS, MS, etc) have been
better than the ones these other systems have tried to make to
accomodate UNIX/Linux.

The chance of getting this change in the kernel is extremely slim on a
number of grounds.  The filesystem maintainers argued this down on
technical merit 10+ years ago and have no interest in reopening the
issue again.  Without their support, and by extension, Linus's support,
such a change would go nowhere.  Some things we just have to live with.


** Changed in: linux (Ubuntu)
       Status: Confirmed => Won't Fix

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Change of capitalization in filenames on FAT32
https://bugs.launchpad.net/bugs/315782
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