RFC: patch to make d_fileno 64bits

Kirk McKusick mckusick at mckusick.com
Sat Nov 22 17:23:51 UTC 2014

> Date: Sat, 22 Nov 2014 17:34:27 +0200
> From: Konstantin Belousov <kostikbel at gmail.com>
> To: Rick Macklem <rmacklem at uoguelph.ca>
> Subject: Re: RFC: patch to make d_fileno 64bits
> Cc: FreeBSD Filesystems <freebsd-fs at freebsd.org>
> On Fri, Nov 21, 2014 at 06:45:52PM -0500, Rick Macklem wrote:
>> Kostik wrote:
>> What about old binaries that do getdirentries(2) and expect the old
>> structure with 32bit d_fileno or the linux compatibility stuff?
>> I suspect that there are some old staticly linked binaries out there
>> that does/expects the old getdirentries.
> No, let me restate my position.  There are two places for backward
> compatibility, one is in-kernel binary interface, and another is
> applications ,i.e. KBI and ABI.
> My opinion is that we must provide strict backward ABI compatibility
> to have even right to be called useful OS.  In particular, the syscalls
> like current getdirentries (156 and 196) providing 32-bit inonums, must
> be kept with their current binary contract.  The userspace issues do
> not end there, but this is not the currently discussed item.
> On the other hand, providing KBI compat for filesystems which work
> right now with 32bit inode numbers, should not be done. I.e., no
> VOP_READDIR_32INO(), all filesystems must be converted once.
> For syscalls 156 and 196 (and some more), the converter must be written
> in the vfs_syscalls.c which translates the new dirents into old dirents,
> at the level of best efforts.

I believe that we are all in agreement with you on the kernel approach
at this point.

Do we have a way of versioning libc so that we can have the old version
that provides the 32-bit version of the syscalls (156 and 196) along
with 32-bit higher-level functions like fts and friends and then a new
libc version that has the 64-bit version of the syscalls and other
higher-level functions?


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