Date: Sat, 22 Nov 2014 09:23:41 -0800 From: Kirk McKusick <mckusick@mckusick.com> To: Konstantin Belousov <kostikbel@gmail.com> Cc: FreeBSD Filesystems <freebsd-fs@freebsd.org> Subject: Re: RFC: patch to make d_fileno 64bits Message-ID: <201411221723.sAMHNfs6005778@chez.mckusick.com> In-Reply-To: <20141122153427.GW17068@kib.kiev.ua>
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> Date: Sat, 22 Nov 2014 17:34:27 +0200 > From: Konstantin Belousov <kostikbel@gmail.com> > To: Rick Macklem <rmacklem@uoguelph.ca> > Subject: Re: RFC: patch to make d_fileno 64bits > Cc: FreeBSD Filesystems <freebsd-fs@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? Kirk
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