On Wed, Jan 03, 2007 at 08:31:32PM +0100, Mikulas Patocka wrote: > >>>>I didn't hardlink directories, I just patched stat, lstat and fstat to > >>>>always return st_ino == 0 --- and I've seen those failures. These > >>>>failures > >>>>are going to happen on non-POSIX filesystems in real world too, very > >>>>rarely. > >>> > >>>I don't want to spoil your day but testing with st_ino==0 is a bad choice > >>>because it is a special number. Anyway, one can only find breakage, > >>>not prove that all the other programs handle this correctly so this is > >>>kind of pointless. > >>> > >>>On any decent filesystem st_ino should uniquely identify an object and > >>>reliably provide hardlink information. The UNIX world has relied upon > >>>this > >>>for decades. A filesystem with st_ino collisions without being hardlinked > >>>(or the other way around) needs a fix. > >> > >>... and that's the problem --- the UNIX world specified something that > >>isn't implementable in real world. > > > >Sure it is. Numerous popular POSIX filesystems do that. There is a lot of > >inode number space in 64 bit (of course it is a matter of time for it to > >jump to 128 bit and more) > > If the filesystem was designed by someone not from Unix world (FAT, SMB, > ...), then not. And users still want to access these filesystems. They can. Hey, it's not perfect but who expects FAT/SMB to be "perfect" anyway? > > 64-bit inode numbers space is not yet implemented on Linux --- the problem > is that if you return ino >= 2^32, programs compiled without > -D_FILE_OFFSET_BITS=64 will fail with stat() returning -EOVERFLOW --- this > failure is specified in POSIX, but not very useful. hmm, checking iunique(), ino_t, __kernel_ino_t... I see. Pity. So at some point in time we may need a sort of "ino64" mount option to be able to switch to a 64 bit number space on mount basis. Or (conversely) refuse to mount without that option if we know there are >32 bit st_ino out there. And invent iunique64() and use that when "ino64" specified for FAT/SMB/... when those filesystems haven't been replaced by a successor by that time. At that time probably all programs are either compiled with -D_FILE_OFFSET_BITS=64 (most already are because of files bigger than 2G) or completely 64 bit. -- Frank - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
