• David Howells's avatar
    [PATCH] VFS: Make filldir_t and struct kstat deal in 64-bit inode numbers · afefdbb2
    David Howells authored
    
    
    These patches make the kernel pass 64-bit inode numbers internally when
    communicating to userspace, even on a 32-bit system.  They are required
    because some filesystems have intrinsic 64-bit inode numbers: NFS3+ and XFS
    for example.  The 64-bit inode numbers are then propagated to userspace
    automatically where the arch supports it.
    
    Problems have been seen with userspace (eg: ld.so) using the 64-bit inode
    number returned by stat64() or getdents64() to differentiate files, and
    failing because the 64-bit inode number space was compressed to 32-bits, and
    so overlaps occur.
    
    This patch:
    
    Make filldir_t take a 64-bit inode number and struct kstat carry a 64-bit
    inode number so that 64-bit inode numbers can be passed back to userspace.
    
    The stat functions then returns the full 64-bit inode number where
    available and where possible.  If it is not possible to represent the inode
    number supplied by the filesystem in the field provided by userspace, then
    error EOVERFLOW will be issued.
    
    Similarly, the getdents/readdir functions now pass the full 64-bit inode
    number to userspace where possible, returning EOVERFLOW instead when a
    directory entry is encountered that can't be properly represented.
    
    Note that this means that some inodes will not be stat'able on a 32-bit
    system with old libraries where they were before - but it does mean that
    there will be no ambiguity over what a 32-bit inode number refers to.
    
    Note similarly that directory scans may be cut short with an error on a
    32-bit system with old libraries where the scan would work before for the
    same reasons.
    
    It is judged unlikely that this situation will occur because modern glibc
    uses 64-bit capable versions of stat and getdents class functions
    exclusively, and that older systems are unlikely to encounter
    unrepresentable inode numbers anyway.
    
    [akpm: alpha build fix]
    Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
    Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
    Cc: Al Viro <viro@zeniv.linux.org.uk>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    afefdbb2
compat_linux.c 24.6 KB