When the linkat() syscall was added the flag parameter was added in the
last minute but it wasn't used so far.  The following patch should change
that.  My tests show that this is all that's needed.

If OLDNAME is a symlink setting the flag causes linkat to follow the
symlink and create a hardlink with the target.  This is actually the
behavior POSIX demands for link() as well but Linux wisely does not do
this.  With this flag (which will most likely be in the next POSIX
revision) the programmer can choose the behavior, defaulting to the safe
variant.  As a side effect it is now possible to implement a
POSIX-compliant link(2) function for those who are interested.

  touch file
  ln -s file symlink

  linkat(fd, "symlink", fd, "newlink", 0)
    -> newlink is hardlink of symlink

  linkat(fd, "symlink", fd, "newlink", AT_SYMLINK_FOLLOW)
    -> newlink is hardlink of file

The value of AT_SYMLINK_FOLLOW is determined by the definition we already
use in glibc.
Signed-off-by: NUlrich Drepper <drepper@redhat.com>
Acked-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Here is a series of patches which introduce in total 13 new system calls
which take a file descriptor/filename pair instead of a single file
name.  These functions, openat etc, have been discussed on numerous
occasions.  They are needed to implement race-free filesystem traversal,
they are necessary to implement a virtual per-thread current working
directory (think multi-threaded backup software), etc.

We have in glibc today implementations of the interfaces which use the
/proc/self/fd magic.  But this code is rather expensive.  Here are some
results (similar to what Jim Meyering posted before).

The test creates a deep directory hierarchy on a tmpfs filesystem.  Then
rm -fr is used to remove all directories.  Without syscall support I get
this:

real    0m31.921s
user    0m0.688s
sys     0m31.234s

With syscall support the results are much better:

real    0m20.699s
user    0m0.536s
sys     0m20.149s

The interfaces are for obvious reasons currently not much used.  But they'll
be used.  coreutils (and Jeff's posixutils) are already using them.
Furthermore, code like ftw/fts in libc (maybe even glob) will also start using
them.  I expect a patch to make follow soon.  Every program which is walking
the filesystem tree will benefit.
Signed-off-by: NUlrich Drepper <drepper@redhat.com>
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@ftp.linux.org.uk>
Acked-by: NIngo Molnar <mingo@elte.hu>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

In ia64 kernel, the O_LARGEFILE flag is forced when opening a file.  This
is problematic for execution of 32 bit processes, which are not largefile
aware, either by SW emulation or by HW execution.

For such processes, the problem is two-fold:

1) When trying to open a file that is larger than 4G
   the operation should fail, but it's not
2) Writing to offset larger than 4G should fail, but
   it's not

The proposed patch takes advantage of the way 32 bit processes are
identified in ia64 systems.  Such processes have PER_LINUX32 for their
personality.  With the patch, the ia64 kernel will not enforce the
O_LARGEFILE flag if the current process has PER_LINUX32 set.  The behavior
for all other architectures remains unchanged.
Signed-off-by: NYoav Zach <yoav.zach@intel.com>
Acked-by: NTony Luck <tony.luck@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!