kernel news – 18.12.2012

Posted: December 18, 2012 in kernel

-Jan Kara announces ext3, UDF and quota fixes, Guenter Roeck has hwmon fixes for -rc1,
Greg KH announces kernels 3.0.57, 3.4.24, 3.6.11 and 3.7.1, Jens Axboe has core block IO
updates for 3.8:

Here are the core block IO bits for 3.8. The branch contains:

– The final version of the surprise device removal fixups from Bart.

– Don’t hide EFI partitions under advanced partition types. It’s fairly
wide spread these days. This is especially dangerous for systems that
have both msdos and efi partition tables, where you want to keep them
in sync.

– Cleanup of using -1 instead of the proper NUMA_NO_NODE

– Export control of bdi flusher thread CPU mask and default to using the
home node (if known) from Jeff.

– Export unplug tracepoint for MD.

– Core improvements from Shaohua. Reinstate the recursive merge, as the
original bug has been fixed. Add plugging for discard and also fix a
problem handling non pow-of-2 discard limits.

Please pull! There’s a trivial merge in block/blk-exec.c due to a fix
that went into 3.7-rc at a later point than -rc4 where this is based.

-Chris Mason with btrfs updates:

Hi everyone,

My for-linus branch has a big set of fixes and features:

git:// for-linus

This was against 3.7, and it has two easy conflicts against Linus’
current head. My -next branch has the resolutions, but Linus wills
surely fix these himself.

In terms of line count, most of the code comes from Stefan, who added
the ability to replace a single drive in place. This is different from
how btrfs normally replaces drives, and is much much much faster.

Josef is plowing through our synchronous write performance. This pull
request does not include the DIO_OWN_WAITING patch that was discussed on
the list, but it has a number of other improvements to cut down our
latencies and CPU time during fsync/O_DIRECT writes.

Miao Xie has a big series of fixes and is spreading out ordered
operations over more CPUs. This improves performance and reduces

I’ve put in fixes for error handling around hash collisions. These are
going back to individual stable kernels as I test against them.

Otherwise we have a lot of fixes and cleanups, thanks everyone! raid5/6
is being rebased against the device replacement code. I’ll have it
posted this Friday along with a nice series of benchmarks.

-Trond Myklebust has NFS client updates for 3.8, Neil Brown has a pull
request for md, and Olof Johansson has arm-soc fixes for 3.8:

This is a batch of fixes for arm-soc platforms, most of it is for OMAP
but there are others too (i.MX, Tegra, ep93xx). Fixes warnings, some
broken platforms and drivers, etc. A bit all over the map really.

-Eric W. Biederman has userspace interface updates:

This tree is against v3.7-rc3

The embarrasing oversights that Andy found have been corrected.

While small this set of changes is very significant with respect to
containers in general and user namespaces in particular. The user space
interface is now complete.

This set of changes adds support for unprivileged users to create user
namespaces and as a user namespace root to create other namespaces. The
tyrrany of supporting suid root preventing unprivileged users from using
cool new kernel features is broken.

This set of changes completes the work on setns, adding support for
the pid, user, mount namespaces.

This set of changes includes a bunch of basic pid namespace
cleanups/simplifications. Of particular significance is the rework of
the pid namespace cleanup so it no longer requires sending out tendrils
into all kinds of unexpected cleanup paths for operation. At least one
case of broken error handling is fixed by this cleanup.

The files under /proc//ns/ have been converted from regular files
to magic symlinks which prevents incorrect caching by the VFS, ensuring
the files always refer to the namespace the process is currently using
and ensuring that the ptrace_mayaccess permission checks are always

The files under /proc//ns/ have been given stable inode numbers so
it is now possible to see if different processes share the same

Through the David Miller’s net tree are changes to relax many of the
permission checks in the networking stack to allowing the user namespace
root to usefully use the networking stack. Similar changes for the
mount namespace and the pid namespace are coming through my tree.

Two small changes to add user namespace support were commited here
adn in David Miller’s -net tree so that I could complete the work on the
/proc//ns/ files in this tree.

Work remains to make it safe to build user namespaces and 9p, afs,
ceph, cifs, coda, gfs2, ncpfs, nfs, nfsd, ocfs2, and xfs so the Kconfig
guard remains in place preventing that user namespaces from being built
when any of those filesystems are enabled.

Future design work remains to allow root users outside of the initial
user namespace to mount more than just /proc and /sys.

-Jens Axboe updates block driver for 3.8:

Now that the core bits are in, here are the driver bits for 3.8. The
branch contains:

– A huge pile of drbd bits that were dumped from the 3.7 merge window.
Following that, it was both made perfectly clear that there is going to be
no more over-the-wall pulls and how the situation on individual pulls can
be improved.

– A few cleanups from Akinobu Mita for drbd and cciss.

– Queue improvement for loop from Lukas. This grew into adding a generic
interface for waiting/checking an even with a specific lock, allowing
this to be pulled out of md and now loop and drbd is also using it.

– A few fixes for xen back/front block driver from Roger Pau Monne.

– Partition improvements from Stephen Warren, allowing partiion UUID to be
used as an identifier.


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