libm: Fix a typo in the MLINKS.
kernel - Fix signal masking race assertion panic w/vkernel

* sigsuspend() and pselect() record the old signal mask in order to
  allow an interrupting signal to run its handler before the old mask
  is restored.

* When multiple threads are present a race can ensue where another thread
  changes the signal handler after sigsuspend() or pselect() have interrupted,
  but before they are able to process the signal.

* If the signal is no longer enabled the old signal mask is not restored
  on system call return, resulting in an assertion and panic.

* Fix the problem by checking the flag and restoring the old signal mask
  on return (rather than asserting when the flag is found to be non-zero
  on return).

Reported-by: Venkatesh Srinivas
kernel - Do not use M_USE_INTERRUPT_RESERVE for M_NOWAIT

* Redefine M_NOWAIT to not use M_USE_INTERRUPT_RESERVE.  This can result
  in mbuf exhaustion during bursts of mbuf allocations and cause kernel
  kvm expansion to assert and panic.

Reported-by: sephe
HAMMER VFS - Fix assertion with multi-volume setup

* The RB compare code for hammer_io was extracting the volume number
  from the wrong place, creating a situation where duplicate hammer_io's
  would sometimes be inserted in the RB tree (causing an assertion + panic).

* Pull the volume number from a different field.

Reported-by: Mark Saad <nonesuch@longcount.org>
fsstress: Adjust the sample script a bit.
Merge branch 'master' into gsocdrm_alter
Kernel: Set max io size limit for all disk devices

* Prior to this change, slice and partition devices did not inherit their
  parent maximum IO size limit

* IO transactions on these devices could thus never be bigger than the
  old 64KB DFLTPHYS defaul kernel limit
Sync zoneinfo database with tzdata2012c from munnari.oz.au

africa:         8.33 -> 8.35
asia:           8.70 -> 8.73
northamerica:   8.53 -> 8.54

* africa: Morocco 2012 DST from last Sunday in April through last
    Sunday in September.

* asia: Change start of DST in Syria to last Friday in March in
    2012 and (as a guess) forward. Starts and (guessed) ends of
    DST in West Bank and Gaza for 2012. Also add a missing HTML
    directive at the top of the file.

* northamerica: Start and end of DST in Haiti in 2012 according
    to US rules.
Merge branch 'master' into gsocdrm_jfree
kernel -- FFS: Take softdep lock in softdep_disk_io_initiation.

softdep_disk_io_initiation was using the mplock rather than the softdep
lock to protect the softdep work queue and items on it. Take the softdep
lock and allow it to be taken recursively, so that io_start bioops can
call into other parts of softdep. Prevents softdep completion callback
from racing softdep_disk_io_initiation, remaining panics of 2291.

Eventually the MPLOCK in the bio_ops callback can go away, but that will
require more testing.

Closes-bug: 2291
kernel - Reduce impact of write_behind on small/temporary files

* Do not start issuing write-behind writes until a file has grown past
  a certain size, otherwise we wind up issuing excessive I/O for
  small files and for temporary files which might be quickly deleted.

* Add vfs.write_behind_minfilesize sysctl (defaults to 10MB).
kernel - Add max I/O size cap to vmaxiosize()

* Cap the returned value at MAXPHYS, allowing VCHR devices to set a
  higher max-IO limit (according to DMA limitations) without blowing
  out the pbuf's that the frontend uses to build clustered I/O.
vkernel: cap vdisk max. io size to MAXPHYS
Merge branch 'master' into gsocdrm_merger