Using the syscalls directly rather than calling bin/(u)mount via
system() avoids a few fork + exec calls, and provides better error
handling if something goes wrong.

Users of this functionality are also updated to use slurm_strerror in
order to provide a more informative error message.

The mount and umount syscalls are Linux-specific, but so are cgroups
so no portability is lost.

Using the syscalls directly rather than calling bin/(u)mount via
system() avoids a few fork + exec calls, and provides better error
handling if something goes wrong.

Users of this functionality are also updated to use slurm_strerror in
order to provide a more informative error message.

The mount and umount syscalls are Linux-specific, but so are cgroups
so no portability is lost.

    the current plugin has been loaded when using runjob_mux_refresh_config

These comments were orphaned with this commit:  874f797f
Move the start time calculation of pending jobs into a separate pthread on Nov 3, 2010.

Correct parsing of srun/sbatch input/output/error file names so that only
the name "none" is mapped to /dev/null and not any file name starting
with "none" (e.g. "none.o"). This fixes bug #98.

Gres: If a gres has a count of one and an associated file then when doing
a reconfiguration, the node's bitmap was not cleared resulting in an
underflow upon job termination or removal from scheduling matrix by the
backfill scheduler.

Cray and BlueGene - Do not treat lack of usable front-end nodes when
slurmctld deamon starts as a fatal error. Also preserve correct front-end
node for jobs when there is more than one front-end node and the slurmctld
daemon restarts.

while it is attempting to free underlying hardware is marked in error
making small blocks overlapping with the freeing block.  This only
applies to dynamic layout mode.

This corresponds to commit dd2dce54
from Mark Grondona's work in squeue, but applied to the sview command.

Slurm 2.4 minor fixes

This addresses trouble ticket 85

runjob_mux

is always set when sending or receiving a message.

Set SLURM_CONF in default prolog/epilog environment instead
of only in spank prolog/epilog environment.

This change fixes a potential hang during spank prolog/epilog
execution due to the possibility of memory allocation after
fork(2) and before exec(2) when invoking slurmstepd spank
prolog|epilog.

This also has the benefit that SLURM commands used in prolog and epilog
scripts will use the correct slurm.conf file.

If exec_wait_child_wait_for_parent() fails for any reason, it is safer
to abort immediately rather than proceed to execute the user's job.

On a failure of fork(2), slurmstepd would print an error and exit,
possibly leaving previously forked children waiting.

Ensure a better cleanup by killing all active children on fork failure
before exiting slurmstepd.

Close the read end of the pipe slurmstepd uses to notify children
it is time to call exec(2) in order to save one file descriptor per
task. (Previously, the read side of the pipe wasn't closed until
exec_wait_info was destroyed)

For some reason squeue was treating completing jobs the same as
pending jobs, and reported the number of nodes as the maximum of
requested nodelist, requested node count or CPUs (divided into nodes?)

This is in contrast to the squeue manpage which explicitly states
that the number of nodes reported for completing jobs should
be only the nodes that are still allocated to the job.

This patch removes the special handling of completing jobs in
src/squeue/print.c:_get_node_cnt(), so that the squeue output for
completing jobs matches documentation. A comment is also added
so that developers looking at the code understand what is going on.

than 1 midplane but not the entire allocation.

multi midplane block allocation.