Only automatically mount a clone when 'canmount == on'.

According to the man page, "When the noauto option is set, a dataset
can only be mounted and unmounted explicitly. The dataset is not
mounted automatically when the dataset is created or imported ...."

When cloning a dataset the canmount property was not being honored.
This patch adds the required check to achieve the behavior described
in the man page.

Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2241
Document the fact that ashift is vdev specific, not a pool global.

Users need to be aware that when adding devices to an existing pool
they may need to override automatically detected ashift value.
This will all depend on the exact hardware they are using.

Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes: #2024
Man page updates for 'zfs share'

* Remove the references to share(1M), unshare(1M) and dfstab(4)
  since they are not applicable to Linux.
* Add the exact exportfs command line used when setting sharenfs=on.

Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue: #1641
Expand the description of scan-related and other parameters.

Document that the scan-related parameters are, in fact, applicable only
to scrub and/or resilver operations as appropriate.

Expand a few of the prefetch-related descriptions.

Add clarification to other module parameters.

Signed-off-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2361
Document the -X and -T options to 'zpool import'

These options have existed for a long time but have historically
been undocumented because they are not guaranteed to be safe.  They
should only be used as a last resort when attempting to recover a
damaged pool.

Signed-off-by: Turbo Fredriksson <turbo@bayour.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1130