libcephfs: expose stripe unit granularity

Assists clients in choosing layout parameters.

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
java: add support for get_stripe_unit_granularity

Signed-off-by: Joe Buck <jbbuck@gmail.com>
Reviewed-by: Noah Watkins <noahwatkins@gmail.com>
java: fix whitespace

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
java: update javadoc comments

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
java: add stripe unit granularity tests

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
libcephfs: clarify interface return value

Document that ceph_get_stripe_unit_granularity may return an error code
(e.g. -ENOTCONN). The interface requires a mount, but currently we
return a compile-time constant. Other error codes may be possible in the
future.

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
libcephfs: return -ENOTCONN when call unmounted

Adds -ENOTCONN return value for stat, fchmod, fchown, lchown.

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
test: enforce -ENOTCONN contract in libcephfs

Tests all relevant calls for -ENOTCONN when used with an unmounted
ceph_mount_info param.

Signed-off-by: Noah Watkins <noahwatkins@gmail.com>
Merge branch 'wip-stripe-gran'

Reviewed-by: Greg Farnum <greg@inktank.com>