5169 zdb should limit its ARC size
5170 zdb -c should create more scrub i/os by default
5171 zdb should print status while loading metaslabs for leak detection
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Paul Dagnelie <paul.dagnelie@delphix.com>
Reviewed by: Bayard Bell <Bayard.Bell@nexenta.com>
Approved by: Robert Mustacchi <rm@joyent.com>
5175 implement dmu_read_uio_dbuf() to improve cached read performance
Reviewed by: Adam Leventhal <ahl@delphix.com>
Reviewed by: Alex Reece <alex.reece@delphix.com>
Reviewed by: George Wilson <george@delphix.com>
Reviewed by: Richard Elling <richard.elling@gmail.com>
Approved by: Robert Mustacchi <rm@joyent.com>
3693 restore_object uses at least two transactions to restore an object
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Andriy Gapon <andriy.gapon@hybridcluster.com>
Approved by: Robert Mustacchi <rm@joyent.com>
	[illumos-gate merge]

commit e77d42eaa49fe55bfae1e0e0065c6e99affc001b
    3693 restore_object uses at least two transactions to restore an object
commit f8554bb92be6be88a684bea58293b41a6168a538
    5175 implement dmu_read_uio_dbuf() to improve cached read performance
commit 06be98028b8a84e7f327188613dd09a708294d1a
    5169 zdb should limit its ARC size
    5170 zdb -c should create more scrub i/os by default
    5171 zdb should print status while loading metaslabs for leak detection

Conflicts:
	usr/src/uts/common/fs/zfs/dmu.c (whitespace)