MFC r268084: MFV r267568:

4891 want zdb option to dump all metadata
MFC r268085: MFV r267569:

4897 Space accounting mismatch in L2ARC/zpool
MFC r268086: MFV r267570:

4756 metaslab_group_preload() could deadlock
MFC r268123: MFV r268119:

4914 zfs on-disk bookmark structure should be named *_phys_t