/* data subvol */ [-d agcount=n,agsize=n,file,name=xxx,size=num,\n\
(sunit=value,swidth=value|su=num,sw=num),\n\
sectlog=n|sectsize=num,unwritten=0|1]\n\
-/* inode size */ [-i log=n|perblock=n|size=num,maxpct=n]\n\
+/* inode size */ [-i log=n|perblock=n|size=num,maxpct=n,attr=0|1|2]\n\
/* log subvol */ [-l agnum=n,internal,size=num,logdev=xxx,version=n\n\
sunit=value|su=num,sectlog=n|sectsize=num]\n\
/* label */ [-L label (maximum 12 characters)]\n\