Date: Tue, 30 Oct 2018 10:18:00 +0200 From: Andriy Gapon <avg@FreeBSD.org> To: Rick Macklem <rmacklem@uoguelph.ca>, FreeBSD Filesystems <freebsd-fs@freebsd.org> Subject: Re: How to fill in the fsid for file systems? Message-ID: <d8acf192-8ad8-eed2-cf28-fb412d125c26@FreeBSD.org> In-Reply-To: <YTOPR0101MB11620BAF0E206EE36E927A5ADDF30@YTOPR0101MB1162.CANPRD01.PROD.OUTLOOK.COM> References: <YTOPR0101MB11620BAF0E206EE36E927A5ADDF30@YTOPR0101MB1162.CANPRD01.PROD.OUTLOOK.COM>
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On 29/10/2018 17:56, Rick Macklem wrote: > It seems "fsid=N" does need to set f_fsid.val[1]. I can think of two possibilities: > 1 - Do what ZFS does and set the low order 8bits to vfc_typenum and the high > order 24bits from bits 32->55 of "N". > or > 2 - Just fill the 32bits in with the high order (32->63) bits of "N" and forget about > vfc_typenum. > The only reason I can see for using vfc_typenum is to avoid collisions (same fsid value) > with fsids for mounts of other file system types. I have come up with an option #3 :-) Fill f_fsid.val[1] with some constant magic value that signals that val[0] is manually set. Some possible magic values: 0x0, 0xffffffff. -- Andriy Gapon
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