From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: [PATCH v2 09/12] raid5-ppl: read PPL signature from IMSM metadata Date: Thu, 08 Dec 2016 10:27:58 +1100 Message-ID: <87inqv2ubl.fsf@notabene.neil.brown.name> References: <20161205153113.7268-1-artur.paszkiewicz@intel.com> <20161205153113.7268-10-artur.paszkiewicz@intel.com> <871sxk4jj0.fsf@notabene.neil.brown.name> <0e661d59-033e-6797-b5d1-d30cdb04ef11@intel.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Return-path: In-Reply-To: <0e661d59-033e-6797-b5d1-d30cdb04ef11@intel.com> Sender: linux-raid-owner@vger.kernel.org To: Artur Paszkiewicz , shli@kernel.org Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Thu, Dec 08 2016, Artur Paszkiewicz wrote: > On 12/07/2016 02:25 AM, NeilBrown wrote: >> On Tue, Dec 06 2016, Artur Paszkiewicz wrote: >>=20 >>> The PPL signature is used to determine if the stored PPL is valid for a >>> given array. With IMSM, the PPL signature should match the >>> orig_family_num field of the superblock. To avoid passing this value >>> from userspace, it can be read from the IMSM MPB when initializing the >>> log. >>=20 >> It is up to mdadm to determine if the PPL is valid. It would only tell >> the kernel that a PPL exists if it is valid... > > The kernel also has to know this value because it writes it to the PPL > header. So yet another sysfs attribute just for this value? How about > adding a directory similar to "bitmap" to hold all the PPL related > settings? There is only one PPL header (per device) - correct? md can read that header, change the few fields that it knows about, and write it back out again. Does it ever need to change the PPL signature? When a PPL is created, mdadm can write the initial header. Am I missing something? Thanks, NeilBrown --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEG8Yp69OQ2HB7X0l6Oeye3VZigbkFAlhImv4ACgkQOeye3VZi gbnRrhAArHXLKhvosF9dLaWnG8rB6d2i746ALD8NIjYvpu2Gz/A67qM08MWMSpgH iGKqeSYR8oywQ5Zsa28NF+ffHQy4Emnx/iS+KihI1P3INycQDk1VSGsuQQTPWnBX xlfseW59oflrkphQjBxda/1+ON2xX9z8M+7HEE+V3IJB4YqPkAKxrYZ3XU0oZrtr Ok9AVMGvUcJpJc/HrEecnS6vcMf1DsCzkCx7glUzDL3Ht1sdFK8X0sOajBAULN58 QtEcyTsTHbH6rMyxzj+yF2SLaz+IEKYD1rJBFPi1385zQZt1oDE9nmQLYXuH1xFA PAQy/xJ3QmrrH2Lmwxn372htzyzp3oWdPcV4oS+eoJMjtM/hGgqr3GDFvGEImK1q KslYhUTTo2HoqqH+6FV2MQSivPeWmSLTEyE7KGgrad+mtCvOSK/meDTuQJxcRMv5 gaQbwgX2UkvKRgACFbL6JpndzU2b8/XD+Jra0i37zSenqF87Za9vPUnnCwC1mW2F FyFEN7hRHfGqD4av2Fn6gCorXd9fPIf8Mx/PAPs48XVKrpPnWubiop2R3qi6MONV ZHP1LM0XGhooqya2c+gtVLnZxGNxrsU5luK/qlfCQcLnqboxGaN2Rtlyd0xXSpD/ 3mzzw2Y5evs4l9OHlA0qUh4wqJB29vMmyd23wwRWo2p9cNDFxFE= =yisi -----END PGP SIGNATURE----- --=-=-=--