From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: [PATCH] super1: fix sb->max_dev when adding a new disk in linear array Date: Fri, 19 May 2017 15:37:15 +1000 Message-ID: <87bmqpl850.fsf@notabene.neil.brown.name> References: <20170516045129.21815-1-lzhong@suse.com> <87pof5laxm.fsf@notabene.neil.brown.name> <4b01d20c-be52-eaa1-6809-909fb375b274@suse.com> Mime-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha256; protocol="application/pgp-signature" Return-path: In-Reply-To: <4b01d20c-be52-eaa1-6809-909fb375b274@suse.com> Sender: linux-raid-owner@vger.kernel.org To: Lidong Zhong , linux-raid@vger.kernel.org Cc: colyli@suse.com, Jes.Sorensen@gmail.com List-Id: linux-raid.ids --=-=-= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Fri, May 19 2017, Lidong Zhong wrote: > On 05/19/2017 12:36 PM, NeilBrown wrote: >> On Tue, May 16 2017, Lidong Zhong wrote: >> >>> The value of sb->max_dev will always be increased by 1 when adding >>> a new disk in linear array. It causes an inconsistence between each >>> disk in the array and the "Array State" value of "mdadm --examine DISK" >>> is wrong. For example, when adding the first new disk into linear array >>> it will be: >>> >>> Array State : RAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA >>> ('A' =3D=3D active, '.' =3D=3D missing, 'R' =3D=3D replacing) >>> >>> Adding the second disk into linear array it will be >>> >>> Array State : .AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA >>> ('A' =3D=3D active, '.' =3D=3D missing, 'R' =3D=3D replacing) >>> >>> Signed-off-by: Lidong Zhong >>> --- >>> super1.c | 8 +++++++- >>> 1 file changed, 7 insertions(+), 1 deletion(-) >>> >>> diff --git a/super1.c b/super1.c >>> index 87a74cb..3d49bee 100644 >>> --- a/super1.c >>> +++ b/super1.c >>> @@ -1184,8 +1184,10 @@ static int update_super1(struct supertype *st, s= truct mdinfo *info, >>> break; >>> sb->dev_number =3D __cpu_to_le32(i); >>> info->disk.number =3D i; >>> - if (max >=3D __le32_to_cpu(sb->max_dev)) >>> + if (i >=3D __le32_to_cpu(sb->max_dev)) { >> >> This change is correct - thanks. Though >> if (i >=3D max) { >> >> might be clearer and simpler. >> >> >>> sb->max_dev =3D __cpu_to_le32(max+1); >>> + sb->dev_roles[sb->max_dev] =3D __cpu_to_le16(MD_DISK_ROLE_SPARE); >> >> This change is wrong. >> At the very least, the dev_roles[] array needs to be indexed by a >> host-order number, not a little-endian number. >> But the change is not needed because dev_roles[max_dev] is never used. >> See role_from_sb(). >> dev_rols[max_dev - 1] does need to be set, but the line >> >> sb->dev_roles[i] =3D __cpu_to_le16(info->disk.raid_disk); >> >> almost certainly does that. > Hi Neil, > > The reason I set all the dev_roles[0~max_dev-1] is because > the following code > > 552 printf(" Array State : "); > 553 for (d =3D 0; d < __le32_to_cpu(sb->raid_disks) + delta_extra;= =20 > d++) { > 554 int cnt =3D 0; > 555 unsigned int i; > 556 for (i =3D 0; i < __le32_to_cpu(sb->max_dev); i++) { > 557 unsigned int role =3D __le16_to_cpu(sb->dev_roles[i]);= =20 > > 558 if (role =3D=3D d)=20 > > 559 cnt++;=20 > > 560 } This code does not access dev_roles[max_dev], only up to dev_roles[max_dev-1]. You changed dev_roles[max_dev], which will never be accessed. > > >> It might be better to do >> if (i >=3D max) { >> while (max <=3D i) { >> sb->dev_roles[max] =3D __cpu_to_le16(MD_DISK_ROLE_SPARE); >> max +=3D 1; >> } >> sb->max_dev =3D __cpu_to_le32(max); >> } >> > > > Thanks for the advice. > >>> + } >>> >>> random_uuid(sb->device_uuid); >>> >>> @@ -1214,6 +1216,10 @@ static int update_super1(struct supertype *st, s= truct mdinfo *info, >>> sb->raid_disks =3D __cpu_to_le32(info->array.raid_disks); >>> sb->dev_roles[info->disk.number] =3D >>> __cpu_to_le16(info->disk.raid_disk); >>> + if (sb->raid_disks+1 >=3D __le32_to_cpu(sb->max_dev)) { >>> + sb->max_dev =3D __cpu_to_le32(sb->raid_disks+1); >>> + sb->dev_roles[sb->max_dev] =3D __cpu_to_le16(MD_DISK_ROLE_SPARE); >> >> Again, max_dev is little-endian, so cannot be used as an index. >> And I think you are updating the wrong element in the dev_roles array. > > Yes, I didn't realized the valude is conversed to little-endian and the > index is wrong too. Thank you for pointing this out. I will submit > another version patch. I look forward to it, Thanks, NeilBrown > > Thanks, > Lidong >> >> Thanks, >> NeilBrown >> >> >>> + } >>> } else if (strcmp(update, "resync") =3D=3D 0) { >>> /* make sure resync happens */ >>> sb->resync_offset =3D 0ULL; >>> -- >>> 2.12.0 --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEG8Yp69OQ2HB7X0l6Oeye3VZigbkFAlkehIsACgkQOeye3VZi gblznxAAwkvAyERy0VAlwjXmy6GflgiQVuNnPn1yXFcDn5jjMlZ1eAYiB1wtQBEq VE3zlo0ADPuOWD7pQVHlbnKiY4fQVNMJBmkw8Ruhb8fK+fp7bn1dPOlt1uNwIsGB goel8f8FVM5y78cP2Oxo9Y3xmgjwXUTS/TGzdjlot98ymKwH/F30XTfr+U2Y/8+a P12omElPjy0dmC/Tz5gU8s7hplVUihLxfmyOe0TlHuYpAfyM3fE4Qvz7cmjEkzMA rvTODQliNifB7s1QRVHUgeOCmCfx5mxsQR4TY5WckgSMCpNjS1LE9XJo2JMO/hhZ akIx2Myjbzrhw+y0vS7IiW/xrEitvGO9OYh/TL3X12nIZwITPJXN/1Ng0Uuw/aJV BaW2ttPX14ixw3LQYb7RTGfEjQEbMafy1+qvamkQP5KwNw1xZYkQ3DgoA9OzgcXK gv2Scp7g2L6DEJzGaKEc1G5Tha817Ch005Y0LgynuS/UJtZR9pvn+ISXC1L1zzo0 no9JV0CLtdukZtvqaQDJwVvCScKfjL9IOzySi1Ztt6+GRAWthczzQhTEVnJnNN4u O5EWYUx3IkoxMdLlJRJr/jral7FreHDK+HL5+PiP1ms+mXNa7BsXtui8+bsP9hdC O1PTtegA7+i4J77hUCpGHsdnHP/FEVCVkRFrkcaebd0/gf0v0Ic= =Z5f3 -----END PGP SIGNATURE----- --=-=-=--