From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lidong Zhong Subject: Re: [PATCH] super1: fix sb->max_dev when adding a new disk in linear array Date: Fri, 19 May 2017 13:31:15 +0800 Message-ID: <4b01d20c-be52-eaa1-6809-909fb375b274@suse.com> References: <20170516045129.21815-1-lzhong@suse.com> <87pof5laxm.fsf@notabene.neil.brown.name> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <87pof5laxm.fsf@notabene.neil.brown.name> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown , linux-raid@vger.kernel.org Cc: colyli@suse.com, Jes.Sorensen@gmail.com List-Id: linux-raid.ids 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' == active, '.' == missing, 'R' == replacing) >> >> Adding the second disk into linear array it will be >> >> Array State : .AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA >> ('A' == active, '.' == missing, 'R' == 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, struct mdinfo *info, >> break; >> sb->dev_number = __cpu_to_le32(i); >> info->disk.number = i; >> - if (max >= __le32_to_cpu(sb->max_dev)) >> + if (i >= __le32_to_cpu(sb->max_dev)) { > > This change is correct - thanks. Though > if (i >= max) { > > might be clearer and simpler. > > >> sb->max_dev = __cpu_to_le32(max+1); >> + sb->dev_roles[sb->max_dev] = __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] = __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 = 0; d < __le32_to_cpu(sb->raid_disks) + delta_extra; d++) { 554 int cnt = 0; 555 unsigned int i; 556 for (i = 0; i < __le32_to_cpu(sb->max_dev); i++) { 557 unsigned int role = __le16_to_cpu(sb->dev_roles[i]); 558 if (role == d) 559 cnt++; 560 } > It might be better to do > if (i >= max) { > while (max <= i) { > sb->dev_roles[max] = __cpu_to_le16(MD_DISK_ROLE_SPARE); > max += 1; > } > sb->max_dev = __cpu_to_le32(max); > } > Thanks for the advice. >> + } >> >> random_uuid(sb->device_uuid); >> >> @@ -1214,6 +1216,10 @@ static int update_super1(struct supertype *st, struct mdinfo *info, >> sb->raid_disks = __cpu_to_le32(info->array.raid_disks); >> sb->dev_roles[info->disk.number] = >> __cpu_to_le16(info->disk.raid_disk); >> + if (sb->raid_disks+1 >= __le32_to_cpu(sb->max_dev)) { >> + sb->max_dev = __cpu_to_le32(sb->raid_disks+1); >> + sb->dev_roles[sb->max_dev] = __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. Thanks, Lidong > > Thanks, > NeilBrown > > >> + } >> } else if (strcmp(update, "resync") == 0) { >> /* make sure resync happens */ >> sb->resync_offset = 0ULL; >> -- >> 2.12.0