From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lidong Zhong Subject: Re: [PATCH v4] super1: fix sb->max_dev when adding a new disk in linear array Date: Tue, 23 May 2017 11:55:28 +0800 Message-ID: <20e71aa6-e9e0-312f-747a-d25b872d2af8@suse.com> References: <20170522061612.29410-1-lzhong@suse.com> <87d1b1jgju.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: <87d1b1jgju.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 05/22/2017 07:07 PM, NeilBrown wrote: > On Mon, May 22 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 | 9 ++++++++- >> 1 file changed, 8 insertions(+), 1 deletion(-) >> >> diff --git a/super1.c b/super1.c >> index 2fcb814..03cea72 100644 >> --- a/super1.c >> +++ b/super1.c >> @@ -1267,8 +1267,10 @@ 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 >= max) { >> + sb->dev_roles[max] = __cpu_to_le16(MD_DISK_ROLE_SPARE); > Hi Neil, > Why do you assign to dev_roles[max]? I meant to assure there will always be a spare spot in dev_roles[], that is sb->max_dev at least is at lease 1 more than raid_disks. Now I see what you mean in your reply to my last version patch. > max must equal i here, and a few lines later: > sb->dev_roles[i] = __cpu_to_le16(info->disk.raid_disk); > > your assignment is over-written. So it is pointless. > If i was greater than max (which should be impossible), you assignment > here would corrupt the dev_roles table. > > Please drop this assignment. Yes, just increase the max_dev value is enough. > >> sb->max_dev = __cpu_to_le32(max+1); >> + } >> >> random_uuid(sb->device_uuid); >> >> @@ -1293,9 +1295,14 @@ static int update_super1(struct supertype *st, struct mdinfo *info, >> } >> } >> } else if (strcmp(update, "linear-grow-update") == 0) { >> + unsigned int max = __le32_to_cpu(sb->max_dev); >> sb->raid_disks = __cpu_to_le32(info->array.raid_disks); >> sb->dev_roles[info->disk.number] = >> __cpu_to_le16(info->disk.raid_disk); >> + if (info->array.raid_disks >= max) { > > if raid_disks == max there is no need to change anything. > It is only when raid_disks > max that you need to increase max. > Yes, the max_dev should only be updated when raid_disks > max. >> + sb->dev_roles[max] = __cpu_to_le16(MD_DISK_ROLE_SPARE); > > When you increase max, you do need to assign MD_DISK_ROLE_SPARE to the > new element, but you need to do that *before* disk.raid_disk is > assigned, in case info->disk.number == max (as it could be for the > recently added device). > I think it's also pointless to assign MD_DISK_ROLE_SPARE since there is no SPARE in dev_roles when we need to update sb->max_dev. The newly added device will not meet the condition as max_dev has already been updated, that's saying, we only need to update the max_dev value for original disks. The following code should work 1297 } else if (strcmp(update, "linear-grow-update") == 0) { 1298 unsigned int max = __le32_to_cpu(sb->max_dev); 1299 sb->raid_disks = __cpu_to_le32(info->array.raid_disks); 1300 sb->dev_roles[info->disk.number] = 1301 __cpu_to_le16(info->disk.raid_disk); 1302 if (info->array.raid_disks > max) { 1303 sb->max_dev = __cpu_to_le32(max+1); 1304 } Thank you for your patient review. Lidong > NeilBrown > > >> + sb->max_dev = __cpu_to_le32(max+1); >> + } >> } else if (strcmp(update, "resync") == 0) { >> /* make sure resync happens */ >> sb->resync_offset = 0ULL; >> -- >> 2.12.0