From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from userp1040.oracle.com ([156.151.31.81]:21324 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756380AbaEPPDx (ORCPT ); Fri, 16 May 2014 11:03:53 -0400 Message-ID: <5376297B.9000709@oracle.com> Date: Fri, 16 May 2014 23:06:35 +0800 From: Anand Jain MIME-Version: 1.0 To: Shilong Wang CC: Wang Shilong , linux-btrfs Subject: Re: [PATCH] Btrfs: set right total device count for seeding support References: <1399971906-1237-1-git-send-email-wangsl.fnst@cn.fujitsu.com> <1399971906-1237-2-git-send-email-wangsl.fnst@cn.fujitsu.com> <53761D30.6080207@oracle.com> <53762456.3050005@oracle.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 16/05/14 22:50, Shilong Wang wrote: > 2014-05-16 22:44 GMT+08:00 Anand Jain : >> >> >> Wang, >> >> when we unmount && mount (instead of remount) and followed >> with device del it ends up with null pointer deref at >> btrfs_shrink_dev. Thats because the btrfs_root is not set for >> seed disk as we mounted the writable sprout disk. I am writing >> a separate fix for that as its a new bug. > > You means this one which was addressed by Liu few days ago? > https://patchwork.kernel.org/patch/4150471/ Ah there is already a patch. yes thats the one. Thanks. >>>> Thanks, Anand >> >> >> >> On 16/05/14 22:14, Anand Jain wrote: >>> >>> >>> Wang, >>> >>> There seems to be a problem - after we delete the seed >>> disk, the total_devices didn't decrement back to 1. >>> reproducer as in the below test case. (I used btrfs-devlist >>> (posted) to check fs_devices). >>> >>> > # mkfs.btrfs -f /dev/sdb >>> > # btrfstune -S 1 /dev/sdb >>> > # mount /dev/sdb /mnt >>> > # btrfs device add -f /dev/sdc /mnt --->fs_devices->total_devices = 1 >>> mount -o rw,remount /mnt >>> btrfs dev del /dev/sdb /mnt --> fs_devices->total_devices is still 2 >>> >>> Thanks, Anand >>> >>> >>> On 13/05/14 17:05, Wang Shilong wrote: >>>> >>>> Seeding device support allows us to create a new filesystem >>>> based on existed filesystem. >>>> >>>> However newly created filesystem's @total_devices should include seed >>>> devices. This patch fix the following problem: >>>> >>>> # mkfs.btrfs -f /dev/sdb >>>> # btrfstune -S 1 /dev/sdb >>>> # mount /dev/sdb /mnt >>>> # btrfs device add -f /dev/sdc /mnt --->fs_devices->total_devices = 1 >>>> # umount /mnt >>>> # mount /dev/sdc /mnt --->fs_devices->total_devices = 2 >>>> >>>> This is because we record right @total_devices in superblock, but >>>> @fs_devices->total_devices is reset to be 0 in btrfs_prepare_sprout(). >>>> >>>> Fix this problem by not resetting @fs_devices->total_devices. >>>> >>>> Signed-off-by: Wang Shilong >>>> --- >>>> fs/btrfs/volumes.c | 1 - >>>> 1 file changed, 1 deletion(-) >>>> >>>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c >>>> index 6fd7fe6..19b2d32 100644 >>>> --- a/fs/btrfs/volumes.c >>>> +++ b/fs/btrfs/volumes.c >>>> @@ -1883,7 +1883,6 @@ static int btrfs_prepare_sprout(struct >>>> btrfs_root *root) >>>> fs_devices->seeding = 0; >>>> fs_devices->num_devices = 0; >>>> fs_devices->open_devices = 0; >>>> - fs_devices->total_devices = 0; >>>> fs_devices->seed = seed_devices; >>>> >>>> generate_random_uuid(fs_devices->fsid); >>>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >