From: Anand Jain <anand.jain@oracle.com>
To: Su Yue <l@damenly.su>
Cc: linux-btrfs@vger.kernel.org, dsterba@suse.com
Subject: Re: [PATCH RFC 3/3] btrfs: use latest_bdev in btrfs_show_devname
Date: Fri, 20 Aug 2021 17:13:32 +0800 [thread overview]
Message-ID: <332e2d65-a258-8bf8-8f26-9571535e7075@oracle.com> (raw)
In-Reply-To: <1r6ofu54.fsf@damenly.su>
On 20/08/2021 15:31, Su Yue wrote:
>
> On Fri 20 Aug 2021 at 02:18, Anand Jain <anand.jain@oracle.com> wrote:
>
>> latest_bdev is updated according to the changes to the device list.
>> That means we could use the latest_bdev to show the device name in
>> /proc/self/mounts. So this patch makes that change.
>>
>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>> ---
>>
>> RFC because
>> 1. latest_bdev might not be the lowest devid but, we showed
>> the lowest devid in /proc/self/mount.
>> 2. The device's path is not shown now but, previously we did.
>> So does these break ABI? Maybe yes for 2 howabout for 1 above?
In v2 I am fix the path part. By replacing latest_bdev to latest_dev
which means it shall hold the pointer to btrfs_device instead of
just to its bdev.
> Mabybe a naive question but I have no time to dive into btrfs code
> recently. If a device which has highest devid was replaced, will the
> new device be the fs_devices->latest_bdev instead of the existing older
> one?
It is handled by btrfs_assign_next_active_device().
If the replace source device is also the latest_dev then after replace
it shall point to the replace target device. So the new device path is
seen in /proc/self/mounts. Which is fine and normal to expect.
Similarly btrfs_assign_next_active_device() is called during remove
device as well.
There is a bug that we didn't update the latest_bdev when we sprout
I am fixing this as well in v2.
Thanks.
next prev parent reply other threads:[~2021-08-20 9:13 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-19 18:18 [PATCH 0/3] btrf_show_devname related fixes Anand Jain
2021-08-19 18:18 ` [PATCH 1/3] btrfs: fix comment about the btrfs_show_devname Anand Jain
2021-08-19 18:18 ` [PATCH RFC 2/3] btrfs: consolidate device_list_mutex in prepare_sprout to its parent Anand Jain
2021-08-20 7:51 ` Su Yue
2021-08-20 8:53 ` Anand Jain
2021-08-21 14:57 ` Su Yue
2021-08-21 15:00 ` Su Yue
2021-08-23 10:34 ` Anand Jain
2021-08-23 10:54 ` Anand Jain
2021-08-23 12:20 ` David Sterba
2021-08-19 18:18 ` [PATCH RFC 3/3] btrfs: use latest_bdev in btrfs_show_devname Anand Jain
2021-08-20 7:31 ` Su Yue
2021-08-20 9:13 ` Anand Jain [this message]
2021-08-20 10:57 ` David Sterba
2021-08-20 11:03 ` Anand Jain
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