On 20/08/2021 15:31, Su Yue wrote:

On Fri 20 Aug 2021 at 02:18, Anand Jain [off-list ref] wrote:

quoted

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 <redacted>
---

RFC because
1. latest_bdev might not be the lowest devid but, we showed
the lowest devid in /proc/self/mount.

quoted

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.