On 12/14/21 21:34, Josef Bacik wrote:

On Tue, Dec 14, 2021 at 03:04:32PM -0500, Zygo Blaxell wrote:

quoted

On Tue, Dec 14, 2021 at 08:03:45PM +0100, Goffredo Baroncelli wrote:

quoted

I don't have a strong preference for either sysfs or ioctl, nor am I
opposed to simply implementing both.  I'll let someone who does have
such a preference make their case.

I think echo'ing a name into sysfs is better than bits for sure.  However I want
the ability to set the device properties via a btrfs-progs command offline so I
can setup the storage and then mount the file system.  I want

1) The sysfs interface so you can change things on the fly.  This stays
    persistent of course, so the way it works is perfect.

2) The btrfs-progs command sets it on offline devices.  If you point it at a
    live mounted fs it can simply use the sysfs thing to do it live.

#2 is currently not implemented. However I think that we should do.

The problem is that we need to update both:

- the superblock		(simple)
- the dev_item item		(not so simple...)

What about using only bits from the superblock to store this property ?

Does this seem reasonable?  Thanks,

Josef

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