On 2/19/22 9:23 PM, Matthew Wilcox wrote: > On Fri, Feb 18, 2022 at 11:35:10PM -0800, Christoph Hellwig wrote: >> Err, hell no. Please do not add any new functionality to the legacy >> buffer head code. If you want new features do that on the >> non-bufferhead iomap code path only please. > > I think "first convert the block device code from buffer_heads to > iomap" might be a bit much of a prerequisite. I think running ext4 on > top of a Yes, that's exactly what Christoph was trying to say, but failing to state in an appropriate manner. And we did actually discuss that, I'm not against doing something like that. > block device still requires buffer_heads, for example (I tried to convert > the block device to use mpage in order to avoid creating buffer_heads > when possible, and ext4 stopped working. I didn't try too hard to debug > it as it was a bit of a distraction at the time). That's one of the main reasons why I didn't push this particular path, as it is a bit fraught with weirdness and legacy buffer_head code which isn't that easy to tackle... -- Jens Axboe
