Re: zfs questions

[Takashi YAMAMOTO <yamt9999%gmail.com@localhost>]

hi,

On Sun, Feb 22, 2026 at 9:17 PM Taylor R Campbell <riastradh%netbsd.org@localhost> wrote:
>
> > Date: Sun, 22 Feb 2026 21:04:16 +0900
> > From: Takashi YAMAMOTO <yamt9999%gmail.com@localhost>
> >
> > On Sun, Feb 22, 2026 at 7:41 PM Taylor R Campbell <riastradh%netbsd.org@localhost> wrote:
> > >
> > > If I recall correctly, a vnode with pending writes queued up for the
> > > zil may become inactive and marked for reclamation _before_
> > > zfs_get_data runs to issue those writes to the zil.
> > >
> > > At that point, the NetBSD vnode life cycle forbids acquiring a new
> > > reference, so instead of returning the old vnode, vcache_get will wait
> > > for concurrent references to the vnode to drain and then create a new
> > > vnode initialized with VFS_LOADVNODE.
> > >
> > > I'm fuzzy on what happens at that point (hannken@ or chs@ may remember
> > > better than I can), but I suspect it will be one of:
> > >
> > > 1. data associated with the old vnode (via the old v_data, the znode)
> > >    will be silently lost; or
> >
> > what data?
>
> Pending file content being written to the file system -- the data that
> zfs_get_data is getting in order for the zil to write it out.
>
> Of course, if this only applies to files being removed, then maybe
> that's a moot point.  But I'm not confident in my understanding of
> this, and we should really have the exact problem written down.

at this point, the file contents are in txg. zil either copies them to
the log or
record references to them. either ways, as far as i understand, a possbile
znode reclaim/zget cycle here doesn't make them lost.