On Tue, 22 Aug 2023 at 17:57, Amir Goldstein <amir73il@xxxxxxxxx> wrote: > > On Tue, Aug 22, 2023 at 6:43 PM Alexander Larsson <alexl@xxxxxxxxxx> wrote: > > > > On Tue, Aug 22, 2023 at 5:31 PM Amir Goldstein <amir73il@xxxxxxxxx> wrote: > > > FWIW, there is also DT_WHT that was defined and never used. > > > But that is just an anecdote. Overlay could be the first filesystem to set DT_WHT in its readdir. I wouldn't mind if others would follow suit, but it's not a high priority thing. > > > > > > Regarding the issue of avoiding getxattr for every dirent. > > > Note that in readdir, dirent that goes through ovl_cache_update_ino() > > > calls lookup()/stat() on the overlay itself, so as long as ovl_lookup() > > > will treat overlay.whiteout file as a whiteout, the code > > > /* Mark a stale entry */ > > > p->is_whiteout = true; > > > will kick in and do the right thing for readdir wrt cleaning up > > > lower entries covered with whiteouts, regardless of DT_CHR. > > > > We don't want to treat this file as a whiteout though. We want it to > > be exposed as a regular file that looks like a whiteout marker file > > (i.e. char dev 0,0). Or am I missing something? > > > > Not sure if you really need to emulate chardev(0,0) at all. > > Suppose that you just define a new way to express a whiteout - > an empty regular file with xattr overlay.whiteout. Oh, you mean overlay.overlay.whiteout on realfile, which gets turned into overlay.whiteout on bottom overlay, which gets interpreted as a whiteout on top overlay? I suppose that would work too, but it's a bit of a layering violation. Thanks, Miklos
