Re: [RFC PATCH tarfs 0/6] mmap support for tarfs

[Samuel Thibault]

Sergey Bugaev, le sam. 01 mai 2021 20:23:58 +0300, a ecrit:
> tarfs can be run with --bzip2 and --gzip options, but not with --zip.

Ah, seeing zipstores.c I thought zipfiles were supported, so I was
wondering how since, as you say, they combine both.

> > > Hmm, but doesn't the page reading/writing implementation need to
> > > access the file size, atime/mtime, etc.? All of which may be changed
> > > concurrently.
> >
> > IIRC it isn't handled by the pager itself.
> 
> Is it? I don't think pager (as in libpager) knows anything about
> atime/mtime and other filesystem-specific cruft.

Indeed, so pager itself doesn't handle it and it's libdiskfs that reacts
to writes and updates the mtimes.

> The pager knows the size; but the callbacks need to know the size too,
> to decide how much to read/write in case of the last page.

Yes, ext2fs apparently uses a different lock for that, alloc_lock.

Samuel