Re: [PATCH V11 3/9] famfs_fuse: Plumb the GET_FMAP message/response

Miklos Szeredi <[email protected]> Wed, 22 Jul 2026 15:59:07 +0200
Newsgroups dev.linux.lists.fuse-devel,dev.linux.lists.nvdimm,org.kernel.vger.linux-cxl,org.kernel.vger.linux-doc,org.kernel.vger.linux-fsdevel,org.kernel.vger.linux-kernel
Message-ID <CAJfpeguf3EBgBrf=mrG2Jp=oNp65DDg1fZsdEaqgBn6UNNrZRg@mail.gmail.com>
On Mon, 20 Jul 2026 at 05:45, John Groves <[email protected]> wrote:

> +       /*
> +        * The fmap size is not known in advance. Start with a modest buffer and,
> +        * if the server reports (via the returned header's fmap_size) that the
> +        * whole fmap did not fit, reallocate exactly that size and retry once.
> +        * The server learns our buffer size from the request's
> +        * fuse_getxattr_in.size (GETXATTR-style size probe).

No need to retry.  I'll post a patch to dynamically allocate the reply
buffer (already posted as part of fusex).

> +        */
> +       for (attempt = 0; ; attempt++) {
> +               struct fuse_getxattr_in in = { .size = bufsize };
> +               struct fuse_famfs_fmap_header *fmh;

This struct isn't defined until the next patch.

Thanks,
Miklos