linux-kernel - Re: [PATCH] init: open /initrd.image with O

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Message-ID: <CAFNjLiVws+mCrMp4wMZuWTjaryK+-cKtNR9yFzVdqGf2u44oLg@mail.gmail.com>
Date: Mon, 18 Mar 2024 12:00:56 -0700
From: John Sperbeck <jsperbeck@...gle.com>
To: Randy Dunlap <rdunlap@...radead.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Jens Axboe <axboe@...nel.dk>, 
	"Peter Zijlstra (Intel)" <peterz@...radead.org>, Thomas Gleixner <tglx@...utronix.de>, 
	"ndesaulniers@...gle.com" <ndesaulniers@...gle.com>, linux-kernel@...r.kernel.org, 
	Nazerke Turtayeva <nturtayeva@...b.edu>
Subject: Re: [PATCH] init: open /initrd.image with O_LARGEFILE

On Sun, Mar 17, 2024 at 4:47 PM Randy Dunlap <rdunlap@...radead.org> wrote:
>
> Hi,
>
> On 3/17/24 15:15, John Sperbeck wrote:
> > If initrd data is larger than 2Gb, we'll eventually fail to write to
> > the /initrd.image file when we hit that limit, unless O_LARGEFILE is set.
> >
>
> Could this be related to
> https://lore.kernel.org/lkml/CAHY78BqCpMQptPN0SMaXuRqHOhYi+wnMEUSTYt7OHDZih4e7yQ@mail.gmail.com/
> ?
>
> Thanks.
>

I think there's a separate problem that this patch doesn't address.
If an individual component of a CPIO file is larger than 2Gb, then
there will be an EFBIG error when processing it.  The backtrace where
this occurs would be:

    generic_write_checks_count
    generic_write_checks
    generic_file_write_iter
    __kernel_write_iter
    kernel_write
    xwrite
    do_copy
    unpack_to_rootfs
    do_populate_rootfs
    async_run_entry_fn
    process_scheduled_works
    worker_thread
    kthread
    ret_from_fork
    ret_from_fork_asm

I think that could be dealt with by a patch to add O_LARGEFILE to
'openflags' in initramfs:do_name().