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From: Domenico Andreoli <domenico.andreoli@linux.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Domenico Andreoli <domenico.andreoli@linux.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	 Linux PM <linux-pm@vger.kernel.org>,
	 Linux Memory Management List <linux-mm@kvack.org>,
	linux-fsdevel@vger.kernel.org, mkleinsoft@gmail.com,
	 Christoph Hellwig <hch@lst.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	 "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Len Brown <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>
Subject: Re: [PATCH] hibernate: Allow uswsusp to write to swap
Date: Wed, 4 Mar 2020 17:31:11 +0100	[thread overview]
Message-ID: <CAGH6_ppBraO+A-st4biYoa-+LoXGONG8+ExkBk8sd2F6A2EVZw@mail.gmail.com> (raw)
In-Reply-To: <20200304154526.GH8036@magnolia>

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On Wed, Mar 4, 2020 at 4:45 PM Darrick J. Wong <darrick.wong@oracle.com>
wrote:

> On Wed, Mar 04, 2020 at 09:23:27AM +0100, Domenico Andreoli wrote:
> > From: Domenico Andreoli <domenico.andreoli@linux.com>
> >
> > It turns out that there is one use case for programs being able to
> > write to swap devices, and that is the userspace hibernation code.
>
> You might want to start a separate thread for this... :)
>

Right

> Quick fix: disable the S_SWAPFILE check if hibernation is configured.
> >
> > Fixes: 1638045c3677 ("mm: set S_SWAPFILE on blockdev swap devices")
>
> Also, this should be
>
> Fixes: dc617f29dbe5 ("vfs: don't allow writes to swap files")
>

Of course

since we still want to set S_SWAPFILE on active swap devices.
>
> > Reported-by: Domenico Andreoli <domenico.andreoli@linux.com>
> > Reported-by: Marian Klein <mkleinsoft@gmail.com>
> > Signed-off-by: Domenico Andreoli <domenico.andreoli@linux.com>
> >
> > ---
> >  fs/block_dev.c |    3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > Index: b/fs/block_dev.c
> > ===================================================================
> > --- a/fs/block_dev.c
> > +++ b/fs/block_dev.c
> > @@ -2001,7 +2001,8 @@ ssize_t blkdev_write_iter(struct kiocb *
> >       if (bdev_read_only(I_BDEV(bd_inode)))
> >               return -EPERM;
> >
> > -     if (IS_SWAPFILE(bd_inode))
> > +     /* uswsusp needs to write to the swap */
> > +     if (IS_SWAPFILE(bd_inode) && !IS_ENABLED(CONFIG_HIBERNATION))
>
> ...&& hibernation_available() ?  That way we can configure this
> dynamically.
>

Then it would just be "if (IS_SWAPFILE(bd_inode) &&
!hibernation_available())", right?

Thanks for taking this on, I'll go self-NAK the revert patch I sent
> yesterday.
>

Thanks,
Dom

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  reply	other threads:[~2020-03-04 16:31 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-29 17:08 [PATCH] hibernate: unlock swap bdev for writing when uswsusp is active Darrick J. Wong
2020-02-29 18:07 ` Domenico Andreoli
2020-02-29 18:38   ` Darrick J. Wong
2020-02-29 20:02     ` Domenico Andreoli
2020-03-01 21:35       ` Rafael J. Wysocki
2020-03-02  4:51         ` Marian Klein
2020-03-03 19:02         ` Darrick J. Wong
2020-03-03 22:51           ` Domenico Andreoli
2020-03-04  1:18             ` Darrick J. Wong
2020-03-04  8:23               ` [PATCH] hibernate: Allow uswsusp to write to swap Domenico Andreoli
2020-03-04 15:45                 ` Darrick J. Wong
2020-03-04 16:31                   ` Domenico Andreoli [this message]
2020-03-04  8:34               ` [PATCH] hibernate: unlock swap bdev for writing when uswsusp is active Domenico Andreoli
2020-04-20 18:52         ` Domenico Andreoli
2020-04-21 15:43           ` Darrick J. Wong
2020-04-21 18:39             ` Domenico Andreoli

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