From: Johannes Thumshirn <johannes.thumshirn@wdc.com>
To: David Sterba <dsterba@suse.cz>
Cc: linux-btrfs@vger.kernel.org, Naohiro Aota <naohiro.aota@wdc.com>,
David Sterba <dsterba@suse.com>, Qu Wenruo <wqu@suse.com>
Subject: Re: [PATCH 4/4] btrfs: zoned: avoid underflow of bytes_zone_unusable
Date: Fri, 2 Oct 2026 09:32:04 +0200 [thread overview]
Message-ID: <ar9dTrpxbbJ2ha9D@mayhem.fritz.box> (raw)
In-Reply-To: <20260914150811.GJ54722@twin.jikos.cz>
On Mon, Sep 14, 2026 at 05:08:11PM +0200, David Sterba wrote:
> On Mon, Sep 14, 2026 at 10:52:48AM +0200, Johannes Thumshirn wrote:
> > The two functions btrfs_free_reserved_bytes() and
> > btrfs_reset_unused_block_groups() both manipulate
> > space_info->bytes_zone_unusable without using the accessor function
> > btrfs_space_info_update_bytes_zone_unusable() potentially risking an
> > underflow (in case of btrfs_reset_unused_block_groups()).
> >
> > Use btrfs_space_info_update_bytes_zone_unusable() in both function, in
> > the case of btrfs_free_reserved_bytes() it is mostly for documenting
> > purposes.
> >
> > Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
>
> The two cases cover all modifications of the bytes_zone_unusable, it
> could make sense to force using that wrapper, eg. renaming the
> identifier and providing only a get/set helpers.
I have a local version of this, but I don't really like it, sorry. It's a lot
of churn.
prev parent reply other threads:[~2026-10-02 7:32 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-14 8:52 [PATCH 0/4] btrfs: zoned: LLM inspired fixes Johannes Thumshirn
2026-09-14 8:52 ` [PATCH 1/4] btrfs: zoned: only change active zone counter on successful (de)activation Johannes Thumshirn
2026-09-14 8:52 ` [PATCH 2/4] btrfs: zoned: fix possible UAF in wait_eb_writebacks Johannes Thumshirn
2026-09-14 15:05 ` David Sterba
2026-10-02 7:32 ` Johannes Thumshirn
2026-09-14 8:52 ` [PATCH 3/4] btrfs: zoned: requeue block group if zone reset bails out Johannes Thumshirn
2026-09-14 8:52 ` [PATCH 4/4] btrfs: zoned: avoid underflow of bytes_zone_unusable Johannes Thumshirn
2026-09-14 15:08 ` David Sterba
2026-10-02 7:32 ` Johannes Thumshirn [this message]
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