From: David Sterba <dsterba@suse.cz>
To: Qu Wenruo <quwenruo.btrfs@gmx.com>
Cc: Johannes Thumshirn <Johannes.Thumshirn@wdc.com>,
Qu Wenruo <wqu@suse.com>,
"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH 1/2] btrfs: fix wild pointer access during metadata read failure for subpage
Date: Mon, 15 Mar 2021 19:51:09 +0100 [thread overview]
Message-ID: <20210315185108.GA7604@twin.jikos.cz> (raw)
In-Reply-To: <f4ebad22-2004-b051-2871-8f1ed64cc6cc@gmx.com>
On Mon, Mar 15, 2021 at 04:25:32PM +0800, Qu Wenruo wrote:
>
>
> On 2021/3/15 下午3:55, Johannes Thumshirn wrote:
> > On 15/03/2021 06:40, Qu Wenruo wrote:
> >> The difference against find_extent_buffer_nospinlock() is:
> >> - Also handles regular sectorsize == PAGE_SIZE case
> >> - No extent buffer refs increase/decrease
> >> As extent buffer under IO must has non-zero refs.
> >
> > Can these be merged into a single function? The sectorsie == PAGE_SIZE case
> > won't do anything for find_extent_buffer_nospinlock() and the
> > atomic_inc_not_zero(&eb->refs) can be hidden behind a 'if (write)' check.
>
> That would make the eb refs change too inconsistent.
>
> But I get your point.
>
> How about calling find_extent_buffer_nospinlock() and then dec the refs
> manually?
Is this equivalent to this patch? Ie. the atomic_inc_not_zero in
find_extent_buffer_nospinlock happens inside the RCU section, while what
you suggest looks like
find_extent_buffer_nospinlock()
rcu_lock
radix_lookup
rcu_unlock
atomic_inc_not_zero()
next prev parent reply other threads:[~2021-03-15 18:53 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-15 5:39 [PATCH 0/2] btrfs: fixes for subpage which also affect read-only mount Qu Wenruo
2021-03-15 5:39 ` [PATCH 1/2] btrfs: fix wild pointer access during metadata read failure for subpage Qu Wenruo
2021-03-15 7:55 ` Johannes Thumshirn
2021-03-15 8:25 ` Qu Wenruo
2021-03-15 18:51 ` David Sterba [this message]
2021-03-16 0:03 ` Qu Wenruo
2021-03-15 5:39 ` [PATCH 2/2] btrfs: make reada to be subpage compatible Qu Wenruo
2021-03-15 9:39 ` Johannes Thumshirn
2021-03-15 15:42 ` [PATCH 0/2] btrfs: fixes for subpage which also affect read-only mount David Sterba
2021-03-16 0:29 ` Qu Wenruo
2021-03-16 10:08 ` David Sterba
2021-03-16 10:15 ` David Sterba
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