From: David Sterba <dsterba@suse.cz>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: dsterba@suse.cz, Chris Mason <clm@fb.com>,
Josef Bacik <jbacik@fb.com>, David Sterba <dsterba@suse.com>,
Qu Wenruo <wqu@suse.com>,
Sakari Ailus <sakari.ailus@linux.intel.com>,
Mike Rapoport <rppt@linux.ibm.com>,
Bjorn Helgaas <bhelgaas@google.com>,
linux-btrfs@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [PATCH v2] btrfs: Fix btrfs_find_create_tree_block() testing
Date: Tue, 3 Dec 2019 20:06:27 +0100 [thread overview]
Message-ID: <20191203190627.GW2734@twin.jikos.cz> (raw)
In-Reply-To: <20191203184601.GI1787@kadam>
On Tue, Dec 03, 2019 at 09:46:01PM +0300, Dan Carpenter wrote:
> On Tue, Dec 03, 2019 at 07:40:39PM +0100, David Sterba wrote:
> > On Tue, Dec 03, 2019 at 02:24:58PM +0300, Dan Carpenter wrote:
> > > The btrfs_find_create_tree_block() uses alloc_test_extent_buffer() for
> > > testing and alloc_extent_buffer() for production. The problem is that
> > > the test code returns NULL and the production code returns error
> > > pointers. The callers only check for error pointers.
> > >
> > > I have changed alloc_test_extent_buffer() to return error pointers and
> > > updated the two callers which use it directly.
> > >
> > > Fixes: faa2dbf004e8 ("Btrfs: add sanity tests for new qgroup accounting code")
> > > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> >
> > I edited the changelog because btrfs_find_create_tree_block is
> > misleading and seems to be unrelated to the actual fix that's just for
> > alloc_test_extent_buffer. Patch added to misc-next, thanks.
>
> The bug is in btrfs_find_create_tree_block()
>
> fs/btrfs/disk-io.c
> 1046 struct extent_buffer *btrfs_find_create_tree_block(
> 1047 struct btrfs_fs_info *fs_info,
> 1048 u64 bytenr)
> 1049 {
> 1050 if (btrfs_is_testing(fs_info))
> 1051 return alloc_test_extent_buffer(fs_info, bytenr);
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> NULL
>
> 1052 return alloc_extent_buffer(fs_info, bytenr);
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Error pointers.
>
> 1053 }
>
> None of the callers of btrfs_find_create_tree_block() check for NULL.
I see, though my view is a bug in alloc_test_extent_buffer that should
follow alloc_extent_buffer semantics, and this gets fixed. I'll update
the changelog again, makes sense to mention that it namely affects
btrfs_find_create_tree_block.
prev parent reply other threads:[~2019-12-03 19:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-03 9:33 [PATCH] btrfs: Fix btrfs_find_create_tree_block() testing Dan Carpenter
2019-12-03 11:04 ` Mike Rapoport
2019-12-03 11:24 ` [PATCH v2] " Dan Carpenter
2019-12-03 18:40 ` David Sterba
2019-12-03 18:46 ` Dan Carpenter
2019-12-03 19:06 ` David Sterba [this message]
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