From: "Ernesto A. Fernández" <ernesto.mnd.fernandez@gmail.com>
To: Viacheslav Dubeyko <slava@dubeyko.com>
Cc: linux-fsdevel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 1/6] hfsplus: prevent btree data loss on root split
Date: Thu, 25 Oct 2018 16:42:31 -0300 [thread overview]
Message-ID: <20181025194231.mbfwmt6fhmokrn52@eaf> (raw)
In-Reply-To: <1540486317.2669.6.camel@dubeyko.com>
On Thu, Oct 25, 2018 at 09:51:57AM -0700, Viacheslav Dubeyko wrote:
> On Tue, 2018-10-23 at 22:32 -0300, Ernesto A. Fernández wrote:
> > On Tue, Oct 23, 2018 at 06:23:53PM -0700, Viacheslav Dubeyko wrote:
> > >
> > > On Fri, 2018-08-31 at 00:58 -0300, Ernesto A. Fernández wrote:
> > > >
> > > > Creating, renaming or deleting a file may cause catalog
> > > > corruption and
> > > > data loss. This bug is randomly triggered by xfstests
> > > > generic/027, but
> > > > here is a faster reproducer:
> > > >
> > > > truncate -s 50M fs.iso
> > > > mkfs.hfsplus fs.iso
> > > > mount fs.iso /mnt
> > > > i=100
> > > > while [ $i -le 150 ]; do
> > > > touch /mnt/$i &>/dev/null
> > > > ((++i))
> > > > done
> > > > i=100
> > > > while [ $i -le 150 ]; do
> > > > mv /mnt/$i /mnt/$(perl -e "print $i x82") &>/dev/null
> > > > ((++i))
> > > > done
> > > > umount /mnt
> > > > fsck.hfsplus -n fs.iso
> > > >
> > > > The bug is triggered whenever hfs_brec_update_parent() needs to
> > > > split
> > > > the root node. The height of the btree is not increased, which
> > > > leaves
> > > > the new node orphaned and its records lost.
> > > >
> > > > Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.
> > > > com>
> > > > ---
> > > > fs/hfsplus/brec.c | 4 ++++
> > > > 1 file changed, 4 insertions(+)
> > > >
> > > > diff --git a/fs/hfsplus/brec.c b/fs/hfsplus/brec.c
> > > > index ed8eacb34452..aa17a392b414 100644
> > > > --- a/fs/hfsplus/brec.c
> > > > +++ b/fs/hfsplus/brec.c
> > > > @@ -429,6 +429,10 @@ static int hfs_brec_update_parent(struct
> > > > hfs_find_data *fd)
> > > > if (new_node) {
> > > > __be32 cnid;
> > > >
> > > > + if (!new_node->parent) {
> > > > + hfs_btree_inc_height(tree);
> > > > + new_node->parent = tree->root;
> > > I worry about the case when we are adding the node on intermediate
> > > (not
> > > root) level. As far as I can see, we will be in trouble here
> > > because I
> > > don't see any processing of two possible cases: (1) root node; (2)
> > > node
> > > of intermediate level. Do I miss something here?
> > If 'new_node' had been the result of splitting a node other than
> > root,
> > then it would have a parent.
> >
>
> Could you please share the callstack or/and more detailed explanation
> that would show the correctness of the fix? Currently, it's not enough
> details in the comment for easy understanding the issue's environment
> and correctness of the fix.
This patch is two months old now. Why did you wait until the merge
window to give me your traditional "the patch is confusing" reply?
> I simply mean here that as implementation
> as concept of the HFS+ b-trees is not trivial. But everybody should
> easy understand the patch.
Those two sentences are not compatible. Reviewers need to have some
understanding of the code they review. No royal road...
> Thanks,
> Vyacheslav Dubeyko.
>
next prev parent reply other threads:[~2018-10-26 4:16 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-31 3:58 [PATCH 1/6] hfsplus: prevent btree data loss on root split Ernesto A. Fernández
2018-08-31 3:59 ` [PATCH 2/6] hfsplus: fix BUG on bnode parent update Ernesto A. Fernández
2018-10-24 1:33 ` Viacheslav Dubeyko
2018-10-24 2:48 ` Ernesto A. Fernández
[not found] ` <20181024143947.4e30cca3ddda937db70237e9@linux-foundation.org>
2018-10-24 22:45 ` Ernesto A. Fernández
2018-08-31 4:00 ` [PATCH 3/6] hfsplus: prevent btree data loss on ENOSPC Ernesto A. Fernández
2018-08-31 4:00 ` [PATCH 4/6] hfs: prevent btree data loss on root split Ernesto A. Fernández
2018-08-31 4:01 ` [PATCH 5/6] hfs: fix BUG on bnode parent update Ernesto A. Fernández
2018-08-31 4:01 ` [PATCH 6/6] hfs: prevent btree data loss on ENOSPC Ernesto A. Fernández
2018-08-31 5:36 ` [PATCH 1/6] hfsplus: prevent btree data loss on root split Christoph Hellwig
2018-08-31 14:55 ` Ernesto A. Fernández
2018-09-01 4:49 ` Dave Chinner
2018-09-02 4:33 ` Ernesto A. Fernández
2018-09-02 23:32 ` Dave Chinner
2018-09-03 0:06 ` Ernesto A. Fernández
2018-09-06 18:28 ` Ernesto A. Fernández
2018-10-24 1:23 ` Viacheslav Dubeyko
2018-10-24 1:32 ` Ernesto A. Fernández
2018-10-25 16:51 ` Viacheslav Dubeyko
2018-10-25 19:42 ` Ernesto A. Fernández [this message]
2018-10-26 16:58 ` Viacheslav Dubeyko
2018-10-27 5:15 ` Ernesto A. Fernández
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