[U-Boot] [PATCH] fs: btrfs: Fix tree traversal with btrfs_next_slot()

[Marek Behún]

I shall test this today or tomorrow, but have too many things on my
head, sorry :(
You saying that this will fix reading large files? I haven't
encountered such an error yet, but can try creating a large enough
file. How large should it be? 

On Mon, 1 Oct 2018 08:50:11 +0300
Yevgeny Popovych <yevgenyp at pointgrab.com> wrote:

> Just a kindly reminder :)
> 
> On 09/07/2018 12:59 PM, Yevgeny Popovych wrote:
> > When traversing slots in a btree (via btrfs_path) with
> > btrfs_next_slot(), we didn't correctly identify that the last slot
> > in the leaf was reached and we should jump to the next leaf.
> > 
> > This could lead to any kind of runtime errors or corruptions, like:
> > * file data not being read at all, or is read partially
> > * file is read but is corrupted
> > * (any) metadata being corrupted or not read at all, etc
> > 
> > The easiest way to reproduce this is to read a large enough file
> > that its EXTENT_DATA items don't fit into a single leaf.
> > 
> > Signed-off-by: Yevgeny Popovych <yevgenyp at pointgrab.com>
> > Cc: Marek Behun <marek.behun at nic.cz>
> > ---
> >  fs/btrfs/ctree.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
> > index 4da36a9..b44a47e 100644
> > --- a/fs/btrfs/ctree.c
> > +++ b/fs/btrfs/ctree.c
> > @@ -270,7 +270,7 @@ int btrfs_next_slot(struct btrfs_path *p)
> >  {
> >  	struct btrfs_leaf *leaf = &p->nodes[0]->leaf;
> >  
> > -	if (p->slots[0] >= leaf->header.nritems)
> > +	if (p->slots[0] + 1 >= leaf->header.nritems)
> >  		return jump_leaf(p, 1);
> >  
> >  	p->slots[0]++;
> >   
>