Re: [PATCH] ext4: Fix ERR_PTR(0) in ext4_mkdir()

[Hongling Zeng]

  Hi ,

  Good point! I've been systematically fixing this across filesystems.
  Several fixes have already been merged (9p, jfs, orangefs,cachefiles....)

  Still working on a few more filesystems.

  Thanks for the suggestion!

  Best regards,
  Hongling

在 2026年05月20日 17:19, Zhang Yi 写道:
> On 5/20/2026 3:46 PM, Hongling Zeng wrote:
> > When mkdir succeeds, ext4_mkdir() returns ERR_PTR(0) which is incorrect.
> > It should return NULL instead for success and ERR_PTR() only with
> > negative error codes for failure.
> This point is indeed very easy to overlook. However, why not modify
> other file systems as well? Commit 88d5baf69082 made changes not only
> to ext4.
>
> Thanks,
> Yi.
>
> > Fixes: 88d5baf69082 ("Change inode_operations.mkdir to return struct dentry *")
> > Signed-off-by: Hongling Zeng <zenghongling@xxxxxxxxxx>
> > ---
> >   fs/ext4/namei.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
> > index 4a47fbd8dd30..8cadaeb15b2b 100644
> > --- a/fs/ext4/namei.c
> > +++ b/fs/ext4/namei.c
> > @@ -3054,7 +3054,7 @@ static struct dentry *ext4_mkdir(struct mnt_idmap *idmap, struct inode *dir,
> >   out_retry:
> >   	if (err == -ENOSPC && ext4_should_retry_alloc(dir->i_sb, &retries))
> >   		goto retry;
> > -	return ERR_PTR(err);
> > +	return err ? ERR_PTR(err) : NULL;
> >   }
> >   
> >   /*