From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaegeuk Kim Subject: Re: [f2fs-dev] [PATCH] f2fs: fix multiple f2fs_add_link() calls having same name Date: Tue, 14 Feb 2017 17:39:47 -0800 Message-ID: <20170215013947.GA5332@jaegeuk.local> References: <20170214180345.2074-1-jaegeuk@kernel.org> <4fb2c86e-a50c-512f-2fa7-964540101138@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <4fb2c86e-a50c-512f-2fa7-964540101138@huawei.com> Sender: stable-owner@vger.kernel.org To: Chao Yu Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, stable@vger.kernel.org List-Id: linux-f2fs-devel.lists.sourceforge.net On 02/15, Chao Yu wrote: > On 2017/2/15 2:03, Jaegeuk Kim wrote: > > VFS uses f2fs_lookup() to decide f2fs_add_link() call during file creation. > > But, if there is a race condition, f2fs_add_link() can be called multiple > > times, resulting in multiple dentries with a same name. This patches fixes > > it by adding __f2fs_find_entry() in f2fs_add_link() path. > > As during ->lookup, i_mutex will be held all the time, so there is no race > condition in between different file creators? Hehe, yup. I dropped this patch. Thanks, > > Thanks, > > > > > Cc: > > Signed-off-by: Jaegeuk Kim > > --- > > fs/f2fs/dir.c | 14 ++++++++++++-- > > 1 file changed, 12 insertions(+), 2 deletions(-) > > > > diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c > > index 827c5daef4fc..bc7c48839bec 100644 > > --- a/fs/f2fs/dir.c > > +++ b/fs/f2fs/dir.c > > @@ -643,14 +643,24 @@ int __f2fs_add_link(struct inode *dir, const struct qstr *name, > > struct inode *inode, nid_t ino, umode_t mode) > > { > > struct fscrypt_name fname; > > + struct page *page; > > + struct f2fs_dir_entry *de; > > int err; > > > > err = fscrypt_setup_filename(dir, name, 0, &fname); > > if (err) > > return err; > > > > - err = __f2fs_do_add_link(dir, &fname, inode, ino, mode); > > - > > + de = __f2fs_find_entry(dir, &fname, &page); > > + if (de) { > > + f2fs_dentry_kunmap(dir, page); > > + f2fs_put_page(page, 0); > > + err = -EEXIST; > > + } else if (!IS_ERR(page)) { > > + err = __f2fs_do_add_link(dir, &fname, inode, ino, mode); > > + } else { > > + err = PTR_ERR(page); > > + } > > fscrypt_free_filename(&fname); > > return err; > > } > >