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: <stable@xxxxxxxxxxxxxxx>
> > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
> > ---
> > 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;
> > }
> >