udf: Do not bother merging very long extents

stable inclusion
from stable-v5.10.173
commit 965982feb333aefa9256c0fe188b5f1b958aef63
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8BFR3

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=965982feb333aefa9256c0fe188b5f1b958aef63



--------------------------------

commit 53cafe1d upstream.

When merging very long extents we try to push as much length as possible
to the first extent. However this is unnecessarily complicated and not
really worth the trouble. Furthermore there was a bug in the logic
resulting in corrupting extents in the file as syzbot reproducer shows.
So just don't bother with the merging of extents that are too long
together.

CC: stable@vger.kernel.org
Reported-by:  <syzbot+60f291a24acecb3c2bd5@syzkaller.appspotmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>