FS: JFS: Check for read-only mounted filesystem in txBegin

stable inclusion
from stable-v5.10.192
commit 5c094ca994824e038b6a97835ded4e5d1d808504
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I933RF

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5c094ca994824e038b6a97835ded4e5d1d808504



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

[ Upstream commit 95e2b352 ]

 This patch adds a check for read-only mounted filesystem
 in txBegin before starting a transaction potentially saving
 from NULL pointer deref.

Signed-off-by: Immad Mir <mirimmad17@gmail.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>