dm: don't lock fs when the map is NULL during suspend or resume

mainline inclusion
from mainline-v6.4-rc8
commit 2760904d
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7FI78
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v6.4-rc7&id=2760904d895279f87196f0fa9ec570c79fe6a2e4



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As described in commit 38d11da5 ("dm: don't lock fs when the map is
NULL in process of resume"), a deadlock may be triggered between
do_resume() and do_mount().

This commit preserves the fix from commit 38d11da5 but moves it to
where it also serves to fix a similar deadlock between do_suspend()
and do_mount().  It does so, if the active map is NULL, by clearing
DM_SUSPEND_LOCKFS_FLAG in dm_suspend() which is called by both
do_suspend() and do_resume().

Fixes: 38d11da5 ("dm: don't lock fs when the map is NULL in process of resume")
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>

Conflicts:
  drivers/md/dm-ioctl.c
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>