From: Li Lingfeng <lilingfeng3@xxxxxxxxxx>
[ Upstream commit 2760904d895279f87196f0fa9ec570c79fe6a2e4 ]
As described in commit 38d11da522aa ("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 38d11da522aa 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: 38d11da522aa ("dm: don't lock fs when the map is NULL in process of resume")
Signed-off-by: Li Lingfeng <lilingfeng3@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/md/dm-ioctl.c | 5 +----
drivers/md/dm.c | 4 ++++
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index 83aecd9250ba6..6ae1c19b82433 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1151,13 +1151,10 @@ static int do_resume(struct dm_ioctl *param)
/* Do we need to load a new map ? */
if (new_map) {
sector_t old_size, new_size;
- int srcu_idx;
/* Suspend if it isn't already suspended */
- old_map = dm_get_live_table(md, &srcu_idx);
- if ((param->flags & DM_SKIP_LOCKFS_FLAG) || !old_map)
+ if (param->flags & DM_SKIP_LOCKFS_FLAG)
suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG;
- dm_put_live_table(md, srcu_idx);
if (param->flags & DM_NOFLUSH_FLAG)
suspend_flags |= DM_SUSPEND_NOFLUSH_FLAG;
if (!dm_suspended_md(md))
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 24284d22f15bc..acf7e7551c941 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2801,6 +2801,10 @@ int dm_suspend(struct mapped_device *md, unsigned int suspend_flags)
}
map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
+ if (!map) {
+ /* avoid deadlock with fs/namespace.c:do_mount() */
+ suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG;
+ }
r = __dm_suspend(md, map, suspend_flags, TASK_INTERRUPTIBLE, DMF_SUSPENDED);
if (r)
--
2.39.2
