[PATCH 4.19 127/170] btrfs: dev-replace: go back to suspend state if another EXCL_OP is running

From: Greg Kroah-Hartman
Date: Mon Jan 07 2019 - 07:56:45 EST

4.19-stable review patch. If anyone has any objections, please let me know.


From: Anand Jain <anand.jain@xxxxxxxxxx>

commit 05c49e6bc1e8866ecfd674ebeeb58cdbff9145c2 upstream.

In a secnario where balance and replace co-exists as below,

- start balance
- pause balance
- start replace
- reboot

and when system restarts, balance resumes first. Then the replace is
attempted to restart but will fail as the EXCL_OP lock is already held
by the balance. If so place the replace state back to

Fixes: 010a47bde9420 ("btrfs: add proper safety check before resuming dev-replace")
CC: stable@xxxxxxxxxxxxxxx # 4.18+
Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

fs/btrfs/dev-replace.c | 4 ++++
1 file changed, 4 insertions(+)

--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -900,6 +900,10 @@ int btrfs_resume_dev_replace_async(struc
* dev-replace to start anyway.
if (test_and_set_bit(BTRFS_FS_EXCL_OP, &fs_info->flags)) {
+ btrfs_dev_replace_write_lock(dev_replace);
+ dev_replace->replace_state =
+ btrfs_dev_replace_write_unlock(dev_replace);
"cannot resume dev-replace, other exclusive operation running");
return 0;