btrfs: dev-replace: go back to suspend state if another EXCL_OP is running

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
BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED state.

Fixes: 010a47bde9420 ("btrfs: add proper safety check before resuming dev-replace")
CC: stable@vger.kernel.org # 4.18+
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 8eb9307..b2b283e 100644 (file)
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -900,6 +900,10 @@ int btrfs_resume_dev_replace_async(struct btrfs_fs_info *fs_info)
         * 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_IOCTL_DEV_REPLACE_STATE_SUSPENDED;
+               btrfs_dev_replace_write_unlock(dev_replace);
                btrfs_info(fs_info,
                "cannot resume dev-replace, other exclusive operation running");
                return 0;