btrfs: dev-replace: set result code of cancel by status of scrub

The device-replace needs to check the result code of the scrub workers
in btrfs_dev_replace_cancel and distinguish if successful cancel
operation and when the there was no operation running.

If btrfs_scrub_cancel() fails, return
BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED so that user can try
to cancel the replace again.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 14 insertions, 7 deletions

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 08092d329f66..c0878ff8185a 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -805,16 +805,23 @@ int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
                 btrfs_dev_replace_write_unlock(dev_replace);
                 break;
         case BTRFS_IOCTL_DEV_REPLACE_STATE_STARTED:
-                result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
                 tgt_device = dev_replace->tgtdev;
                 src_device = dev_replace->srcdev;
                 btrfs_dev_replace_write_unlock(dev_replace);
-                btrfs_scrub_cancel(fs_info);
-                /* btrfs_dev_replace_finishing() will handle the cleanup part */
-                btrfs_info_in_rcu(fs_info,
-                        "dev_replace from %s (devid %llu) to %s canceled",
-                        btrfs_dev_name(src_device), src_device->devid,
-                        btrfs_dev_name(tgt_device));
+                ret = btrfs_scrub_cancel(fs_info);
+                if (ret < 0) {
+                        result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NOT_STARTED;
+                } else {
+                        result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
+                        /*
+                         * btrfs_dev_replace_finishing() will handle the
+                         * cleanup part
+                         */
+                        btrfs_info_in_rcu(fs_info,
+                                "dev_replace from %s (devid %llu) to %s canceled",
+                                btrfs_dev_name(src_device), src_device->devid,
+                                btrfs_dev_name(tgt_device));
+                }
                 break;
         case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
                 /*