Allow block cloning to be interrupted by a signal.

Even though block cloning is much faster than regular copying,
it is not instantaneous - the file might be large and the recordsize
small. It would be nice to be able to interrupt it with a signal
(e.g., SIGINFO on FreeBSD to see the progress).

Signed-off-by: Pawel Jakub Dawidek <[email protected]>

Author: pjd

module/zfs/zfs_vnops.c

@@ -1309,6 +1309,11 @@ zfs_clone_range(znode_t *inzp, uint64_t *inoffp, znode_t *outzp,
 			break;
 		}
 
+		if (issig(JUSTLOOKING) && issig(FORREAL)) {
+			error = SET_ERROR(EINTR);
+			break;
+		}
+
 		nbps = maxblocks;
 		last_synced_txg = spa_last_synced_txg(dmu_objset_spa(inos));
 		error = dmu_read_l0_bps(inos, inzp->z_id, inoff, size, bps,