xfs: add a separate tracepoint for stealing an open zone for GC

The case where we have to reuse an already open zone warrants a different
trace point vs the normal opening of a GC zone.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hans Holmberg <hans.holmberg@wdc.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

Author: Christoph Hellwig

fs/xfs/xfs_trace.h

@@ -394,6 +394,7 @@ DEFINE_ZONE_EVENT(xfs_zone_full);
 DEFINE_ZONE_EVENT(xfs_zone_opened);
 DEFINE_ZONE_EVENT(xfs_zone_reset);
 DEFINE_ZONE_EVENT(xfs_zone_gc_target_opened);
+DEFINE_ZONE_EVENT(xfs_zone_gc_target_stolen);
 
 TRACE_EVENT(xfs_zone_free_blocks,
 	TP_PROTO(struct xfs_rtgroup *rtg, xfs_rgblock_t rgbno,

fs/xfs/xfs_zone_gc.c

@@ -543,7 +543,7 @@ xfs_zone_gc_steal_open(
 		return -EIO;
 	}
 
-	trace_xfs_zone_gc_target_opened(found->oz_rtg);
+	trace_xfs_zone_gc_target_stolen(found->oz_rtg);
 	found->oz_is_gc = true;
 	list_del_init(&found->oz_entry);
 	zi->zi_nr_open_zones--;