pNFS: Add prepare commit trace to block/scsi layout

Replace dprintk with trace event in ext_tree_prepare_commit() function.

Co-developed-by: Konstantin Evtushenko <[e-mail]>
Signed-off-by: Konstantin Evtushenko <[e-mail]>
Signed-off-by: Sergey Bashirov <[e-mail]>
Reviewed-by: Christoph Hellwig <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Trond Myklebust <[e-mail]>

fs/nfs/blocklayout/extent_tree.c

···
 #include <linux/vmalloc.h>
 
 #include "blocklayout.h"
+#include "../nfs4trace.h"
 
 #define NFSDBG_FACILITY		NFSDBG_PNFS_LD
 
···
 	__be32 *start_p;
 	int ret;
 
-	dprintk("%s enter\n", __func__);
-
 	arg->layoutupdate_page = alloc_page(GFP_NOFS);
 	if (!arg->layoutupdate_page)
 		return -ENOMEM;
···
 		}
 	}
 
-	dprintk("%s found %zu ranges\n", __func__, count);
+	trace_bl_ext_tree_prepare_commit(ret, count,
+			arg->lastbytewritten, !!ret);
 	return ret;
 }
 

fs/nfs/nfs4trace.c

···
 EXPORT_TRACEPOINT_SYMBOL_GPL(ff_layout_write_error);
 EXPORT_TRACEPOINT_SYMBOL_GPL(ff_layout_commit_error);
 
+EXPORT_TRACEPOINT_SYMBOL_GPL(bl_ext_tree_prepare_commit);
 EXPORT_TRACEPOINT_SYMBOL_GPL(bl_pr_key_reg);
 EXPORT_TRACEPOINT_SYMBOL_GPL(bl_pr_key_reg_err);
 EXPORT_TRACEPOINT_SYMBOL_GPL(bl_pr_key_unreg);

fs/nfs/nfs4trace.h

···
 		)
 );
 
+TRACE_EVENT(bl_ext_tree_prepare_commit,
+		TP_PROTO(
+			int ret,
+			size_t count,
+			u64 lwb,
+			bool not_all_ranges
+		),
+
+		TP_ARGS(ret, count, lwb, not_all_ranges),
+
+		TP_STRUCT__entry(
+			__field(int, ret)
+			__field(size_t, count)
+			__field(u64, lwb)
+			__field(bool, not_all_ranges)
+		),
+
+		TP_fast_assign(
+			__entry->ret = ret;
+			__entry->count = count;
+			__entry->lwb = lwb;
+			__entry->not_all_ranges = not_all_ranges;
+		),
+
+		TP_printk(
+			"ret=%d, found %zu ranges, lwb=%llu%s",
+			__entry->ret,
+			__entry->count,
+			__entry->lwb,
+			__entry->not_all_ranges ? ", not all ranges encoded" :
+						  ""
+		)
+);
+
 DECLARE_EVENT_CLASS(pnfs_bl_pr_key_class,
 	TP_PROTO(
 		const struct block_device *bdev,