btrfs: tracepoints: add trace event for log_conflicting_inodes()

log_conflicting_inodes() is an important step called during a fsync, as
well as during rename and link operations on inodes that were previously
logged. Add trace events for when entering and exiting that function.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

2 files changed, 62 insertions, 0 deletions

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 63553d72ff1a..f91924372494 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -6261,7 +6261,15 @@ static int log_conflicting_inodes(struct btrfs_trans_handle *trans,
 	if (ctx->logging_conflict_inodes)
 		return 0;
 
+	/*
+	 * Avoid any work if no conflicting inodes and emitting the trace event
+	 * which only adds noise and it's useless if there are no inodes.
+	 */
+	if (list_empty(&ctx->conflict_inodes))
+		return 0;
+
 	ctx->logging_conflict_inodes = true;
+	trace_btrfs_log_conflicting_inodes_enter(trans, ctx);
 
 	/*
 	 * New conflicting inodes may be found and added to the list while we
@@ -6355,6 +6363,7 @@ static int log_conflicting_inodes(struct btrfs_trans_handle *trans,
 	ctx->logging_conflict_inodes = false;
 	if (ret)
 		free_conflicting_inodes(ctx);
+	trace_btrfs_log_conflicting_inodes_exit(trans, ctx, ret);
 
 	return ret;
 }
diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h
index ad18b09fb3cd..2eff817026a4 100644
--- a/include/trace/events/btrfs.h
+++ b/include/trace/events/btrfs.h
@@ -1294,6 +1294,59 @@ TRACE_EVENT(btrfs_add_conflicting_inode_exit,
 			__entry->conflict_ino_parent, __entry->ret)
 );
 
+TRACE_EVENT(btrfs_log_conflicting_inodes_enter,
+
+	TP_PROTO(const struct btrfs_trans_handle *trans,
+		 const struct btrfs_log_ctx *ctx),
+
+	TP_ARGS(trans, ctx),
+
+	TP_STRUCT__entry_btrfs(
+		__field(	u64,     	root_objectid		)
+		__field(	u64,		transid			)
+		__field(	u64,	 	ctx_ino			)
+	),
+
+	TP_fast_assign(
+		TP_fast_assign_fsid(trans->fs_info);
+		__entry->root_objectid		= btrfs_root_id(ctx->inode->root);
+		__entry->transid		= trans->transid;
+		__entry->ctx_ino		= btrfs_ino(ctx->inode);
+	),
+
+	TP_printk_btrfs("root=%llu(%s) transid=%llu ctx_ino=%llu",
+			show_root_type(__entry->root_objectid), __entry->transid,
+			__entry->ctx_ino)
+);
+
+TRACE_EVENT(btrfs_log_conflicting_inodes_exit,
+
+	TP_PROTO(const struct btrfs_trans_handle *trans,
+		 const struct btrfs_log_ctx *ctx,
+		 int ret),
+
+	TP_ARGS(trans, ctx, ret),
+
+	TP_STRUCT__entry_btrfs(
+		__field(	u64,     	root_objectid		)
+		__field(	u64,		transid			)
+		__field(	u64,	 	ctx_ino			)
+		__field(	int,		ret			)
+	),
+
+	TP_fast_assign(
+		TP_fast_assign_fsid(trans->fs_info);
+		__entry->root_objectid		= btrfs_root_id(ctx->inode->root);
+		__entry->transid		= trans->transid;
+		__entry->ctx_ino		= btrfs_ino(ctx->inode);
+		__entry->ret			= ret;
+	),
+
+	TP_printk_btrfs("root=%llu(%s) transid=%llu ctx_ino=%llu ret=%d",
+			show_root_type(__entry->root_objectid), __entry->transid,
+			__entry->ctx_ino, __entry->ret)
+);
+
 TRACE_EVENT(btrfs_sync_fs,
 
 	TP_PROTO(const struct btrfs_fs_info *fs_info, int wait),