f2fs: introduce data read/write showing path info

This was used in Android for a long time. Let's upstream it.
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

fs/f2fs/file.c

@@ -4329,17 +4329,39 @@ static ssize_t f2fs_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
 static ssize_t f2fs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
 	struct inode *inode = file_inode(iocb->ki_filp);
+	const loff_t pos = iocb->ki_pos;
 	ssize_t ret;
 
 	if (!f2fs_is_compress_backend_ready(inode))
 		return -EOPNOTSUPP;
 
-	if (f2fs_should_use_dio(inode, iocb, to))
-		return f2fs_dio_read_iter(iocb, to);
+	if (trace_f2fs_dataread_start_enabled()) {
+		char *p = f2fs_kmalloc(F2FS_I_SB(inode), PATH_MAX, GFP_KERNEL);
+		char *path;
+
+		if (!p)
+			goto skip_read_trace;
+
+		path = dentry_path_raw(file_dentry(iocb->ki_filp), p, PATH_MAX);
+		if (IS_ERR(path)) {
+			kfree(p);
+			goto skip_read_trace;
+		}
 
-	ret = filemap_read(iocb, to, 0);
-	if (ret > 0)
-		f2fs_update_iostat(F2FS_I_SB(inode), APP_BUFFERED_READ_IO, ret);
+		trace_f2fs_dataread_start(inode, pos, iov_iter_count(to),
+					current->pid, path, current->comm);
+		kfree(p);
+	}
+skip_read_trace:
+	if (f2fs_should_use_dio(inode, iocb, to)) {
+		ret = f2fs_dio_read_iter(iocb, to);
+	} else {
+		ret = filemap_read(iocb, to, 0);
+		if (ret > 0)
+			f2fs_update_iostat(F2FS_I_SB(inode), APP_BUFFERED_READ_IO, ret);
+	}
+	if (trace_f2fs_dataread_end_enabled())
+		trace_f2fs_dataread_end(inode, pos, ret);
 	return ret;
 }
 
@@ -4631,14 +4653,36 @@ static ssize_t f2fs_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	/* Possibly preallocate the blocks for the write. */
 	target_size = iocb->ki_pos + iov_iter_count(from);
 	preallocated = f2fs_preallocate_blocks(iocb, from, dio);
-	if (preallocated < 0)
+	if (preallocated < 0) {
 		ret = preallocated;
-	else
+	} else {
+		if (trace_f2fs_datawrite_start_enabled()) {
+			char *p = f2fs_kmalloc(F2FS_I_SB(inode),
+						PATH_MAX, GFP_KERNEL);
+			char *path;
+
+			if (!p)
+				goto skip_write_trace;
+			path = dentry_path_raw(file_dentry(iocb->ki_filp),
+								p, PATH_MAX);
+			if (IS_ERR(path)) {
+				kfree(p);
+				goto skip_write_trace;
+			}
+			trace_f2fs_datawrite_start(inode, orig_pos, orig_count,
+					current->pid, path, current->comm);
+			kfree(p);
+		}
+skip_write_trace:
 		/* Do the actual write. */
 		ret = dio ?
 			f2fs_dio_write_iter(iocb, from, &may_need_sync):
 			f2fs_buffered_write_iter(iocb, from);
 
+		if (trace_f2fs_datawrite_end_enabled())
+			trace_f2fs_datawrite_end(inode, orig_pos, ret);
+	}
+
 	/* Don't leave any preallocated blocks around past i_size. */
 	if (preallocated && i_size_read(inode) < target_size) {
 		f2fs_down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);

include/trace/events/f2fs.h

@@ -2067,6 +2067,100 @@ TRACE_EVENT(f2fs_fiemap,
 		__entry->ret)
 );
 
+DECLARE_EVENT_CLASS(f2fs__rw_start,
+
+	TP_PROTO(struct inode *inode, loff_t offset, int bytes,
+			pid_t pid, char *pathname, char *command),
+
+	TP_ARGS(inode, offset, bytes, pid, pathname, command),
+
+	TP_STRUCT__entry(
+		__string(pathbuf, pathname)
+		__field(loff_t, offset)
+		__field(int, bytes)
+		__field(loff_t, i_size)
+		__string(cmdline, command)
+		__field(pid_t, pid)
+		__field(ino_t, ino)
+	),
+
+	TP_fast_assign(
+		/*
+		 * Replace the spaces in filenames and cmdlines
+		 * because this screws up the tooling that parses
+		 * the traces.
+		 */
+		__assign_str(pathbuf, pathname);
+		(void)strreplace(__get_str(pathbuf), ' ', '_');
+		__entry->offset = offset;
+		__entry->bytes = bytes;
+		__entry->i_size = i_size_read(inode);
+		__assign_str(cmdline, command);
+		(void)strreplace(__get_str(cmdline), ' ', '_');
+		__entry->pid = pid;
+		__entry->ino = inode->i_ino;
+	),
+
+	TP_printk("entry_name %s, offset %llu, bytes %d, cmdline %s,"
+		" pid %d, i_size %llu, ino %lu",
+		__get_str(pathbuf), __entry->offset, __entry->bytes,
+		__get_str(cmdline), __entry->pid, __entry->i_size,
+		(unsigned long) __entry->ino)
+);
+
+DECLARE_EVENT_CLASS(f2fs__rw_end,
+
+	TP_PROTO(struct inode *inode, loff_t offset, int bytes),
+
+	TP_ARGS(inode, offset, bytes),
+
+	TP_STRUCT__entry(
+		__field(ino_t,	ino)
+		__field(loff_t,	offset)
+		__field(int,	bytes)
+	),
+
+	TP_fast_assign(
+		__entry->ino		= inode->i_ino;
+		__entry->offset		= offset;
+		__entry->bytes		= bytes;
+	),
+
+	TP_printk("ino %lu, offset %llu, bytes %d",
+		(unsigned long) __entry->ino,
+		__entry->offset, __entry->bytes)
+);
+
+DEFINE_EVENT(f2fs__rw_start, f2fs_dataread_start,
+
+	TP_PROTO(struct inode *inode, loff_t offset, int bytes,
+		pid_t pid, char *pathname, char *command),
+
+	TP_ARGS(inode, offset, bytes, pid, pathname, command)
+);
+
+DEFINE_EVENT(f2fs__rw_end, f2fs_dataread_end,
+
+	TP_PROTO(struct inode *inode, loff_t offset, int bytes),
+
+	TP_ARGS(inode, offset, bytes)
+);
+
+DEFINE_EVENT(f2fs__rw_start, f2fs_datawrite_start,
+
+	TP_PROTO(struct inode *inode, loff_t offset, int bytes,
+		pid_t pid, char *pathname, char *command),
+
+	TP_ARGS(inode, offset, bytes, pid, pathname, command)
+);
+
+DEFINE_EVENT(f2fs__rw_end, f2fs_datawrite_end,
+
+	TP_PROTO(struct inode *inode, loff_t offset, int bytes),
+
+	TP_ARGS(inode, offset, bytes)
+);
+
 #endif /* _TRACE_F2FS_H */
 
  /* This part must be outside protection */