Re: [PATCH] vfs: Add a trace point in the mark_inode_dirty function

[Li Zefan <lizf@cn.fujitsu.com>]

> +/*
> + * Tracepoint for dirtying an inode:
> + */
> +TRACE_EVENT(dirty_inode,
> +
> +	TP_PROTO(struct inode *inode, struct task_struct *task),
> +
> +	TP_ARGS(inode, task),
> +
> +	TP_STRUCT__entry(
> +		__array( char,	comm,	TASK_COMM_LEN	)
> +		__field( pid_t,	pid			)
> +		__array( char,  dev,    16		)
> +		__array( char,  file,   32		)
> +	),
> +
> +	TP_fast_assign(
> +		if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) {
> +                	struct dentry *dentry;
> +                	const char *name = "?";
> +
> +			dentry = d_find_alias(inode);
> +			if (dentry) {
> +				spin_lock(&dentry->d_lock);
> +				name = (const char *) dentry->d_name.name;
> +			}
> +
> +			memcpy(__entry->comm, task->comm, TASK_COMM_LEN);
> +			__entry->pid = task->pid;
> +			strlcpy(__entry->file, name, 32);
> +			strlcpy(__entry->dev, inode->i_sb->s_id, 16);
> +
> +			if (dentry) {
> +				spin_unlock(&dentry->d_lock);
> +				dput(dentry);
> +			}
> +		}

This will leave __entry->comm, __entry->file and __entry->dev
uninitialized in the "else" case..

And is there any reason that we have to use __array() but can't
use __string()?

> +	),
> +
> +	TP_printk("task=%i (%s) file=%s dev=%s",
> +		__entry->pid, __entry->comm, __entry->file, __entry->dev)
> +);
> +
> +#endif /* _TRACE_VFS_H */