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Commit 02c62304 authored by Alan D. Brunelle's avatar Alan D. Brunelle Committed by Jens Axboe
Browse files

Added in user-injected messages into blk traces 



This allows a user to annotate the blk trace stream: writing a suitable
message to {/sys/kernel/debug}/block/<dsf>/msg will have it propagated
into the trace stream.

Signed-off-by: default avatarAlan D. Brunelle <alan.brunelle@hp.com>
Signed-off-by: default avatarJens Axboe <jens.axboe@oracle.com>
parent 7b679138

block/blktrace.c

+45 −0
Original line number Diff line number Diff line
@@ -244,6 +244,7 @@ static struct dentry *blk_create_tree(const char *blk_name) 
static void blk_trace_cleanup(struct blk_trace *bt)

{

	relay_close(bt->rchan);

	debugfs_remove(bt->msg_file);

	debugfs_remove(bt->dropped_file);

	blk_remove_tree(bt->dir);

	free_percpu(bt->sequence);
@@ -291,6 +292,44 @@ static const struct file_operations blk_dropped_fops = { 
	.read =		blk_dropped_read,

};



static int blk_msg_open(struct inode *inode, struct file *filp)

{

	filp->private_data = inode->i_private;



	return 0;

}



static ssize_t blk_msg_write(struct file *filp, const char __user *buffer,

				size_t count, loff_t *ppos)

{

	char *msg;

	struct blk_trace *bt;



	if (count > BLK_TN_MAX_MSG)

		return -EINVAL;



	msg = kmalloc(count, GFP_KERNEL);

	if (msg == NULL)

		return -ENOMEM;



	if (copy_from_user(msg, buffer, count)) {

		kfree(msg);

		return -EFAULT;

	}



	bt = filp->private_data;

	__trace_note_message(bt, "%s", msg);

	kfree(msg);



	return count;

}



static const struct file_operations blk_msg_fops = {

	.owner =	THIS_MODULE,

	.open =		blk_msg_open,

	.write =	blk_msg_write,

};



/*

 * Keep track of how many times we encountered a full subbuffer, to aid

 * the user space app in telling how many lost events there were.
@@ -380,6 +419,10 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev, 
	if (!bt->dropped_file)

		goto err;



	bt->msg_file = debugfs_create_file("msg", 0222, dir, bt, &blk_msg_fops);

	if (!bt->msg_file)

		goto err;



	bt->rchan = relay_open("trace", dir, buts->buf_size,

				buts->buf_nr, &blk_relay_callbacks, bt);

	if (!bt->rchan)
@@ -409,6 +452,8 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev, 
	if (dir)

		blk_remove_tree(dir);

	if (bt) {

		if (bt->msg_file)

			debugfs_remove(bt->msg_file);

		if (bt->dropped_file)

			debugfs_remove(bt->dropped_file);

		free_percpu(bt->sequence);

include/linux/blktrace_api.h

+1 −0
Original line number Diff line number Diff line
@@ -129,6 +129,7 @@ struct blk_trace { 
	u32 dev;

	struct dentry *dir;

	struct dentry *dropped_file;

	struct dentry *msg_file;

	atomic_t dropped;

};