I can't say I'm a fan of all these long backtraces in commit logs..
> +static struct dentry *blk_debugfs_dir_register(const char *name)
> +{
> + return debugfs_create_dir(name, blk_debugfs_root);
> +}
I don't think we really need this helper.
> +void blk_part_debugfs_unregister(struct hd_struct *p)
> +{
> + debugfs_remove_recursive(p->debugfs_dir);
> + p->debugfs_dir = NULL;
> +}
Why do we need to clear the pointer here?
> +#ifdef CONFIG_DEBUG_FS
> + /* Currently only used by kernel/trace/blktrace.c */
> + struct dentry *debugfs_dir;
> +#endif
Does that comment really add value?
> +static struct dentry *blk_trace_debugfs_dir(struct block_device *bdev,
> + struct request_queue *q)
> {
> + struct hd_struct *p = NULL;
>
> + * Some drivers like scsi-generic use a NULL block device. For
> + * other drivers when bdev != bdev->bd_contain we are doing a blktrace
> + * on a parition, otherwise we know we are working on the whole
> + * disk, and for that the request_queue already has its own debugfs_dir.
> + * which we have been using for other things other than blktrace.
> + */
> + if (bdev && bdev != bdev->bd_contains)
> + p = bdev->bd_part;
>
> + if (p)
> + return p->debugfs_dir;
> +
> + return q->debugfs_dir;
This could be simplified down to:
if (bdev && bdev != bdev->bd_contains)
return bdev->bd_part->debugfs_dir;
return q->debugfs_dir;
Given that bd_part is in __blkdev_get very near bd_contains.
Also given that this patch completely rewrites blk_trace_debugfs_dir is
there any point in the previous patch?
> @@ -491,6 +500,7 @@ static int do_blk_trace_setup(struct request_queue *q,
> char *name, dev_t dev,
> struct dentry *dir = NULL;
> int ret;
>
> +
> if (!buts->buf_size || !buts->buf_nr)
> return -EINVAL;
>
Spurious whitespace change.
