Re: i_mutex locking in generic_file_splice_write()

[Andreas Dilger <adilger@xxxxxxxxxxxxx>]

On Oct 15, 2006  13:14 -0700, Mark Fasheh wrote:
> +void inode_double_lock(struct inode *inode1, struct inode *inode2)
> +{
> +	if (!inode1 || !inode2) {
> +		if (inode1)
> +			mutex_lock(&inode1->i_mutex);
> +		else if (inode2)
> +			mutex_lock(&inode2->i_mutex);
> +		return;
> +	}
> +
> +	if (inode1 == inode2) {
> +		mutex_lock(&inode1->i_mutex);

Could be a tiny bit cleaner if you put the "inode1 == inode2" case above:

void inode_double_lock(struct inode *inode1, struct inode *inode2)
{
	if (inode1 == NULL || inode2 == NULL || inode1 == inode2) {
		if (inode1)
			mutex_lock(&inode1->i_mutex);
		else if (inode2)
			mutex_lock(&inode2->i_mutex);
		return;
	}

	if (inode1 < inode2) {
		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);
		mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);
	} else {
		mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);
		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);
	}
}

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

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