Viewing: range_lock.h
/* SPDX-License-Identifier: GPL-2.0 */
/*
* This file is part of Lustre, http://www.lustre.org/
*
* Range lock is used to allow multiple threads writing a single shared
* file given each thread is writing to a non-overlapping portion of the
* file.
*
* Refer to the possible upstream kernel version of range lock by
* Jan Kara <jack@suse.cz>: https://lkml.org/lkml/2013/1/31/480
*
* This file could later replaced by the upstream kernel version.
*
* Author: Prakash Surya <surya1@llnl.gov>
* Author: Bobi Jam <bobijam.xu@intel.com>
*/
#ifndef _RANGE_LOCK_H
#define _RANGE_LOCK_H
#include <linux/spinlock.h>
#include <linux/rbtree.h>
#define RL_FMT "[%llu, %llu]"
#define RL_PARA(range) \
(unsigned long long)(range)->rl_start, \
(unsigned long long)(range)->rl_end
struct range_lock {
__u64 rl_start,
rl_end,
rl_subtree_last;
struct rb_node rl_rb;
/**
* Process to enqueue this lock.
*/
struct task_struct *rl_task;
/**
* Number of ranges which are blocking acquisition of the lock
*/
unsigned int rl_blocking_ranges;
/**
* Sequence number of range lock. This number is used to get to know
* the order the locks are queued. One lock can only block another
* if it has a higher rl_sequence.
*/
__u64 rl_sequence;
};
struct range_lock_tree {
struct rb_root_cached rlt_root;
spinlock_t rlt_lock;
__u64 rlt_sequence;
};
void range_lock_tree_init(struct range_lock_tree *tree);
void range_lock_init(struct range_lock *lock, __u64 start, __u64 end);
int range_lock(struct range_lock_tree *tree, struct range_lock *lock);
void range_unlock(struct range_lock_tree *tree, struct range_lock *lock);
#endif
