| Prakash Surya | 5b8a39c | 2016-09-18 16:37:29 -0400 | [diff] [blame] | 1 | /* |
| 2 | * GPL HEADER START |
| 3 | * |
| 4 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License version 2 only, |
| 8 | * as published by the Free Software Foundation. |
| 9 | * |
| 10 | * This program is distributed in the hope that it will be useful, but |
| 11 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 13 | * General Public License version 2 for more details (a copy is included |
| 14 | * in the LICENSE file that accompanied this code). |
| 15 | * |
| 16 | * You should have received a copy of the GNU General Public License |
| 17 | * version 2 along with this program; If not, see |
| 18 | * http://www.gnu.org/licenses/gpl-2.0.html |
| 19 | * |
| 20 | * GPL HEADER END |
| 21 | */ |
| 22 | /* |
| 23 | * Range lock is used to allow multiple threads writing a single shared |
| 24 | * file given each thread is writing to a non-overlapping portion of the |
| 25 | * file. |
| 26 | * |
| 27 | * Refer to the possible upstream kernel version of range lock by |
| 28 | * Jan Kara <jack@suse.cz>: https://lkml.org/lkml/2013/1/31/480 |
| 29 | * |
| 30 | * This file could later replaced by the upstream kernel version. |
| 31 | */ |
| 32 | /* |
| 33 | * Author: Prakash Surya <surya1@llnl.gov> |
| 34 | * Author: Bobi Jam <bobijam.xu@intel.com> |
| 35 | */ |
| 36 | #ifndef _RANGE_LOCK_H |
| 37 | #define _RANGE_LOCK_H |
| 38 | |
| 39 | #include "../../include/linux/libcfs/libcfs.h" |
| 40 | #include "../include/interval_tree.h" |
| 41 | |
| 42 | struct range_lock { |
| 43 | struct interval_node rl_node; |
| 44 | /** |
| 45 | * Process to enqueue this lock. |
| 46 | */ |
| 47 | struct task_struct *rl_task; |
| 48 | /** |
| 49 | * List of locks with the same range. |
| 50 | */ |
| 51 | struct list_head rl_next_lock; |
| 52 | /** |
| 53 | * Number of locks in the list rl_next_lock |
| 54 | */ |
| 55 | unsigned int rl_lock_count; |
| 56 | /** |
| 57 | * Number of ranges which are blocking acquisition of the lock |
| 58 | */ |
| 59 | unsigned int rl_blocking_ranges; |
| 60 | /** |
| 61 | * Sequence number of range lock. This number is used to get to know |
| 62 | * the order the locks are queued; this is required for range_cancel(). |
| 63 | */ |
| 64 | __u64 rl_sequence; |
| 65 | }; |
| 66 | |
| 67 | static inline struct range_lock *node2rangelock(const struct interval_node *n) |
| 68 | { |
| 69 | return container_of(n, struct range_lock, rl_node); |
| 70 | } |
| 71 | |
| 72 | struct range_lock_tree { |
| 73 | struct interval_node *rlt_root; |
| 74 | spinlock_t rlt_lock; /* protect range lock tree */ |
| 75 | __u64 rlt_sequence; |
| 76 | }; |
| 77 | |
| 78 | void range_lock_tree_init(struct range_lock_tree *tree); |
| 79 | void range_lock_init(struct range_lock *lock, __u64 start, __u64 end); |
| 80 | int range_lock(struct range_lock_tree *tree, struct range_lock *lock); |
| 81 | void range_unlock(struct range_lock_tree *tree, struct range_lock *lock); |
| 82 | #endif |