1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * Copyright (C) 2011-2017 Red Hat, Inc. 4 * 5 * This file is released under the GPL. 6 */ 7 8 #ifndef DM_BIO_PRISON_V2_H 9 #define DM_BIO_PRISON_V2_H 10 11 #include "persistent-data/dm-block-manager.h" /* FIXME: for dm_block_t */ 12 #include "dm-thin-metadata.h" /* FIXME: for dm_thin_id */ 13 14 #include <linux/bio.h> 15 #include <linux/rbtree.h> 16 #include <linux/workqueue.h> 17 18 /*----------------------------------------------------------------*/ 19 20 int dm_bio_prison_init_v2(void); 21 void dm_bio_prison_exit_v2(void); 22 23 /* 24 * Sometimes we can't deal with a bio straight away. We put them in prison 25 * where they can't cause any mischief. Bios are put in a cell identified 26 * by a key, multiple bios can be in the same cell. When the cell is 27 * subsequently unlocked the bios become available. 28 */ 29 struct dm_bio_prison_v2; 30 31 /* 32 * Keys define a range of blocks within either a virtual or physical 33 * device. 34 */ 35 struct dm_cell_key_v2 { 36 int virtual; 37 dm_thin_id dev; 38 dm_block_t block_begin, block_end; 39 }; 40 41 /* 42 * Treat this as opaque, only in header so callers can manage allocation 43 * themselves. 44 */ 45 struct dm_bio_prison_cell_v2 { 46 // FIXME: pack these 47 bool exclusive_lock; 48 unsigned int exclusive_level; 49 unsigned int shared_count; 50 struct work_struct *quiesce_continuation; 51 52 struct rb_node node; 53 struct dm_cell_key_v2 key; 54 struct bio_list bios; 55 }; 56 57 struct dm_bio_prison_v2 *dm_bio_prison_create_v2(struct workqueue_struct *wq); 58 void dm_bio_prison_destroy_v2(struct dm_bio_prison_v2 *prison); 59 60 /* 61 * These two functions just wrap a mempool. This is a transitory step: 62 * Eventually all bio prison clients should manage their own cell memory. 63 * 64 * Like mempool_alloc(), dm_bio_prison_alloc_cell_v2() can only fail if called 65 * in interrupt context or passed GFP_NOWAIT. 66 */ 67 struct dm_bio_prison_cell_v2 *dm_bio_prison_alloc_cell_v2(struct dm_bio_prison_v2 *prison, 68 gfp_t gfp); 69 void dm_bio_prison_free_cell_v2(struct dm_bio_prison_v2 *prison, 70 struct dm_bio_prison_cell_v2 *cell); 71 72 /* 73 * Shared locks have a bio associated with them. 74 * 75 * If the lock is granted the caller can continue to use the bio, and must 76 * call dm_cell_put_v2() to drop the reference count when finished using it. 77 * 78 * If the lock cannot be granted then the bio will be tracked within the 79 * cell, and later given to the holder of the exclusive lock. 80 * 81 * See dm_cell_lock_v2() for discussion of the lock_level parameter. 82 * 83 * Compare *cell_result with cell_prealloc to see if the prealloc was used. 84 * If cell_prealloc was used then inmate wasn't added to it. 85 * 86 * Returns true if the lock is granted. 87 */ 88 bool dm_cell_get_v2(struct dm_bio_prison_v2 *prison, 89 struct dm_cell_key_v2 *key, 90 unsigned int lock_level, 91 struct bio *inmate, 92 struct dm_bio_prison_cell_v2 *cell_prealloc, 93 struct dm_bio_prison_cell_v2 **cell_result); 94 95 /* 96 * Decrement the shared reference count for the lock. Returns true if 97 * returning ownership of the cell (ie. you should free it). 98 */ 99 bool dm_cell_put_v2(struct dm_bio_prison_v2 *prison, 100 struct dm_bio_prison_cell_v2 *cell); 101 102 /* 103 * Locks a cell. No associated bio. Exclusive locks get priority. These 104 * locks constrain whether the io locks are granted according to level. 105 * 106 * Shared locks will still be granted if the lock_level is > (not = to) the 107 * exclusive lock level. 108 * 109 * If an _exclusive_ lock is already held then -EBUSY is returned. 110 * 111 * Return values: 112 * < 0 - error 113 * 0 - locked; no quiescing needed 114 * 1 - locked; quiescing needed 115 */ 116 int dm_cell_lock_v2(struct dm_bio_prison_v2 *prison, 117 struct dm_cell_key_v2 *key, 118 unsigned int lock_level, 119 struct dm_bio_prison_cell_v2 *cell_prealloc, 120 struct dm_bio_prison_cell_v2 **cell_result); 121 122 void dm_cell_quiesce_v2(struct dm_bio_prison_v2 *prison, 123 struct dm_bio_prison_cell_v2 *cell, 124 struct work_struct *continuation); 125 126 /* 127 * Promotes an _exclusive_ lock to a higher lock level. 128 * 129 * Return values: 130 * < 0 - error 131 * 0 - promoted; no quiescing needed 132 * 1 - promoted; quiescing needed 133 */ 134 int dm_cell_lock_promote_v2(struct dm_bio_prison_v2 *prison, 135 struct dm_bio_prison_cell_v2 *cell, 136 unsigned int new_lock_level); 137 138 /* 139 * Adds any held bios to the bio list. 140 * 141 * There may be shared locks still held at this point even if you quiesced 142 * (ie. different lock levels). 143 * 144 * Returns true if returning ownership of the cell (ie. you should free 145 * it). 146 */ 147 bool dm_cell_unlock_v2(struct dm_bio_prison_v2 *prison, 148 struct dm_bio_prison_cell_v2 *cell, 149 struct bio_list *bios); 150 151 /*----------------------------------------------------------------*/ 152 153 #endif 154