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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_H9#define DM_BIO_PRISON_H10 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 17/*----------------------------------------------------------------*/18 19/*20 * Sometimes we can't deal with a bio straight away. We put them in prison21 * where they can't cause any mischief. Bios are put in a cell identified22 * by a key, multiple bios can be in the same cell. When the cell is23 * subsequently unlocked the bios become available.24 */25struct dm_bio_prison;26 27/*28 * Keys define a range of blocks within either a virtual or physical29 * device.30 */31struct dm_cell_key {32 int virtual;33 dm_thin_id dev;34 dm_block_t block_begin, block_end;35};36 37/*38 * The range of a key (block_end - block_begin) must not39 * exceed BIO_PRISON_MAX_RANGE. Also the range must not40 * cross a similarly sized boundary.41 *42 * Must be a power of 2.43 */44#define BIO_PRISON_MAX_RANGE 102445#define BIO_PRISON_MAX_RANGE_SHIFT 1046 47/*48 * Treat this as opaque, only in header so callers can manage allocation49 * themselves.50 */51struct dm_bio_prison_cell {52 struct list_head user_list; /* for client use */53 struct rb_node node;54 55 struct dm_cell_key key;56 struct bio *holder;57 struct bio_list bios;58};59 60struct dm_bio_prison *dm_bio_prison_create(void);61void dm_bio_prison_destroy(struct dm_bio_prison *prison);62 63/*64 * These two functions just wrap a mempool. This is a transitory step:65 * Eventually all bio prison clients should manage their own cell memory.66 *67 * Like mempool_alloc(), dm_bio_prison_alloc_cell() can only fail if called68 * in interrupt context or passed GFP_NOWAIT.69 */70struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison,71 gfp_t gfp);72void dm_bio_prison_free_cell(struct dm_bio_prison *prison,73 struct dm_bio_prison_cell *cell);74 75/*76 * Creates, or retrieves a cell that overlaps the given key.77 *78 * Returns 1 if pre-existing cell returned, zero if new cell created using79 * @cell_prealloc.80 */81int dm_get_cell(struct dm_bio_prison *prison,82 struct dm_cell_key *key,83 struct dm_bio_prison_cell *cell_prealloc,84 struct dm_bio_prison_cell **cell_result);85 86/*87 * Returns false if key is beyond BIO_PRISON_MAX_RANGE or spans a boundary.88 */89bool dm_cell_key_has_valid_range(struct dm_cell_key *key);90 91/*92 * An atomic op that combines retrieving or creating a cell, and adding a93 * bio to it.94 *95 * Returns 1 if the cell was already held, 0 if @inmate is the new holder.96 */97int dm_bio_detain(struct dm_bio_prison *prison,98 struct dm_cell_key *key,99 struct bio *inmate,100 struct dm_bio_prison_cell *cell_prealloc,101 struct dm_bio_prison_cell **cell_result);102 103void dm_cell_release(struct dm_bio_prison *prison,104 struct dm_bio_prison_cell *cell,105 struct bio_list *bios);106void dm_cell_release_no_holder(struct dm_bio_prison *prison,107 struct dm_bio_prison_cell *cell,108 struct bio_list *inmates);109void dm_cell_error(struct dm_bio_prison *prison,110 struct dm_bio_prison_cell *cell, blk_status_t error);111 112/*113 * Visits the cell and then releases. Guarantees no new inmates are114 * inserted between the visit and release.115 */116void dm_cell_visit_release(struct dm_bio_prison *prison,117 void (*visit_fn)(void *, struct dm_bio_prison_cell *),118 void *context, struct dm_bio_prison_cell *cell);119 120/*121 * Rather than always releasing the prisoners in a cell, the client may122 * want to promote one of them to be the new holder. There is a race here123 * though between releasing an empty cell, and other threads adding new124 * inmates. So this function makes the decision with its lock held.125 *126 * This function can have two outcomes:127 * i) An inmate is promoted to be the holder of the cell (return value of 0).128 * ii) The cell has no inmate for promotion and is released (return value of 1).129 */130int dm_cell_promote_or_release(struct dm_bio_prison *prison,131 struct dm_bio_prison_cell *cell);132 133/*----------------------------------------------------------------*/134 135/*136 * We use the deferred set to keep track of pending reads to shared blocks.137 * We do this to ensure the new mapping caused by a write isn't performed138 * until these prior reads have completed. Otherwise the insertion of the139 * new mapping could free the old block that the read bios are mapped to.140 */141 142struct dm_deferred_set;143struct dm_deferred_entry;144 145struct dm_deferred_set *dm_deferred_set_create(void);146void dm_deferred_set_destroy(struct dm_deferred_set *ds);147 148struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds);149void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head);150int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work);151 152/*----------------------------------------------------------------*/153 154#endif155