1 /* 2 * Copyright (C) 2011-2017 Red Hat, Inc. 3 * 4 * This file is released under the GPL. 5 */ 6 7 #ifndef DM_BIO_PRISON_H 8 #define DM_BIO_PRISON_H 9 10 #include "persistent-data/dm-block-manager.h" /* FIXME: for dm_block_t */ 11 #include "dm-thin-metadata.h" /* FIXME: for dm_thin_id */ 12 13 #include <linux/bio.h> 14 #include <linux/rbtree.h> 15 16 /*----------------------------------------------------------------*/ 17 18 /* 19 * Sometimes we can't deal with a bio straight away. We put them in prison 20 * where they can't cause any mischief. Bios are put in a cell identified 21 * by a key, multiple bios can be in the same cell. When the cell is 22 * subsequently unlocked the bios become available. 23 */ 24 struct dm_bio_prison; 25 26 /* 27 * Keys define a range of blocks within either a virtual or physical 28 * device. 29 */ 30 struct dm_cell_key { 31 int virtual; 32 dm_thin_id dev; 33 dm_block_t block_begin, block_end; 34 }; 35 36 /* 37 * Treat this as opaque, only in header so callers can manage allocation 38 * themselves. 39 */ 40 struct dm_bio_prison_cell { 41 struct list_head user_list; /* for client use */ 42 struct rb_node node; 43 44 struct dm_cell_key key; 45 struct bio *holder; 46 struct bio_list bios; 47 }; 48 49 struct dm_bio_prison *dm_bio_prison_create(void); 50 void dm_bio_prison_destroy(struct dm_bio_prison *prison); 51 52 /* 53 * These two functions just wrap a mempool. This is a transitory step: 54 * Eventually all bio prison clients should manage their own cell memory. 55 * 56 * Like mempool_alloc(), dm_bio_prison_alloc_cell() can only fail if called 57 * in interrupt context or passed GFP_NOWAIT. 58 */ 59 struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, 60 gfp_t gfp); 61 void dm_bio_prison_free_cell(struct dm_bio_prison *prison, 62 struct dm_bio_prison_cell *cell); 63 64 /* 65 * Creates, or retrieves a cell that overlaps the given key. 66 * 67 * Returns 1 if pre-existing cell returned, zero if new cell created using 68 * @cell_prealloc. 69 */ 70 int dm_get_cell(struct dm_bio_prison *prison, 71 struct dm_cell_key *key, 72 struct dm_bio_prison_cell *cell_prealloc, 73 struct dm_bio_prison_cell **cell_result); 74 75 /* 76 * An atomic op that combines retrieving or creating a cell, and adding a 77 * bio to it. 78 * 79 * Returns 1 if the cell was already held, 0 if @inmate is the new holder. 80 */ 81 int dm_bio_detain(struct dm_bio_prison *prison, 82 struct dm_cell_key *key, 83 struct bio *inmate, 84 struct dm_bio_prison_cell *cell_prealloc, 85 struct dm_bio_prison_cell **cell_result); 86 87 void dm_cell_release(struct dm_bio_prison *prison, 88 struct dm_bio_prison_cell *cell, 89 struct bio_list *bios); 90 void dm_cell_release_no_holder(struct dm_bio_prison *prison, 91 struct dm_bio_prison_cell *cell, 92 struct bio_list *inmates); 93 void dm_cell_error(struct dm_bio_prison *prison, 94 struct dm_bio_prison_cell *cell, blk_status_t error); 95 96 /* 97 * Visits the cell and then releases. Guarantees no new inmates are 98 * inserted between the visit and release. 99 */ 100 void dm_cell_visit_release(struct dm_bio_prison *prison, 101 void (*visit_fn)(void *, struct dm_bio_prison_cell *), 102 void *context, struct dm_bio_prison_cell *cell); 103 104 /* 105 * Rather than always releasing the prisoners in a cell, the client may 106 * want to promote one of them to be the new holder. There is a race here 107 * though between releasing an empty cell, and other threads adding new 108 * inmates. So this function makes the decision with its lock held. 109 * 110 * This function can have two outcomes: 111 * i) An inmate is promoted to be the holder of the cell (return value of 0). 112 * ii) The cell has no inmate for promotion and is released (return value of 1). 113 */ 114 int dm_cell_promote_or_release(struct dm_bio_prison *prison, 115 struct dm_bio_prison_cell *cell); 116 117 /*----------------------------------------------------------------*/ 118 119 /* 120 * We use the deferred set to keep track of pending reads to shared blocks. 121 * We do this to ensure the new mapping caused by a write isn't performed 122 * until these prior reads have completed. Otherwise the insertion of the 123 * new mapping could free the old block that the read bios are mapped to. 124 */ 125 126 struct dm_deferred_set; 127 struct dm_deferred_entry; 128 129 struct dm_deferred_set *dm_deferred_set_create(void); 130 void dm_deferred_set_destroy(struct dm_deferred_set *ds); 131 132 struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds); 133 void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head); 134 int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work); 135 136 /*----------------------------------------------------------------*/ 137 138 #endif 139