466 lines
10 KiB
C
466 lines
10 KiB
C
/*
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* Copyright (C) 2012 Red Hat, Inc.
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*
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* This file is released under the GPL.
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*/
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#include "dm.h"
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#include "dm-bio-prison-v1.h"
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#include "dm-bio-prison-v2.h"
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#include <linux/spinlock.h>
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#include <linux/mempool.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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/*----------------------------------------------------------------*/
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#define MIN_CELLS 1024
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struct dm_bio_prison {
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spinlock_t lock;
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struct rb_root cells;
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mempool_t cell_pool;
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};
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static struct kmem_cache *_cell_cache;
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/*----------------------------------------------------------------*/
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/*
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* @nr_cells should be the number of cells you want in use _concurrently_.
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* Don't confuse it with the number of distinct keys.
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*/
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struct dm_bio_prison *dm_bio_prison_create(void)
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{
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struct dm_bio_prison *prison = kzalloc(sizeof(*prison), GFP_KERNEL);
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int ret;
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if (!prison)
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return NULL;
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spin_lock_init(&prison->lock);
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ret = mempool_init_slab_pool(&prison->cell_pool, MIN_CELLS, _cell_cache);
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if (ret) {
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kfree(prison);
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return NULL;
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}
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prison->cells = RB_ROOT;
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return prison;
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}
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EXPORT_SYMBOL_GPL(dm_bio_prison_create);
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void dm_bio_prison_destroy(struct dm_bio_prison *prison)
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{
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mempool_exit(&prison->cell_pool);
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kfree(prison);
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}
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EXPORT_SYMBOL_GPL(dm_bio_prison_destroy);
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struct dm_bio_prison_cell *dm_bio_prison_alloc_cell(struct dm_bio_prison *prison, gfp_t gfp)
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{
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return mempool_alloc(&prison->cell_pool, gfp);
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}
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EXPORT_SYMBOL_GPL(dm_bio_prison_alloc_cell);
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void dm_bio_prison_free_cell(struct dm_bio_prison *prison,
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struct dm_bio_prison_cell *cell)
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{
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mempool_free(cell, &prison->cell_pool);
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}
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EXPORT_SYMBOL_GPL(dm_bio_prison_free_cell);
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static void __setup_new_cell(struct dm_cell_key *key,
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struct bio *holder,
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struct dm_bio_prison_cell *cell)
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{
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memcpy(&cell->key, key, sizeof(cell->key));
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cell->holder = holder;
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bio_list_init(&cell->bios);
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}
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static int cmp_keys(struct dm_cell_key *lhs,
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struct dm_cell_key *rhs)
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{
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if (lhs->virtual < rhs->virtual)
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return -1;
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if (lhs->virtual > rhs->virtual)
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return 1;
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if (lhs->dev < rhs->dev)
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return -1;
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if (lhs->dev > rhs->dev)
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return 1;
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if (lhs->block_end <= rhs->block_begin)
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return -1;
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if (lhs->block_begin >= rhs->block_end)
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return 1;
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return 0;
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}
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static int __bio_detain(struct dm_bio_prison *prison,
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struct dm_cell_key *key,
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struct bio *inmate,
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struct dm_bio_prison_cell *cell_prealloc,
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struct dm_bio_prison_cell **cell_result)
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{
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int r;
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struct rb_node **new = &prison->cells.rb_node, *parent = NULL;
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while (*new) {
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struct dm_bio_prison_cell *cell =
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rb_entry(*new, struct dm_bio_prison_cell, node);
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r = cmp_keys(key, &cell->key);
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parent = *new;
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if (r < 0)
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new = &((*new)->rb_left);
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else if (r > 0)
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new = &((*new)->rb_right);
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else {
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if (inmate)
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bio_list_add(&cell->bios, inmate);
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*cell_result = cell;
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return 1;
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}
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}
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__setup_new_cell(key, inmate, cell_prealloc);
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*cell_result = cell_prealloc;
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rb_link_node(&cell_prealloc->node, parent, new);
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rb_insert_color(&cell_prealloc->node, &prison->cells);
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return 0;
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}
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static int bio_detain(struct dm_bio_prison *prison,
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struct dm_cell_key *key,
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struct bio *inmate,
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struct dm_bio_prison_cell *cell_prealloc,
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struct dm_bio_prison_cell **cell_result)
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{
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int r;
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unsigned long flags;
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spin_lock_irqsave(&prison->lock, flags);
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r = __bio_detain(prison, key, inmate, cell_prealloc, cell_result);
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spin_unlock_irqrestore(&prison->lock, flags);
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return r;
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}
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int dm_bio_detain(struct dm_bio_prison *prison,
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struct dm_cell_key *key,
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struct bio *inmate,
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struct dm_bio_prison_cell *cell_prealloc,
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struct dm_bio_prison_cell **cell_result)
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{
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return bio_detain(prison, key, inmate, cell_prealloc, cell_result);
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}
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EXPORT_SYMBOL_GPL(dm_bio_detain);
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int dm_get_cell(struct dm_bio_prison *prison,
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struct dm_cell_key *key,
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struct dm_bio_prison_cell *cell_prealloc,
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struct dm_bio_prison_cell **cell_result)
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{
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return bio_detain(prison, key, NULL, cell_prealloc, cell_result);
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}
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EXPORT_SYMBOL_GPL(dm_get_cell);
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/*
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* @inmates must have been initialised prior to this call
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*/
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static void __cell_release(struct dm_bio_prison *prison,
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struct dm_bio_prison_cell *cell,
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struct bio_list *inmates)
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{
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rb_erase(&cell->node, &prison->cells);
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if (inmates) {
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if (cell->holder)
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bio_list_add(inmates, cell->holder);
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bio_list_merge(inmates, &cell->bios);
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}
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}
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void dm_cell_release(struct dm_bio_prison *prison,
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struct dm_bio_prison_cell *cell,
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struct bio_list *bios)
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{
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unsigned long flags;
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spin_lock_irqsave(&prison->lock, flags);
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__cell_release(prison, cell, bios);
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spin_unlock_irqrestore(&prison->lock, flags);
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}
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EXPORT_SYMBOL_GPL(dm_cell_release);
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/*
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* Sometimes we don't want the holder, just the additional bios.
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*/
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static void __cell_release_no_holder(struct dm_bio_prison *prison,
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struct dm_bio_prison_cell *cell,
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struct bio_list *inmates)
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{
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rb_erase(&cell->node, &prison->cells);
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bio_list_merge(inmates, &cell->bios);
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}
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void dm_cell_release_no_holder(struct dm_bio_prison *prison,
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struct dm_bio_prison_cell *cell,
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struct bio_list *inmates)
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{
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unsigned long flags;
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spin_lock_irqsave(&prison->lock, flags);
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__cell_release_no_holder(prison, cell, inmates);
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spin_unlock_irqrestore(&prison->lock, flags);
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}
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EXPORT_SYMBOL_GPL(dm_cell_release_no_holder);
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void dm_cell_error(struct dm_bio_prison *prison,
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struct dm_bio_prison_cell *cell, blk_status_t error)
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{
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struct bio_list bios;
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struct bio *bio;
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bio_list_init(&bios);
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dm_cell_release(prison, cell, &bios);
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while ((bio = bio_list_pop(&bios))) {
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bio->bi_status = error;
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bio_endio(bio);
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}
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}
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EXPORT_SYMBOL_GPL(dm_cell_error);
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void dm_cell_visit_release(struct dm_bio_prison *prison,
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void (*visit_fn)(void *, struct dm_bio_prison_cell *),
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void *context,
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struct dm_bio_prison_cell *cell)
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{
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unsigned long flags;
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spin_lock_irqsave(&prison->lock, flags);
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visit_fn(context, cell);
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rb_erase(&cell->node, &prison->cells);
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spin_unlock_irqrestore(&prison->lock, flags);
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}
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EXPORT_SYMBOL_GPL(dm_cell_visit_release);
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static int __promote_or_release(struct dm_bio_prison *prison,
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struct dm_bio_prison_cell *cell)
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{
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if (bio_list_empty(&cell->bios)) {
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rb_erase(&cell->node, &prison->cells);
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return 1;
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}
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cell->holder = bio_list_pop(&cell->bios);
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return 0;
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}
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int dm_cell_promote_or_release(struct dm_bio_prison *prison,
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struct dm_bio_prison_cell *cell)
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{
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int r;
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unsigned long flags;
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spin_lock_irqsave(&prison->lock, flags);
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r = __promote_or_release(prison, cell);
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spin_unlock_irqrestore(&prison->lock, flags);
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return r;
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}
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EXPORT_SYMBOL_GPL(dm_cell_promote_or_release);
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/*----------------------------------------------------------------*/
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#define DEFERRED_SET_SIZE 64
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struct dm_deferred_entry {
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struct dm_deferred_set *ds;
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unsigned count;
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struct list_head work_items;
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};
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struct dm_deferred_set {
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spinlock_t lock;
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unsigned current_entry;
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unsigned sweeper;
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struct dm_deferred_entry entries[DEFERRED_SET_SIZE];
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};
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struct dm_deferred_set *dm_deferred_set_create(void)
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{
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int i;
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struct dm_deferred_set *ds;
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ds = kmalloc(sizeof(*ds), GFP_KERNEL);
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if (!ds)
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return NULL;
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spin_lock_init(&ds->lock);
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ds->current_entry = 0;
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ds->sweeper = 0;
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for (i = 0; i < DEFERRED_SET_SIZE; i++) {
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ds->entries[i].ds = ds;
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ds->entries[i].count = 0;
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INIT_LIST_HEAD(&ds->entries[i].work_items);
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}
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return ds;
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}
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EXPORT_SYMBOL_GPL(dm_deferred_set_create);
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void dm_deferred_set_destroy(struct dm_deferred_set *ds)
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{
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kfree(ds);
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}
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EXPORT_SYMBOL_GPL(dm_deferred_set_destroy);
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struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds)
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{
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unsigned long flags;
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struct dm_deferred_entry *entry;
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spin_lock_irqsave(&ds->lock, flags);
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entry = ds->entries + ds->current_entry;
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entry->count++;
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spin_unlock_irqrestore(&ds->lock, flags);
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return entry;
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}
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EXPORT_SYMBOL_GPL(dm_deferred_entry_inc);
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static unsigned ds_next(unsigned index)
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{
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return (index + 1) % DEFERRED_SET_SIZE;
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}
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static void __sweep(struct dm_deferred_set *ds, struct list_head *head)
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{
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while ((ds->sweeper != ds->current_entry) &&
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!ds->entries[ds->sweeper].count) {
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list_splice_init(&ds->entries[ds->sweeper].work_items, head);
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ds->sweeper = ds_next(ds->sweeper);
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}
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if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count)
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list_splice_init(&ds->entries[ds->sweeper].work_items, head);
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}
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void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head)
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{
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unsigned long flags;
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spin_lock_irqsave(&entry->ds->lock, flags);
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BUG_ON(!entry->count);
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--entry->count;
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__sweep(entry->ds, head);
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spin_unlock_irqrestore(&entry->ds->lock, flags);
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}
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EXPORT_SYMBOL_GPL(dm_deferred_entry_dec);
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/*
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* Returns 1 if deferred or 0 if no pending items to delay job.
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*/
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int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work)
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{
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int r = 1;
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unsigned long flags;
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unsigned next_entry;
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spin_lock_irqsave(&ds->lock, flags);
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if ((ds->sweeper == ds->current_entry) &&
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!ds->entries[ds->current_entry].count)
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r = 0;
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else {
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list_add(work, &ds->entries[ds->current_entry].work_items);
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next_entry = ds_next(ds->current_entry);
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if (!ds->entries[next_entry].count)
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ds->current_entry = next_entry;
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}
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spin_unlock_irqrestore(&ds->lock, flags);
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return r;
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}
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EXPORT_SYMBOL_GPL(dm_deferred_set_add_work);
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/*----------------------------------------------------------------*/
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static int __init dm_bio_prison_init_v1(void)
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{
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_cell_cache = KMEM_CACHE(dm_bio_prison_cell, 0);
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if (!_cell_cache)
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return -ENOMEM;
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return 0;
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}
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static void dm_bio_prison_exit_v1(void)
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{
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kmem_cache_destroy(_cell_cache);
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_cell_cache = NULL;
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}
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static int (*_inits[])(void) __initdata = {
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dm_bio_prison_init_v1,
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dm_bio_prison_init_v2,
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};
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static void (*_exits[])(void) = {
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dm_bio_prison_exit_v1,
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dm_bio_prison_exit_v2,
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};
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static int __init dm_bio_prison_init(void)
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{
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const int count = ARRAY_SIZE(_inits);
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int r, i;
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for (i = 0; i < count; i++) {
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r = _inits[i]();
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if (r)
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goto bad;
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}
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return 0;
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bad:
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while (i--)
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_exits[i]();
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return r;
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}
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static void __exit dm_bio_prison_exit(void)
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{
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int i = ARRAY_SIZE(_exits);
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while (i--)
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_exits[i]();
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}
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/*
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* module hooks
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*/
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module_init(dm_bio_prison_init);
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module_exit(dm_bio_prison_exit);
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MODULE_DESCRIPTION(DM_NAME " bio prison");
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MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
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MODULE_LICENSE("GPL");
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