371 lines
8.2 KiB
C
371 lines
8.2 KiB
C
/*
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* Copyright (C) 2012-2017 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-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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#include <linux/rwsem.h>
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/*----------------------------------------------------------------*/
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#define MIN_CELLS 1024
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struct dm_bio_prison_v2 {
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struct workqueue_struct *wq;
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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_v2 *dm_bio_prison_create_v2(struct workqueue_struct *wq)
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{
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struct dm_bio_prison_v2 *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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prison->wq = wq;
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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_v2);
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void dm_bio_prison_destroy_v2(struct dm_bio_prison_v2 *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_v2);
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struct dm_bio_prison_cell_v2 *dm_bio_prison_alloc_cell_v2(struct dm_bio_prison_v2 *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_v2);
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void dm_bio_prison_free_cell_v2(struct dm_bio_prison_v2 *prison,
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struct dm_bio_prison_cell_v2 *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_v2);
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static void __setup_new_cell(struct dm_cell_key_v2 *key,
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struct dm_bio_prison_cell_v2 *cell)
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{
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memset(cell, 0, sizeof(*cell));
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memcpy(&cell->key, key, sizeof(cell->key));
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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_v2 *lhs,
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struct dm_cell_key_v2 *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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/*
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* Returns true if node found, otherwise it inserts a new one.
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*/
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static bool __find_or_insert(struct dm_bio_prison_v2 *prison,
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struct dm_cell_key_v2 *key,
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struct dm_bio_prison_cell_v2 *cell_prealloc,
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struct dm_bio_prison_cell_v2 **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_v2 *cell =
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rb_entry(*new, struct dm_bio_prison_cell_v2, 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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*result = cell;
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return true;
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}
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}
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__setup_new_cell(key, cell_prealloc);
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*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 false;
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}
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static bool __get(struct dm_bio_prison_v2 *prison,
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struct dm_cell_key_v2 *key,
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unsigned lock_level,
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struct bio *inmate,
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struct dm_bio_prison_cell_v2 *cell_prealloc,
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struct dm_bio_prison_cell_v2 **cell)
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{
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if (__find_or_insert(prison, key, cell_prealloc, cell)) {
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if ((*cell)->exclusive_lock) {
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if (lock_level <= (*cell)->exclusive_level) {
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bio_list_add(&(*cell)->bios, inmate);
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return false;
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}
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}
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(*cell)->shared_count++;
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} else
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(*cell)->shared_count = 1;
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return true;
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}
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bool dm_cell_get_v2(struct dm_bio_prison_v2 *prison,
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struct dm_cell_key_v2 *key,
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unsigned lock_level,
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struct bio *inmate,
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struct dm_bio_prison_cell_v2 *cell_prealloc,
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struct dm_bio_prison_cell_v2 **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 = __get(prison, key, lock_level, 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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EXPORT_SYMBOL_GPL(dm_cell_get_v2);
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static bool __put(struct dm_bio_prison_v2 *prison,
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struct dm_bio_prison_cell_v2 *cell)
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{
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BUG_ON(!cell->shared_count);
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cell->shared_count--;
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// FIXME: shared locks granted above the lock level could starve this
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if (!cell->shared_count) {
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if (cell->exclusive_lock){
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if (cell->quiesce_continuation) {
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queue_work(prison->wq, cell->quiesce_continuation);
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cell->quiesce_continuation = NULL;
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}
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} else {
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rb_erase(&cell->node, &prison->cells);
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return true;
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}
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}
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return false;
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}
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bool dm_cell_put_v2(struct dm_bio_prison_v2 *prison,
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struct dm_bio_prison_cell_v2 *cell)
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{
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bool r;
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unsigned long flags;
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spin_lock_irqsave(&prison->lock, flags);
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r = __put(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_put_v2);
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static int __lock(struct dm_bio_prison_v2 *prison,
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struct dm_cell_key_v2 *key,
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unsigned lock_level,
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struct dm_bio_prison_cell_v2 *cell_prealloc,
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struct dm_bio_prison_cell_v2 **cell_result)
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{
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struct dm_bio_prison_cell_v2 *cell;
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if (__find_or_insert(prison, key, cell_prealloc, &cell)) {
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if (cell->exclusive_lock)
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return -EBUSY;
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cell->exclusive_lock = true;
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cell->exclusive_level = lock_level;
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*cell_result = cell;
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// FIXME: we don't yet know what level these shared locks
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// were taken at, so have to quiesce them all.
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return cell->shared_count > 0;
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} else {
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cell = cell_prealloc;
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cell->shared_count = 0;
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cell->exclusive_lock = true;
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cell->exclusive_level = lock_level;
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*cell_result = cell;
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}
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return 0;
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}
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int dm_cell_lock_v2(struct dm_bio_prison_v2 *prison,
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struct dm_cell_key_v2 *key,
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unsigned lock_level,
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struct dm_bio_prison_cell_v2 *cell_prealloc,
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struct dm_bio_prison_cell_v2 **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 = __lock(prison, key, lock_level, 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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EXPORT_SYMBOL_GPL(dm_cell_lock_v2);
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static void __quiesce(struct dm_bio_prison_v2 *prison,
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struct dm_bio_prison_cell_v2 *cell,
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struct work_struct *continuation)
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{
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if (!cell->shared_count)
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queue_work(prison->wq, continuation);
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else
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cell->quiesce_continuation = continuation;
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}
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void dm_cell_quiesce_v2(struct dm_bio_prison_v2 *prison,
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struct dm_bio_prison_cell_v2 *cell,
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struct work_struct *continuation)
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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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__quiesce(prison, cell, continuation);
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spin_unlock_irqrestore(&prison->lock, flags);
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}
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EXPORT_SYMBOL_GPL(dm_cell_quiesce_v2);
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static int __promote(struct dm_bio_prison_v2 *prison,
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struct dm_bio_prison_cell_v2 *cell,
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unsigned new_lock_level)
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{
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if (!cell->exclusive_lock)
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return -EINVAL;
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cell->exclusive_level = new_lock_level;
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return cell->shared_count > 0;
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}
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int dm_cell_lock_promote_v2(struct dm_bio_prison_v2 *prison,
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struct dm_bio_prison_cell_v2 *cell,
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unsigned new_lock_level)
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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(prison, cell, new_lock_level);
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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_lock_promote_v2);
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static bool __unlock(struct dm_bio_prison_v2 *prison,
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struct dm_bio_prison_cell_v2 *cell,
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struct bio_list *bios)
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{
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BUG_ON(!cell->exclusive_lock);
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bio_list_merge(bios, &cell->bios);
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bio_list_init(&cell->bios);
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if (cell->shared_count) {
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cell->exclusive_lock = 0;
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return false;
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}
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rb_erase(&cell->node, &prison->cells);
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return true;
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}
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bool dm_cell_unlock_v2(struct dm_bio_prison_v2 *prison,
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struct dm_bio_prison_cell_v2 *cell,
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struct bio_list *bios)
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{
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bool r;
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unsigned long flags;
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spin_lock_irqsave(&prison->lock, flags);
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r = __unlock(prison, cell, bios);
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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_unlock_v2);
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/*----------------------------------------------------------------*/
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int __init dm_bio_prison_init_v2(void)
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{
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_cell_cache = KMEM_CACHE(dm_bio_prison_cell_v2, 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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void dm_bio_prison_exit_v2(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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