93e6442c76
Add the ability to poll on the /dev/mapper/control device. The select or poll function waits until any event happens on any dm device since opening the /dev/mapper/control device. When select or poll returns the device as readable, we must close and reopen the device to wait for new dm events. Usage: 1. open the /dev/mapper/control device 2. scan the event numbers of all devices we are interested in and process them 3. call select, poll or epoll on the handle (it waits until some new event happens since opening the device) 4. close the /dev/mapper/control handle 5. go to step 1 The next commit allows to re-arm the polling without closing and reopening the device. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Andy Grover <agrover@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
154 lines
3.3 KiB
C
154 lines
3.3 KiB
C
/*
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* Internal header file _only_ for device mapper core
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*
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* Copyright (C) 2016 Red Hat, Inc. All rights reserved.
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*
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* This file is released under the LGPL.
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*/
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#ifndef DM_CORE_INTERNAL_H
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#define DM_CORE_INTERNAL_H
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#include <linux/kthread.h>
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#include <linux/ktime.h>
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#include <linux/blk-mq.h>
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#include <trace/events/block.h>
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#include "dm.h"
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#define DM_RESERVED_MAX_IOS 1024
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struct dm_kobject_holder {
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struct kobject kobj;
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struct completion completion;
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};
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/*
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* DM core internal structure that used directly by dm.c and dm-rq.c
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* DM targets must _not_ deference a mapped_device to directly access its members!
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*/
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struct mapped_device {
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struct srcu_struct io_barrier;
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struct mutex suspend_lock;
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/*
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* The current mapping (struct dm_table *).
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* Use dm_get_live_table{_fast} or take suspend_lock for
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* dereference.
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*/
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void __rcu *map;
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struct list_head table_devices;
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struct mutex table_devices_lock;
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unsigned long flags;
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struct request_queue *queue;
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int numa_node_id;
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enum dm_queue_mode type;
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/* Protect queue and type against concurrent access. */
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struct mutex type_lock;
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atomic_t holders;
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atomic_t open_count;
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struct dm_target *immutable_target;
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struct target_type *immutable_target_type;
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struct gendisk *disk;
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struct dax_device *dax_dev;
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char name[16];
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void *interface_ptr;
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/*
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* A list of ios that arrived while we were suspended.
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*/
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atomic_t pending[2];
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wait_queue_head_t wait;
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struct work_struct work;
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spinlock_t deferred_lock;
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struct bio_list deferred;
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/*
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* Event handling.
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*/
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wait_queue_head_t eventq;
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atomic_t event_nr;
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atomic_t uevent_seq;
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struct list_head uevent_list;
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spinlock_t uevent_lock; /* Protect access to uevent_list */
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/* the number of internal suspends */
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unsigned internal_suspend_count;
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/*
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* Processing queue (flush)
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*/
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struct workqueue_struct *wq;
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/*
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* io objects are allocated from here.
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*/
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mempool_t *io_pool;
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struct bio_set *bs;
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/*
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* freeze/thaw support require holding onto a super block
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*/
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struct super_block *frozen_sb;
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/* forced geometry settings */
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struct hd_geometry geometry;
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struct block_device *bdev;
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/* kobject and completion */
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struct dm_kobject_holder kobj_holder;
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/* zero-length flush that will be cloned and submitted to targets */
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struct bio flush_bio;
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struct dm_stats stats;
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struct kthread_worker kworker;
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struct task_struct *kworker_task;
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/* for request-based merge heuristic in dm_request_fn() */
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unsigned seq_rq_merge_deadline_usecs;
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int last_rq_rw;
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sector_t last_rq_pos;
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ktime_t last_rq_start_time;
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/* for blk-mq request-based DM support */
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struct blk_mq_tag_set *tag_set;
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bool use_blk_mq:1;
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bool init_tio_pdu:1;
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};
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void dm_init_md_queue(struct mapped_device *md);
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void dm_init_normal_md_queue(struct mapped_device *md);
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int md_in_flight(struct mapped_device *md);
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void disable_write_same(struct mapped_device *md);
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void disable_write_zeroes(struct mapped_device *md);
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static inline struct completion *dm_get_completion_from_kobject(struct kobject *kobj)
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{
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return &container_of(kobj, struct dm_kobject_holder, kobj)->completion;
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}
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unsigned __dm_get_module_param(unsigned *module_param, unsigned def, unsigned max);
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static inline bool dm_message_test_buffer_overflow(char *result, unsigned maxlen)
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{
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return !maxlen || strlen(result) + 1 >= maxlen;
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}
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extern atomic_t dm_global_event_nr;
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extern wait_queue_head_t dm_global_eventq;
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#endif
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