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The structure srcu_struct can be very big, its size is proportional to the value CONFIG_NR_CPUS. The Fedora kernel has CONFIG_NR_CPUS 8192, the field io_barrier in the struct mapped_device has 84kB in the debugging kernel and 50kB in the non-debugging kernel. The large size may result in failure of the function kzalloc_node. In order to avoid the allocation failure, we use the function kvzalloc_node, this function falls back to vmalloc if a large contiguous chunk of memory is not available. This patch also moves the field io_barrier to the last position of struct mapped_device - the reason is that on many processor architectures, short memory offsets result in smaller code than long memory offsets - on x86-64 it reduces code size by 320 bytes. Note to stable kernel maintainers - the kernels 4.11 and older don't have the function kvzalloc_node, you can use the function vzalloc_node instead. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: Mike Snitzer <snitzer@redhat.com>
155 lines
3.4 KiB
C
155 lines
3.4 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 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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struct srcu_struct io_barrier;
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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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void dm_issue_global_event(void);
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#endif
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