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![Ming Lei](/assets/img/avatar_default.png)
Commit7dd76d1fee
("dm: improve bio splitting and associated IO accounting") removed using cloned bio when dm io splitting is needed. Using bio_trim()+bio_inc_remaining() rather than bio_split()+bio_chain() causes multiple dm_io instances to share the same original bio, and it works fine if IOs are completed successfully. But a regression was caused for the case when BLK_STS_DM_REQUEUE is returned from any one of DM's cloned bios (whose dm_io share the same orig_bio). In this BLK_STS_DM_REQUEUE case only the mapped subset of the original bio for the current exact dm_io needs to be re-submitted. However, since the original bio is shared among all dm_io instances, the ->orig_bio actually only represents the last dm_io instance, so requeue can't work as expected. Also when more than one dm_io is requeued, the same original bio is requeued from all dm_io's completion handler, then race is caused. Fix this issue by still allocating one clone bio for completing io only, then io accounting can rely on ->orig_bio being unmodified. This is needed because the dm_io's sector_offset and sectors members are recorded relative to an unmodified ->orig_bio. In the future, we can go back to using bio_trim()+bio_inc_remaining() for dm's io splitting but then delay needing a bio clone only when handling BLK_STS_DM_REQUEUE, but that approach is a bit complicated (so it needs a development cycle): 1) bio clone needs to be done in task context 2) a block interface for unwinding bio is required Fixes:7dd76d1fee
("dm: improve bio splitting and associated IO accounting") Reported-by: Benjamin Marzinski <bmarzins@redhat.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
319 lines
6.6 KiB
C
319 lines
6.6 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 <linux/blk-crypto-profile.h>
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#include <linux/jump_label.h>
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#include <trace/events/block.h>
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#include "dm.h"
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#include "dm-ima.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 structures used directly by dm.c, dm-rq.c and dm-table.c.
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* DM targets must _not_ deference a mapped_device or dm_table to directly
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* access their members!
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*/
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/*
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* For mempools pre-allocation at the table loading time.
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*/
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struct dm_md_mempools {
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struct bio_set bs;
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struct bio_set io_bs;
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};
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struct mapped_device {
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struct mutex suspend_lock;
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struct mutex table_devices_lock;
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struct list_head table_devices;
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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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unsigned long flags;
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/* Protect queue and type against concurrent access. */
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struct mutex type_lock;
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enum dm_queue_mode type;
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int numa_node_id;
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struct request_queue *queue;
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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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char name[16];
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struct gendisk *disk;
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struct dax_device *dax_dev;
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wait_queue_head_t wait;
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unsigned long __percpu *pending_io;
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/* forced geometry settings */
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struct hd_geometry geometry;
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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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* A list of ios that arrived while we were suspended.
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*/
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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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void *interface_ptr;
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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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/* for blk-mq request-based DM support */
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bool init_tio_pdu:1;
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struct blk_mq_tag_set *tag_set;
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struct dm_stats stats;
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/* the number of internal suspends */
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unsigned internal_suspend_count;
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int swap_bios;
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struct semaphore swap_bios_semaphore;
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struct mutex swap_bios_lock;
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/*
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* io objects are allocated from here.
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*/
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struct dm_md_mempools *mempools;
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/* kobject and completion */
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struct dm_kobject_holder kobj_holder;
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struct srcu_struct io_barrier;
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#ifdef CONFIG_BLK_DEV_ZONED
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unsigned int nr_zones;
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unsigned int *zwp_offset;
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#endif
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#ifdef CONFIG_IMA
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struct dm_ima_measurements ima;
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#endif
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};
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/*
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* Bits for the flags field of struct mapped_device.
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*/
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#define DMF_BLOCK_IO_FOR_SUSPEND 0
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#define DMF_SUSPENDED 1
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#define DMF_FROZEN 2
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#define DMF_FREEING 3
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#define DMF_DELETING 4
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#define DMF_NOFLUSH_SUSPENDING 5
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#define DMF_DEFERRED_REMOVE 6
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#define DMF_SUSPENDED_INTERNALLY 7
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#define DMF_POST_SUSPENDING 8
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#define DMF_EMULATE_ZONE_APPEND 9
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void disable_discard(struct mapped_device *md);
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void disable_write_zeroes(struct mapped_device *md);
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static inline sector_t dm_get_size(struct mapped_device *md)
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{
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return get_capacity(md->disk);
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}
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static inline struct dm_stats *dm_get_stats(struct mapped_device *md)
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{
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return &md->stats;
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}
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DECLARE_STATIC_KEY_FALSE(stats_enabled);
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DECLARE_STATIC_KEY_FALSE(swap_bios_enabled);
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DECLARE_STATIC_KEY_FALSE(zoned_enabled);
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static inline bool dm_emulate_zone_append(struct mapped_device *md)
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{
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if (blk_queue_is_zoned(md->queue))
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return test_bit(DMF_EMULATE_ZONE_APPEND, &md->flags);
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return false;
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}
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#define DM_TABLE_MAX_DEPTH 16
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struct dm_table {
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struct mapped_device *md;
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enum dm_queue_mode type;
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/* btree table */
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unsigned int depth;
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unsigned int counts[DM_TABLE_MAX_DEPTH]; /* in nodes */
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sector_t *index[DM_TABLE_MAX_DEPTH];
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unsigned int num_targets;
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unsigned int num_allocated;
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sector_t *highs;
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struct dm_target *targets;
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struct target_type *immutable_target_type;
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bool integrity_supported:1;
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bool singleton:1;
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unsigned integrity_added:1;
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/*
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* Indicates the rw permissions for the new logical
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* device. This should be a combination of FMODE_READ
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* and FMODE_WRITE.
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*/
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fmode_t mode;
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/* a list of devices used by this table */
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struct list_head devices;
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/* events get handed up using this callback */
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void (*event_fn)(void *);
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void *event_context;
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struct dm_md_mempools *mempools;
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#ifdef CONFIG_BLK_INLINE_ENCRYPTION
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struct blk_crypto_profile *crypto_profile;
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#endif
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};
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/*
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* One of these is allocated per clone bio.
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*/
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#define DM_TIO_MAGIC 28714
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struct dm_target_io {
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unsigned short magic;
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blk_short_t flags;
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unsigned int target_bio_nr;
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struct dm_io *io;
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struct dm_target *ti;
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unsigned int *len_ptr;
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sector_t old_sector;
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struct bio clone;
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};
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/*
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* dm_target_io flags
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*/
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enum {
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DM_TIO_INSIDE_DM_IO,
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DM_TIO_IS_DUPLICATE_BIO
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};
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static inline bool dm_tio_flagged(struct dm_target_io *tio, unsigned int bit)
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{
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return (tio->flags & (1U << bit)) != 0;
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}
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static inline void dm_tio_set_flag(struct dm_target_io *tio, unsigned int bit)
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{
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tio->flags |= (1U << bit);
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}
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static inline bool dm_tio_is_normal(struct dm_target_io *tio)
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{
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return (dm_tio_flagged(tio, DM_TIO_INSIDE_DM_IO) &&
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!dm_tio_flagged(tio, DM_TIO_IS_DUPLICATE_BIO));
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}
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/*
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* One of these is allocated per original bio.
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* It contains the first clone used for that original.
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*/
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#define DM_IO_MAGIC 19577
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struct dm_io {
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unsigned short magic;
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blk_short_t flags;
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spinlock_t lock;
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unsigned long start_time;
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void *data;
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struct dm_io *next;
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struct dm_stats_aux stats_aux;
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blk_status_t status;
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atomic_t io_count;
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struct mapped_device *md;
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struct bio *split_bio;
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/* The three fields represent mapped part of original bio */
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struct bio *orig_bio;
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unsigned int sector_offset; /* offset to end of orig_bio */
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unsigned int sectors;
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/* last member of dm_target_io is 'struct bio' */
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struct dm_target_io tio;
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};
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/*
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* dm_io flags
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*/
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enum {
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DM_IO_ACCOUNTED,
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DM_IO_WAS_SPLIT
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};
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static inline bool dm_io_flagged(struct dm_io *io, unsigned int bit)
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{
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return (io->flags & (1U << bit)) != 0;
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}
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static inline void dm_io_set_flag(struct dm_io *io, unsigned int bit)
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{
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io->flags |= (1U << bit);
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}
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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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