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86f1152b11
Until this change, when loading a new DM table, DM core would re-open all of the devices in the DM table. Now, DM core will avoid redundant device opens (and closes when destroying the old table) if the old table already has a device open using the same mode. This is achieved by managing reference counts on the table_devices that DM core now stores in the mapped_device structure (rather than in the dm_table structure). So a mapped_device's active and inactive dm_tables' dm_dev lists now just point to the dm_devs stored in the mapped_device's table_devices list. This improvement in DM core's device reference counting has the side-effect of fixing a long-standing limitation of the multipath target: a DM multipath table couldn't include any paths that were unusable (failed). For example: if all paths have failed and you add a new, working, path to the table; you can't use it since the table load would fail due to it still containing failed paths. Now a re-load of a multipath table can include failed devices and when those devices become active again they can be used instantly. The device list code in dm.c isn't a straight copy/paste from the code in dm-table.c, but it's very close (aside from some variable renames). One subtle difference is that find_table_device for the tables_devices list will only match devices with the same name and mode. This is because we don't want to upgrade a device's mode in the active table when an inactive table is loaded. Access to the mapped_device structure's tables_devices list requires a mutex (tables_devices_lock), so that tables cannot be created and destroyed concurrently. Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
226 lines
6.5 KiB
C
226 lines
6.5 KiB
C
/*
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* Internal header file for device mapper
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*
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* Copyright (C) 2001, 2002 Sistina Software
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* Copyright (C) 2004-2006 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_INTERNAL_H
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#define DM_INTERNAL_H
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#include <linux/fs.h>
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#include <linux/device-mapper.h>
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#include <linux/list.h>
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#include <linux/blkdev.h>
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#include <linux/hdreg.h>
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#include <linux/completion.h>
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#include <linux/kobject.h>
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#include "dm-stats.h"
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/*
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* Suspend feature flags
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*/
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#define DM_SUSPEND_LOCKFS_FLAG (1 << 0)
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#define DM_SUSPEND_NOFLUSH_FLAG (1 << 1)
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/*
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* Status feature flags
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*/
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#define DM_STATUS_NOFLUSH_FLAG (1 << 0)
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/*
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* Type of table and mapped_device's mempool
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*/
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#define DM_TYPE_NONE 0
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#define DM_TYPE_BIO_BASED 1
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#define DM_TYPE_REQUEST_BASED 2
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/*
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* List of devices that a metadevice uses and should open/close.
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*/
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struct dm_dev_internal {
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struct list_head list;
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atomic_t count;
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struct dm_dev *dm_dev;
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};
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struct dm_table;
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struct dm_md_mempools;
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/*-----------------------------------------------------------------
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* Internal table functions.
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*---------------------------------------------------------------*/
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void dm_table_destroy(struct dm_table *t);
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void dm_table_event_callback(struct dm_table *t,
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void (*fn)(void *), void *context);
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struct dm_target *dm_table_get_target(struct dm_table *t, unsigned int index);
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struct dm_target *dm_table_find_target(struct dm_table *t, sector_t sector);
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bool dm_table_has_no_data_devices(struct dm_table *table);
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int dm_calculate_queue_limits(struct dm_table *table,
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struct queue_limits *limits);
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void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
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struct queue_limits *limits);
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struct list_head *dm_table_get_devices(struct dm_table *t);
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void dm_table_presuspend_targets(struct dm_table *t);
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void dm_table_postsuspend_targets(struct dm_table *t);
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int dm_table_resume_targets(struct dm_table *t);
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int dm_table_any_congested(struct dm_table *t, int bdi_bits);
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int dm_table_any_busy_target(struct dm_table *t);
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unsigned dm_table_get_type(struct dm_table *t);
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struct target_type *dm_table_get_immutable_target_type(struct dm_table *t);
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bool dm_table_request_based(struct dm_table *t);
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void dm_table_free_md_mempools(struct dm_table *t);
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struct dm_md_mempools *dm_table_get_md_mempools(struct dm_table *t);
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int dm_queue_merge_is_compulsory(struct request_queue *q);
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void dm_lock_md_type(struct mapped_device *md);
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void dm_unlock_md_type(struct mapped_device *md);
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void dm_set_md_type(struct mapped_device *md, unsigned type);
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unsigned dm_get_md_type(struct mapped_device *md);
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struct target_type *dm_get_immutable_target_type(struct mapped_device *md);
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int dm_setup_md_queue(struct mapped_device *md);
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/*
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* To check the return value from dm_table_find_target().
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*/
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#define dm_target_is_valid(t) ((t)->table)
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/*
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* To check whether the target type is bio-based or not (request-based).
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*/
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#define dm_target_bio_based(t) ((t)->type->map != NULL)
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/*
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* To check whether the target type is request-based or not (bio-based).
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*/
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#define dm_target_request_based(t) ((t)->type->map_rq != NULL)
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/*
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* To check whether the target type is a hybrid (capable of being
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* either request-based or bio-based).
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*/
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#define dm_target_hybrid(t) (dm_target_bio_based(t) && dm_target_request_based(t))
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/*-----------------------------------------------------------------
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* A registry of target types.
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*---------------------------------------------------------------*/
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int dm_target_init(void);
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void dm_target_exit(void);
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struct target_type *dm_get_target_type(const char *name);
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void dm_put_target_type(struct target_type *tt);
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int dm_target_iterate(void (*iter_func)(struct target_type *tt,
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void *param), void *param);
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int dm_split_args(int *argc, char ***argvp, char *input);
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/*
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* Is this mapped_device being deleted?
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*/
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int dm_deleting_md(struct mapped_device *md);
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/*
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* Is this mapped_device suspended?
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*/
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int dm_suspended_md(struct mapped_device *md);
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/*
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* Test if the device is scheduled for deferred remove.
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*/
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int dm_test_deferred_remove_flag(struct mapped_device *md);
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/*
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* Try to remove devices marked for deferred removal.
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*/
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void dm_deferred_remove(void);
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/*
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* The device-mapper can be driven through one of two interfaces;
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* ioctl or filesystem, depending which patch you have applied.
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*/
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int dm_interface_init(void);
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void dm_interface_exit(void);
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/*
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* sysfs interface
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*/
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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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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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int dm_sysfs_init(struct mapped_device *md);
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void dm_sysfs_exit(struct mapped_device *md);
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struct kobject *dm_kobject(struct mapped_device *md);
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struct mapped_device *dm_get_from_kobject(struct kobject *kobj);
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/*
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* The kobject helper
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*/
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void dm_kobject_release(struct kobject *kobj);
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/*
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* Targets for linear and striped mappings
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*/
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int dm_linear_init(void);
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void dm_linear_exit(void);
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int dm_stripe_init(void);
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void dm_stripe_exit(void);
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/*
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* mapped_device operations
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*/
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void dm_destroy(struct mapped_device *md);
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void dm_destroy_immediate(struct mapped_device *md);
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int dm_open_count(struct mapped_device *md);
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int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred, bool only_deferred);
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int dm_cancel_deferred_remove(struct mapped_device *md);
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int dm_request_based(struct mapped_device *md);
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sector_t dm_get_size(struct mapped_device *md);
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struct request_queue *dm_get_md_queue(struct mapped_device *md);
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int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode,
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struct dm_dev **result);
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void dm_put_table_device(struct mapped_device *md, struct dm_dev *d);
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struct dm_stats *dm_get_stats(struct mapped_device *md);
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int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
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unsigned cookie);
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void dm_internal_suspend(struct mapped_device *md);
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void dm_internal_resume(struct mapped_device *md);
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int dm_io_init(void);
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void dm_io_exit(void);
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int dm_kcopyd_init(void);
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void dm_kcopyd_exit(void);
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/*
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* Mempool operations
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*/
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struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity, unsigned per_bio_data_size);
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void dm_free_md_mempools(struct dm_md_mempools *pools);
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/*
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* Helpers that are used by DM core
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*/
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unsigned dm_get_reserved_bio_based_ios(void);
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unsigned dm_get_reserved_rq_based_ios(void);
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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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#endif
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