d5b9dd04bd
Add a new flag DMF_MERGE_IS_OPTIONAL to struct mapped_device to indicate whether the device can accept bios larger than the size its merge function returns. When set, use this to send large bios to snapshots which can split them if necessary. Snapshot I/O may be significantly fragmented and this approach seems to improve peformance. Before the patch, dm_set_device_limits restricted bio size to page size if the underlying device had a merge function and the target didn't provide a merge function. After the patch, dm_set_device_limits restricts bio size to page size if the underlying device has a merge function, doesn't have DMF_MERGE_IS_OPTIONAL flag and the target doesn't provide a merge function. The snapshot target can't provide a merge function because when the merge function is called, it is impossible to determine where the bio will be remapped. Previously this led us to impose a 4k limit, which we can now remove if the snapshot store is located on a device without a merge function. Together with another patch for optimizing full chunk writes, it improves performance from 29MB/s to 40MB/s when writing to the filesystem on snapshot store. If the snapshot store is placed on a non-dm device with a merge function (such as md-raid), device mapper still limits all bios to page size. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
158 lines
4.5 KiB
C
158 lines
4.5 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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/*
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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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* 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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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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bool dm_table_request_based(struct dm_table *t);
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bool dm_table_supports_discards(struct dm_table *t);
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int dm_table_alloc_md_mempools(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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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 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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* 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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* 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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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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* 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);
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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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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);
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void dm_free_md_mempools(struct dm_md_mempools *pools);
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#endif
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