2005-04-16 22:20:36 +00:00
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#ifndef _LINUX_ELEVATOR_H
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#define _LINUX_ELEVATOR_H
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2006-07-22 13:37:43 +00:00
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#include <linux/percpu.h>
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[PATCH] BLOCK: Make it possible to disable the block layer [try #6]
Make it possible to disable the block layer. Not all embedded devices require
it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require
the block layer to be present.
This patch does the following:
(*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev
support.
(*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls
an item that uses the block layer. This includes:
(*) Block I/O tracing.
(*) Disk partition code.
(*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS.
(*) The SCSI layer. As far as I can tell, even SCSI chardevs use the
block layer to do scheduling. Some drivers that use SCSI facilities -
such as USB storage - end up disabled indirectly from this.
(*) Various block-based device drivers, such as IDE and the old CDROM
drivers.
(*) MTD blockdev handling and FTL.
(*) JFFS - which uses set_bdev_super(), something it could avoid doing by
taking a leaf out of JFFS2's book.
(*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and
linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is,
however, still used in places, and so is still available.
(*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and
parts of linux/fs.h.
(*) Makes a number of files in fs/ contingent on CONFIG_BLOCK.
(*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK.
(*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK
is not enabled.
(*) fs/no-block.c is created to hold out-of-line stubs and things that are
required when CONFIG_BLOCK is not set:
(*) Default blockdev file operations (to give error ENODEV on opening).
(*) Makes some /proc changes:
(*) /proc/devices does not list any blockdevs.
(*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK.
(*) Makes some compat ioctl handling contingent on CONFIG_BLOCK.
(*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if
given command other than Q_SYNC or if a special device is specified.
(*) In init/do_mounts.c, no reference is made to the blockdev routines if
CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2.
(*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return
error ENOSYS by way of cond_syscall if so).
(*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if
CONFIG_BLOCK is not set, since they can't then happen.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2006-09-30 18:45:40 +00:00
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#ifdef CONFIG_BLOCK
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2007-07-24 07:28:11 +00:00
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typedef int (elevator_merge_fn) (struct request_queue *, struct request **,
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2005-04-16 22:20:36 +00:00
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struct bio *);
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2007-07-24 07:28:11 +00:00
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typedef void (elevator_merge_req_fn) (struct request_queue *, struct request *, struct request *);
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2005-04-16 22:20:36 +00:00
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2007-07-24 07:28:11 +00:00
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typedef void (elevator_merged_fn) (struct request_queue *, struct request *, int);
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2005-04-16 22:20:36 +00:00
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2007-07-24 07:28:11 +00:00
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typedef int (elevator_allow_merge_fn) (struct request_queue *, struct request *, struct bio *);
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2006-12-20 10:04:12 +00:00
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2007-07-24 07:28:11 +00:00
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typedef int (elevator_dispatch_fn) (struct request_queue *, int);
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2005-04-16 22:20:36 +00:00
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2007-07-24 07:28:11 +00:00
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typedef void (elevator_add_req_fn) (struct request_queue *, struct request *);
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typedef int (elevator_queue_empty_fn) (struct request_queue *);
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typedef struct request *(elevator_request_list_fn) (struct request_queue *, struct request *);
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typedef void (elevator_completed_req_fn) (struct request_queue *, struct request *);
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typedef int (elevator_may_queue_fn) (struct request_queue *, int);
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2005-04-16 22:20:36 +00:00
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2007-07-24 07:28:11 +00:00
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typedef int (elevator_set_req_fn) (struct request_queue *, struct request *, gfp_t);
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2006-12-01 09:42:33 +00:00
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typedef void (elevator_put_req_fn) (struct request *);
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2007-07-24 07:28:11 +00:00
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typedef void (elevator_activate_req_fn) (struct request_queue *, struct request *);
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typedef void (elevator_deactivate_req_fn) (struct request_queue *, struct request *);
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2005-04-16 22:20:36 +00:00
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2007-07-24 07:28:11 +00:00
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typedef void *(elevator_init_fn) (struct request_queue *);
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2005-04-16 22:20:36 +00:00
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typedef void (elevator_exit_fn) (elevator_t *);
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struct elevator_ops
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{
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elevator_merge_fn *elevator_merge_fn;
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elevator_merged_fn *elevator_merged_fn;
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elevator_merge_req_fn *elevator_merge_req_fn;
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2006-12-20 10:04:12 +00:00
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elevator_allow_merge_fn *elevator_allow_merge_fn;
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2005-04-16 22:20:36 +00:00
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2005-10-20 14:23:44 +00:00
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elevator_dispatch_fn *elevator_dispatch_fn;
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2005-04-16 22:20:36 +00:00
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elevator_add_req_fn *elevator_add_req_fn;
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2005-10-20 14:23:44 +00:00
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elevator_activate_req_fn *elevator_activate_req_fn;
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2005-04-16 22:20:36 +00:00
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elevator_deactivate_req_fn *elevator_deactivate_req_fn;
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elevator_queue_empty_fn *elevator_queue_empty_fn;
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elevator_completed_req_fn *elevator_completed_req_fn;
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elevator_request_list_fn *elevator_former_req_fn;
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elevator_request_list_fn *elevator_latter_req_fn;
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elevator_set_req_fn *elevator_set_req_fn;
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elevator_put_req_fn *elevator_put_req_fn;
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elevator_may_queue_fn *elevator_may_queue_fn;
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elevator_init_fn *elevator_init_fn;
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elevator_exit_fn *elevator_exit_fn;
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2006-03-18 18:21:20 +00:00
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void (*trim)(struct io_context *);
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2005-04-16 22:20:36 +00:00
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};
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#define ELV_NAME_MAX (16)
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2006-03-19 03:27:18 +00:00
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struct elv_fs_entry {
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struct attribute attr;
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ssize_t (*show)(elevator_t *, char *);
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ssize_t (*store)(elevator_t *, const char *, size_t);
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};
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2005-04-16 22:20:36 +00:00
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/*
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* identifies an elevator type, such as AS or deadline
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*/
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struct elevator_type
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{
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struct list_head list;
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struct elevator_ops ops;
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2006-03-19 03:27:18 +00:00
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struct elv_fs_entry *elevator_attrs;
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2005-04-16 22:20:36 +00:00
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char elevator_name[ELV_NAME_MAX];
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struct module *elevator_owner;
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};
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/*
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2006-01-09 23:09:36 +00:00
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* each queue has an elevator_queue associated with it
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2005-04-16 22:20:36 +00:00
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*/
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struct elevator_queue
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{
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struct elevator_ops *ops;
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void *elevator_data;
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struct kobject kobj;
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struct elevator_type *elevator_type;
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2006-03-18 23:35:43 +00:00
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struct mutex sysfs_lock;
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2006-07-28 07:23:08 +00:00
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struct hlist_head *hash;
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2005-04-16 22:20:36 +00:00
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};
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/*
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* block elevator interface
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*/
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2007-07-24 07:28:11 +00:00
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extern void elv_dispatch_sort(struct request_queue *, struct request *);
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extern void elv_dispatch_add_tail(struct request_queue *, struct request *);
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extern void elv_add_request(struct request_queue *, struct request *, int, int);
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extern void __elv_add_request(struct request_queue *, struct request *, int, int);
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extern void elv_insert(struct request_queue *, struct request *, int);
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extern int elv_merge(struct request_queue *, struct request **, struct bio *);
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extern void elv_merge_requests(struct request_queue *, struct request *,
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2005-04-16 22:20:36 +00:00
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struct request *);
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2007-07-24 07:28:11 +00:00
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extern void elv_merged_request(struct request_queue *, struct request *, int);
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extern void elv_dequeue_request(struct request_queue *, struct request *);
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extern void elv_requeue_request(struct request_queue *, struct request *);
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extern int elv_queue_empty(struct request_queue *);
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2005-04-16 22:20:36 +00:00
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extern struct request *elv_next_request(struct request_queue *q);
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2007-07-24 07:28:11 +00:00
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extern struct request *elv_former_request(struct request_queue *, struct request *);
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extern struct request *elv_latter_request(struct request_queue *, struct request *);
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extern int elv_register_queue(struct request_queue *q);
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extern void elv_unregister_queue(struct request_queue *q);
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extern int elv_may_queue(struct request_queue *, int);
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extern void elv_completed_request(struct request_queue *, struct request *);
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extern int elv_set_request(struct request_queue *, struct request *, gfp_t);
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extern void elv_put_request(struct request_queue *, struct request *);
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2005-04-16 22:20:36 +00:00
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/*
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* io scheduler registration
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*/
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2007-12-12 17:51:56 +00:00
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extern void elv_register(struct elevator_type *);
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2005-04-16 22:20:36 +00:00
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extern void elv_unregister(struct elevator_type *);
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/*
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* io scheduler sysfs switching
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*/
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2007-07-24 07:28:11 +00:00
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extern ssize_t elv_iosched_show(struct request_queue *, char *);
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extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
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2005-04-16 22:20:36 +00:00
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2007-07-24 07:28:11 +00:00
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extern int elevator_init(struct request_queue *, char *);
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2005-04-16 22:20:36 +00:00
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extern void elevator_exit(elevator_t *);
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extern int elv_rq_merge_ok(struct request *, struct bio *);
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2006-07-13 09:55:04 +00:00
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/*
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* Helper functions.
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*/
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2007-07-24 07:28:11 +00:00
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extern struct request *elv_rb_former_request(struct request_queue *, struct request *);
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extern struct request *elv_rb_latter_request(struct request_queue *, struct request *);
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2006-07-13 09:55:04 +00:00
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/*
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* rb support functions.
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*/
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extern struct request *elv_rb_add(struct rb_root *, struct request *);
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extern void elv_rb_del(struct rb_root *, struct request *);
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extern struct request *elv_rb_find(struct rb_root *, sector_t);
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2005-04-16 22:20:36 +00:00
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/*
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* Return values from elevator merger
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*/
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#define ELEVATOR_NO_MERGE 0
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#define ELEVATOR_FRONT_MERGE 1
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#define ELEVATOR_BACK_MERGE 2
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/*
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* Insertion selection
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*/
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#define ELEVATOR_INSERT_FRONT 1
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#define ELEVATOR_INSERT_BACK 2
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#define ELEVATOR_INSERT_SORT 3
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2006-01-06 08:51:03 +00:00
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#define ELEVATOR_INSERT_REQUEUE 4
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2005-04-16 22:20:36 +00:00
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/*
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* return values from elevator_may_queue_fn
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*/
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enum {
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ELV_MQUEUE_MAY,
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ELV_MQUEUE_NO,
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ELV_MQUEUE_MUST,
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};
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2005-10-20 14:37:00 +00:00
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#define rq_end_sector(rq) ((rq)->sector + (rq)->nr_sectors)
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2006-07-13 09:55:04 +00:00
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#define rb_entry_rq(node) rb_entry((node), struct request, rb_node)
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2005-10-20 14:37:00 +00:00
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2006-07-11 19:49:15 +00:00
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/*
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2008-09-13 18:26:01 +00:00
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* Hack to reuse the csd.list list_head as the fifo time holder while
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2006-07-11 19:49:15 +00:00
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* the request is in the io scheduler. Saves an unsigned long in rq.
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*/
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2008-09-13 18:26:01 +00:00
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#define rq_fifo_time(rq) ((unsigned long) (rq)->csd.list.next)
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#define rq_set_fifo_time(rq,exp) ((rq)->csd.list.next = (void *) (exp))
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2006-07-11 19:49:15 +00:00
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#define rq_entry_fifo(ptr) list_entry((ptr), struct request, queuelist)
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#define rq_fifo_clear(rq) do { \
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list_del_init(&(rq)->queuelist); \
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2008-09-13 18:26:01 +00:00
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INIT_LIST_HEAD(&(rq)->csd.list); \
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2006-07-11 19:49:15 +00:00
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} while (0)
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2006-07-22 13:37:43 +00:00
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/*
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* io context count accounting
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*/
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#define elv_ioc_count_mod(name, __val) \
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do { \
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preempt_disable(); \
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__get_cpu_var(name) += (__val); \
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preempt_enable(); \
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} while (0)
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#define elv_ioc_count_inc(name) elv_ioc_count_mod(name, 1)
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#define elv_ioc_count_dec(name) elv_ioc_count_mod(name, -1)
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#define elv_ioc_count_read(name) \
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({ \
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unsigned long __val = 0; \
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int __cpu; \
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smp_wmb(); \
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for_each_possible_cpu(__cpu) \
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__val += per_cpu(name, __cpu); \
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__val; \
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})
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[PATCH] BLOCK: Make it possible to disable the block layer [try #6]
Make it possible to disable the block layer. Not all embedded devices require
it, some can make do with just JFFS2, NFS, ramfs, etc - none of which require
the block layer to be present.
This patch does the following:
(*) Introduces CONFIG_BLOCK to disable the block layer, buffering and blockdev
support.
(*) Adds dependencies on CONFIG_BLOCK to any configuration item that controls
an item that uses the block layer. This includes:
(*) Block I/O tracing.
(*) Disk partition code.
(*) All filesystems that are block based, eg: Ext3, ReiserFS, ISOFS.
(*) The SCSI layer. As far as I can tell, even SCSI chardevs use the
block layer to do scheduling. Some drivers that use SCSI facilities -
such as USB storage - end up disabled indirectly from this.
(*) Various block-based device drivers, such as IDE and the old CDROM
drivers.
(*) MTD blockdev handling and FTL.
(*) JFFS - which uses set_bdev_super(), something it could avoid doing by
taking a leaf out of JFFS2's book.
(*) Makes most of the contents of linux/blkdev.h, linux/buffer_head.h and
linux/elevator.h contingent on CONFIG_BLOCK being set. sector_div() is,
however, still used in places, and so is still available.
(*) Also made contingent are the contents of linux/mpage.h, linux/genhd.h and
parts of linux/fs.h.
(*) Makes a number of files in fs/ contingent on CONFIG_BLOCK.
(*) Makes mm/bounce.c (bounce buffering) contingent on CONFIG_BLOCK.
(*) set_page_dirty() doesn't call __set_page_dirty_buffers() if CONFIG_BLOCK
is not enabled.
(*) fs/no-block.c is created to hold out-of-line stubs and things that are
required when CONFIG_BLOCK is not set:
(*) Default blockdev file operations (to give error ENODEV on opening).
(*) Makes some /proc changes:
(*) /proc/devices does not list any blockdevs.
(*) /proc/diskstats and /proc/partitions are contingent on CONFIG_BLOCK.
(*) Makes some compat ioctl handling contingent on CONFIG_BLOCK.
(*) If CONFIG_BLOCK is not defined, makes sys_quotactl() return -ENODEV if
given command other than Q_SYNC or if a special device is specified.
(*) In init/do_mounts.c, no reference is made to the blockdev routines if
CONFIG_BLOCK is not defined. This does not prohibit NFS roots or JFFS2.
(*) The bdflush, ioprio_set and ioprio_get syscalls can now be absent (return
error ENOSYS by way of cond_syscall if so).
(*) The seclvl_bd_claim() and seclvl_bd_release() security calls do nothing if
CONFIG_BLOCK is not set, since they can't then happen.
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2006-09-30 18:45:40 +00:00
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#endif /* CONFIG_BLOCK */
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2005-04-16 22:20:36 +00:00
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#endif
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