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linux/drivers/md/md.h
NeilBrown 97658cdd3a md: provide generic support for handling unplug callbacks. 
When an md device adds a request to a queue, it can call
mddev_check_plugged.
If this succeeds then we know that the md thread will be woken up
shortly, and ->plug_cnt will be non-zero until then, so some
processing can be delayed.

If it fails, then no unplug callback is expected and the make_request
function needs to do whatever is required to make the request happen.

Signed-off-by: NeilBrown <neilb@suse.de>
2011-04-18 18:25:42 +10:00

516 lines
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/*
md_k.h : kernel internal structure of the Linux MD driver
Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
You should have received a copy of the GNU General Public License
(for example /usr/src/linux/COPYING); if not, write to the Free
Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#ifndef _MD_MD_H
#define _MD_MD_H
#include <linux/blkdev.h>
#include <linux/kobject.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/timer.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
#define MaxSector (~(sector_t)0)
typedef struct mddev_s mddev_t;
typedef struct mdk_rdev_s mdk_rdev_t;
/*
* MD's 'extended' device
*/
struct mdk_rdev_s
{
struct list_head same_set; /* RAID devices within the same set */
sector_t sectors; /* Device size (in 512bytes sectors) */
mddev_t *mddev; /* RAID array if running */
int last_events; /* IO event timestamp */
/*
* If meta_bdev is non-NULL, it means that a separate device is
* being used to store the metadata (superblock/bitmap) which
* would otherwise be contained on the same device as the data (bdev).
*/
struct block_device *meta_bdev;
struct block_device *bdev; /* block device handle */
struct page *sb_page;
int sb_loaded;
__u64 sb_events;
sector_t data_offset; /* start of data in array */
sector_t sb_start; /* offset of the super block (in 512byte sectors) */
int sb_size; /* bytes in the superblock */
int preferred_minor; /* autorun support */
struct kobject kobj;
/* A device can be in one of three states based on two flags:
* Not working: faulty==1 in_sync==0
* Fully working: faulty==0 in_sync==1
* Working, but not
* in sync with array
* faulty==0 in_sync==0
*
* It can never have faulty==1, in_sync==1
* This reduces the burden of testing multiple flags in many cases
*/
unsigned long flags;
#define Faulty 1 /* device is known to have a fault */
#define In_sync 2 /* device is in_sync with rest of array */
#define WriteMostly 4 /* Avoid reading if at all possible */
#define AutoDetected 7 /* added by auto-detect */
#define Blocked 8 /* An error occurred on an externally
* managed array, don't allow writes
* until it is cleared */
wait_queue_head_t blocked_wait;
int desc_nr; /* descriptor index in the superblock */
int raid_disk; /* role of device in array */
int new_raid_disk; /* role that the device will have in
* the array after a level-change completes.
*/
int saved_raid_disk; /* role that device used to have in the
* array and could again if we did a partial
* resync from the bitmap
*/
sector_t recovery_offset;/* If this device has been partially
* recovered, this is where we were
* up to.
*/
atomic_t nr_pending; /* number of pending requests.
* only maintained for arrays that
* support hot removal
*/
atomic_t read_errors; /* number of consecutive read errors that
* we have tried to ignore.
*/
struct timespec last_read_error; /* monotonic time since our
* last read error
*/
atomic_t corrected_errors; /* number of corrected read errors,
* for reporting to userspace and storing
* in superblock.
*/
struct work_struct del_work; /* used for delayed sysfs removal */
struct sysfs_dirent *sysfs_state; /* handle for 'state'
* sysfs entry */
};
struct mddev_s
{
void *private;
struct mdk_personality *pers;
dev_t unit;
int md_minor;
struct list_head disks;
unsigned long flags;
#define MD_CHANGE_DEVS 0 /* Some device status has changed */
#define MD_CHANGE_CLEAN 1 /* transition to or from 'clean' */
#define MD_CHANGE_PENDING 2 /* switch from 'clean' to 'active' in progress */
int suspended;
atomic_t active_io;
int ro;
int sysfs_active; /* set when sysfs deletes
* are happening, so run/
* takeover/stop are not safe
*/
int ready; /* See when safe to pass
* IO requests down */
struct gendisk *gendisk;
struct kobject kobj;
int hold_active;
#define UNTIL_IOCTL 1
#define UNTIL_STOP 2
/* Superblock information */
int major_version,
minor_version,
patch_version;
int persistent;
int external; /* metadata is
* managed externally */
char metadata_type[17]; /* externally set*/
int chunk_sectors;
time_t ctime, utime;
int level, layout;
char clevel[16];
int raid_disks;
int max_disks;
sector_t dev_sectors; /* used size of
* component devices */
sector_t array_sectors; /* exported array size */
int external_size; /* size managed
* externally */
__u64 events;
/* If the last 'event' was simply a clean->dirty transition, and
* we didn't write it to the spares, then it is safe and simple
* to just decrement the event count on a dirty->clean transition.
* So we record that possibility here.
*/
int can_decrease_events;
char uuid[16];
/* If the array is being reshaped, we need to record the
* new shape and an indication of where we are up to.
* This is written to the superblock.
* If reshape_position is MaxSector, then no reshape is happening (yet).
*/
sector_t reshape_position;
int delta_disks, new_level, new_layout;
int new_chunk_sectors;
atomic_t plug_cnt; /* If device is expecting
* more bios soon.
*/
struct mdk_thread_s *thread; /* management thread */
struct mdk_thread_s *sync_thread; /* doing resync or reconstruct */
sector_t curr_resync; /* last block scheduled */
/* As resync requests can complete out of order, we cannot easily track
* how much resync has been completed. So we occasionally pause until
* everything completes, then set curr_resync_completed to curr_resync.
* As such it may be well behind the real resync mark, but it is a value
* we are certain of.
*/
sector_t curr_resync_completed;
unsigned long resync_mark; /* a recent timestamp */
sector_t resync_mark_cnt;/* blocks written at resync_mark */
sector_t curr_mark_cnt; /* blocks scheduled now */
sector_t resync_max_sectors; /* may be set by personality */
sector_t resync_mismatches; /* count of sectors where
* parity/replica mismatch found
*/
/* allow user-space to request suspension of IO to regions of the array */
sector_t suspend_lo;
sector_t suspend_hi;
/* if zero, use the system-wide default */
int sync_speed_min;
int sync_speed_max;
/* resync even though the same disks are shared among md-devices */
int parallel_resync;
int ok_start_degraded;
/* recovery/resync flags
* NEEDED: we might need to start a resync/recover
* RUNNING: a thread is running, or about to be started
* SYNC: actually doing a resync, not a recovery
* RECOVER: doing recovery, or need to try it.
* INTR: resync needs to be aborted for some reason
* DONE: thread is done and is waiting to be reaped
* REQUEST: user-space has requested a sync (used with SYNC)
* CHECK: user-space request for check-only, no repair
* RESHAPE: A reshape is happening
*
* If neither SYNC or RESHAPE are set, then it is a recovery.
*/
#define MD_RECOVERY_RUNNING 0
#define MD_RECOVERY_SYNC 1
#define MD_RECOVERY_RECOVER 2
#define MD_RECOVERY_INTR 3
#define MD_RECOVERY_DONE 4
#define MD_RECOVERY_NEEDED 5
#define MD_RECOVERY_REQUESTED 6
#define MD_RECOVERY_CHECK 7
#define MD_RECOVERY_RESHAPE 8
#define MD_RECOVERY_FROZEN 9
unsigned long recovery;
int recovery_disabled; /* if we detect that recovery
* will always fail, set this
* so we don't loop trying */
int in_sync; /* know to not need resync */
/* 'open_mutex' avoids races between 'md_open' and 'do_md_stop', so
* that we are never stopping an array while it is open.
* 'reconfig_mutex' protects all other reconfiguration.
* These locks are separate due to conflicting interactions
* with bdev->bd_mutex.
* Lock ordering is:
* reconfig_mutex -> bd_mutex : e.g. do_md_run -> revalidate_disk
* bd_mutex -> open_mutex: e.g. __blkdev_get -> md_open
*/
struct mutex open_mutex;
struct mutex reconfig_mutex;
atomic_t active; /* general refcount */
atomic_t openers; /* number of active opens */
int changed; /* True if we might need to
* reread partition info */
int degraded; /* whether md should consider
* adding a spare
*/
atomic_t recovery_active; /* blocks scheduled, but not written */
wait_queue_head_t recovery_wait;
sector_t recovery_cp;
sector_t resync_min; /* user requested sync
* starts here */
sector_t resync_max; /* resync should pause
* when it gets here */
struct sysfs_dirent *sysfs_state; /* handle for 'array_state'
* file in sysfs.
*/
struct sysfs_dirent *sysfs_action; /* handle for 'sync_action' */
struct work_struct del_work; /* used for delayed sysfs removal */
spinlock_t write_lock;
wait_queue_head_t sb_wait; /* for waiting on superblock updates */
atomic_t pending_writes; /* number of active superblock writes */
unsigned int safemode; /* if set, update "clean" superblock
* when no writes pending.
*/
unsigned int safemode_delay;
struct timer_list safemode_timer;
atomic_t writes_pending;
struct request_queue *queue; /* for plugging ... */
struct bitmap *bitmap; /* the bitmap for the device */
struct {
struct file *file; /* the bitmap file */
loff_t offset; /* offset from superblock of
* start of bitmap. May be
* negative, but not '0'
* For external metadata, offset
* from start of device.
*/
loff_t default_offset; /* this is the offset to use when
* hot-adding a bitmap. It should
* eventually be settable by sysfs.
*/
/* When md is serving under dm, it might use a
* dirty_log to store the bits.
*/
struct dm_dirty_log *log;
struct mutex mutex;
unsigned long chunksize;
unsigned long daemon_sleep; /* how many jiffies between updates? */
unsigned long max_write_behind; /* write-behind mode */
int external;
} bitmap_info;
atomic_t max_corr_read_errors; /* max read retries */
struct list_head all_mddevs;
struct attribute_group *to_remove;
struct bio_set *bio_set;
/* Generic flush handling.
* The last to finish preflush schedules a worker to submit
* the rest of the request (without the REQ_FLUSH flag).
*/
struct bio *flush_bio;
atomic_t flush_pending;
struct work_struct flush_work;
struct work_struct event_work; /* used by dm to report failure event */
};
static inline void rdev_dec_pending(mdk_rdev_t *rdev, mddev_t *mddev)
{
int faulty = test_bit(Faulty, &rdev->flags);
if (atomic_dec_and_test(&rdev->nr_pending) && faulty)
set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
}
static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors)
{
atomic_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io);
}
struct mdk_personality
{
char *name;
int level;
struct list_head list;
struct module *owner;
int (*make_request)(mddev_t *mddev, struct bio *bio);
int (*run)(mddev_t *mddev);
int (*stop)(mddev_t *mddev);
void (*status)(struct seq_file *seq, mddev_t *mddev);
/* error_handler must set ->faulty and clear ->in_sync
* if appropriate, and should abort recovery if needed
*/
void (*error_handler)(mddev_t *mddev, mdk_rdev_t *rdev);
int (*hot_add_disk) (mddev_t *mddev, mdk_rdev_t *rdev);
int (*hot_remove_disk) (mddev_t *mddev, int number);
int (*spare_active) (mddev_t *mddev);
sector_t (*sync_request)(mddev_t *mddev, sector_t sector_nr, int *skipped, int go_faster);
int (*resize) (mddev_t *mddev, sector_t sectors);
sector_t (*size) (mddev_t *mddev, sector_t sectors, int raid_disks);
int (*check_reshape) (mddev_t *mddev);
int (*start_reshape) (mddev_t *mddev);
void (*finish_reshape) (mddev_t *mddev);
/* quiesce moves between quiescence states
* 0 - fully active
* 1 - no new requests allowed
* others - reserved
*/
void (*quiesce) (mddev_t *mddev, int state);
/* takeover is used to transition an array from one
* personality to another. The new personality must be able
* to handle the data in the current layout.
* e.g. 2drive raid1 -> 2drive raid5
* ndrive raid5 -> degraded n+1drive raid6 with special layout
* If the takeover succeeds, a new 'private' structure is returned.
* This needs to be installed and then ->run used to activate the
* array.
*/
void *(*takeover) (mddev_t *mddev);
};
struct md_sysfs_entry {
struct attribute attr;
ssize_t (*show)(mddev_t *, char *);
ssize_t (*store)(mddev_t *, const char *, size_t);
};
extern struct attribute_group md_bitmap_group;
static inline struct sysfs_dirent *sysfs_get_dirent_safe(struct sysfs_dirent *sd, char *name)
{
if (sd)
return sysfs_get_dirent(sd, NULL, name);
return sd;
}
static inline void sysfs_notify_dirent_safe(struct sysfs_dirent *sd)
{
if (sd)
sysfs_notify_dirent(sd);
}
static inline char * mdname (mddev_t * mddev)
{
return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
}
/*
* iterates through some rdev ringlist. It's safe to remove the
* current 'rdev'. Dont touch 'tmp' though.
*/
#define rdev_for_each_list(rdev, tmp, head) \
list_for_each_entry_safe(rdev, tmp, head, same_set)
/*
* iterates through the 'same array disks' ringlist
*/
#define rdev_for_each(rdev, tmp, mddev) \
list_for_each_entry_safe(rdev, tmp, &((mddev)->disks), same_set)
#define rdev_for_each_rcu(rdev, mddev) \
list_for_each_entry_rcu(rdev, &((mddev)->disks), same_set)
typedef struct mdk_thread_s {
void (*run) (mddev_t *mddev);
mddev_t *mddev;
wait_queue_head_t wqueue;
unsigned long flags;
struct task_struct *tsk;
unsigned long timeout;
} mdk_thread_t;
#define THREAD_WAKEUP 0
#define __wait_event_lock_irq(wq, condition, lock, cmd) \
do { \
wait_queue_t __wait; \
init_waitqueue_entry(&__wait, current); \
\
add_wait_queue(&wq, &__wait); \
for (;;) { \
set_current_state(TASK_UNINTERRUPTIBLE); \
if (condition) \
break; \
spin_unlock_irq(&lock); \
cmd; \
schedule(); \
spin_lock_irq(&lock); \
} \
current->state = TASK_RUNNING; \
remove_wait_queue(&wq, &__wait); \
} while (0)
#define wait_event_lock_irq(wq, condition, lock, cmd) \
do { \
if (condition) \
break; \
__wait_event_lock_irq(wq, condition, lock, cmd); \
} while (0)
static inline void safe_put_page(struct page *p)
{
if (p) put_page(p);
}
extern int register_md_personality(struct mdk_personality *p);
extern int unregister_md_personality(struct mdk_personality *p);
extern mdk_thread_t * md_register_thread(void (*run) (mddev_t *mddev),
mddev_t *mddev, const char *name);
extern void md_unregister_thread(mdk_thread_t *thread);
extern void md_wakeup_thread(mdk_thread_t *thread);
extern void md_check_recovery(mddev_t *mddev);
extern void md_write_start(mddev_t *mddev, struct bio *bi);
extern void md_write_end(mddev_t *mddev);
extern void md_done_sync(mddev_t *mddev, int blocks, int ok);
extern void md_error(mddev_t *mddev, mdk_rdev_t *rdev);
extern int mddev_congested(mddev_t *mddev, int bits);
extern void md_flush_request(mddev_t *mddev, struct bio *bio);
extern void md_super_write(mddev_t *mddev, mdk_rdev_t *rdev,
sector_t sector, int size, struct page *page);
extern void md_super_wait(mddev_t *mddev);
extern int sync_page_io(mdk_rdev_t *rdev, sector_t sector, int size,
struct page *page, int rw, bool metadata_op);
extern void md_do_sync(mddev_t *mddev);
extern void md_new_event(mddev_t *mddev);
extern int md_allow_write(mddev_t *mddev);
extern void md_wait_for_blocked_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
extern void md_set_array_sectors(mddev_t *mddev, sector_t array_sectors);
extern int md_check_no_bitmap(mddev_t *mddev);
extern int md_integrity_register(mddev_t *mddev);
extern void md_integrity_add_rdev(mdk_rdev_t *rdev, mddev_t *mddev);
extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
extern void restore_bitmap_write_access(struct file *file);
extern void mddev_init(mddev_t *mddev);
extern int md_run(mddev_t *mddev);
extern void md_stop(mddev_t *mddev);
extern void md_stop_writes(mddev_t *mddev);
extern void md_rdev_init(mdk_rdev_t *rdev);
extern void mddev_suspend(mddev_t *mddev);
extern void mddev_resume(mddev_t *mddev);
extern struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
mddev_t *mddev);
extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
mddev_t *mddev);
extern int mddev_check_plugged(mddev_t *mddev);
#endif /* _MD_MD_H */
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