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md.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>
#include "md-cluster.h"
#define MaxSector (~(sector_t)0)
/* Bad block numbers are stored sorted in a single page.
* 64bits is used for each block or extent.
* 54 bits are sector number, 9 bits are extent size,
* 1 bit is an 'acknowledged' flag.
* MD's 'extended' device
struct md_rdev {
struct list_head same_set; /* RAID devices within the same set */
sector_t sectors; /* Device size (in 512bytes sectors) */
struct mddev *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, *bb_page;
int sb_loaded;
__u64 sb_events;
sector_t data_offset; /* start of data in array */
sector_t new_data_offset;/* only relevant while reshaping */
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; /* bit set of 'enum flag_bits' bits. */
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 kernfs_node *sysfs_state; /* handle for 'state'
* sysfs entry */
struct badblocks {
int count; /* count of bad blocks */
int unacked_exist; /* there probably are unacknowledged
* bad blocks. This is only cleared
* when a read discovers none
int shift; /* shift from sectors to block size
* a -ve shift means badblocks are
* disabled.*/
u64 *page; /* badblock list */
int changed;
seqlock_t lock;
sector_t sector;
sector_t size; /* in sectors */
} badblocks;
enum flag_bits {
Faulty, /* device is known to have a fault */
In_sync, /* device is in_sync with rest of array */
Bitmap_sync, /* ..actually, not quite In_sync. Need a
* bitmap-based recovery to get fully in sync
Unmerged, /* device is being added to array and should
* be considerred for bvec_merge_fn but not
* yet for actual IO
WriteMostly, /* Avoid reading if at all possible */
AutoDetected, /* added by auto-detect */
Blocked, /* An error occurred but has not yet
* been acknowledged by the metadata
* handler, so don't allow writes
* until it is cleared */
WriteErrorSeen, /* A write error has been seen on this
* device
FaultRecorded, /* Intermediate state for clearing
* Blocked. The Fault is/will-be
* recorded in the metadata, but that
* metadata hasn't been stored safely
* on disk yet.
BlockedBadBlocks, /* A writer is blocked because they
* found an unacknowledged bad-block.
* This can safely be cleared at any
* time, and the writer will re-check.
* It may be set at any time, and at
* worst the writer will timeout and
* re-check. So setting it as
* accurately as possible is good, but
* not absolutely critical.
WantReplacement, /* This device is a candidate to be
* hot-replaced, either because it has
* reported some faults, or because
* of explicit request.
Replacement, /* This device is a replacement for
* a want_replacement device with same
* raid_disk number.
Candidate, /* For clustered environments only:
* This device is seen locally but not
* by the whole cluster
#define BB_LEN_MASK (0x00000000000001FFULL)
#define BB_ACK_MASK (0x8000000000000000ULL)
#define BB_MAX_LEN 512
#define BB_OFFSET(x) (((x) & BB_OFFSET_MASK) >> 9)
#define BB_LEN(x) (((x) & BB_LEN_MASK) + 1)
#define BB_ACK(x) (!!((x) & BB_ACK_MASK))
#define BB_MAKE(a, l, ack) (((a)<<9) | ((l)-1) | ((u64)(!!(ack)) << 63))
extern int md_is_badblock(struct badblocks *bb, sector_t s, int sectors,
sector_t *first_bad, int *bad_sectors);
static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors,
sector_t *first_bad, int *bad_sectors)
if (unlikely(rdev->badblocks.count)) {
int rv = md_is_badblock(&rdev->badblocks, rdev->data_offset + s,
first_bad, bad_sectors);
if (rv)
*first_bad -= rdev->data_offset;
return rv;
return 0;
extern int rdev_set_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
int is_new);
extern int rdev_clear_badblocks(struct md_rdev *rdev, sector_t s, int sectors,
int is_new);
extern void md_ack_all_badblocks(struct badblocks *bb);
struct md_cluster_info;
struct mddev {
void *private;
struct md_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 */
#define MD_UPDATE_SB_FLAGS (1 | 2 | 4) /* If these are set, md_update_sb needed */
#define MD_ARRAY_FIRST_USE 3 /* First use of array, needs initialization */
#define MD_STILL_CLOSED 4 /* If set, then array has not been opened since
* md_ioctl checked on it.
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,
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;
int reshape_backwards;
struct md_thread *thread; /* management thread */
struct md_thread *sync_thread; /* doing resync or reconstruct */
/* 'last_sync_action' is initialized to "none". It is set when a
* sync operation (i.e "data-check", "requested-resync", "resync",
* "recovery", or "reshape") is started. It holds this value even
* when the sync thread is "frozen" (interrupted) or "idle" (stopped
* or finished). It is overwritten when a new sync operation is begun.
char *last_sync_action;
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 */
atomic64_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
* ERROR: sync-action interrupted because io-error
* If neither SYNC or RESHAPE are set, then it is a recovery.
unsigned long recovery;
/* If a RAID personality determines that recovery (of a particular
* device) will fail due to a read error on the source device, it
* takes a copy of this number and does not attempt recovery again
* until this number changes.
int recovery_disabled;
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
int merge_check_needed; /* at least one
* member device
* has a
* merge_bvec_fn */
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 kernfs_node *sysfs_state; /* handle for 'array_state'
* file in sysfs.
struct kernfs_node *sysfs_action; /* handle for 'sync_action' */
struct work_struct del_work; /* used for delayed sysfs removal */
/* "lock" protects:
* flush_bio transition from NULL to !NULL
* rdev superblocks, events
* clearing MD_CHANGE_*
* in_sync - and related safemode and MD_CHANGE changes
* pers (also protected by reconfig_mutex and pending IO).
* clearing ->bitmap
* clearing ->bitmap_info.file
* changing ->resync_{min,max}
* setting MD_RECOVERY_RUNNING (which interacts with resync_{min,max})
spinlock_t 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.
unsigned long space; /* space available at this offset */
loff_t default_offset; /* this is the offset to use when
* hot-adding a bitmap. It should
* eventually be settable by sysfs.
unsigned long default_space; /* space available at
* default offset */
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;
int nodes; /* Maximum number of nodes in the cluster */
char cluster_name[64]; /* Name of the cluster */
} 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 */
void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
struct md_cluster_info *cluster_info;
static inline int __must_check mddev_lock(struct mddev *mddev)
return mutex_lock_interruptible(&mddev->reconfig_mutex);
/* Sometimes we need to take the lock in a situation where
* failure due to interrupts is not acceptable.
static inline void mddev_lock_nointr(struct mddev *mddev)
static inline int mddev_is_locked(struct mddev *mddev)
return mutex_is_locked(&mddev->reconfig_mutex);
static inline int mddev_trylock(struct mddev *mddev)
return mutex_trylock(&mddev->reconfig_mutex);
extern void mddev_unlock(struct mddev *mddev);
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 md_personality
char *name;
int level;
struct list_head list;
struct module *owner;
void (*make_request)(struct mddev *mddev, struct bio *bio);
int (*run)(struct mddev *mddev);
void (*free)(struct mddev *mddev, void *priv);
void (*status)(struct seq_file *seq, struct mddev *mddev);
/* error_handler must set ->faulty and clear ->in_sync
* if appropriate, and should abort recovery if needed
void (*error_handler)(struct mddev *mddev, struct md_rdev *rdev);
int (*hot_add_disk) (struct mddev *mddev, struct md_rdev *rdev);
int (*hot_remove_disk) (struct mddev *mddev, struct md_rdev *rdev);
int (*spare_active) (struct mddev *mddev);
sector_t (*sync_request)(struct mddev *mddev, sector_t sector_nr, int *skipped);
int (*resize) (struct mddev *mddev, sector_t sectors);
sector_t (*size) (struct mddev *mddev, sector_t sectors, int raid_disks);
int (*check_reshape) (struct mddev *mddev);
int (*start_reshape) (struct mddev *mddev);
void (*finish_reshape) (struct mddev *mddev);
/* quiesce moves between quiescence states
* 0 - fully active
* 1 - no new requests allowed
* others - reserved
void (*quiesce) (struct mddev *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) (struct mddev *mddev);
/* congested implements bdi.congested_fn().
* Will not be called while array is 'suspended' */
int (*congested)(struct mddev *mddev, int bits);
/* mergeable_bvec is use to implement ->merge_bvec_fn */
int (*mergeable_bvec)(struct mddev *mddev,
struct bvec_merge_data *bvm,
struct bio_vec *biovec);
struct md_sysfs_entry {
struct attribute attr;
ssize_t (*show)(struct mddev *, char *);
ssize_t (*store)(struct mddev *, const char *, size_t);
extern struct attribute_group md_bitmap_group;
static inline struct kernfs_node *sysfs_get_dirent_safe(struct kernfs_node *sd, char *name)
if (sd)
return sysfs_get_dirent(sd, name);
return sd;
static inline void sysfs_notify_dirent_safe(struct kernfs_node *sd)
if (sd)
static inline char * mdname (struct mddev * mddev)
return mddev->gendisk ? mddev->gendisk->disk_name : "mdX";
static inline int sysfs_link_rdev(struct mddev *mddev, struct md_rdev *rdev)
char nm[20];
if (!test_bit(Replacement, &rdev->flags) && mddev-> {
sprintf(nm, "rd%d", rdev->raid_disk);
return sysfs_create_link(&mddev->kobj, &rdev->kobj, nm);
} else
return 0;
static inline void sysfs_unlink_rdev(struct mddev *mddev, struct md_rdev *rdev)
char nm[20];
if (!test_bit(Replacement, &rdev->flags) && mddev-> {
sprintf(nm, "rd%d", rdev->raid_disk);
sysfs_remove_link(&mddev->kobj, nm);
* 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, mddev) \
list_for_each_entry(rdev, &((mddev)->disks), same_set)
#define rdev_for_each_safe(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)
struct md_thread {
void (*run) (struct md_thread *thread);
struct mddev *mddev;
wait_queue_head_t wqueue;
unsigned long flags;
struct task_struct *tsk;
unsigned long timeout;
void *private;
static inline void safe_put_page(struct page *p)
if (p) put_page(p);
extern int register_md_personality(struct md_personality *p);
extern int unregister_md_personality(struct md_personality *p);
extern int register_md_cluster_operations(struct md_cluster_operations *ops,
struct module *module);
extern int unregister_md_cluster_operations(void);
extern int md_setup_cluster(struct mddev *mddev, int nodes);
extern void md_cluster_stop(struct mddev *mddev);
extern struct md_thread *md_register_thread(
void (*run)(struct md_thread *thread),
struct mddev *mddev,
const char *name);
extern void md_unregister_thread(struct md_thread **threadp);
extern void md_wakeup_thread(struct md_thread *thread);
extern void md_check_recovery(struct mddev *mddev);
extern void md_reap_sync_thread(struct mddev *mddev);
extern void md_write_start(struct mddev *mddev, struct bio *bi);
extern void md_write_end(struct mddev *mddev);
extern void md_done_sync(struct mddev *mddev, int blocks, int ok);
extern void md_error(struct mddev *mddev, struct md_rdev *rdev);
extern void md_finish_reshape(struct mddev *mddev);
extern int mddev_congested(struct mddev *mddev, int bits);
extern void md_flush_request(struct mddev *mddev, struct bio *bio);
extern void md_super_write(struct mddev *mddev, struct md_rdev *rdev,
sector_t sector, int size, struct page *page);
extern void md_super_wait(struct mddev *mddev);
extern int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
struct page *page, int rw, bool metadata_op);
extern void md_do_sync(struct md_thread *thread);
extern void md_new_event(struct mddev *mddev);
extern int md_allow_write(struct mddev *mddev);
extern void md_wait_for_blocked_rdev(struct md_rdev *rdev, struct mddev *mddev);
extern void md_set_array_sectors(struct mddev *mddev, sector_t array_sectors);
extern int md_check_no_bitmap(struct mddev *mddev);
extern int md_integrity_register(struct mddev *mddev);
extern void md_integrity_add_rdev(struct md_rdev *rdev, struct mddev *mddev);
extern int strict_strtoul_scaled(const char *cp, unsigned long *res, int scale);
extern void mddev_init(struct mddev *mddev);
extern int md_run(struct mddev *mddev);
extern void md_stop(struct mddev *mddev);
extern void md_stop_writes(struct mddev *mddev);
extern int md_rdev_init(struct md_rdev *rdev);
extern void md_rdev_clear(struct md_rdev *rdev);
extern void mddev_suspend(struct mddev *mddev);
extern void mddev_resume(struct mddev *mddev);
extern struct bio *bio_clone_mddev(struct bio *bio, gfp_t gfp_mask,
struct mddev *mddev);
extern struct bio *bio_alloc_mddev(gfp_t gfp_mask, int nr_iovecs,
struct mddev *mddev);
extern void md_unplug(struct blk_plug_cb *cb, bool from_schedule);
extern void md_reload_sb(struct mddev *mddev);
extern void md_update_sb(struct mddev *mddev, int force);
extern void md_kick_rdev_from_array(struct md_rdev * rdev);
struct md_rdev *md_find_rdev_nr_rcu(struct mddev *mddev, int nr);
static inline int mddev_check_plugged(struct mddev *mddev)
return !!blk_check_plugged(md_unplug, mddev,
sizeof(struct blk_plug_cb));
static inline void rdev_dec_pending(struct md_rdev *rdev, struct mddev *mddev)
int faulty = test_bit(Faulty, &rdev->flags);
if (atomic_dec_and_test(&rdev->nr_pending) && faulty) {
set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
extern struct md_cluster_operations *md_cluster_ops;
static inline int mddev_is_clustered(struct mddev *mddev)
return mddev->cluster_info && mddev->bitmap_info.nodes > 1;
#endif /* _MD_MD_H */
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