Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 838 insertions, 0 deletions

diff --git a/drivers/md/md.h b/drivers/md/md.h
new file mode 100644
index 000000000..4f0b48097
--- /dev/null
+++ b/drivers/md/md.h
@@ -0,0 +1,838 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+   md.h : kernel internal structure of the Linux MD driver
+          Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman
+
+*/
+
+#ifndef _MD_MD_H
+#define _MD_MD_H
+
+#include <linux/blkdev.h>
+#include <linux/backing-dev.h>
+#include <linux/badblocks.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)
+
+/*
+ * These flags should really be called "NO_RETRY" rather than
+ * "FAILFAST" because they don't make any promise about time lapse,
+ * only about the number of retries, which will be zero.
+ * REQ_FAILFAST_DRIVER is not included because
+ * Commit: 4a27446f3e39 ("[SCSI] modify scsi to handle new fail fast flags.")
+ * seems to suggest that the errors it avoids retrying should usually
+ * be retried.
+ */
+#define	MD_FAILFAST	(REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT)
+
+/*
+ * The struct embedded in rdev is used to serialize IO.
+ */
+struct serial_in_rdev {
+	struct rb_root_cached serial_rb;
+	spinlock_t serial_lock;
+	wait_queue_head_t serial_io_wait;
+};
+
+/*
+ * 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
+					 */
+	union {
+		sector_t recovery_offset;/* If this device has been partially
+					 * recovered, this is where we were
+					 * up to.
+					 */
+		sector_t journal_tail;	/* If this device is a journal device,
+					 * this is the journal tail (journal
+					 * recovery start point)
+					 */
+	};
+
+	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.
+					 */
+	time64_t	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 serial_in_rdev *serial;  /* used for raid1 io serialization */
+
+	struct work_struct del_work;	/* used for delayed sysfs removal */
+
+	struct kernfs_node *sysfs_state; /* handle for 'state'
+					   * sysfs entry */
+	/* handle for 'unacknowledged_bad_blocks' sysfs dentry */
+	struct kernfs_node *sysfs_unack_badblocks;
+	/* handle for 'bad_blocks' sysfs dentry */
+	struct kernfs_node *sysfs_badblocks;
+	struct badblocks badblocks;
+
+	struct {
+		short offset;	/* Offset from superblock to start of PPL.
+				 * Not used by external metadata. */
+		unsigned int size;	/* Size in sectors of the PPL space */
+		sector_t sector;	/* First sector of the PPL space */
+	} ppl;
+};
+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.
+				 * The bit is only meaningful before device
+				 * has been passed to pers->hot_add_disk.
+				 */
+	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
+				 */
+	Journal,		/* This device is used as journal for
+				 * raid-5/6.
+				 * Usually, this device should be faster
+				 * than other devices in the array
+				 */
+	ClusterRemove,
+	RemoveSynchronized,	/* synchronize_rcu() was called after
+				 * this device was known to be faulty,
+				 * so it is safe to remove without
+				 * another synchronize_rcu() call.
+				 */
+	ExternalBbl,            /* External metadata provides bad
+				 * block management for a disk
+				 */
+	FailFast,		/* Minimal retries should be attempted on
+				 * this device, so use REQ_FAILFAST_DEV.
+				 * Also don't try to repair failed reads.
+				 * It is expects that no bad block log
+				 * is present.
+				 */
+	LastDev,		/* Seems to be the last working dev as
+				 * it didn't fail, so don't use FailFast
+				 * any more for metadata
+				 */
+	CollisionCheck,		/*
+				 * check if there is collision between raid1
+				 * serial bios.
+				 */
+};
+
+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 = badblocks_check(&rdev->badblocks, rdev->data_offset + s,
+					sectors,
+					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);
+struct md_cluster_info;
+
+/**
+ * enum mddev_flags - md device flags.
+ * @MD_ARRAY_FIRST_USE: First use of array, needs initialization.
+ * @MD_CLOSING: If set, we are closing the array, do not open it then.
+ * @MD_JOURNAL_CLEAN: A raid with journal is already clean.
+ * @MD_HAS_JOURNAL: The raid array has journal feature set.
+ * @MD_CLUSTER_RESYNC_LOCKED: cluster raid only, which means node, already took
+ *			       resync lock, need to release the lock.
+ * @MD_FAILFAST_SUPPORTED: Using MD_FAILFAST on metadata writes is supported as
+ *			    calls to md_error() will never cause the array to
+ *			    become failed.
+ * @MD_HAS_PPL:  The raid array has PPL feature set.
+ * @MD_HAS_MULTIPLE_PPLS: The raid array has multiple PPLs feature set.
+ * @MD_ALLOW_SB_UPDATE: md_check_recovery is allowed to update the metadata
+ *			 without taking reconfig_mutex.
+ * @MD_UPDATING_SB: md_check_recovery is updating the metadata without
+ *		     explicitly holding reconfig_mutex.
+ * @MD_NOT_READY: do_md_run() is active, so 'array_state', ust not report that
+ *		   array is ready yet.
+ * @MD_BROKEN: This is used to stop writes and mark array as failed.
+ * @MD_DELETED: This device is being deleted
+ *
+ * change UNSUPPORTED_MDDEV_FLAGS for each array type if new flag is added
+ */
+enum mddev_flags {
+	MD_ARRAY_FIRST_USE,
+	MD_CLOSING,
+	MD_JOURNAL_CLEAN,
+	MD_HAS_JOURNAL,
+	MD_CLUSTER_RESYNC_LOCKED,
+	MD_FAILFAST_SUPPORTED,
+	MD_HAS_PPL,
+	MD_HAS_MULTIPLE_PPLS,
+	MD_ALLOW_SB_UPDATE,
+	MD_UPDATING_SB,
+	MD_NOT_READY,
+	MD_BROKEN,
+	MD_DELETED,
+};
+
+enum mddev_sb_flags {
+	MD_SB_CHANGE_DEVS,		/* Some device status has changed */
+	MD_SB_CHANGE_CLEAN,	/* transition to or from 'clean' */
+	MD_SB_CHANGE_PENDING,	/* switch from 'clean' to 'active' in progress */
+	MD_SB_NEED_REWRITE,	/* metadata write needs to be repeated */
+};
+
+#define NR_SERIAL_INFOS		8
+/* record current range of serialize IOs */
+struct serial_info {
+	struct rb_node node;
+	sector_t start;		/* start sector of rb node */
+	sector_t last;		/* end sector of rb node */
+	sector_t _subtree_last; /* highest sector in subtree of rb node */
+};
+
+/*
+ * mddev->curr_resync stores the current sector of the resync but
+ * also has some overloaded values.
+ */
+enum {
+	/* No resync in progress */
+	MD_RESYNC_NONE = 0,
+	/* Yielded to allow another conflicting resync to commence */
+	MD_RESYNC_YIELDED = 1,
+	/* Delayed to check that there is no conflict with another sync */
+	MD_RESYNC_DELAYED = 2,
+	/* Any value greater than or equal to this is in an active resync */
+	MD_RESYNC_ACTIVE = 3,
+};
+
+struct mddev {
+	void				*private;
+	struct md_personality		*pers;
+	dev_t				unit;
+	int				md_minor;
+	struct list_head		disks;
+	unsigned long			flags;
+	unsigned long			sb_flags;
+
+	int				suspended;
+	struct percpu_ref		active_io;
+	int				ro;
+	int				sysfs_active; /* set when sysfs deletes
+						       * are happening, so run/
+						       * takeover/stop are not safe
+						       */
+	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;
+	time64_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;
+
+	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 disk->open_mutex.
+	 * Lock ordering is:
+	 *  reconfig_mutex -> disk->open_mutex
+	 *  disk->open_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 kernfs_node		*sysfs_state;	/* handle for 'array_state'
+							 * file in sysfs.
+							 */
+	struct kernfs_node		*sysfs_action;  /* handle for 'sync_action' */
+	struct kernfs_node		*sysfs_completed;	/*handle for 'sync_completed' */
+	struct kernfs_node		*sysfs_degraded;	/*handle for 'degraded' */
+	struct kernfs_node		*sysfs_level;		/*handle for 'level' */
+
+	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;
+	struct percpu_ref		writes_pending;
+	int				sync_checkers;	/* # of threads checking 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;
+
+	const struct attribute_group	*to_remove;
+
+	struct bio_set			bio_set;
+	struct bio_set			sync_set; /* for sync operations like
+						   * metadata and bitmap writes
+						   */
+	struct bio_set			io_acct_set; /* for raid0 and raid5 io accounting */
+
+	/* Generic flush handling.
+	 * The last to finish preflush schedules a worker to submit
+	 * the rest of the request (without the REQ_PREFLUSH flag).
+	 */
+	struct bio *flush_bio;
+	atomic_t flush_pending;
+	ktime_t start_flush, prev_flush_start; /* prev_flush_start is when the previous completed
+						* flush was started.
+						*/
+	struct work_struct flush_work;
+	struct work_struct event_work;	/* used by dm to report failure event */
+	mempool_t *serial_info_pool;
+	void (*sync_super)(struct mddev *mddev, struct md_rdev *rdev);
+	struct md_cluster_info		*cluster_info;
+	unsigned int			good_device_nr;	/* good device num within cluster raid */
+	unsigned int			noio_flag; /* for memalloc scope API */
+
+	bool	has_superblocks:1;
+	bool	fail_last_dev:1;
+	bool	serialize_policy:1;
+};
+
+enum recovery_flags {
+	/*
+	 * If neither SYNC or RESHAPE are set, then it is a recovery.
+	 */
+	MD_RECOVERY_RUNNING,	/* a thread is running, or about to be started */
+	MD_RECOVERY_SYNC,	/* actually doing a resync, not a recovery */
+	MD_RECOVERY_RECOVER,	/* doing recovery, or need to try it. */
+	MD_RECOVERY_INTR,	/* resync needs to be aborted for some reason */
+	MD_RECOVERY_DONE,	/* thread is done and is waiting to be reaped */
+	MD_RECOVERY_NEEDED,	/* we might need to start a resync/recover */
+	MD_RECOVERY_REQUESTED,	/* user-space has requested a sync (used with SYNC) */
+	MD_RECOVERY_CHECK,	/* user-space request for check-only, no repair */
+	MD_RECOVERY_RESHAPE,	/* A reshape is happening */
+	MD_RECOVERY_FROZEN,	/* User request to abort, and not restart, any action */
+	MD_RECOVERY_ERROR,	/* sync-action interrupted because io-error */
+	MD_RECOVERY_WAIT,	/* waiting for pers->start() to finish */
+	MD_RESYNCING_REMOTE,	/* remote node is running resync thread */
+};
+
+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)
+{
+	mutex_lock(&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_disk->sync_io);
+}
+
+static inline void md_sync_acct_bio(struct bio *bio, unsigned long nr_sectors)
+{
+	md_sync_acct(bio->bi_bdev, nr_sectors);
+}
+
+struct md_personality
+{
+	char *name;
+	int level;
+	struct list_head list;
+	struct module *owner;
+	bool __must_check (*make_request)(struct mddev *mddev, struct bio *bio);
+	/*
+	 * start up works that do NOT require md_thread. tasks that
+	 * requires md_thread should go into start()
+	 */
+	int (*run)(struct mddev *mddev);
+	/* start up works that require md threads */
+	int (*start)(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);
+	void (*update_reshape_pos) (struct mddev *mddev);
+	/* quiesce suspends or resumes internal processing.
+	 * 1 - stop new actions and wait for action io to complete
+	 * 0 - return to normal behaviour
+	 */
+	void (*quiesce) (struct mddev *mddev, int quiesce);
+	/* 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);
+	/* Changes the consistency policy of an active array. */
+	int (*change_consistency_policy)(struct mddev *mddev, const char *buf);
+};
+
+struct md_sysfs_entry {
+	struct attribute attr;
+	ssize_t (*show)(struct mddev *, char *);
+	ssize_t (*store)(struct mddev *, const char *, size_t);
+};
+extern const 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)
+		sysfs_notify_dirent(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) &&
+	    !test_bit(Journal, &rdev->flags) &&
+	    mddev->kobj.sd) {
+		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) &&
+	    !test_bit(Journal, &rdev->flags) &&
+	    mddev->kobj.sd) {
+		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;
+};
+
+struct md_io_acct {
+	struct bio *orig_bio;
+	unsigned long start_time;
+	struct bio bio_clone;
+};
+
+#define THREAD_WAKEUP  0
+
+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 int mddev_init_writes_pending(struct mddev *mddev);
+extern bool md_write_start(struct mddev *mddev, struct bio *bi);
+extern void md_write_inc(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);
+void md_submit_discard_bio(struct mddev *mddev, struct md_rdev *rdev,
+			struct bio *bio, sector_t start, sector_t size);
+int acct_bioset_init(struct mddev *mddev);
+void acct_bioset_exit(struct mddev *mddev);
+void md_account_bio(struct mddev *mddev, struct bio **bio);
+
+extern bool __must_check 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 int md_super_wait(struct mddev *mddev);
+extern int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
+		struct page *page, blk_opf_t opf, bool metadata_op);
+extern void md_do_sync(struct md_thread *thread);
+extern void md_new_event(void);
+extern void 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 int 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);
+struct mddev *md_alloc(dev_t dev, char *name);
+void mddev_put(struct mddev *mddev);
+extern int md_run(struct mddev *mddev);
+extern int md_start(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 md_handle_request(struct mddev *mddev, struct bio *bio);
+extern void mddev_suspend(struct mddev *mddev);
+extern void mddev_resume(struct mddev *mddev);
+
+extern void md_reload_sb(struct mddev *mddev, int raid_disk);
+extern void md_update_sb(struct mddev *mddev, int force);
+extern void md_kick_rdev_from_array(struct md_rdev * rdev);
+extern void mddev_create_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
+				     bool is_suspend);
+extern void mddev_destroy_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
+				      bool is_suspend);
+struct md_rdev *md_find_rdev_nr_rcu(struct mddev *mddev, int nr);
+struct md_rdev *md_find_rdev_rcu(struct mddev *mddev, dev_t dev);
+
+static inline bool is_rdev_broken(struct md_rdev *rdev)
+{
+	return !disk_live(rdev->bdev->bd_disk);
+}
+
+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);
+		md_wakeup_thread(mddev->thread);
+	}
+}
+
+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;
+}
+
+/* clear unsupported mddev_flags */
+static inline void mddev_clear_unsupported_flags(struct mddev *mddev,
+	unsigned long unsupported_flags)
+{
+	mddev->flags &= ~unsupported_flags;
+}
+
+static inline void mddev_check_write_zeroes(struct mddev *mddev, struct bio *bio)
+{
+	if (bio_op(bio) == REQ_OP_WRITE_ZEROES &&
+	    !bio->bi_bdev->bd_disk->queue->limits.max_write_zeroes_sectors)
+		mddev->queue->limits.max_write_zeroes_sectors = 0;
+}
+
+struct mdu_array_info_s;
+struct mdu_disk_info_s;
+
+extern int mdp_major;
+void md_autostart_arrays(int part);
+int md_set_array_info(struct mddev *mddev, struct mdu_array_info_s *info);
+int md_add_new_disk(struct mddev *mddev, struct mdu_disk_info_s *info);
+int do_md_run(struct mddev *mddev);
+
+extern const struct block_device_operations md_fops;
+
+#endif /* _MD_MD_H */