fs/btrfs/volumes.h - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Copyright (C) 2007 Oracle.  All rights reserved.
  */

 #ifndef BTRFS_VOLUMES_H
 #define BTRFS_VOLUMES_H

 #include <linux/bio.h>
 #include <linux/sort.h>
 #include <linux/btrfs.h>
 #include "async-thread.h"

 #define BTRFS_MAX_DATA_CHUNK_SIZE	(10ULL * SZ_1G)

 extern struct mutex uuid_mutex;

 #define BTRFS_STRIPE_LEN	SZ_64K

 struct buffer_head;
 struct btrfs_pending_bios {
 	struct bio *head;
 	struct bio *tail;
 };

 /*
  * Use sequence counter to get consistent device stat data on
  * 32-bit processors.
  */
 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
 #include <linux/seqlock.h>
 #define __BTRFS_NEED_DEVICE_DATA_ORDERED
 #define btrfs_device_data_ordered_init(device)	\
 	seqcount_init(&device->data_seqcount)
 #else
 #define btrfs_device_data_ordered_init(device) do { } while (0)
 #endif

 #define BTRFS_DEV_STATE_WRITEABLE	(0)
 #define BTRFS_DEV_STATE_IN_FS_METADATA	(1)
 #define BTRFS_DEV_STATE_MISSING		(2)
 #define BTRFS_DEV_STATE_REPLACE_TGT	(3)
 #define BTRFS_DEV_STATE_FLUSH_SENT	(4)

 struct btrfs_device {
 	struct list_head dev_list; /* device_list_mutex */
 	struct list_head dev_alloc_list; /* chunk mutex */
 	struct list_head post_commit_list; /* chunk mutex */
 	struct btrfs_fs_devices *fs_devices;
 	struct btrfs_fs_info *fs_info;

 	struct rcu_string *name;

 	u64 generation;

 	spinlock_t io_lock ____cacheline_aligned;
 	int running_pending;
 	/* regular prio bios */
 	struct btrfs_pending_bios pending_bios;
 	/* sync bios */
 	struct btrfs_pending_bios pending_sync_bios;

 	struct block_device *bdev;

 	/* the mode sent to blkdev_get */
 	fmode_t mode;

 	unsigned long dev_state;
 	blk_status_t last_flush_error;
 	int flush_bio_sent;

 #ifdef __BTRFS_NEED_DEVICE_DATA_ORDERED
 	seqcount_t data_seqcount;
 #endif

 	/* the internal btrfs device id */
 	u64 devid;

 	/* size of the device in memory */
 	u64 total_bytes;

 	/* size of the device on disk */
 	u64 disk_total_bytes;

 	/* bytes used */
 	u64 bytes_used;

 	/* optimal io alignment for this device */
 	u32 io_align;

 	/* optimal io width for this device */
 	u32 io_width;
 	/* type and info about this device */
 	u64 type;

 	/* minimal io size for this device */
 	u32 sector_size;

 	/* physical drive uuid (or lvm uuid) */
 	u8 uuid[BTRFS_UUID_SIZE];

 	/*
 	 * size of the device on the current transaction
 	 *
 	 * This variant is update when committing the transaction,
 	 * and protected by chunk mutex
 	 */
 	u64 commit_total_bytes;

 	/* bytes used on the current transaction */
 	u64 commit_bytes_used;

 	/* for sending down flush barriers */
 	struct bio *flush_bio;
 	struct completion flush_wait;

 	/* per-device scrub information */
 	struct scrub_ctx *scrub_ctx;

 	struct btrfs_work work;

 	/* readahead state */
 	atomic_t reada_in_flight;
 	u64 reada_next;
 	struct reada_zone *reada_curr_zone;
 	struct radix_tree_root reada_zones;
 	struct radix_tree_root reada_extents;

 	/* disk I/O failure stats. For detailed description refer to
 	 * enum btrfs_dev_stat_values in ioctl.h */
 	int dev_stats_valid;

 	/* Counter to record the change of device stats */
 	atomic_t dev_stats_ccnt;
 	atomic_t dev_stat_values[BTRFS_DEV_STAT_VALUES_MAX];

 	struct extent_io_tree alloc_state;
 };

 /*
  * If we read those variants at the context of their own lock, we needn't
  * use the following helpers, reading them directly is safe.
  */
 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
 #define BTRFS_DEVICE_GETSET_FUNCS(name)					\
 static inline u64							\
 btrfs_device_get_##name(const struct btrfs_device *dev)			\
 {									\
 	u64 size;							\
 	unsigned int seq;						\
 									\
 	do {								\
 		seq = read_seqcount_begin(&dev->data_seqcount);		\
 		size = dev->name;					\
 	} while (read_seqcount_retry(&dev->data_seqcount, seq));	\
 	return size;							\
 }									\
 									\
 static inline void							\
 btrfs_device_set_##name(struct btrfs_device *dev, u64 size)		\
 {									\
 	preempt_disable();						\
 	write_seqcount_begin(&dev->data_seqcount);			\
 	dev->name = size;						\
 	write_seqcount_end(&dev->data_seqcount);			\
 	preempt_enable();						\
 }
 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)
 #define BTRFS_DEVICE_GETSET_FUNCS(name)					\
 static inline u64							\
 btrfs_device_get_##name(const struct btrfs_device *dev)			\
 {									\
 	u64 size;							\
 									\
 	preempt_disable();						\
 	size = dev->name;						\
 	preempt_enable();						\
 	return size;							\
 }									\
 									\
 static inline void							\
 btrfs_device_set_##name(struct btrfs_device *dev, u64 size)		\
 {									\
 	preempt_disable();						\
 	dev->name = size;						\
 	preempt_enable();						\
 }
 #else
 #define BTRFS_DEVICE_GETSET_FUNCS(name)					\
 static inline u64							\
 btrfs_device_get_##name(const struct btrfs_device *dev)			\
 {									\
 	return dev->name;						\
 }									\
 									\
 static inline void							\
 btrfs_device_set_##name(struct btrfs_device *dev, u64 size)		\
 {									\
 	dev->name = size;						\
 }
 #endif

 BTRFS_DEVICE_GETSET_FUNCS(total_bytes);
 BTRFS_DEVICE_GETSET_FUNCS(disk_total_bytes);
 BTRFS_DEVICE_GETSET_FUNCS(bytes_used);

 struct btrfs_fs_devices {
 	u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
 	u8 metadata_uuid[BTRFS_FSID_SIZE];
 	bool fsid_change;
 	struct list_head fs_list;

 	u64 num_devices;
 	u64 open_devices;
 	u64 rw_devices;
 	u64 missing_devices;
 	u64 total_rw_bytes;
 	u64 total_devices;

 	/* Highest generation number of seen devices */
 	u64 latest_generation;

 	struct block_device *latest_bdev;

 	/* all of the devices in the FS, protected by a mutex
 	 * so we can safely walk it to write out the supers without
 	 * worrying about add/remove by the multi-device code.
 	 * Scrubbing super can kick off supers writing by holding
 	 * this mutex lock.
 	 */
 	struct mutex device_list_mutex;

 	/* List of all devices, protected by device_list_mutex */
 	struct list_head devices;

 	/*
 	 * Devices which can satisfy space allocation. Protected by
 	 * chunk_mutex
 	 */
 	struct list_head alloc_list;

 	struct btrfs_fs_devices *seed;
 	int seeding;

 	int opened;

 	/* set when we find or add a device that doesn't have the
 	 * nonrot flag set
 	 */
 	int rotating;

 	struct btrfs_fs_info *fs_info;
 	/* sysfs kobjects */
 	struct kobject fsid_kobj;
 	struct kobject *device_dir_kobj;
 	struct completion kobj_unregister;
 };

 #define BTRFS_BIO_INLINE_CSUM_SIZE	64

 #define BTRFS_MAX_DEVS(info) ((BTRFS_MAX_ITEM_SIZE(info)	\
 			- sizeof(struct btrfs_chunk))		\
 			/ sizeof(struct btrfs_stripe) + 1)

 #define BTRFS_MAX_DEVS_SYS_CHUNK ((BTRFS_SYSTEM_CHUNK_ARRAY_SIZE	\
 				- 2 * sizeof(struct btrfs_disk_key)	\
 				- 2 * sizeof(struct btrfs_chunk))	\
 				/ sizeof(struct btrfs_stripe) + 1)

 /*
  * we need the mirror number and stripe index to be passed around
  * the call chain while we are processing end_io (especially errors).
  * Really, what we need is a btrfs_bio structure that has this info
  * and is properly sized with its stripe array, but we're not there
  * quite yet.  We have our own btrfs bioset, and all of the bios
  * we allocate are actually btrfs_io_bios.  We'll cram as much of
  * struct btrfs_bio as we can into this over time.
  */
 struct btrfs_io_bio {
 	unsigned int mirror_num;
 	unsigned int stripe_index;
 	u64 logical;
 	u8 *csum;
 	u8 csum_inline[BTRFS_BIO_INLINE_CSUM_SIZE];
 	struct bvec_iter iter;
 	/*
 	 * This member must come last, bio_alloc_bioset will allocate enough
 	 * bytes for entire btrfs_io_bio but relies on bio being last.
 	 */
 	struct bio bio;
 };

 static inline struct btrfs_io_bio *btrfs_io_bio(struct bio *bio)
 {
 	return container_of(bio, struct btrfs_io_bio, bio);
 }

 static inline void btrfs_io_bio_free_csum(struct btrfs_io_bio *io_bio)
 {
 	if (io_bio->csum != io_bio->csum_inline) {
 		kfree(io_bio->csum);
 		io_bio->csum = NULL;
 	}
 }

 struct btrfs_bio_stripe {
 	struct btrfs_device *dev;
 	u64 physical;
 	u64 length; /* only used for discard mappings */
 };

 struct btrfs_bio {
 	refcount_t refs;
 	atomic_t stripes_pending;
 	struct btrfs_fs_info *fs_info;
 	u64 map_type; /* get from map_lookup->type */
 	bio_end_io_t *end_io;
 	struct bio *orig_bio;
 	unsigned long flags;
 	void *private;
 	atomic_t error;
 	int max_errors;
 	int num_stripes;
 	int mirror_num;
 	int num_tgtdevs;
 	int *tgtdev_map;
 	/*
 	 * logical block numbers for the start of each stripe
 	 * The last one or two are p/q.  These are sorted,
 	 * so raid_map[0] is the start of our full stripe
 	 */
 	u64 *raid_map;
 	struct btrfs_bio_stripe stripes[];
 };

 struct btrfs_device_info {
 	struct btrfs_device *dev;
 	u64 dev_offset;
 	u64 max_avail;
 	u64 total_avail;
 };

 struct btrfs_raid_attr {
 	u8 sub_stripes;		/* sub_stripes info for map */
 	u8 dev_stripes;		/* stripes per dev */
 	u8 devs_max;		/* max devs to use */
 	u8 devs_min;		/* min devs needed */
 	u8 tolerated_failures;	/* max tolerated fail devs */
 	u8 devs_increment;	/* ndevs has to be a multiple of this */
 	u8 ncopies;		/* how many copies to data has */
 	u8 nparity;		/* number of stripes worth of bytes to store
 				 * parity information */
 	u8 mindev_error;	/* error code if min devs requisite is unmet */
 	const char raid_name[8]; /* name of the raid */
 	u64 bg_flag;		/* block group flag of the raid */
 };

 extern const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES];

 struct map_lookup {
 	u64 type;
 	int io_align;
 	int io_width;
 	u64 stripe_len;
 	int num_stripes;
 	int sub_stripes;
 	int verified_stripes; /* For mount time dev extent verification */
 	struct btrfs_bio_stripe stripes[];
 };

 #define map_lookup_size(n) (sizeof(struct map_lookup) + \
 			    (sizeof(struct btrfs_bio_stripe) * (n)))

 struct btrfs_balance_args;
 struct btrfs_balance_progress;
 struct btrfs_balance_control {
 	struct btrfs_balance_args data;
 	struct btrfs_balance_args meta;
 	struct btrfs_balance_args sys;

 	u64 flags;

 	struct btrfs_balance_progress stat;
 };

 enum btrfs_map_op {
 	BTRFS_MAP_READ,
 	BTRFS_MAP_WRITE,
 	BTRFS_MAP_DISCARD,
 	BTRFS_MAP_GET_READ_MIRRORS,
 };

 static inline enum btrfs_map_op btrfs_op(struct bio *bio)
 {
 	switch (bio_op(bio)) {
 	case REQ_OP_DISCARD:
 		return BTRFS_MAP_DISCARD;
 	case REQ_OP_WRITE:
 		return BTRFS_MAP_WRITE;
 	default:
 		WARN_ON_ONCE(1);
 		/* fall through */
 	case REQ_OP_READ:
 		return BTRFS_MAP_READ;
 	}
 }

 void btrfs_get_bbio(struct btrfs_bio *bbio);
 void btrfs_put_bbio(struct btrfs_bio *bbio);
 int btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
 		    u64 logical, u64 *length,
 		    struct btrfs_bio **bbio_ret, int mirror_num);
 int btrfs_map_sblock(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
 		     u64 logical, u64 *length,
 		     struct btrfs_bio **bbio_ret);
 int btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start,
 		     u64 physical, u64 **logical, int *naddrs, int *stripe_len);
 int btrfs_read_sys_array(struct btrfs_fs_info *fs_info);
 int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info);
 int btrfs_alloc_chunk(struct btrfs_trans_handle *trans, u64 type);
 void btrfs_mapping_tree_free(struct extent_map_tree *tree);
 blk_status_t btrfs_map_bio(struct btrfs_fs_info *fs_info, struct bio *bio,
 			   int mirror_num, int async_submit);
 int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
 		       fmode_t flags, void *holder);
 struct btrfs_device *btrfs_scan_one_device(const char *path,
 					   fmode_t flags, void *holder);
 int btrfs_forget_devices(const char *path);
 int btrfs_close_devices(struct btrfs_fs_devices *fs_devices);
 void btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices, int step);
 void btrfs_assign_next_active_device(struct btrfs_device *device,
 				     struct btrfs_device *this_dev);
 struct btrfs_device *btrfs_find_device_by_devspec(struct btrfs_fs_info *fs_info,
 						  u64 devid,
 						  const char *devpath);
 struct btrfs_device *btrfs_alloc_device(struct btrfs_fs_info *fs_info,
 					const u64 *devid,
 					const u8 *uuid);
 void btrfs_free_device(struct btrfs_device *device);
 int btrfs_rm_device(struct btrfs_fs_info *fs_info,
 		    const char *device_path, u64 devid);
 void __exit btrfs_cleanup_fs_uuids(void);
 int btrfs_num_copies(struct btrfs_fs_info *fs_info, u64 logical, u64 len);
 int btrfs_grow_device(struct btrfs_trans_handle *trans,
 		      struct btrfs_device *device, u64 new_size);
 struct btrfs_device *btrfs_find_device(struct btrfs_fs_devices *fs_devices,
 				       u64 devid, u8 *uuid, u8 *fsid, bool seed);
 int btrfs_shrink_device(struct btrfs_device *device, u64 new_size);
 int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *path);
 int btrfs_balance(struct btrfs_fs_info *fs_info,
 		  struct btrfs_balance_control *bctl,
 		  struct btrfs_ioctl_balance_args *bargs);
 void btrfs_describe_block_groups(u64 flags, char *buf, u32 size_buf);
 int btrfs_resume_balance_async(struct btrfs_fs_info *fs_info);
 int btrfs_recover_balance(struct btrfs_fs_info *fs_info);
 int btrfs_pause_balance(struct btrfs_fs_info *fs_info);
 int btrfs_cancel_balance(struct btrfs_fs_info *fs_info);
 int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info);
 int btrfs_check_uuid_tree(struct btrfs_fs_info *fs_info);
 int btrfs_chunk_readonly(struct btrfs_fs_info *fs_info, u64 chunk_offset);
 int find_free_dev_extent_start(struct btrfs_device *device, u64 num_bytes,
 			       u64 search_start, u64 *start, u64 *max_avail);
 int find_free_dev_extent(struct btrfs_device *device, u64 num_bytes,
 			 u64 *start, u64 *max_avail);
 void btrfs_dev_stat_inc_and_print(struct btrfs_device *dev, int index);
 int btrfs_get_dev_stats(struct btrfs_fs_info *fs_info,
 			struct btrfs_ioctl_get_dev_stats *stats);
 void btrfs_init_devices_late(struct btrfs_fs_info *fs_info);
 int btrfs_init_dev_stats(struct btrfs_fs_info *fs_info);
 int btrfs_run_dev_stats(struct btrfs_trans_handle *trans);
 void btrfs_rm_dev_replace_remove_srcdev(struct btrfs_device *srcdev);
 void btrfs_rm_dev_replace_free_srcdev(struct btrfs_device *srcdev);
 void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev);
 void btrfs_scratch_superblocks(struct block_device *bdev, const char *device_path);
 int btrfs_is_parity_mirror(struct btrfs_fs_info *fs_info,
 			   u64 logical, u64 len);
 unsigned long btrfs_full_stripe_len(struct btrfs_fs_info *fs_info,
 				    u64 logical);
 int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
 			     u64 chunk_offset, u64 chunk_size);
 int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset);
 struct extent_map *btrfs_get_chunk_map(struct btrfs_fs_info *fs_info,
 				       u64 logical, u64 length);

 static inline void btrfs_dev_stat_inc(struct btrfs_device *dev,
 				      int index)
 {
 	atomic_inc(dev->dev_stat_values + index);
 	/*
 	 * This memory barrier orders stores updating statistics before stores
 	 * updating dev_stats_ccnt.
 	 *
 	 * It pairs with smp_rmb() in btrfs_run_dev_stats().
 	 */
 	smp_mb__before_atomic();
 	atomic_inc(&dev->dev_stats_ccnt);
 }

 static inline int btrfs_dev_stat_read(struct btrfs_device *dev,
 				      int index)
 {
 	return atomic_read(dev->dev_stat_values + index);
 }

 static inline int btrfs_dev_stat_read_and_reset(struct btrfs_device *dev,
 						int index)
 {
 	int ret;

 	ret = atomic_xchg(dev->dev_stat_values + index, 0);
 	/*
 	 * atomic_xchg implies a full memory barriers as per atomic_t.txt:
 	 * - RMW operations that have a return value are fully ordered;
 	 *
 	 * This implicit memory barriers is paired with the smp_rmb in
 	 * btrfs_run_dev_stats
 	 */
 	atomic_inc(&dev->dev_stats_ccnt);
 	return ret;
 }

 static inline void btrfs_dev_stat_set(struct btrfs_device *dev,
 				      int index, unsigned long val)
 {
 	atomic_set(dev->dev_stat_values + index, val);
 	/*
 	 * This memory barrier orders stores updating statistics before stores
 	 * updating dev_stats_ccnt.
 	 *
 	 * It pairs with smp_rmb() in btrfs_run_dev_stats().
 	 */
 	smp_mb__before_atomic();
 	atomic_inc(&dev->dev_stats_ccnt);
 }

 static inline void btrfs_dev_stat_reset(struct btrfs_device *dev,
 					int index)
 {
 	btrfs_dev_stat_set(dev, index, 0);
 }

 /*
  * Convert block group flags (BTRFS_BLOCK_GROUP_*) to btrfs_raid_types, which
  * can be used as index to access btrfs_raid_array[].
  */
 static inline enum btrfs_raid_types btrfs_bg_flags_to_raid_index(u64 flags)
 {
 	if (flags & BTRFS_BLOCK_GROUP_RAID10)
 		return BTRFS_RAID_RAID10;
 	else if (flags & BTRFS_BLOCK_GROUP_RAID1)
 		return BTRFS_RAID_RAID1;
 	else if (flags & BTRFS_BLOCK_GROUP_DUP)
 		return BTRFS_RAID_DUP;
 	else if (flags & BTRFS_BLOCK_GROUP_RAID0)
 		return BTRFS_RAID_RAID0;
 	else if (flags & BTRFS_BLOCK_GROUP_RAID5)
 		return BTRFS_RAID_RAID5;
 	else if (flags & BTRFS_BLOCK_GROUP_RAID6)
 		return BTRFS_RAID_RAID6;

 	return BTRFS_RAID_SINGLE; /* BTRFS_BLOCK_GROUP_SINGLE */
 }

 void btrfs_commit_device_sizes(struct btrfs_transaction *trans);

 struct list_head *btrfs_get_fs_uuids(void);
 void btrfs_set_fs_info_ptr(struct btrfs_fs_info *fs_info);
 void btrfs_reset_fs_info_ptr(struct btrfs_fs_info *fs_info);
 bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info,
 					struct btrfs_device *failing_dev);

 int btrfs_bg_type_to_factor(u64 flags);
 const char *btrfs_bg_type_to_raid_name(u64 flags);
 int btrfs_verify_dev_extents(struct btrfs_fs_info *fs_info);

 #endif
	/* SPDX-License-Identifier: GPL-2.0 */
	/*
	* Copyright (C) 2007 Oracle. All rights reserved.
	*/

	#ifndef BTRFS_VOLUMES_H
	#define BTRFS_VOLUMES_H

	#include <linux/bio.h>
	#include <linux/sort.h>
	#include <linux/btrfs.h>
	#include "async-thread.h"

	#define BTRFS_MAX_DATA_CHUNK_SIZE (10ULL * SZ_1G)

	extern struct mutex uuid_mutex;

	#define BTRFS_STRIPE_LEN SZ_64K

	struct buffer_head;
	struct btrfs_pending_bios {
	struct bio *head;
	struct bio *tail;
	};

	/*
	* Use sequence counter to get consistent device stat data on
	* 32-bit processors.
	*/
	#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
	#include <linux/seqlock.h>
	#define __BTRFS_NEED_DEVICE_DATA_ORDERED
	#define btrfs_device_data_ordered_init(device) \
	seqcount_init(&device->data_seqcount)
	#else
	#define btrfs_device_data_ordered_init(device) do { } while (0)
	#endif

	#define BTRFS_DEV_STATE_WRITEABLE (0)
	#define BTRFS_DEV_STATE_IN_FS_METADATA (1)
	#define BTRFS_DEV_STATE_MISSING (2)
	#define BTRFS_DEV_STATE_REPLACE_TGT (3)
	#define BTRFS_DEV_STATE_FLUSH_SENT (4)

	struct btrfs_device {
	struct list_head dev_list; /* device_list_mutex */
	struct list_head dev_alloc_list; /* chunk mutex */
	struct list_head post_commit_list; /* chunk mutex */
	struct btrfs_fs_devices *fs_devices;
	struct btrfs_fs_info *fs_info;

	struct rcu_string *name;

	u64 generation;

	spinlock_t io_lock ____cacheline_aligned;
	int running_pending;
	/* regular prio bios */
	struct btrfs_pending_bios pending_bios;
	/* sync bios */
	struct btrfs_pending_bios pending_sync_bios;

	struct block_device *bdev;

	/* the mode sent to blkdev_get */
	fmode_t mode;

	unsigned long dev_state;
	blk_status_t last_flush_error;
	int flush_bio_sent;

	#ifdef __BTRFS_NEED_DEVICE_DATA_ORDERED
	seqcount_t data_seqcount;
	#endif

	/* the internal btrfs device id */
	u64 devid;

	/* size of the device in memory */
	u64 total_bytes;

	/* size of the device on disk */
	u64 disk_total_bytes;

	/* bytes used */
	u64 bytes_used;

	/* optimal io alignment for this device */
	u32 io_align;

	/* optimal io width for this device */
	u32 io_width;
	/* type and info about this device */
	u64 type;

	/* minimal io size for this device */
	u32 sector_size;

	/* physical drive uuid (or lvm uuid) */
	u8 uuid[BTRFS_UUID_SIZE];

	/*
	* size of the device on the current transaction
	*
	* This variant is update when committing the transaction,
	* and protected by chunk mutex
	*/
	u64 commit_total_bytes;

	/* bytes used on the current transaction */
	u64 commit_bytes_used;

	/* for sending down flush barriers */
	struct bio *flush_bio;
	struct completion flush_wait;

	/* per-device scrub information */
	struct scrub_ctx *scrub_ctx;

	struct btrfs_work work;

	/* readahead state */
	atomic_t reada_in_flight;
	u64 reada_next;
	struct reada_zone *reada_curr_zone;
	struct radix_tree_root reada_zones;
	struct radix_tree_root reada_extents;

	/* disk I/O failure stats. For detailed description refer to
	* enum btrfs_dev_stat_values in ioctl.h */
	int dev_stats_valid;

	/* Counter to record the change of device stats */
	atomic_t dev_stats_ccnt;
	atomic_t dev_stat_values[BTRFS_DEV_STAT_VALUES_MAX];

	struct extent_io_tree alloc_state;
	};

	/*
	* If we read those variants at the context of their own lock, we needn't
	* use the following helpers, reading them directly is safe.
	*/
	#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
	#define BTRFS_DEVICE_GETSET_FUNCS(name) \
	static inline u64 \
	btrfs_device_get_##name(const struct btrfs_device *dev) \
	{ \
	u64 size; \
	unsigned int seq; \
	\
	do { \
	seq = read_seqcount_begin(&dev->data_seqcount); \
	size = dev->name; \
	} while (read_seqcount_retry(&dev->data_seqcount, seq)); \
	return size; \
	} \
	\
	static inline void \
	btrfs_device_set_##name(struct btrfs_device *dev, u64 size) \
	{ \
	preempt_disable(); \
	write_seqcount_begin(&dev->data_seqcount); \
	dev->name = size; \
	write_seqcount_end(&dev->data_seqcount); \
	preempt_enable(); \
	}
	#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPT)
	#define BTRFS_DEVICE_GETSET_FUNCS(name) \
	static inline u64 \
	btrfs_device_get_##name(const struct btrfs_device *dev) \
	{ \
	u64 size; \
	\
	preempt_disable(); \
	size = dev->name; \
	preempt_enable(); \
	return size; \
	} \
	\
	static inline void \
	btrfs_device_set_##name(struct btrfs_device *dev, u64 size) \
	{ \
	preempt_disable(); \
	dev->name = size; \
	preempt_enable(); \
	}
	#else
	#define BTRFS_DEVICE_GETSET_FUNCS(name) \
	static inline u64 \
	btrfs_device_get_##name(const struct btrfs_device *dev) \
	{ \
	return dev->name; \
	} \
	\
	static inline void \
	btrfs_device_set_##name(struct btrfs_device *dev, u64 size) \
	{ \
	dev->name = size; \
	}
	#endif

	BTRFS_DEVICE_GETSET_FUNCS(total_bytes);
	BTRFS_DEVICE_GETSET_FUNCS(disk_total_bytes);
	BTRFS_DEVICE_GETSET_FUNCS(bytes_used);

	struct btrfs_fs_devices {
	u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
	u8 metadata_uuid[BTRFS_FSID_SIZE];
	bool fsid_change;
	struct list_head fs_list;

	u64 num_devices;
	u64 open_devices;
	u64 rw_devices;
	u64 missing_devices;
	u64 total_rw_bytes;
	u64 total_devices;

	/* Highest generation number of seen devices */
	u64 latest_generation;

	struct block_device *latest_bdev;

	/* all of the devices in the FS, protected by a mutex
	* so we can safely walk it to write out the supers without
	* worrying about add/remove by the multi-device code.
	* Scrubbing super can kick off supers writing by holding
	* this mutex lock.
	*/
	struct mutex device_list_mutex;

	/* List of all devices, protected by device_list_mutex */
	struct list_head devices;

	/*
	* Devices which can satisfy space allocation. Protected by
	* chunk_mutex
	*/
	struct list_head alloc_list;

	struct btrfs_fs_devices *seed;
	int seeding;

	int opened;

	/* set when we find or add a device that doesn't have the
	* nonrot flag set
	*/
	int rotating;

	struct btrfs_fs_info *fs_info;
	/* sysfs kobjects */
	struct kobject fsid_kobj;
	struct kobject *device_dir_kobj;
	struct completion kobj_unregister;
	};

	#define BTRFS_BIO_INLINE_CSUM_SIZE 64

	#define BTRFS_MAX_DEVS(info) ((BTRFS_MAX_ITEM_SIZE(info) \
	- sizeof(struct btrfs_chunk)) \
	/ sizeof(struct btrfs_stripe) + 1)

	#define BTRFS_MAX_DEVS_SYS_CHUNK ((BTRFS_SYSTEM_CHUNK_ARRAY_SIZE \
	- 2 * sizeof(struct btrfs_disk_key) \
	- 2 * sizeof(struct btrfs_chunk)) \
	/ sizeof(struct btrfs_stripe) + 1)

	/*
	* we need the mirror number and stripe index to be passed around
	* the call chain while we are processing end_io (especially errors).
	* Really, what we need is a btrfs_bio structure that has this info
	* and is properly sized with its stripe array, but we're not there
	* quite yet. We have our own btrfs bioset, and all of the bios
	* we allocate are actually btrfs_io_bios. We'll cram as much of
	* struct btrfs_bio as we can into this over time.
	*/
	struct btrfs_io_bio {
	unsigned int mirror_num;
	unsigned int stripe_index;
	u64 logical;
	u8 *csum;
	u8 csum_inline[BTRFS_BIO_INLINE_CSUM_SIZE];
	struct bvec_iter iter;
	/*
	* This member must come last, bio_alloc_bioset will allocate enough
	* bytes for entire btrfs_io_bio but relies on bio being last.
	*/
	struct bio bio;
	};

	static inline struct btrfs_io_bio btrfs_io_bio(struct bio bio)
	{
	return container_of(bio, struct btrfs_io_bio, bio);
	}

	static inline void btrfs_io_bio_free_csum(struct btrfs_io_bio *io_bio)
	{
	if (io_bio->csum != io_bio->csum_inline) {
	kfree(io_bio->csum);
	io_bio->csum = NULL;
	}
	}

	struct btrfs_bio_stripe {
	struct btrfs_device *dev;
	u64 physical;
	u64 length; /* only used for discard mappings */
	};

	struct btrfs_bio {
	refcount_t refs;
	atomic_t stripes_pending;
	struct btrfs_fs_info *fs_info;
	u64 map_type; /* get from map_lookup->type */
	bio_end_io_t *end_io;
	struct bio *orig_bio;
	unsigned long flags;
	void *private;
	atomic_t error;
	int max_errors;
	int num_stripes;
	int mirror_num;
	int num_tgtdevs;
	int *tgtdev_map;
	/*
	* logical block numbers for the start of each stripe
	* The last one or two are p/q. These are sorted,
	* so raid_map[0] is the start of our full stripe
	*/
	u64 *raid_map;
	struct btrfs_bio_stripe stripes[];
	};

	struct btrfs_device_info {
	struct btrfs_device *dev;
	u64 dev_offset;
	u64 max_avail;
	u64 total_avail;
	};

	struct btrfs_raid_attr {
	u8 sub_stripes; /* sub_stripes info for map */
	u8 dev_stripes; /* stripes per dev */
	u8 devs_max; /* max devs to use */
	u8 devs_min; /* min devs needed */
	u8 tolerated_failures; /* max tolerated fail devs */
	u8 devs_increment; /* ndevs has to be a multiple of this */
	u8 ncopies; /* how many copies to data has */
	u8 nparity; /* number of stripes worth of bytes to store
	* parity information */
	u8 mindev_error; /* error code if min devs requisite is unmet */
	const char raid_name[8]; /* name of the raid */
	u64 bg_flag; /* block group flag of the raid */
	};

	extern const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES];

	struct map_lookup {
	u64 type;
	int io_align;
	int io_width;
	u64 stripe_len;
	int num_stripes;
	int sub_stripes;
	int verified_stripes; /* For mount time dev extent verification */
	struct btrfs_bio_stripe stripes[];
	};

	#define map_lookup_size(n) (sizeof(struct map_lookup) + \
	(sizeof(struct btrfs_bio_stripe) * (n)))

	struct btrfs_balance_args;
	struct btrfs_balance_progress;
	struct btrfs_balance_control {
	struct btrfs_balance_args data;
	struct btrfs_balance_args meta;
	struct btrfs_balance_args sys;

	u64 flags;

	struct btrfs_balance_progress stat;
	};

	enum btrfs_map_op {
	BTRFS_MAP_READ,
	BTRFS_MAP_WRITE,
	BTRFS_MAP_DISCARD,
	BTRFS_MAP_GET_READ_MIRRORS,
	};

	static inline enum btrfs_map_op btrfs_op(struct bio *bio)
	{
	switch (bio_op(bio)) {
	case REQ_OP_DISCARD:
	return BTRFS_MAP_DISCARD;
	case REQ_OP_WRITE:
	return BTRFS_MAP_WRITE;
	default:
	WARN_ON_ONCE(1);
	/* fall through */
	case REQ_OP_READ:
	return BTRFS_MAP_READ;
	}
	}

	void btrfs_get_bbio(struct btrfs_bio *bbio);
	void btrfs_put_bbio(struct btrfs_bio *bbio);
	int btrfs_map_block(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
	u64 logical, u64 *length,
	struct btrfs_bio **bbio_ret, int mirror_num);
	int btrfs_map_sblock(struct btrfs_fs_info *fs_info, enum btrfs_map_op op,
	u64 logical, u64 *length,
	struct btrfs_bio **bbio_ret);
	int btrfs_rmap_block(struct btrfs_fs_info *fs_info, u64 chunk_start,
	u64 physical, u64 *logical, int naddrs, int *stripe_len);
	int btrfs_read_sys_array(struct btrfs_fs_info *fs_info);
	int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info);
	int btrfs_alloc_chunk(struct btrfs_trans_handle *trans, u64 type);
	void btrfs_mapping_tree_free(struct extent_map_tree *tree);
	blk_status_t btrfs_map_bio(struct btrfs_fs_info fs_info, struct bio bio,
	int mirror_num, int async_submit);
	int btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
	fmode_t flags, void *holder);
	struct btrfs_device btrfs_scan_one_device(const char path,
	fmode_t flags, void *holder);
	int btrfs_forget_devices(const char *path);
	int btrfs_close_devices(struct btrfs_fs_devices *fs_devices);
	void btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices, int step);
	void btrfs_assign_next_active_device(struct btrfs_device *device,
	struct btrfs_device *this_dev);
	struct btrfs_device btrfs_find_device_by_devspec(struct btrfs_fs_info fs_info,
	u64 devid,
	const char *devpath);
	struct btrfs_device btrfs_alloc_device(struct btrfs_fs_info fs_info,
	const u64 *devid,
	const u8 *uuid);
	void btrfs_free_device(struct btrfs_device *device);
	int btrfs_rm_device(struct btrfs_fs_info *fs_info,
	const char *device_path, u64 devid);
	void __exit btrfs_cleanup_fs_uuids(void);
	int btrfs_num_copies(struct btrfs_fs_info *fs_info, u64 logical, u64 len);
	int btrfs_grow_device(struct btrfs_trans_handle *trans,
	struct btrfs_device *device, u64 new_size);
	struct btrfs_device btrfs_find_device(struct btrfs_fs_devices fs_devices,
	u64 devid, u8 uuid, u8 fsid, bool seed);
	int btrfs_shrink_device(struct btrfs_device *device, u64 new_size);
	int btrfs_init_new_device(struct btrfs_fs_info fs_info, const char path);
	int btrfs_balance(struct btrfs_fs_info *fs_info,
	struct btrfs_balance_control *bctl,
	struct btrfs_ioctl_balance_args *bargs);
	void btrfs_describe_block_groups(u64 flags, char *buf, u32 size_buf);
	int btrfs_resume_balance_async(struct btrfs_fs_info *fs_info);
	int btrfs_recover_balance(struct btrfs_fs_info *fs_info);
	int btrfs_pause_balance(struct btrfs_fs_info *fs_info);
	int btrfs_cancel_balance(struct btrfs_fs_info *fs_info);
	int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info);
	int btrfs_check_uuid_tree(struct btrfs_fs_info *fs_info);
	int btrfs_chunk_readonly(struct btrfs_fs_info *fs_info, u64 chunk_offset);
	int find_free_dev_extent_start(struct btrfs_device *device, u64 num_bytes,
	u64 search_start, u64 start, u64 max_avail);
	int find_free_dev_extent(struct btrfs_device *device, u64 num_bytes,
	u64 start, u64 max_avail);
	void btrfs_dev_stat_inc_and_print(struct btrfs_device *dev, int index);
	int btrfs_get_dev_stats(struct btrfs_fs_info *fs_info,
	struct btrfs_ioctl_get_dev_stats *stats);
	void btrfs_init_devices_late(struct btrfs_fs_info *fs_info);
	int btrfs_init_dev_stats(struct btrfs_fs_info *fs_info);
	int btrfs_run_dev_stats(struct btrfs_trans_handle *trans);
	void btrfs_rm_dev_replace_remove_srcdev(struct btrfs_device *srcdev);
	void btrfs_rm_dev_replace_free_srcdev(struct btrfs_device *srcdev);
	void btrfs_destroy_dev_replace_tgtdev(struct btrfs_device *tgtdev);
	void btrfs_scratch_superblocks(struct block_device bdev, const char device_path);
	int btrfs_is_parity_mirror(struct btrfs_fs_info *fs_info,
	u64 logical, u64 len);
	unsigned long btrfs_full_stripe_len(struct btrfs_fs_info *fs_info,
	u64 logical);
	int btrfs_finish_chunk_alloc(struct btrfs_trans_handle *trans,
	u64 chunk_offset, u64 chunk_size);
	int btrfs_remove_chunk(struct btrfs_trans_handle *trans, u64 chunk_offset);
	struct extent_map btrfs_get_chunk_map(struct btrfs_fs_info fs_info,
	u64 logical, u64 length);

	static inline void btrfs_dev_stat_inc(struct btrfs_device *dev,
	int index)
	{
	atomic_inc(dev->dev_stat_values + index);
	/*
	* This memory barrier orders stores updating statistics before stores
	* updating dev_stats_ccnt.
	*
	* It pairs with smp_rmb() in btrfs_run_dev_stats().
	*/
	smp_mb__before_atomic();
	atomic_inc(&dev->dev_stats_ccnt);
	}

	static inline int btrfs_dev_stat_read(struct btrfs_device *dev,
	int index)
	{
	return atomic_read(dev->dev_stat_values + index);
	}

	static inline int btrfs_dev_stat_read_and_reset(struct btrfs_device *dev,
	int index)
	{
	int ret;

	ret = atomic_xchg(dev->dev_stat_values + index, 0);
	/*
	* atomic_xchg implies a full memory barriers as per atomic_t.txt:
	* - RMW operations that have a return value are fully ordered;
	*
	* This implicit memory barriers is paired with the smp_rmb in
	* btrfs_run_dev_stats
	*/
	atomic_inc(&dev->dev_stats_ccnt);
	return ret;
	}

	static inline void btrfs_dev_stat_set(struct btrfs_device *dev,
	int index, unsigned long val)
	{
	atomic_set(dev->dev_stat_values + index, val);
	/*
	* This memory barrier orders stores updating statistics before stores
	* updating dev_stats_ccnt.
	*
	* It pairs with smp_rmb() in btrfs_run_dev_stats().
	*/
	smp_mb__before_atomic();
	atomic_inc(&dev->dev_stats_ccnt);
	}

	static inline void btrfs_dev_stat_reset(struct btrfs_device *dev,
	int index)
	{
	btrfs_dev_stat_set(dev, index, 0);
	}

	/*
	* Convert block group flags (BTRFS_BLOCK_GROUP_*) to btrfs_raid_types, which
	* can be used as index to access btrfs_raid_array[].
	*/
	static inline enum btrfs_raid_types btrfs_bg_flags_to_raid_index(u64 flags)
	{
	if (flags & BTRFS_BLOCK_GROUP_RAID10)
	return BTRFS_RAID_RAID10;
	else if (flags & BTRFS_BLOCK_GROUP_RAID1)
	return BTRFS_RAID_RAID1;
	else if (flags & BTRFS_BLOCK_GROUP_DUP)
	return BTRFS_RAID_DUP;
	else if (flags & BTRFS_BLOCK_GROUP_RAID0)
	return BTRFS_RAID_RAID0;
	else if (flags & BTRFS_BLOCK_GROUP_RAID5)
	return BTRFS_RAID_RAID5;
	else if (flags & BTRFS_BLOCK_GROUP_RAID6)
	return BTRFS_RAID_RAID6;

	return BTRFS_RAID_SINGLE; /* BTRFS_BLOCK_GROUP_SINGLE */
	}

	void btrfs_commit_device_sizes(struct btrfs_transaction *trans);

	struct list_head *btrfs_get_fs_uuids(void);
	void btrfs_set_fs_info_ptr(struct btrfs_fs_info *fs_info);
	void btrfs_reset_fs_info_ptr(struct btrfs_fs_info *fs_info);
	bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info,
	struct btrfs_device *failing_dev);

	int btrfs_bg_type_to_factor(u64 flags);
	const char *btrfs_bg_type_to_raid_name(u64 flags);
	int btrfs_verify_dev_extents(struct btrfs_fs_info *fs_info);

	#endif