kernel / fs / btrfs / fs.h

/* SPDX-License-Identifier: GPL-2.0 */

#ifndef BTRFS_FS_H
#define BTRFS_FS_H

#include <linux/blkdev.h>
#include <linux/sizes.h>
#include <linux/time64.h>
#include <linux/compiler.h>
#include <linux/math.h>
#include <linux/atomic.h>
#include <linux/percpu_counter.h>
#include <linux/completion.h>
#include <linux/lockdep.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <linux/rwsem.h>
#include <linux/semaphore.h>
#include <linux/list.h>
#include <linux/pagemap.h>
#include <linux/radix-tree.h>
#include <linux/workqueue.h>
#include <linux/wait.h>
#include <linux/wait_bit.h>
#include <linux/sched.h>
#include <linux/rbtree.h>
#include <uapi/linux/btrfs.h>
#include <uapi/linux/btrfs_tree.h>
#include "extent-io-tree.h"
#include "async-thread.h"
#include "block-rsv.h"
#include "messages.h"

struct inode;
struct super_block;
struct kobject;
struct reloc_control;
struct crypto_shash;
struct ulist;
struct btrfs_device;
struct btrfs_block_group;
struct btrfs_root;
struct btrfs_fs_devices;
struct btrfs_transaction;
struct btrfs_delayed_root;
struct btrfs_balance_control;
struct btrfs_subpage_info;
struct btrfs_stripe_hash_table;
struct btrfs_space_info;

/*
 * Minimum data and metadata block size.
 *
 * Normally it's 4K, but for testing subpage block size on 4K page systems, we
 * allow DEBUG builds to accept 2K page size.
 */
#ifdef CONFIG_BTRFS_DEBUG
#define BTRFS_MIN_BLOCKSIZE	(SZ_2K)
#else
#define BTRFS_MIN_BLOCKSIZE	(SZ_4K)
#endif

#define BTRFS_MAX_BLOCKSIZE	(SZ_64K)

#define BTRFS_MAX_EXTENT_SIZE SZ_128M

#define BTRFS_OLDEST_GENERATION	0ULL

#define BTRFS_EMPTY_DIR_SIZE 0

#define BTRFS_DIRTY_METADATA_THRESH		SZ_32M

#define BTRFS_SUPER_INFO_OFFSET			SZ_64K
#define BTRFS_SUPER_INFO_SIZE			4096
static_assert(sizeof(struct btrfs_super_block) == BTRFS_SUPER_INFO_SIZE);

/* Array of bytes with variable length, hexadecimal format 0x1234 */
#define BTRFS_CSUM_FMT				"0x%*phN"
#define BTRFS_CSUM_FMT_VALUE(size, bytes)	size, bytes

#define BTRFS_KEY_FMT			"(%llu %u %llu)"
#define BTRFS_KEY_FMT_VALUE(key)	(key)->objectid, (key)->type, (key)->offset

/*
 * Number of metadata items necessary for an unlink operation:
 *
 * 1 for the possible orphan item
 * 1 for the dir item
 * 1 for the dir index
 * 1 for the inode ref
 * 1 for the inode
 * 1 for the parent inode
 */
#define BTRFS_UNLINK_METADATA_UNITS		6

/*
 * The reserved space at the beginning of each device.  It covers the primary
 * super block and leaves space for potential use by other tools like
 * bootloaders or to lower potential damage of accidental overwrite.
 */
#define BTRFS_DEVICE_RANGE_RESERVED			(SZ_1M)
/*
 * Runtime (in-memory) states of filesystem
 */
enum {
	/*
	 * Filesystem is being remounted, allow to skip some operations, like
	 * defrag
	 */
	BTRFS_FS_STATE_REMOUNTING,
	/* Filesystem in RO mode */
	BTRFS_FS_STATE_RO,
	/* Track if a transaction abort has been reported on this filesystem */
	BTRFS_FS_STATE_TRANS_ABORTED,
	/* Track if log replay has failed. */
	BTRFS_FS_STATE_LOG_REPLAY_ABORTED,
	/*
	 * Bio operations should be blocked on this filesystem because a source
	 * or target device is being destroyed as part of a device replace
	 */
	BTRFS_FS_STATE_DEV_REPLACING,
	/* The btrfs_fs_info created for self-tests */
	BTRFS_FS_STATE_DUMMY_FS_INFO,

	/* Checksum errors are ignored. */
	BTRFS_FS_STATE_NO_DATA_CSUMS,
	BTRFS_FS_STATE_SKIP_META_CSUMS,

	/* Indicates there was an error cleaning up a log tree. */
	BTRFS_FS_STATE_LOG_CLEANUP_ERROR,

	/* No more delayed iput can be queued. */
	BTRFS_FS_STATE_NO_DELAYED_IPUT,

	/*
	 * Emergency shutdown, a step further than transaction aborted by
	 * rejecting all operations.
	 */
	BTRFS_FS_STATE_EMERGENCY_SHUTDOWN,

	BTRFS_FS_STATE_COUNT
};

enum {
	BTRFS_FS_CLOSING_START,
	BTRFS_FS_CLOSING_DONE,
	BTRFS_FS_LOG_RECOVERING,
	BTRFS_FS_OPEN,
	BTRFS_FS_QUOTA_ENABLED,
	BTRFS_FS_UPDATE_UUID_TREE_GEN,
	BTRFS_FS_CREATING_FREE_SPACE_TREE,
	BTRFS_FS_BTREE_ERR,
	BTRFS_FS_LOG1_ERR,
	BTRFS_FS_LOG2_ERR,
	BTRFS_FS_QUOTA_OVERRIDE,
	/* Used to record internally whether fs has been frozen */
	BTRFS_FS_FROZEN,
	/*
	 * Indicate that balance has been set up from the ioctl and is in the
	 * main phase. The fs_info::balance_ctl is initialized.
	 */
	BTRFS_FS_BALANCE_RUNNING,

	/*
	 * Indicate that relocation of a chunk has started, it's set per chunk
	 * and is toggled between chunks.
	 */
	BTRFS_FS_RELOC_RUNNING,

	/* Indicate that the cleaner thread is awake and doing something. */
	BTRFS_FS_CLEANER_RUNNING,

	/*
	 * The checksumming has an optimized version and is considered fast,
	 * so we don't need to offload checksums to workqueues.
	 */
	BTRFS_FS_CSUM_IMPL_FAST,

	/* Indicate that the discard workqueue can service discards. */
	BTRFS_FS_DISCARD_RUNNING,

	/* Indicate that we need to cleanup space cache v1 */
	BTRFS_FS_CLEANUP_SPACE_CACHE_V1,

	/* Indicate that we can't trust the free space tree for caching yet */
	BTRFS_FS_FREE_SPACE_TREE_UNTRUSTED,

	/* Indicate whether there are any tree modification log users */
	BTRFS_FS_TREE_MOD_LOG_USERS,

	/* Indicate that we want the transaction kthread to commit right now. */
	BTRFS_FS_COMMIT_TRANS,

	/* Indicate we have half completed snapshot deletions pending. */
	BTRFS_FS_UNFINISHED_DROPS,

	/* Indicate we have to finish a zone to do next allocation. */
	BTRFS_FS_NEED_ZONE_FINISH,

	/* Indicate that we want to commit the transaction. */
	BTRFS_FS_NEED_TRANS_COMMIT,

	/* This is set when active zone tracking is needed. */
	BTRFS_FS_ACTIVE_ZONE_TRACKING,

	/*
	 * Indicate if we have some features changed, this is mostly for
	 * cleaner thread to update the sysfs interface.
	 */
	BTRFS_FS_FEATURE_CHANGED,

	/*
	 * Indicate that we have found a tree block which is only aligned to
	 * sectorsize, but not to nodesize.  This should be rare nowadays.
	 */
	BTRFS_FS_UNALIGNED_TREE_BLOCK,

#if BITS_PER_LONG == 32
	/* Indicate if we have error/warn message printed on 32bit systems */
	BTRFS_FS_32BIT_ERROR,
	BTRFS_FS_32BIT_WARN,
#endif
};

/*
 * Flags for mount options.
 *
 * Note: don't forget to add new options to btrfs_show_options()
 */
enum {
	BTRFS_MOUNT_NODATASUM			= (1ULL << 0),
	BTRFS_MOUNT_NODATACOW			= (1ULL << 1),
	BTRFS_MOUNT_NOBARRIER			= (1ULL << 2),
	BTRFS_MOUNT_SSD				= (1ULL << 3),
	BTRFS_MOUNT_DEGRADED			= (1ULL << 4),
	BTRFS_MOUNT_COMPRESS			= (1ULL << 5),
	BTRFS_MOUNT_NOTREELOG			= (1ULL << 6),
	BTRFS_MOUNT_FLUSHONCOMMIT		= (1ULL << 7),
	BTRFS_MOUNT_SSD_SPREAD			= (1ULL << 8),
	BTRFS_MOUNT_NOSSD			= (1ULL << 9),
	BTRFS_MOUNT_DISCARD_SYNC		= (1ULL << 10),
	BTRFS_MOUNT_FORCE_COMPRESS		= (1ULL << 11),
	BTRFS_MOUNT_SPACE_CACHE			= (1ULL << 12),
	BTRFS_MOUNT_CLEAR_CACHE			= (1ULL << 13),
	BTRFS_MOUNT_USER_SUBVOL_RM_ALLOWED	= (1ULL << 14),
	BTRFS_MOUNT_ENOSPC_DEBUG		= (1ULL << 15),
	BTRFS_MOUNT_AUTO_DEFRAG			= (1ULL << 16),
	BTRFS_MOUNT_USEBACKUPROOT		= (1ULL << 17),
	BTRFS_MOUNT_SKIP_BALANCE		= (1ULL << 18),
	BTRFS_MOUNT_PANIC_ON_FATAL_ERROR	= (1ULL << 19),
	BTRFS_MOUNT_RESCAN_UUID_TREE		= (1ULL << 20),
	BTRFS_MOUNT_FRAGMENT_DATA		= (1ULL << 21),
	BTRFS_MOUNT_FRAGMENT_METADATA		= (1ULL << 22),
	BTRFS_MOUNT_FREE_SPACE_TREE		= (1ULL << 23),
	BTRFS_MOUNT_NOLOGREPLAY			= (1ULL << 24),
	BTRFS_MOUNT_REF_VERIFY			= (1ULL << 25),
	BTRFS_MOUNT_DISCARD_ASYNC		= (1ULL << 26),
	BTRFS_MOUNT_IGNOREBADROOTS		= (1ULL << 27),
	BTRFS_MOUNT_IGNOREDATACSUMS		= (1ULL << 28),
	BTRFS_MOUNT_NODISCARD			= (1ULL << 29),
	BTRFS_MOUNT_NOSPACECACHE		= (1ULL << 30),
	BTRFS_MOUNT_IGNOREMETACSUMS		= (1ULL << 31),
	BTRFS_MOUNT_IGNORESUPERFLAGS		= (1ULL << 32),
	BTRFS_MOUNT_REF_TRACKER			= (1ULL << 33),
};

/*
 * Compat flags that we support.  If any incompat flags are set other than the
 * ones specified below then we will fail to mount
 */
#define BTRFS_FEATURE_COMPAT_SUPP		0ULL
#define BTRFS_FEATURE_COMPAT_SAFE_SET		0ULL
#define BTRFS_FEATURE_COMPAT_SAFE_CLEAR		0ULL

#define BTRFS_FEATURE_COMPAT_RO_SUPP			\
	(BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE |	\
	 BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID | \
	 BTRFS_FEATURE_COMPAT_RO_VERITY |		\
	 BTRFS_FEATURE_COMPAT_RO_BLOCK_GROUP_TREE)

#define BTRFS_FEATURE_COMPAT_RO_SAFE_SET	0ULL
#define BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR	0ULL

#define BTRFS_FEATURE_INCOMPAT_SUPP_STABLE		\
	(BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF |		\
	 BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL |	\
	 BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS |		\
	 BTRFS_FEATURE_INCOMPAT_BIG_METADATA |		\
	 BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO |		\
	 BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD |		\
	 BTRFS_FEATURE_INCOMPAT_RAID56 |		\
	 BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF |		\
	 BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA |	\
	 BTRFS_FEATURE_INCOMPAT_NO_HOLES	|	\
	 BTRFS_FEATURE_INCOMPAT_METADATA_UUID	|	\
	 BTRFS_FEATURE_INCOMPAT_RAID1C34	|	\
	 BTRFS_FEATURE_INCOMPAT_ZONED		|	\
	 BTRFS_FEATURE_INCOMPAT_SIMPLE_QUOTA)

#ifdef CONFIG_BTRFS_EXPERIMENTAL
	/*
	 * Features under development like Extent tree v2 support is enabled
	 * only under CONFIG_BTRFS_EXPERIMENTAL
	 */
#define BTRFS_FEATURE_INCOMPAT_SUPP		\
	(BTRFS_FEATURE_INCOMPAT_SUPP_STABLE |	\
	 BTRFS_FEATURE_INCOMPAT_RAID_STRIPE_TREE | \
	 BTRFS_FEATURE_INCOMPAT_EXTENT_TREE_V2)

#else

#define BTRFS_FEATURE_INCOMPAT_SUPP		\
	(BTRFS_FEATURE_INCOMPAT_SUPP_STABLE)

#endif

#define BTRFS_FEATURE_INCOMPAT_SAFE_SET			\
	(BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF)
#define BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR		0ULL

#define BTRFS_DEFAULT_COMMIT_INTERVAL	(30)
#define BTRFS_WARNING_COMMIT_INTERVAL	(300)
#define BTRFS_DEFAULT_MAX_INLINE	(2048)

enum btrfs_compression_type {
	BTRFS_COMPRESS_NONE  = 0,
	BTRFS_COMPRESS_ZLIB  = 1,
	BTRFS_COMPRESS_LZO   = 2,
	BTRFS_COMPRESS_ZSTD  = 3,
	BTRFS_NR_COMPRESS_TYPES = 4,

	BTRFS_DEFRAG_DONT_COMPRESS,
};

struct btrfs_dev_replace {
	/* See #define above */
	u64 replace_state;
	/* Seconds since 1-Jan-1970 */
	time64_t time_started;
	/* Seconds since 1-Jan-1970 */
	time64_t time_stopped;
	atomic64_t num_write_errors;
	atomic64_t num_uncorrectable_read_errors;

	u64 cursor_left;
	u64 committed_cursor_left;
	u64 cursor_left_last_write_of_item;
	u64 cursor_right;

	/* See #define above */
	u64 cont_reading_from_srcdev_mode;

	int is_valid;
	int item_needs_writeback;
	struct btrfs_device *srcdev;
	struct btrfs_device *tgtdev;

	struct mutex lock_finishing_cancel_unmount;
	struct rw_semaphore rwsem;

	struct btrfs_scrub_progress scrub_progress;

	struct percpu_counter bio_counter;
	wait_queue_head_t replace_wait;

	struct task_struct *replace_task;
};

/*
 * Free clusters are used to claim free space in relatively large chunks,
 * allowing us to do less seeky writes. They are used for all metadata
 * allocations. In ssd_spread mode they are also used for data allocations.
 */
struct btrfs_free_cluster {
	spinlock_t lock;
	spinlock_t refill_lock;
	struct rb_root root;

	/* Largest extent in this cluster */
	u64 max_size;

	/* First extent starting offset */
	u64 window_start;

	/* We did a full search and couldn't create a cluster */
	bool fragmented;

	struct btrfs_block_group *block_group;
	/*
	 * When a cluster is allocated from a block group, we put the cluster
	 * onto a list in the block group so that it can be freed before the
	 * block group is freed.
	 */
	struct list_head block_group_list;
};

/* Discard control. */
/*
 * Async discard uses multiple lists to differentiate the discard filter
 * parameters.  Index 0 is for completely free block groups where we need to
 * ensure the entire block group is trimmed without being lossy.  Indices
 * afterwards represent monotonically decreasing discard filter sizes to
 * prioritize what should be discarded next.
 */
#define BTRFS_NR_DISCARD_LISTS		3
#define BTRFS_DISCARD_INDEX_UNUSED	0
#define BTRFS_DISCARD_INDEX_START	1

struct btrfs_discard_ctl {
	struct workqueue_struct *discard_workers;
	struct delayed_work work;
	spinlock_t lock;
	struct btrfs_block_group *block_group;
	struct list_head discard_list[BTRFS_NR_DISCARD_LISTS];
	u64 prev_discard;
	u64 prev_discard_time;
	atomic_t discardable_extents;
	atomic64_t discardable_bytes;
	u64 max_discard_size;
	u64 delay_ms;
	u32 iops_limit;
	u32 kbps_limit;
	u64 discard_extent_bytes;
	u64 discard_bitmap_bytes;
	atomic64_t discard_bytes_saved;
};

/*
 * Exclusive operations (device replace, resize, device add/remove, balance)
 */
enum btrfs_exclusive_operation {
	BTRFS_EXCLOP_NONE,
	BTRFS_EXCLOP_BALANCE_PAUSED,
	BTRFS_EXCLOP_BALANCE,
	BTRFS_EXCLOP_DEV_ADD,
	BTRFS_EXCLOP_DEV_REMOVE,
	BTRFS_EXCLOP_DEV_REPLACE,
	BTRFS_EXCLOP_RESIZE,
	BTRFS_EXCLOP_SWAP_ACTIVATE,
};

/* Store data about transaction commits, exported via sysfs. */
struct btrfs_commit_stats {
	/* Total number of commits */
	u64 commit_count;
	/* The maximum commit duration so far in ns */
	u64 max_commit_dur;
	/* The last commit duration in ns */
	u64 last_commit_dur;
	/* The total commit duration in ns */
	u64 total_commit_dur;
	/* Start of the last critical section in ns. */
	u64 critical_section_start_time;
};

struct btrfs_fs_info {
	u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
	unsigned long flags;
	struct btrfs_root *tree_root;
	struct btrfs_root *chunk_root;
	struct btrfs_root *dev_root;
	struct btrfs_root *fs_root;
	struct btrfs_root *quota_root;
	struct btrfs_root *uuid_root;
	struct btrfs_root *data_reloc_root;
	struct btrfs_root *block_group_root;
	struct btrfs_root *stripe_root;

	/* The log root tree is a directory of all the other log roots */
	struct btrfs_root *log_root_tree;

	/* The tree that holds the global roots (csum, extent, etc) */
	rwlock_t global_root_lock;
	struct rb_root global_root_tree;

	spinlock_t fs_roots_radix_lock;
	struct radix_tree_root fs_roots_radix;

	/* Block group cache stuff */
	rwlock_t block_group_cache_lock;
	struct rb_root_cached block_group_cache_tree;

	/* Keep track of unallocated space */
	atomic64_t free_chunk_space;

	/* Track ranges which are used by log trees blocks/logged data extents */
	struct extent_io_tree excluded_extents;

	/* logical->physical extent mapping */
	struct rb_root_cached mapping_tree;
	rwlock_t mapping_tree_lock;

	/*
	 * Block reservation for extent, checksum, root tree and delayed dir
	 * index item.
	 */
	struct btrfs_block_rsv global_block_rsv;
	/* Block reservation for metadata operations */
	struct btrfs_block_rsv trans_block_rsv;
	/* Block reservation for chunk tree */
	struct btrfs_block_rsv chunk_block_rsv;
	/* Block reservation for delayed operations */
	struct btrfs_block_rsv delayed_block_rsv;
	/* Block reservation for delayed refs */
	struct btrfs_block_rsv delayed_refs_rsv;
	/* Block reservation for treelog tree */
	struct btrfs_block_rsv treelog_rsv;

	struct btrfs_block_rsv empty_block_rsv;

	/*
	 * Updated while holding the lock 'trans_lock'. Due to the life cycle of
	 * a transaction, it can be directly read while holding a transaction
	 * handle, everywhere else must be read with btrfs_get_fs_generation().
	 * Should always be updated using btrfs_set_fs_generation().
	 */
	u64 generation;
	/*
	 * Always use btrfs_get_last_trans_committed() and
	 * btrfs_set_last_trans_committed() to read and update this field.
	 */
	u64 last_trans_committed;
	/*
	 * Generation of the last transaction used for block group relocation
	 * since the filesystem was last mounted (or 0 if none happened yet).
	 * Must be written and read while holding btrfs_fs_info::commit_root_sem.
	 */
	u64 last_reloc_trans;

	/*
	 * This is updated to the current trans every time a full commit is
	 * required instead of the faster short fsync log commits
	 */
	u64 last_trans_log_full_commit;
	unsigned long long mount_opt;

	/* Compress related structures. */
	void *compr_wsm[BTRFS_NR_COMPRESS_TYPES];

	int compress_type;
	int compress_level;
	u32 commit_interval;
	/*
	 * It is a suggestive number, the read side is safe even it gets a
	 * wrong number because we will write out the data into a regular
	 * extent. The write side(mount/remount) is under ->s_umount lock,
	 * so it is also safe.
	 */
	u64 max_inline;

	struct btrfs_transaction *running_transaction;
	wait_queue_head_t transaction_throttle;
	wait_queue_head_t transaction_wait;
	wait_queue_head_t transaction_blocked_wait;
	wait_queue_head_t async_submit_wait;

	/*
	 * Used to protect the incompat_flags, compat_flags, compat_ro_flags
	 * when they are updated.
	 *
	 * Because we do not clear the flags for ever, so we needn't use
	 * the lock on the read side.
	 *
	 * We also needn't use the lock when we mount the fs, because
	 * there is no other task which will update the flag.
	 */
	spinlock_t super_lock;
	struct btrfs_super_block *super_copy;
	struct btrfs_super_block *super_for_commit;
	struct super_block *sb;
	struct inode *btree_inode;
	struct mutex tree_log_mutex;
	struct mutex transaction_kthread_mutex;
	struct mutex cleaner_mutex;
	struct mutex chunk_mutex;

	/*
	 * This is taken to make sure we don't set block groups ro after the
	 * free space cache has been allocated on them.
	 */
	struct mutex ro_block_group_mutex;

	/*
	 * This is used during read/modify/write to make sure no two ios are
	 * trying to mod the same stripe at the same time.
	 */
	struct btrfs_stripe_hash_table *stripe_hash_table;

	/*
	 * This protects the ordered operations list only while we are
	 * processing all of the entries on it.  This way we make sure the
	 * commit code doesn't find the list temporarily empty because another
	 * function happens to be doing non-waiting preflush before jumping
	 * into the main commit.
	 */
	struct mutex ordered_operations_mutex;

	struct rw_semaphore commit_root_sem;

	struct rw_semaphore cleanup_work_sem;

	struct rw_semaphore subvol_sem;

	spinlock_t trans_lock;
	/*
	 * The reloc mutex goes with the trans lock, it is taken during commit
	 * to protect us from the relocation code.
	 */
	struct mutex reloc_mutex;

	struct list_head trans_list;
	struct list_head dead_roots;
	struct list_head caching_block_groups;

	spinlock_t delayed_iput_lock;
	struct list_head delayed_iputs;
	atomic_t nr_delayed_iputs;
	wait_queue_head_t delayed_iputs_wait;

	atomic64_t tree_mod_seq;

	/* This protects tree_mod_log and tree_mod_seq_list */
	rwlock_t tree_mod_log_lock;
	struct rb_root tree_mod_log;
	struct list_head tree_mod_seq_list;

	atomic_t async_delalloc_pages;

	/* This is used to protect the following list -- ordered_roots. */
	spinlock_t ordered_root_lock;

	/*
	 * All fs/file tree roots in which there are data=ordered extents
	 * pending writeback are added into this list.
	 *
	 * These can span multiple transactions and basically include every
	 * dirty data page that isn't from nodatacow.
	 */
	struct list_head ordered_roots;

	struct mutex delalloc_root_mutex;
	spinlock_t delalloc_root_lock;
	/* All fs/file tree roots that have delalloc inodes. */
	struct list_head delalloc_roots;

	/*
	 * There is a pool of worker threads for checksumming during writes and
	 * a pool for checksumming after reads.  This is because readers can
	 * run with FS locks held, and the writers may be waiting for those
	 * locks.  We don't want ordering in the pending list to cause
	 * deadlocks, and so the two are serviced separately.
	 *
	 * A third pool does submit_bio to avoid deadlocking with the other two.
	 */
	struct btrfs_workqueue *workers;
	struct btrfs_workqueue *delalloc_workers;
	struct btrfs_workqueue *flush_workers;
	struct workqueue_struct *endio_workers;
	struct workqueue_struct *endio_meta_workers;
	struct workqueue_struct *rmw_workers;
	struct btrfs_workqueue *endio_write_workers;
	struct btrfs_workqueue *endio_freespace_worker;
	struct btrfs_workqueue *caching_workers;

	/*
	 * Fixup workers take dirty pages that didn't properly go through the
	 * cow mechanism and make them safe to write.  It happens for the
	 * sys_munmap function call path.
	 */
	struct btrfs_workqueue *fixup_workers;
	struct btrfs_workqueue *delayed_workers;

	struct task_struct *transaction_kthread;
	struct task_struct *cleaner_kthread;
	u32 thread_pool_size;

	struct kobject *space_info_kobj;
	struct kobject *qgroups_kobj;
	struct kobject *discard_kobj;

	/* Track the number of blocks (sectors) read by the filesystem. */
	struct percpu_counter stats_read_blocks;

	/* Used to keep from writing metadata until there is a nice batch */
	struct percpu_counter dirty_metadata_bytes;
	struct percpu_counter delalloc_bytes;
	struct percpu_counter ordered_bytes;
	s32 dirty_metadata_batch;
	s32 delalloc_batch;

	struct percpu_counter evictable_extent_maps;
	u64 em_shrinker_last_root;
	u64 em_shrinker_last_ino;
	atomic64_t em_shrinker_nr_to_scan;
	struct work_struct em_shrinker_work;

	/* Protected by 'trans_lock'. */
	struct list_head dirty_cowonly_roots;

	struct btrfs_fs_devices *fs_devices;

	/*
	 * The space_info list is effectively read only after initial setup.
	 * It is populated at mount time and cleaned up after all block groups
	 * are removed.  RCU is used to protect it.
	 */
	struct list_head space_info;

	struct btrfs_space_info *data_sinfo;

	struct reloc_control *reloc_ctl;

	/* data_alloc_cluster is only used in ssd_spread mode */
	struct btrfs_free_cluster data_alloc_cluster;

	/* All metadata allocations go through this cluster. */
	struct btrfs_free_cluster meta_alloc_cluster;

	/* Auto defrag inodes go here. */
	spinlock_t defrag_inodes_lock;
	struct rb_root defrag_inodes;
	atomic_t defrag_running;

	/* Used to protect avail_{data, metadata, system}_alloc_bits */
	seqlock_t profiles_lock;
	/*
	 * These three are in extended format (availability of single chunks is
	 * denoted by BTRFS_AVAIL_ALLOC_BIT_SINGLE bit, other types are denoted
	 * by corresponding BTRFS_BLOCK_GROUP_* bits)
	 */
	u64 avail_data_alloc_bits;
	u64 avail_metadata_alloc_bits;
	u64 avail_system_alloc_bits;

	/* Balance state */
	spinlock_t balance_lock;
	struct mutex balance_mutex;
	atomic_t balance_pause_req;
	atomic_t balance_cancel_req;
	struct btrfs_balance_control *balance_ctl;
	wait_queue_head_t balance_wait_q;

	/* Cancellation requests for chunk relocation */
	atomic_t reloc_cancel_req;

	u32 data_chunk_allocations;
	u32 metadata_ratio;

	/* Private scrub information */
	struct mutex scrub_lock;
	atomic_t scrubs_running;
	atomic_t scrub_pause_req;
	atomic_t scrubs_paused;
	atomic_t scrub_cancel_req;
	wait_queue_head_t scrub_pause_wait;
	/*
	 * The worker pointers are NULL iff the refcount is 0, ie. scrub is not
	 * running.
	 */
	refcount_t scrub_workers_refcnt;
	struct workqueue_struct *scrub_workers;

	struct btrfs_discard_ctl discard_ctl;

	/* Is qgroup tracking in a consistent state? */
	u64 qgroup_flags;

	/* Holds configuration and tracking. Protected by qgroup_lock. */
	struct rb_root qgroup_tree;
	spinlock_t qgroup_lock;

	/*
	 * Protect user change for quota operations. If a transaction is needed,
	 * it must be started before locking this lock.
	 */
	struct mutex qgroup_ioctl_lock;

	/* List of dirty qgroups to be written at next commit. */
	struct list_head dirty_qgroups;

	/* Used by qgroup for an efficient tree traversal. */
	u64 qgroup_seq;

	/* Qgroup rescan items. */
	/* Protects the progress item */
	struct mutex qgroup_rescan_lock;
	struct btrfs_key qgroup_rescan_progress;
	struct btrfs_workqueue *qgroup_rescan_workers;
	struct completion qgroup_rescan_completion;
	struct btrfs_work qgroup_rescan_work;
	/* Protected by qgroup_rescan_lock */
	bool qgroup_rescan_running;
	u8 qgroup_drop_subtree_thres;
	u64 qgroup_enable_gen;

	/*
	 * If this is not 0, then it indicates a serious filesystem error has
	 * happened and it contains that error (negative errno value).
	 */
	int fs_error;

	/* Filesystem state */
	unsigned long fs_state;

	struct btrfs_delayed_root *delayed_root;

	/* Entries are eb->start >> nodesize_bits */
	struct xarray buffer_tree;

	/* Next backup root to be overwritten */
	int backup_root_index;

	/* Device replace state */
	struct btrfs_dev_replace dev_replace;

	struct semaphore uuid_tree_rescan_sem;

	/* Used to reclaim the metadata space in the background. */
	struct work_struct async_reclaim_work;
	struct work_struct async_data_reclaim_work;
	struct work_struct preempt_reclaim_work;

	/* Reclaim partially filled block groups in the background */
	struct work_struct reclaim_bgs_work;
	/* Protected by unused_bgs_lock. */
	struct list_head reclaim_bgs;
	int bg_reclaim_threshold;

	/* Protects the lists unused_bgs and reclaim_bgs. */
	spinlock_t unused_bgs_lock;
	/* Protected by unused_bgs_lock. */
	struct list_head unused_bgs;
	struct mutex unused_bg_unpin_mutex;
	/* Protect block groups that are going to be deleted */
	struct mutex reclaim_bgs_lock;

	/* Cached block sizes */
	u32 nodesize;
	u32 nodesize_bits;
	u32 sectorsize;
	/* ilog2 of sectorsize, use to avoid 64bit division */
	u32 sectorsize_bits;
	u32 block_min_order;
	u32 block_max_order;
	u32 csum_size;
	u32 csums_per_leaf;
	u32 stripesize;

	/*
	 * Maximum size of an extent. BTRFS_MAX_EXTENT_SIZE on regular
	 * filesystem, on zoned it depends on the device constraints.
	 */
	u64 max_extent_size;

	/* Block groups and devices containing active swapfiles. */
	spinlock_t swapfile_pins_lock;
	struct rb_root swapfile_pins;

	struct crypto_shash *csum_shash;

	/* Type of exclusive operation running, protected by super_lock */
	enum btrfs_exclusive_operation exclusive_operation;

	/*
	 * Zone size > 0 when in ZONED mode, otherwise it's used for a check
	 * if the mode is enabled
	 */
	u64 zone_size;

	/* Constraints for ZONE_APPEND commands: */
	struct queue_limits limits;
	u64 max_zone_append_size;

	struct mutex zoned_meta_io_lock;
	spinlock_t treelog_bg_lock;
	u64 treelog_bg;

	/*
	 * Start of the dedicated data relocation block group, protected by
	 * relocation_bg_lock.
	 */
	spinlock_t relocation_bg_lock;
	u64 data_reloc_bg;
	struct mutex zoned_data_reloc_io_lock;

	struct btrfs_block_group *active_meta_bg;
	struct btrfs_block_group *active_system_bg;

	u64 nr_global_roots;

	spinlock_t zone_active_bgs_lock;
	struct list_head zone_active_bgs;

	/* Updates are not protected by any lock */
	struct btrfs_commit_stats commit_stats;

	/*
	 * Last generation where we dropped a non-relocation root.
	 * Use btrfs_set_last_root_drop_gen() and btrfs_get_last_root_drop_gen()
	 * to change it and to read it, respectively.
	 */
	u64 last_root_drop_gen;

	/*
	 * Annotations for transaction events (structures are empty when
	 * compiled without lockdep).
	 */
	struct lockdep_map btrfs_trans_num_writers_map;
	struct lockdep_map btrfs_trans_num_extwriters_map;
	struct lockdep_map btrfs_state_change_map[4];
	struct lockdep_map btrfs_trans_pending_ordered_map;
	struct lockdep_map btrfs_ordered_extent_map;

#ifdef CONFIG_BTRFS_DEBUG
	spinlock_t ref_verify_lock;
	struct rb_root block_tree;

	struct kobject *debug_kobj;
	struct list_head allocated_roots;

	spinlock_t eb_leak_lock;
	struct list_head allocated_ebs;
#endif
};

#define folio_to_inode(_folio)	(BTRFS_I(_Generic((_folio),			\
					  struct folio *: (_folio))->mapping->host))

#define folio_to_fs_info(_folio) (folio_to_inode(_folio)->root->fs_info)

#define inode_to_fs_info(_inode) (BTRFS_I(_Generic((_inode),			\
					   struct inode *: (_inode)))->root->fs_info)

static inline gfp_t btrfs_alloc_write_mask(struct address_space *mapping)
{
	return mapping_gfp_constraint(mapping, ~__GFP_FS);
}

/* Return the minimal folio size of the fs. */
static inline unsigned int btrfs_min_folio_size(struct btrfs_fs_info *fs_info)
{
	return 1U << (PAGE_SHIFT + fs_info->block_min_order);
}

static inline u64 btrfs_get_fs_generation(const struct btrfs_fs_info *fs_info)
{
	return READ_ONCE(fs_info->generation);
}

static inline void btrfs_set_fs_generation(struct btrfs_fs_info *fs_info, u64 gen)
{
	WRITE_ONCE(fs_info->generation, gen);
}

static inline u64 btrfs_get_last_trans_committed(const struct btrfs_fs_info *fs_info)
{
	return READ_ONCE(fs_info->last_trans_committed);
}

static inline void btrfs_set_last_trans_committed(struct btrfs_fs_info *fs_info, u64 gen)
{
	WRITE_ONCE(fs_info->last_trans_committed, gen);
}

static inline void btrfs_set_last_root_drop_gen(struct btrfs_fs_info *fs_info,
						u64 gen)
{
	WRITE_ONCE(fs_info->last_root_drop_gen, gen);
}

static inline u64 btrfs_get_last_root_drop_gen(const struct btrfs_fs_info *fs_info)
{
	return READ_ONCE(fs_info->last_root_drop_gen);
}

/*
 * Take the number of bytes to be checksummed and figure out how many leaves
 * it would require to store the csums for that many bytes.
 */
static inline u64 btrfs_csum_bytes_to_leaves(
			const struct btrfs_fs_info *fs_info, u64 csum_bytes)
{
	const u64 num_csums = csum_bytes >> fs_info->sectorsize_bits;

	return DIV_ROUND_UP_ULL(num_csums, fs_info->csums_per_leaf);
}

/*
 * Use this if we would be adding new items, as we could split nodes as we cow
 * down the tree.
 */
static inline u64 btrfs_calc_insert_metadata_size(const struct btrfs_fs_info *fs_info,
						  unsigned num_items)
{
	return (u64)fs_info->nodesize * BTRFS_MAX_LEVEL * 2 * num_items;
}

/*
 * Doing a truncate or a modification won't result in new nodes or leaves, just
 * what we need for COW.
 */
static inline u64 btrfs_calc_metadata_size(const struct btrfs_fs_info *fs_info,
						 unsigned num_items)
{
	return (u64)fs_info->nodesize * BTRFS_MAX_LEVEL * num_items;
}

#define BTRFS_MAX_EXTENT_ITEM_SIZE(r) ((BTRFS_LEAF_DATA_SIZE(r->fs_info) >> 4) - \
					sizeof(struct btrfs_item))

#define BTRFS_BYTES_TO_BLKS(fs_info, bytes) ((bytes) >> (fs_info)->sectorsize_bits)

static inline bool btrfs_is_zoned(const struct btrfs_fs_info *fs_info)
{
	return IS_ENABLED(CONFIG_BLK_DEV_ZONED) && fs_info->zone_size > 0;
}

/*
 * Count how many fs_info->max_extent_size cover the @size
 */
static inline u32 count_max_extents(const struct btrfs_fs_info *fs_info, u64 size)
{
#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
	if (!fs_info)
		return div_u64(size + BTRFS_MAX_EXTENT_SIZE - 1, BTRFS_MAX_EXTENT_SIZE);
#endif

	return div_u64(size + fs_info->max_extent_size - 1, fs_info->max_extent_size);
}

static inline unsigned int btrfs_blocks_per_folio(const struct btrfs_fs_info *fs_info,
						  const struct folio *folio)
{
	return folio_size(folio) >> fs_info->sectorsize_bits;
}

bool __attribute_const__ btrfs_supported_blocksize(u32 blocksize);
bool btrfs_exclop_start(struct btrfs_fs_info *fs_info,
			enum btrfs_exclusive_operation type);
bool btrfs_exclop_start_try_lock(struct btrfs_fs_info *fs_info,
				 enum btrfs_exclusive_operation type);
void btrfs_exclop_start_unlock(struct btrfs_fs_info *fs_info);
void btrfs_exclop_finish(struct btrfs_fs_info *fs_info);
void btrfs_exclop_balance(struct btrfs_fs_info *fs_info,
			  enum btrfs_exclusive_operation op);

int btrfs_check_ioctl_vol_args_path(const struct btrfs_ioctl_vol_args *vol_args);

u16 btrfs_csum_type_size(u16 type);
int btrfs_super_csum_size(const struct btrfs_super_block *s);
const char *btrfs_super_csum_name(u16 csum_type);
const char *btrfs_super_csum_driver(u16 csum_type);
size_t __attribute_const__ btrfs_get_num_csums(void);

static inline bool btrfs_is_empty_uuid(const u8 *uuid)
{
	return uuid_is_null((const uuid_t *)uuid);
}

/* Compatibility and incompatibility defines */
void __btrfs_set_fs_incompat(struct btrfs_fs_info *fs_info, u64 flag,
			     const char *name);
void __btrfs_clear_fs_incompat(struct btrfs_fs_info *fs_info, u64 flag,
			       const char *name);
void __btrfs_set_fs_compat_ro(struct btrfs_fs_info *fs_info, u64 flag,
			      const char *name);
void __btrfs_clear_fs_compat_ro(struct btrfs_fs_info *fs_info, u64 flag,
				const char *name);

#define __btrfs_fs_incompat(fs_info, flags)				\
	(!!(btrfs_super_incompat_flags((fs_info)->super_copy) & (flags)))

#define __btrfs_fs_compat_ro(fs_info, flags)				\
	(!!(btrfs_super_compat_ro_flags((fs_info)->super_copy) & (flags)))

#define btrfs_set_fs_incompat(__fs_info, opt)				\
	__btrfs_set_fs_incompat((__fs_info), BTRFS_FEATURE_INCOMPAT_##opt, #opt)

#define btrfs_clear_fs_incompat(__fs_info, opt)				\
	__btrfs_clear_fs_incompat((__fs_info), BTRFS_FEATURE_INCOMPAT_##opt, #opt)

#define btrfs_fs_incompat(fs_info, opt)					\
	__btrfs_fs_incompat((fs_info), BTRFS_FEATURE_INCOMPAT_##opt)

#define btrfs_set_fs_compat_ro(__fs_info, opt)				\
	__btrfs_set_fs_compat_ro((__fs_info), BTRFS_FEATURE_COMPAT_RO_##opt, #opt)

#define btrfs_clear_fs_compat_ro(__fs_info, opt)			\
	__btrfs_clear_fs_compat_ro((__fs_info), BTRFS_FEATURE_COMPAT_RO_##opt, #opt)

#define btrfs_fs_compat_ro(fs_info, opt)				\
	__btrfs_fs_compat_ro((fs_info), BTRFS_FEATURE_COMPAT_RO_##opt)

#define btrfs_clear_opt(o, opt)		((o) &= ~BTRFS_MOUNT_##opt)
#define btrfs_set_opt(o, opt)		((o) |= BTRFS_MOUNT_##opt)
#define btrfs_raw_test_opt(o, opt)	((o) & BTRFS_MOUNT_##opt)
#define btrfs_test_opt(fs_info, opt)	((fs_info)->mount_opt & \
					 BTRFS_MOUNT_##opt)

static inline int btrfs_fs_closing(const struct btrfs_fs_info *fs_info)
{
	/* Do it this way so we only ever do one test_bit in the normal case. */
	if (test_bit(BTRFS_FS_CLOSING_START, &fs_info->flags)) {
		if (test_bit(BTRFS_FS_CLOSING_DONE, &fs_info->flags))
			return 2;
		return 1;
	}
	return 0;
}

/*
 * If we remount the fs to be R/O or umount the fs, the cleaner needn't do
 * anything except sleeping. This function is used to check the status of
 * the fs.
 * We check for BTRFS_FS_STATE_RO to avoid races with a concurrent remount,
 * since setting and checking for SB_RDONLY in the superblock's flags is not
 * atomic.
 */
static inline int btrfs_need_cleaner_sleep(const struct btrfs_fs_info *fs_info)
{
	return test_bit(BTRFS_FS_STATE_RO, &fs_info->fs_state) ||
		btrfs_fs_closing(fs_info);
}

static inline void btrfs_wake_unfinished_drop(struct btrfs_fs_info *fs_info)
{
	clear_and_wake_up_bit(BTRFS_FS_UNFINISHED_DROPS, &fs_info->flags);
}

#define BTRFS_FS_ERROR(fs_info)	(READ_ONCE((fs_info)->fs_error))

#define BTRFS_FS_LOG_CLEANUP_ERROR(fs_info)				\
	(unlikely(test_bit(BTRFS_FS_STATE_LOG_CLEANUP_ERROR,		\
			   &(fs_info)->fs_state)))

static inline bool btrfs_is_shutdown(struct btrfs_fs_info *fs_info)
{
	return test_bit(BTRFS_FS_STATE_EMERGENCY_SHUTDOWN, &fs_info->fs_state);
}

static inline void btrfs_force_shutdown(struct btrfs_fs_info *fs_info)
{
	/*
	 * Here we do not want to use handle_fs_error(), which will mark the fs
	 * read-only.
	 * Some call sites like shutdown ioctl will mark the fs shutdown when
	 * the fs is frozen. But thaw path will handle RO and RW fs
	 * differently.
	 *
	 * So here we only mark the fs error without flipping it RO.
	 */
	WRITE_ONCE(fs_info->fs_error, -EIO);
	if (!test_and_set_bit(BTRFS_FS_STATE_EMERGENCY_SHUTDOWN, &fs_info->fs_state))
		btrfs_crit(fs_info, "emergency shutdown");
}

/*
 * We use folio flag owner_2 to indicate there is an ordered extent with
 * unfinished IO.
 */
#define folio_test_ordered(folio)	folio_test_owner_2(folio)
#define folio_set_ordered(folio)	folio_set_owner_2(folio)
#define folio_clear_ordered(folio)	folio_clear_owner_2(folio)

#ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS

#define EXPORT_FOR_TESTS

static inline bool btrfs_is_testing(const struct btrfs_fs_info *fs_info)
{
	return unlikely(test_bit(BTRFS_FS_STATE_DUMMY_FS_INFO, &fs_info->fs_state));
}

void btrfs_test_destroy_inode(struct inode *inode);

#else

#define EXPORT_FOR_TESTS static

static inline bool btrfs_is_testing(const struct btrfs_fs_info *fs_info)
{
	return false;
}
#endif

#endif