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

#ifndef BTRFS_FS_H
#define BTRFS_FS_H

#include <crypto/blake2b.h>
#include <crypto/sha2.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 <linux/xxhash.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 ulist;
struct btrfs_device;
struct btrfs_block_group;
struct btrfs_root;
struct btrfs_fs_devices;
struct btrfs_transaction;
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

/*
 * Maximum length to trim in a single iteration to avoid holding device list
 * mutex for too long.
 */
#define BTRFS_MAX_TRIM_LENGTH                   SZ_2G

#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),
};

/* These mount options require a full read-only fs, no new transaction is allowed. */
#define BTRFS_MOUNT_FULL_RO_MASK                \
        (BTRFS_MOUNT_NOLOGREPLAY |              \
         BTRFS_MOUNT_IGNOREBADROOTS |           \
         BTRFS_MOUNT_IGNOREDATACSUMS |          \
         BTRFS_MOUNT_IGNOREMETACSUMS |          \
         BTRFS_MOUNT_IGNORESUPERFLAGS)

/*
 * 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 | \
         BTRFS_FEATURE_INCOMPAT_REMAP_TREE)

#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_delayed_root {
        spinlock_t lock;
        int nodes;              /* for delayed nodes */
        struct list_head node_list;
        /*
         * Used for delayed nodes which is waiting to be dealt with by the
         * worker. If the delayed node is inserted into the work queue, we
         * drop it from this list.
         */
        struct list_head prepare_list;
        atomic_t items;         /* for delayed items */
        atomic_t items_seq;     /* for delayed items */
        wait_queue_head_t wait;
};

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;
        struct btrfs_root *remap_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 remap tree. */
        struct btrfs_block_rsv remap_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;
        struct mutex remap_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, reclaim_bgs, and fully_remapped_bgs. */
        spinlock_t unused_bgs_lock;
        /* Protected by unused_bgs_lock. */
        struct list_head unused_bgs;
        struct list_head fully_remapped_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 stripesize;
        u32 csum_size;
        u32 csums_per_leaf;
        u32 csum_type;

        /*
         * 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;

        /* 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);
size_t __attribute_const__ btrfs_get_num_csums(void);
struct btrfs_csum_ctx {
        u16 csum_type;
        union {
                u32 crc32;
                struct xxh64_state xxh64;
                struct sha256_ctx sha256;
                struct blake2b_ctx blake2b;
        };
};
void btrfs_csum(u16 csum_type, const u8 *data, size_t len, u8 *out);
void btrfs_csum_init(struct btrfs_csum_ctx *ctx, u16 csum_type);
void btrfs_csum_update(struct btrfs_csum_ctx *ctx, const u8 *data, size_t len);
void btrfs_csum_final(struct btrfs_csum_ctx *ctx, u8 *out);

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 bool btrfs_fs_closing(const struct btrfs_fs_info *fs_info)
{
        return unlikely(test_bit(BTRFS_FS_CLOSING_START, &fs_info->flags));
}

static inline bool btrfs_fs_closing_done(const struct btrfs_fs_info *fs_info)
{
        if (btrfs_fs_closing(fs_info) && test_bit(BTRFS_FS_CLOSING_DONE, &fs_info->flags))
                return true;

        return false;
}

/*
 * 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(const struct btrfs_fs_info *fs_info)
{
        return unlikely(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