Merged in f5soh/librepilot/update_credits (pull request #529)

[librepilot.git] / flight / pios / common / libraries / yaffs2 / inc / yaffs_guts.h

/*
 * YAFFS: Yet another Flash File System . A NAND-flash specific file system.
 *
 * Copyright (C) 2002-2011 Aleph One Ltd.
 *   for Toby Churchill Ltd and Brightstar Engineering
 *
 * Created by Charles Manning <charles@aleph1.co.uk>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License version 2.1 as
 * published by the Free Software Foundation.
 *
 * Note: Only YAFFS headers are LGPL, YAFFS C code is covered by GPL.
 */

#ifndef __YAFFS_GUTS_H__
#define __YAFFS_GUTS_H__

#include "yportenv.h"

#define YAFFS_OK        1
#define YAFFS_FAIL  0

/* Give us a  Y=0x59,
 * Give us an A=0x41,
 * Give us an FF=0xff
 * Give us an S=0x53
 * And what have we got...
 */
#define YAFFS_MAGIC                     0x5941ff53

/*
 * Tnodes form a tree with the tnodes in "levels"
 * Levels greater than 0 hold 8 slots which point to other tnodes.
 * Those at level 0 hold 16 slots which point to chunks in NAND.
 *
 * A maximum level of 8 thust supports files of size up to:
 *
 * 2^(3*MAX_LEVEL+4)
 *
 * Thus a max level of 8 supports files with up to 2^^28 chunks which gives
 * a maximum file size of around 512Gbytees with 2k chunks.
 */
#define YAFFS_NTNODES_LEVEL0            16
#define YAFFS_TNODES_LEVEL0_BITS        4
#define YAFFS_TNODES_LEVEL0_MASK        0xf

#define YAFFS_NTNODES_INTERNAL          (YAFFS_NTNODES_LEVEL0 / 2)
#define YAFFS_TNODES_INTERNAL_BITS      (YAFFS_TNODES_LEVEL0_BITS - 1)
#define YAFFS_TNODES_INTERNAL_MASK      0x7
#define YAFFS_TNODES_MAX_LEVEL          8
#define YAFFS_TNODES_MAX_BITS           (YAFFS_TNODES_LEVEL0_BITS + \
                                        YAFFS_TNODES_INTERNAL_BITS * \
                                        YAFFS_TNODES_MAX_LEVEL)
#define YAFFS_MAX_CHUNK_ID              ((1 << YAFFS_TNODES_MAX_BITS) - 1)

#define YAFFS_MAX_FILE_SIZE_32          0x7fffffff

/* Constants for YAFFS1 mode */
#define YAFFS_BYTES_PER_SPARE           16
#define YAFFS_BYTES_PER_CHUNK           512
#define YAFFS_CHUNK_SIZE_SHIFT          9
#define YAFFS_CHUNKS_PER_BLOCK          32
#define YAFFS_BYTES_PER_BLOCK   (YAFFS_CHUNKS_PER_BLOCK*YAFFS_BYTES_PER_CHUNK)

#define YAFFS_MIN_YAFFS2_CHUNK_SIZE     1024
#define YAFFS_MIN_YAFFS2_SPARE_SIZE     32



#define YAFFS_ALLOCATION_NOBJECTS       100
#define YAFFS_ALLOCATION_NTNODES        100
#define YAFFS_ALLOCATION_NLINKS         100

#define YAFFS_NOBJECT_BUCKETS           256

#define YAFFS_OBJECT_SPACE              0x40000
#define YAFFS_MAX_OBJECT_ID             (YAFFS_OBJECT_SPACE - 1)

/* Binary data version stamps */
#define YAFFS_SUMMARY_VERSION           1
#define YAFFS_CHECKPOINT_VERSION        7

#ifdef CONFIG_YAFFS_UNICODE
#define YAFFS_MAX_NAME_LENGTH           127
#define YAFFS_MAX_ALIAS_LENGTH          79
#else
#define YAFFS_MAX_NAME_LENGTH           255
#define YAFFS_MAX_ALIAS_LENGTH          159
#endif

#define YAFFS_SHORT_NAME_LENGTH         15

/* Some special object ids for pseudo objects */
#define YAFFS_OBJECTID_ROOT             1
#define YAFFS_OBJECTID_LOSTNFOUND       2
#define YAFFS_OBJECTID_UNLINKED         3
#define YAFFS_OBJECTID_DELETED          4

/* Fake object Id for summary data */
#define YAFFS_OBJECTID_SUMMARY          0x10

/* Pseudo object ids for checkpointing */
#define YAFFS_OBJECTID_CHECKPOINT_DATA  0x20
#define YAFFS_SEQUENCE_CHECKPOINT_DATA  0x21

#define YAFFS_MAX_SHORT_OP_CACHES       20

#define YAFFS_N_TEMP_BUFFERS            6

/* We limit the number attempts at sucessfully saving a chunk of data.
 * Small-page devices have 32 pages per block; large-page devices have 64.
 * Default to something in the order of 5 to 10 blocks worth of chunks.
 */
#define YAFFS_WR_ATTEMPTS               (5*64)

/* Sequence numbers are used in YAFFS2 to determine block allocation order.
 * The range is limited slightly to help distinguish bad numbers from good.
 * This also allows us to perhaps in the future use special numbers for
 * special purposes.
 * EFFFFF00 allows the allocation of 8 blocks/second (~1Mbytes) for 15 years,
 * and is a larger number than the lifetime of a 2GB device.
 */
#define YAFFS_LOWEST_SEQUENCE_NUMBER    0x00001000
#define YAFFS_HIGHEST_SEQUENCE_NUMBER   0xefffff00

/* Special sequence number for bad block that failed to be marked bad */
#define YAFFS_SEQUENCE_BAD_BLOCK        0xffff0000

/* ChunkCache is used for short read/write operations.*/
struct yaffs_cache {
        struct yaffs_obj *object;
        int chunk_id;
        int last_use;
        int dirty;
        int n_bytes;            /* Only valid if the cache is dirty */
        int locked;             /* Can't push out or flush while locked. */
        u8 *data;
};

/* yaffs1 tags structures in RAM
 * NB This uses bitfield. Bitfields should not straddle a u32 boundary
 * otherwise the structure size will get blown out.
 */

struct yaffs_tags {
        u32 chunk_id:20;
        u32 serial_number:2;
        u32 n_bytes_lsb:10;
        u32 obj_id:18;
        u32 ecc:12;
        u32 n_bytes_msb:2;
};

union yaffs_tags_union {
        struct yaffs_tags as_tags;
        u8 as_bytes[8];
};


/* Stuff used for extended tags in YAFFS2 */

enum yaffs_ecc_result {
        YAFFS_ECC_RESULT_UNKNOWN,
        YAFFS_ECC_RESULT_NO_ERROR,
        YAFFS_ECC_RESULT_FIXED,
        YAFFS_ECC_RESULT_UNFIXED
};

enum yaffs_obj_type {
        YAFFS_OBJECT_TYPE_UNKNOWN,
        YAFFS_OBJECT_TYPE_FILE,
        YAFFS_OBJECT_TYPE_SYMLINK,
        YAFFS_OBJECT_TYPE_DIRECTORY,
        YAFFS_OBJECT_TYPE_HARDLINK,
        YAFFS_OBJECT_TYPE_SPECIAL
};

#define YAFFS_OBJECT_TYPE_MAX YAFFS_OBJECT_TYPE_SPECIAL

struct yaffs_ext_tags {
        unsigned chunk_used;    /*  Status of the chunk: used or unused */
        unsigned obj_id;        /* If 0 this is not used */
        unsigned chunk_id;      /* If 0 this is a header, else a data chunk */
        unsigned n_bytes;       /* Only valid for data chunks */

        /* The following stuff only has meaning when we read */
        enum yaffs_ecc_result ecc_result;
        unsigned block_bad;

        /* YAFFS 1 stuff */
        unsigned is_deleted;    /* The chunk is marked deleted */
        unsigned serial_number; /* Yaffs1 2-bit serial number */

        /* YAFFS2 stuff */
        unsigned seq_number;    /* The sequence number of this block */

        /* Extra info if this is an object header (YAFFS2 only) */

        unsigned extra_available;       /* Extra info available if not zero */
        unsigned extra_parent_id;       /* The parent object */
        unsigned extra_is_shrink;       /* Is it a shrink header? */
        unsigned extra_shadows; /* Does this shadow another object? */

        enum yaffs_obj_type extra_obj_type;     /* What object type? */

        Y_LOFF_T extra_file_size;               /* Length if it is a file */
        unsigned extra_equiv_id;        /* Equivalent object for a hard link */
};

/* Spare structure for YAFFS1 */
struct yaffs_spare {
        u8 tb0;
        u8 tb1;
        u8 tb2;
        u8 tb3;
        u8 page_status;         /* set to 0 to delete the chunk */
        u8 block_status;
        u8 tb4;
        u8 tb5;
        u8 ecc1[3];
        u8 tb6;
        u8 tb7;
        u8 ecc2[3];
};

/*Special structure for passing through to mtd */
struct yaffs_nand_spare {
        struct yaffs_spare spare;
        int eccres1;
        int eccres2;
};

/* Block data in RAM */

enum yaffs_block_state {
        YAFFS_BLOCK_STATE_UNKNOWN = 0,

        YAFFS_BLOCK_STATE_SCANNING,
        /* Being scanned */

        YAFFS_BLOCK_STATE_NEEDS_SCAN,
        /* The block might have something on it (ie it is allocating or full,
         * perhaps empty) but it needs to be scanned to determine its true
         * state.
         * This state is only valid during scanning.
         * NB We tolerate empty because the pre-scanner might be incapable of
         * deciding
         * However, if this state is returned on a YAFFS2 device,
         * then we expect a sequence number
         */

        YAFFS_BLOCK_STATE_EMPTY,
        /* This block is empty */

        YAFFS_BLOCK_STATE_ALLOCATING,
        /* This block is partially allocated.
         * At least one page holds valid data.
         * This is the one currently being used for page
         * allocation. Should never be more than one of these.
         * If a block is only partially allocated at mount it is treated as
         * full.
         */

        YAFFS_BLOCK_STATE_FULL,
        /* All the pages in this block have been allocated.
         * If a block was only partially allocated when mounted we treat
         * it as fully allocated.
         */

        YAFFS_BLOCK_STATE_DIRTY,
        /* The block was full and now all chunks have been deleted.
         * Erase me, reuse me.
         */

        YAFFS_BLOCK_STATE_CHECKPOINT,
        /* This block is assigned to holding checkpoint data. */

        YAFFS_BLOCK_STATE_COLLECTING,
        /* This block is being garbage collected */

        YAFFS_BLOCK_STATE_DEAD
            /* This block has failed and is not in use */
};

#define YAFFS_NUMBER_OF_BLOCK_STATES (YAFFS_BLOCK_STATE_DEAD + 1)

struct yaffs_block_info {

        s32 soft_del_pages:10;  /* number of soft deleted pages */
        s32 pages_in_use:10;    /* number of pages in use */
        u32 block_state:4;      /* One of the above block states. */
                                /* NB use unsigned because enum is sometimes
                                 * an int */
        u32 needs_retiring:1;   /* Data has failed on this block, */
                                /*need to get valid data off and retire*/
        u32 skip_erased_check:1;/* Skip the erased check on this block */
        u32 gc_prioritise:1;    /* An ECC check or blank check has failed.
                                   Block should be prioritised for GC */
        u32 chunk_error_strikes:3;      /* How many times we've had ecc etc
                                failures on this block and tried to reuse it */
        u32 has_summary:1;      /* The block has a summary */

        u32 has_shrink_hdr:1;   /* This block has at least one shrink header */
        u32 seq_number;         /* block sequence number for yaffs2 */

};

/* -------------------------- Object structure -------------------------------*/
/* This is the object structure as stored on NAND */

struct yaffs_obj_hdr {
        enum yaffs_obj_type type;

        /* Apply to everything  */
        int parent_obj_id;
        u16 sum_no_longer_used; /* checksum of name. No longer used */
        YCHAR name[YAFFS_MAX_NAME_LENGTH + 1];

        /* The following apply to all object types except for hard links */
        u32 yst_mode;           /* protection */

        u32 yst_uid;
        u32 yst_gid;
        u32 yst_atime;
        u32 yst_mtime;
        u32 yst_ctime;

        /* File size  applies to files only */
        u32 file_size_low;

        /* Equivalent object id applies to hard links only. */
        int equiv_id;

        /* Alias is for symlinks only. */
        YCHAR alias[YAFFS_MAX_ALIAS_LENGTH + 1];

        u32 yst_rdev;   /* stuff for block and char devices (major/min) */

        u32 win_ctime[2];
        u32 win_atime[2];
        u32 win_mtime[2];

        u32 inband_shadowed_obj_id;
        u32 inband_is_shrink;

        u32 file_size_high;
        u32 reserved[1];
        int shadows_obj;        /* This object header shadows the
                                specified object if > 0 */

        /* is_shrink applies to object headers written when wemake a hole. */
        u32 is_shrink;

};

/*--------------------------- Tnode -------------------------- */

struct yaffs_tnode {
        struct yaffs_tnode *internal[YAFFS_NTNODES_INTERNAL];
};

/*------------------------  Object -----------------------------*/
/* An object can be one of:
 * - a directory (no data, has children links
 * - a regular file (data.... not prunes :->).
 * - a symlink [symbolic link] (the alias).
 * - a hard link
 */

struct yaffs_file_var {
        Y_LOFF_T file_size;
        Y_LOFF_T scanned_size;
        Y_LOFF_T shrink_size;
        int top_level;
        struct yaffs_tnode *top;
};

struct yaffs_dir_var {
        struct list_head children;      /* list of child links */
        struct list_head dirty; /* Entry for list of dirty directories */
};

struct yaffs_symlink_var {
        YCHAR *alias;
};

struct yaffs_hardlink_var {
        struct yaffs_obj *equiv_obj;
        u32 equiv_id;
};

union yaffs_obj_var {
        struct yaffs_file_var file_variant;
        struct yaffs_dir_var dir_variant;
        struct yaffs_symlink_var symlink_variant;
        struct yaffs_hardlink_var hardlink_variant;
};

struct yaffs_obj {
        u8 deleted:1;           /* This should only apply to unlinked files. */
        u8 soft_del:1;          /* it has also been soft deleted */
        u8 unlinked:1;          /* An unlinked file.*/
        u8 fake:1;              /* A fake object has no presence on NAND. */
        u8 rename_allowed:1;    /* Some objects cannot be renamed. */
        u8 unlink_allowed:1;
        u8 dirty:1;             /* the object needs to be written to flash */
        u8 valid:1;             /* When the file system is being loaded up, this
                                 * object might be created before the data
                                 * is available
                                 * ie. file data chunks encountered before
                                * the header.
                                 */
        u8 lazy_loaded:1;       /* This object has been lazy loaded and
                                 * is missing some detail */

        u8 defered_free:1;      /* Object is removed from NAND, but is
                                 * still in the inode cache.
                                 * Free of object is defered.
                                 * until the inode is released.
                                 */
        u8 being_created:1;     /* This object is still being created
                                 * so skip some verification checks. */
        u8 is_shadowed:1;       /* This object is shadowed on the way
                                 * to being renamed. */

        u8 xattr_known:1;       /* We know if this has object has xattribs
                                 * or not. */
        u8 has_xattr:1;         /* This object has xattribs.
                                 * Only valid if xattr_known. */

        u8 serial;              /* serial number of chunk in NAND.*/
        u16 sum;                /* sum of the name to speed searching */

        struct yaffs_dev *my_dev;       /* The device I'm on */

        struct list_head hash_link;     /* list of objects in hash bucket */

        struct list_head hard_links;    /* hard linked object chain*/

        /* directory structure stuff */
        /* also used for linking up the free list */
        struct yaffs_obj *parent;
        struct list_head siblings;

        /* Where's my object header in NAND? */
        int hdr_chunk;

        int n_data_chunks;      /* Number of data chunks for this file. */

        u32 obj_id;             /* the object id value */

        u32 yst_mode;

        YCHAR short_name[YAFFS_SHORT_NAME_LENGTH + 1];

#ifdef CONFIG_YAFFS_WINCE
        u32 win_ctime[2];
        u32 win_mtime[2];
        u32 win_atime[2];
#else
        u32 yst_uid;
        u32 yst_gid;
        u32 yst_atime;
        u32 yst_mtime;
        u32 yst_ctime;
#endif

        u32 yst_rdev;

        void *my_inode;

        enum yaffs_obj_type variant_type;

        union yaffs_obj_var variant;

};

struct yaffs_obj_bucket {
        struct list_head list;
        int count;
};

/* yaffs_checkpt_obj holds the definition of an object as dumped
 * by checkpointing.
 */

struct yaffs_checkpt_obj {
        int struct_type;
        u32 obj_id;
        u32 parent_id;
        int hdr_chunk;
        enum yaffs_obj_type variant_type:3;
        u8 deleted:1;
        u8 soft_del:1;
        u8 unlinked:1;
        u8 fake:1;
        u8 rename_allowed:1;
        u8 unlink_allowed:1;
        u8 serial;
        int n_data_chunks;
        Y_LOFF_T size_or_equiv_obj;
};

/*--------------------- Temporary buffers ----------------
 *
 * These are chunk-sized working buffers. Each device has a few.
 */

struct yaffs_buffer {
        u8 *buffer;
        int in_use;
};

/*----------------- Device ---------------------------------*/

struct yaffs_param {
        const YCHAR *name;

        /*
         * Entry parameters set up way early. Yaffs sets up the rest.
         * The structure should be zeroed out before use so that unused
         * and default values are zero.
         */

        int inband_tags;        /* Use unband tags */
        u32 total_bytes_per_chunk;      /* Should be >= 512, does not need to
                                         be a power of 2 */
        int chunks_per_block;   /* does not need to be a power of 2 */
        int spare_bytes_per_chunk;      /* spare area size */
        int start_block;        /* Start block we're allowed to use */
        int end_block;          /* End block we're allowed to use */
        int n_reserved_blocks;  /* Tuneable so that we can reduce
                                 * reserved blocks on NOR and RAM. */

        int n_caches;           /* If <= 0, then short op caching is disabled,
                                 * else the number of short op caches.
                                 */
        int cache_bypass_aligned; /* If non-zero then bypass the cache for
                                   * aligned writes.
                                   */

        int use_nand_ecc;       /* Flag to decide whether or not to use
                                 * NAND driver ECC on data (yaffs1) */
        int tags_9bytes;        /* Use 9 byte tags */
        int no_tags_ecc;        /* Flag to decide whether or not to do ECC
                                 * on packed tags (yaffs2) */

        int is_yaffs2;          /* Use yaffs2 mode on this device */

        int empty_lost_n_found; /* Auto-empty lost+found directory on mount */

        int refresh_period;     /* How often to check for a block refresh */

        /* Checkpoint control. Can be set before or after initialisation */
        u8 skip_checkpt_rd;
        u8 skip_checkpt_wr;

        int enable_xattr;       /* Enable xattribs */

        int max_objects;        /*
                                 * Set to limit the number of objects created.
                                 * 0 = no limit.
                                */

        /* The remove_obj_fn function must be supplied by OS flavours that
         * need it.
         * yaffs direct uses it to implement the faster readdir.
         * Linux uses it to protect the directory during unlocking.
         */
        void (*remove_obj_fn) (struct yaffs_obj *obj);

        /* Callback to mark the superblock dirty */
        void (*sb_dirty_fn) (struct yaffs_dev *dev);

        /*  Callback to control garbage collection. */
        unsigned (*gc_control_fn) (struct yaffs_dev *dev);

        /* Debug control flags. Don't use unless you know what you're doing */
        int use_header_file_size;       /* Flag to determine if we should use
                                         * file sizes from the header */
        int disable_lazy_load;  /* Disable lazy loading on this device */
        int wide_tnodes_disabled;       /* Set to disable wide tnodes */
        int disable_soft_del;   /* yaffs 1 only: Set to disable the use of
                                 * softdeletion. */

        int defered_dir_update; /* Set to defer directory updates */

#ifdef CONFIG_YAFFS_AUTO_UNICODE
        int auto_unicode;
#endif
        int always_check_erased;        /* Force chunk erased check always on */

        int disable_summary;
        int disable_bad_block_marking;

};

struct yaffs_driver {
        int (*drv_write_chunk_fn) (struct yaffs_dev *dev, int nand_chunk,
                                   const u8 *data, int data_len,
                                   const u8 *oob, int oob_len);
        int (*drv_read_chunk_fn) (struct yaffs_dev *dev, int nand_chunk,
                                   u8 *data, int data_len,
                                   u8 *oob, int oob_len,
                                   enum yaffs_ecc_result *ecc_result);
        int (*drv_erase_fn) (struct yaffs_dev *dev, int block_no);
        int (*drv_mark_bad_fn) (struct yaffs_dev *dev, int block_no);
        int (*drv_check_bad_fn) (struct yaffs_dev *dev, int block_no);
        int (*drv_initialise_fn) (struct yaffs_dev *dev);
        int (*drv_deinitialise_fn) (struct yaffs_dev *dev);
};

struct yaffs_tags_handler {
        int (*write_chunk_tags_fn) (struct yaffs_dev *dev,
                                    int nand_chunk, const u8 *data,
                                    const struct yaffs_ext_tags *tags);
        int (*read_chunk_tags_fn) (struct yaffs_dev *dev,
                                   int nand_chunk, u8 *data,
                                   struct yaffs_ext_tags *tags);

        int (*query_block_fn) (struct yaffs_dev *dev, int block_no,
                               enum yaffs_block_state *state,
                               u32 *seq_number);
        int (*mark_bad_fn) (struct yaffs_dev *dev, int block_no);
};

struct yaffs_dev {
        struct yaffs_param param;
        struct yaffs_driver drv;
        struct yaffs_tags_handler tagger;

        /* Context storage. Holds extra OS specific data for this device */

        void *os_context;
        void *driver_context;

        struct list_head dev_list;

        int ll_init;
        /* Runtime parameters. Set up by YAFFS. */
        int data_bytes_per_chunk;

        /* Non-wide tnode stuff */
        u16 chunk_grp_bits;     /* Number of bits that need to be resolved if
                                 * the tnodes are not wide enough.
                                 */
        u16 chunk_grp_size;     /* == 2^^chunk_grp_bits */

        /* Stuff to support wide tnodes */
        u32 tnode_width;
        u32 tnode_mask;
        u32 tnode_size;

        /* Stuff for figuring out file offset to chunk conversions */
        u32 chunk_shift;        /* Shift value */
        u32 chunk_div;          /* Divisor after shifting: 1 for 2^n sizes */
        u32 chunk_mask;         /* Mask to use for power-of-2 case */

        int is_mounted;
        int read_only;
        int is_checkpointed;

        /* Stuff to support block offsetting to support start block zero */
        int internal_start_block;
        int internal_end_block;
        int block_offset;
        int chunk_offset;

        /* Runtime checkpointing stuff */
        int checkpt_page_seq;   /* running sequence number of checkpt pages */
        int checkpt_byte_count;
        int checkpt_byte_offs;
        u8 *checkpt_buffer;
        int checkpt_open_write;
        int blocks_in_checkpt;
        int checkpt_cur_chunk;
        int checkpt_cur_block;
        int checkpt_next_block;
        int *checkpt_block_list;
        int checkpt_max_blocks;
        u32 checkpt_sum;
        u32 checkpt_xor;

        int checkpoint_blocks_required; /* Number of blocks needed to store
                                         * current checkpoint set */

        /* Block Info */
        struct yaffs_block_info *block_info;
        u8 *chunk_bits;         /* bitmap of chunks in use */
        u8 block_info_alt:1;    /* allocated using alternative alloc */
        u8 chunk_bits_alt:1;    /* allocated using alternative alloc */
        int chunk_bit_stride;   /* Number of bytes of chunk_bits per block.
                                 * Must be consistent with chunks_per_block.
                                 */

        int n_erased_blocks;
        int alloc_block;        /* Current block being allocated off */
        u32 alloc_page;
        int alloc_block_finder; /* Used to search for next allocation block */

        /* Object and Tnode memory management */
        void *allocator;
        int n_obj;
        int n_tnodes;

        int n_hardlinks;

        struct yaffs_obj_bucket obj_bucket[YAFFS_NOBJECT_BUCKETS];
        u32 bucket_finder;

        int n_free_chunks;

        /* Garbage collection control */
        u32 *gc_cleanup_list;   /* objects to delete at the end of a GC. */
        u32 n_clean_ups;

        unsigned has_pending_prioritised_gc;    /* We think this device might
                                                have pending prioritised gcs */
        unsigned gc_disable;
        unsigned gc_block_finder;
        unsigned gc_dirtiest;
        unsigned gc_pages_in_use;
        unsigned gc_not_done;
        unsigned gc_block;
        unsigned gc_chunk;
        unsigned gc_skip;
        struct yaffs_summary_tags *gc_sum_tags;

        /* Special directories */
        struct yaffs_obj *root_dir;
        struct yaffs_obj *lost_n_found;

        int buffered_block;     /* Which block is buffered here? */
        int doing_buffered_block_rewrite;

        struct yaffs_cache *cache;
        int cache_last_use;

        /* Stuff for background deletion and unlinked files. */
        struct yaffs_obj *unlinked_dir; /* Directory where unlinked and deleted
                                         files live. */
        struct yaffs_obj *del_dir;      /* Directory where deleted objects are
                                        sent to disappear. */
        struct yaffs_obj *unlinked_deletion;    /* Current file being
                                                        background deleted. */
        int n_deleted_files;    /* Count of files awaiting deletion; */
        int n_unlinked_files;   /* Count of unlinked files. */
        int n_bg_deletions;     /* Count of background deletions. */

        /* Temporary buffer management */
        struct yaffs_buffer temp_buffer[YAFFS_N_TEMP_BUFFERS];
        int max_temp;
        int temp_in_use;
        int unmanaged_buffer_allocs;
        int unmanaged_buffer_deallocs;

        /* yaffs2 runtime stuff */
        unsigned seq_number;    /* Sequence number of currently
                                        allocating block */
        unsigned oldest_dirty_seq;
        unsigned oldest_dirty_block;

        /* Block refreshing */
        int refresh_skip;       /* A skip down counter.
                                 * Refresh happens when this gets to zero. */

        /* Dirty directory handling */
        struct list_head dirty_dirs;    /* List of dirty directories */

        /* Summary */
        int chunks_per_summary;
        struct yaffs_summary_tags *sum_tags;

        /* Statistics */
        u32 n_page_writes;
        u32 n_page_reads;
        u32 n_erasures;
        u32 n_bad_queries;
        u32 n_bad_markings;
        u32 n_erase_failures;
        u32 n_gc_copies;
        u32 all_gcs;
        u32 passive_gc_count;
        u32 oldest_dirty_gc_count;
        u32 n_gc_blocks;
        u32 bg_gcs;
        u32 n_retried_writes;
        u32 n_retired_blocks;
        u32 n_ecc_fixed;
        u32 n_ecc_unfixed;
        u32 n_tags_ecc_fixed;
        u32 n_tags_ecc_unfixed;
        u32 n_deletions;
        u32 n_unmarked_deletions;
        u32 refresh_count;
        u32 cache_hits;
        u32 tags_used;
        u32 summary_used;

};

/* The CheckpointDevice structure holds the device information that changes
 *at runtime and must be preserved over unmount/mount cycles.
 */
struct yaffs_checkpt_dev {
        int struct_type;
        int n_erased_blocks;
        int alloc_block;        /* Current block being allocated off */
        u32 alloc_page;
        int n_free_chunks;

        int n_deleted_files;    /* Count of files awaiting deletion; */
        int n_unlinked_files;   /* Count of unlinked files. */
        int n_bg_deletions;     /* Count of background deletions. */

        /* yaffs2 runtime stuff */
        unsigned seq_number;    /* Sequence number of currently
                                 * allocating block */

};

struct yaffs_checkpt_validity {
        int struct_type;
        u32 magic;
        u32 version;
        u32 head;
};

struct yaffs_shadow_fixer {
        int obj_id;
        int shadowed_id;
        struct yaffs_shadow_fixer *next;
};

/* Structure for doing xattr modifications */
struct yaffs_xattr_mod {
        int set;                /* If 0 then this is a deletion */
        const YCHAR *name;
        const void *data;
        int size;
        int flags;
        int result;
};

/*----------------------- YAFFS Functions -----------------------*/

int yaffs_guts_initialise(struct yaffs_dev *dev);
void yaffs_deinitialise(struct yaffs_dev *dev);

int yaffs_get_n_free_chunks(struct yaffs_dev *dev);

int yaffs_rename_obj(struct yaffs_obj *old_dir, const YCHAR * old_name,
                     struct yaffs_obj *new_dir, const YCHAR * new_name);

int yaffs_unlinker(struct yaffs_obj *dir, const YCHAR * name);
int yaffs_del_obj(struct yaffs_obj *obj);
struct yaffs_obj *yaffs_retype_obj(struct yaffs_obj *obj,
                                   enum yaffs_obj_type type);


int yaffs_get_obj_name(struct yaffs_obj *obj, YCHAR * name, int buffer_size);
Y_LOFF_T yaffs_get_obj_length(struct yaffs_obj *obj);
int yaffs_get_obj_inode(struct yaffs_obj *obj);
unsigned yaffs_get_obj_type(struct yaffs_obj *obj);
int yaffs_get_obj_link_count(struct yaffs_obj *obj);

/* File operations */
int yaffs_file_rd(struct yaffs_obj *obj, u8 * buffer, Y_LOFF_T offset,
                  int n_bytes);
int yaffs_wr_file(struct yaffs_obj *obj, const u8 * buffer, Y_LOFF_T offset,
                  int n_bytes, int write_trhrough);
int yaffs_resize_file(struct yaffs_obj *obj, Y_LOFF_T new_size);

struct yaffs_obj *yaffs_create_file(struct yaffs_obj *parent,
                                    const YCHAR *name, u32 mode, u32 uid,
                                    u32 gid);

int yaffs_flush_file(struct yaffs_obj *in,
                     int update_time,
                     int data_sync,
                     int discard_cache);

/* Flushing and checkpointing */
void yaffs_flush_whole_cache(struct yaffs_dev *dev, int discard);

int yaffs_checkpoint_save(struct yaffs_dev *dev);
int yaffs_checkpoint_restore(struct yaffs_dev *dev);

/* Directory operations */
struct yaffs_obj *yaffs_create_dir(struct yaffs_obj *parent, const YCHAR *name,
                                   u32 mode, u32 uid, u32 gid);
struct yaffs_obj *yaffs_find_by_name(struct yaffs_obj *the_dir,
                                     const YCHAR *name);
struct yaffs_obj *yaffs_find_by_number(struct yaffs_dev *dev, u32 number);

/* Link operations */
struct yaffs_obj *yaffs_link_obj(struct yaffs_obj *parent, const YCHAR *name,
                                 struct yaffs_obj *equiv_obj);

struct yaffs_obj *yaffs_get_equivalent_obj(struct yaffs_obj *obj);

/* Symlink operations */
struct yaffs_obj *yaffs_create_symlink(struct yaffs_obj *parent,
                                       const YCHAR *name, u32 mode, u32 uid,
                                       u32 gid, const YCHAR *alias);
YCHAR *yaffs_get_symlink_alias(struct yaffs_obj *obj);

/* Special inodes (fifos, sockets and devices) */
struct yaffs_obj *yaffs_create_special(struct yaffs_obj *parent,
                                       const YCHAR *name, u32 mode, u32 uid,
                                       u32 gid, u32 rdev);

int yaffs_set_xattrib(struct yaffs_obj *obj, const YCHAR *name,
                      const void *value, int size, int flags);
int yaffs_get_xattrib(struct yaffs_obj *obj, const YCHAR *name, void *value,
                      int size);
int yaffs_list_xattrib(struct yaffs_obj *obj, char *buffer, int size);
int yaffs_remove_xattrib(struct yaffs_obj *obj, const YCHAR *name);

/* Special directories */
struct yaffs_obj *yaffs_root(struct yaffs_dev *dev);
struct yaffs_obj *yaffs_lost_n_found(struct yaffs_dev *dev);

void yaffs_handle_defered_free(struct yaffs_obj *obj);

void yaffs_update_dirty_dirs(struct yaffs_dev *dev);

int yaffs_bg_gc(struct yaffs_dev *dev, unsigned urgency);

/* Debug dump  */
int yaffs_dump_obj(struct yaffs_obj *obj);

void yaffs_guts_test(struct yaffs_dev *dev);
int yaffs_guts_ll_init(struct yaffs_dev *dev);


/* A few useful functions to be used within the core files*/
void yaffs_chunk_del(struct yaffs_dev *dev, int chunk_id, int mark_flash,
                     int lyn);
int yaffs_check_ff(u8 *buffer, int n_bytes);
void yaffs_handle_chunk_error(struct yaffs_dev *dev,
                              struct yaffs_block_info *bi);

u8 *yaffs_get_temp_buffer(struct yaffs_dev *dev);
void yaffs_release_temp_buffer(struct yaffs_dev *dev, u8 *buffer);

struct yaffs_obj *yaffs_find_or_create_by_number(struct yaffs_dev *dev,
                                                 int number,
                                                 enum yaffs_obj_type type);
int yaffs_put_chunk_in_file(struct yaffs_obj *in, int inode_chunk,
                            int nand_chunk, int in_scan);
void yaffs_set_obj_name(struct yaffs_obj *obj, const YCHAR *name);
void yaffs_set_obj_name_from_oh(struct yaffs_obj *obj,
                                const struct yaffs_obj_hdr *oh);
void yaffs_add_obj_to_dir(struct yaffs_obj *directory, struct yaffs_obj *obj);
YCHAR *yaffs_clone_str(const YCHAR *str);
void yaffs_link_fixup(struct yaffs_dev *dev, struct list_head *hard_list);
void yaffs_block_became_dirty(struct yaffs_dev *dev, int block_no);
int yaffs_update_oh(struct yaffs_obj *in, const YCHAR *name,
                    int force, int is_shrink, int shadows,
                    struct yaffs_xattr_mod *xop);
void yaffs_handle_shadowed_obj(struct yaffs_dev *dev, int obj_id,
                               int backward_scanning);
int yaffs_check_alloc_available(struct yaffs_dev *dev, int n_chunks);
struct yaffs_tnode *yaffs_get_tnode(struct yaffs_dev *dev);
struct yaffs_tnode *yaffs_add_find_tnode_0(struct yaffs_dev *dev,
                                           struct yaffs_file_var *file_struct,
                                           u32 chunk_id,
                                           struct yaffs_tnode *passed_tn);

int yaffs_do_file_wr(struct yaffs_obj *in, const u8 *buffer, Y_LOFF_T offset,
                     int n_bytes, int write_trhrough);
void yaffs_resize_file_down(struct yaffs_obj *obj, Y_LOFF_T new_size);
void yaffs_skip_rest_of_block(struct yaffs_dev *dev);

int yaffs_count_free_chunks(struct yaffs_dev *dev);

struct yaffs_tnode *yaffs_find_tnode_0(struct yaffs_dev *dev,
                                       struct yaffs_file_var *file_struct,
                                       u32 chunk_id);

u32 yaffs_get_group_base(struct yaffs_dev *dev, struct yaffs_tnode *tn,
                         unsigned pos);

int yaffs_is_non_empty_dir(struct yaffs_obj *obj);

int yaffs_guts_format_dev(struct yaffs_dev *dev);

void yaffs_addr_to_chunk(struct yaffs_dev *dev, Y_LOFF_T addr,
                                int *chunk_out, u32 *offset_out);
/*
 * Marshalling functions to get Y_LOFF_T file sizes into aand out of
 * object headers.
 */
void yaffs_oh_size_load(struct yaffs_obj_hdr *oh, Y_LOFF_T fsize);
Y_LOFF_T yaffs_oh_to_size(struct yaffs_obj_hdr *oh);
Y_LOFF_T yaffs_max_file_size(struct yaffs_dev *dev);

/*
 * Debug function to count number of blocks in each state
 * NB Needs to be called with correct number of integers
 */

void yaffs_count_blocks_by_state(struct yaffs_dev *dev, int bs[10]);

int yaffs_find_chunk_in_file(struct yaffs_obj *in, int inode_chunk,
                                    struct yaffs_ext_tags *tags);

#endif