include/linux/jffs.h

   1 /*
   2  * JFFS -- Journalling Flash File System, Linux implementation.
   3  *
   4  * Copyright (C) 1999, 2000  Axis Communications AB.
   5  *
   6  * Created by Finn Hakansson <finn@axis.com>.
   7  *
   8  * This is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * $Id: jffs.h,v 1.11 2000/08/04 12:46:34 dwmw2 Exp $
  14  *
  15  * Ported to Linux 2.3.x and MTD:
  16  * Copyright (C) 2000  Alexander Larsson (alex@cendio.se), Cendio Systems AB
  17  *
  18  */
  19
  20 #ifndef __LINUX_JFFS_H__
  21 #define __LINUX_JFFS_H__
  22
  23 #define JFFS_VERSION_STRING "1.0"
  24
  25 /* This is a magic number that is used as an identification number for
  26    this file system.  It is written to the super_block structure.  */
  27 #define JFFS_MAGIC_SB_BITMASK 0x07c0  /* 1984 */
  28
  29 /* This is a magic number that every on-flash raw inode begins with.  */
  30 #define JFFS_MAGIC_BITMASK 0x34383931 /* "1984" */
  31
  32 /* These two bitmasks are the valid ones for the flash memories we have
  33    for the moment.  */
  34 #define JFFS_EMPTY_BITMASK 0xffffffff
  35 #define JFFS_DIRTY_BITMASK 0x00000000
  36
  37 /* This is the inode number of the root node.  */
  38 #define JFFS_MIN_INO 1
  39
  40 /* How many slots in the file hash table should we have?  */
  41 #define JFFS_HASH_SIZE 40
  42
  43 /* Don't use more than 254 bytes as the maximum allowed length of a file's
  44    name due to errors that could occur during the scanning of the flash
  45    memory. In fact, a name length of 255 or 0xff, could be the result of
  46    an uncompleted write.  For instance, if a raw inode is written to the
  47    flash memory and there is a power lossage just before the length of
  48    the name is written, the length 255 would be interpreted as an illegal
  49    value.  */
  50 #define JFFS_MAX_NAME_LEN 254
  51
  52 /* Commands for ioctl().  */
  53 #define JFFS_IOCTL_MAGIC 't'
  54 #define JFFS_PRINT_HASH _IO(JFFS_IOCTL_MAGIC, 90)
  55 #define JFFS_PRINT_TREE _IO(JFFS_IOCTL_MAGIC, 91)
  56 #define JFFS_GET_STATUS _IO(JFFS_IOCTL_MAGIC, 92)
  57
  58 /* XXX: This is something that we should try to get rid of in the future.  */
  59 #define JFFS_MODIFY_INODE 0x01
  60 #define JFFS_MODIFY_NAME  0x02
  61 #define JFFS_MODIFY_DATA  0x04
  62 #define JFFS_MODIFY_EXIST 0x08
  63
  64 struct jffs_control;
  65
  66 /* The JFFS raw inode structure: Used for storage on physical media.  */
  67 /* Perhaps the uid, gid, atime, mtime and ctime members should have
  68    more space due to future changes in the Linux kernel. Anyhow, since
  69    a user of this filesystem probably have to fix a large number of
  70    other things, we have decided to not be forward compatible.  */
  71 struct jffs_raw_inode
  72 {
  73         __u32 magic;      /* A constant magic number.  */
  74         __u32 ino;        /* Inode number.  */
  75         __u32 pino;       /* Parent's inode number.  */
  76         __u32 version;    /* Version number.  */
  77         __u32 mode;       /* The file's type or mode.  */
  78         __u16 uid;        /* The file's owner.  */
  79         __u16 gid;        /* The file's group.  */
  80         __u32 atime;      /* Last access time.  */
  81         __u32 mtime;      /* Last modification time.  */
  82         __u32 ctime;      /* Creation time.  */
  83         __u32 offset;     /* Where to begin to write.  */
  84         __u32 dsize;      /* Size of the node's data.  */
  85         __u32 rsize;      /* How much are going to be replaced?  */
  86         __u8 nsize;       /* Name length.  */
  87         __u8 nlink;       /* Number of links.  */
  88         __u8 spare : 6;   /* For future use.  */
  89         __u8 rename : 1;  /* Rename to a name of an already existing file?  */
  90         __u8 deleted : 1; /* Has this file been deleted?  */
  91         __u8 accurate;    /* The inode is obsolete if accurate == 0.  */
  92         __u32 dchksum;    /* Checksum for the data.  */
  93         __u16 nchksum;    /* Checksum for the name.  */
  94         __u16 chksum;     /* Checksum for the raw inode.  */
  95 };
  96
  97 /* Define the offset of the accurate byte in struct jffs_raw_inode.  */
  98 #define JFFS_RAW_INODE_ACCURATE_OFFSET (sizeof(struct jffs_raw_inode) \
  99                                         - 2 * sizeof(__u32) - sizeof(__u8))
 100
 101 /* Define the offset of the chksum member in struct jffs_raw_inode.  */
 102 #define JFFS_RAW_INODE_CHKSUM_OFFSET (sizeof(struct jffs_raw_inode) \
 103                                       - sizeof(__u16))
 104
 105 /* Define the offset of the dchksum member in struct jffs_raw_inode.  */
 106 #define JFFS_RAW_INODE_DCHKSUM_OFFSET (sizeof(struct jffs_raw_inode)   \
 107                                        - sizeof(__u16) - sizeof(__u16) \
 108                                        - sizeof(__u32))
 109
 110
 111 /* The RAM representation of the node.  The names of pointers to
 112    jffs_nodes are very often just called `n' in the source code.  */
 113 struct jffs_node
 114 {
 115         __u32 ino;          /* Inode number.  */
 116         __u32 version;      /* Version number.  */
 117         __u32 data_offset;  /* Logic location of the data to insert.  */
 118         __u32 data_size;    /* The amount of data this node inserts.  */
 119         __u32 removed_size; /* The amount of data that this node removes.  */
 120         __u32 fm_offset;    /* Physical location of the data in the actual
 121                                flash memory data chunk.  */
 122         __u8 name_size;     /* Size of the name.  */
 123         struct jffs_fm *fm; /* Physical memory information.  */
 124         struct jffs_node *version_prev;
 125         struct jffs_node *version_next;
 126         struct jffs_node *range_prev;
 127         struct jffs_node *range_next;
 128 };
 129
 130
 131 /* The RAM representation of a file (plain files, directories,
 132    links, etc.).  Pointers to jffs_files are normally named `f'
 133    in the JFFS source code.  */
 134 struct jffs_file
 135 {
 136         __u32 ino;    /* Inode number.  */
 137         __u32 pino;   /* Parent's inode number.  */
 138         __u32 mode;   /* file_type, mode  */
 139         __u16 uid;    /* owner  */
 140         __u16 gid;    /* group  */
 141         __u32 atime;  /* Last access time.  */
 142         __u32 mtime;  /* Last modification time.  */
 143         __u32 ctime;  /* Creation time.  */
 144         __u8 nsize;   /* Name length.  */
 145         __u8 nlink;   /* Number of links.  */
 146         __u8 deleted; /* Has this file been deleted?  */
 147         char *name;   /* The name of this file; NULL-terminated.  */
 148         __u32 size;   /* The total size of the file's data.  */
 149         __u32 highest_version; /* The highest version number of this file.  */
 150         struct jffs_control *c;
 151         struct jffs_file *parent;   /* Reference to the parent directory.  */
 152         struct jffs_file *children; /* Always NULL for plain files.  */
 153         struct jffs_file *sibling_prev; /* Siblings in the same directory.  */
 154         struct jffs_file *sibling_next;
 155         struct list_head hash;    /* hash list.  */
 156         struct jffs_node *range_head;   /* The final data.  */
 157         struct jffs_node *range_tail;   /* The first data.  */
 158         struct jffs_node *version_head; /* The youngest node.  */
 159         struct jffs_node *version_tail; /* The oldest node.  */
 160 };
 161
 162
 163 /* This is just a definition of a simple list used for keeping track of
 164    files deleted due to a rename.  This list is only used during the
 165    mounting of the file system and only if there have been rename operations
 166    earlier.  */
 167 struct jffs_delete_list
 168 {
 169         __u32 ino;
 170         struct jffs_delete_list *next;
 171 };
 172
 173
 174 /* A struct for the overall file system control.  Pointers to
 175    jffs_control structs are named `c' in the source code.  */
 176 struct jffs_control
 177 {
 178         struct super_block *sb;         /* Reference to the VFS super block.  */
 179         struct jffs_file *root;         /* The root directory file.  */
 180         struct list_head *hash;         /* Hash table for finding files by ino.  */
 181         struct jffs_fmcontrol *fmc;     /* Flash memory control structure.  */
 182         __u32 hash_len;                 /* The size of the hash table.  */
 183         __u32 next_ino;                 /* Next inode number to use for new files.  */
 184         __u16 building_fs;              /* Is the file system being built right now?  */
 185         struct jffs_delete_list *delete_list; /* Track deleted files.  */
 186         pid_t thread_pid;               /* GC thread's PID */
 187         struct task_struct *gc_task;    /* GC task struct */
 188         struct semaphore gc_thread_sem; /* GC thread exit mutex */
 189         __u32 gc_minfree_threshold;     /* GC trigger thresholds */
 190         __u32 gc_maxdirty_threshold;
 191 };
 192
 193
 194 /* Used to inform about flash status.  */
 195 struct jffs_flash_status
 196 {
 197         __u32 size;
 198         __u32 used;
 199         __u32 dirty;
 200         __u32 begin;
 201         __u32 end;
 202 };
 203
 204 /* This stuff could be used for finding memory leaks.  */
 205 #define JFFS_MEMORY_DEBUG 0
 206
 207 #if defined(JFFS_MEMORY_DEBUG) && JFFS_MEMORY_DEBUG
 208 extern long no_jffs_file;
 209 extern long no_jffs_node;
 210 extern long no_jffs_control;
 211 extern long no_jffs_raw_inode;
 212 extern long no_jffs_node_ref;
 213 extern long no_jffs_fm;
 214 extern long no_jffs_fmcontrol;
 215 extern long no_hash;
 216 extern long no_name;
 217 #define DJM(x) x
 218 #else
 219 #define DJM(x)
 220 #endif
 221
 222 #endif /* __LINUX_JFFS_H__ */