Modules/Filesystems/Ext2/write.c

   1 /*
   2  * Acess OS
   3  * Ext2 Driver Version 1
   4  */
   5 /**
   6  * \file write.c
   7  * \brief Second Extended Filesystem Driver
   8  * \todo Implement file full write support
   9  */
  10 #define DEBUG   1
  11 #define VERBOSE 0
  12 #include "ext2_common.h"
  13
  14 // === PROTOYPES ===
  15 Uint32          Ext2_int_AllocateBlock(tExt2_Disk *Disk, Uint32 PrevBlock);
  16 void    Ext2_int_DeallocateBlock(tExt2_Disk *Disk, Uint32 Block);
  17  int    Ext2_int_AppendBlock(tExt2_Disk *Disk, tExt2_Inode *Inode, Uint32 Block);
  18
  19 // === CODE ===
  20 /**
  21  * \fn Uint64 Ext2_Write(tVFS_Node *Node, Uint64 Offset, Uint64 Length, void *Buffer)
  22  * \brief Write to a file
  23  */
  24 Uint64 Ext2_Write(tVFS_Node *Node, Uint64 Offset, Uint64 Length, const void *Buffer)
  25 {
  26         tExt2_Disk      *disk = Node->ImplPtr;
  27         tExt2_Inode     inode;
  28         Uint64  base;
  29         Uint64  retLen;
  30         Uint    block;
  31         Uint64  allocSize;
  32          int    bNewBlocks = 0;
  33
  34         Debug_HexDump("Ext2_Write", Buffer, Length);
  35
  36         Ext2_int_ReadInode(disk, Node->Inode, &inode);
  37
  38         // Get the ammount of space already allocated
  39         // - Round size up to block size
  40         // - block size is a power of two, so this will work
  41         allocSize = (inode.i_size + disk->BlockSize-1) & ~(disk->BlockSize-1);
  42
  43         // Are we writing to inside the allocated space?
  44         if( Offset > allocSize )        return 0;
  45
  46         if( Offset < allocSize )
  47         {
  48                 // Will we go out of it?
  49                 if(Offset + Length > allocSize) {
  50                         bNewBlocks = 1;
  51                         retLen = allocSize - Offset;
  52                 } else
  53                         retLen = Length;
  54
  55                 // Within the allocated space
  56                 block = Offset / disk->BlockSize;
  57                 Offset %= disk->BlockSize;
  58                 base = Ext2_int_GetBlockAddr(disk, inode.i_block, block);
  59
  60                 // Write only block (if only one)
  61                 if(Offset + retLen <= disk->BlockSize) {
  62                         VFS_WriteAt(disk->FD, base+Offset, retLen, Buffer);
  63                         if(!bNewBlocks) return Length;
  64                         goto addBlocks; // Ugh! A goto, but it seems unavoidable
  65                 }
  66
  67                 // Write First Block
  68                 VFS_WriteAt(disk->FD, base+Offset, disk->BlockSize-Offset, Buffer);
  69                 Buffer += disk->BlockSize-Offset;
  70                 retLen -= disk->BlockSize-Offset;
  71                 block ++;
  72
  73                 // Write middle blocks
  74                 while(retLen > disk->BlockSize)
  75                 {
  76                         base = Ext2_int_GetBlockAddr(disk, inode.i_block, block);
  77                         VFS_WriteAt(disk->FD, base, disk->BlockSize, Buffer);
  78                         Buffer += disk->BlockSize;
  79                         retLen -= disk->BlockSize;
  80                         block ++;
  81                 }
  82
  83                 // Write last block
  84                 base = Ext2_int_GetBlockAddr(disk, inode.i_block, block);
  85                 VFS_WriteAt(disk->FD, base, retLen, Buffer);
  86                 if(!bNewBlocks) return Length;  // Writing in only allocated space
  87         }
  88         else
  89                 base = Ext2_int_GetBlockAddr(disk, inode.i_block, allocSize/disk->BlockSize-1);
  90
  91 addBlocks:
  92         Log_Notice("EXT2", "File extending is untested");
  93
  94         // Allocate blocks and copy data to them
  95         retLen = Length - (allocSize-Offset);
  96         while( retLen > disk->BlockSize )
  97         {
  98                 // Allocate a block
  99                 block = Ext2_int_AllocateBlock(disk, base/disk->BlockSize);
 100                 if(!block)      return Length - retLen;
 101                 // Add it to this inode
 102                 if( !Ext2_int_AppendBlock(disk, &inode, block) ) {
 103                         Ext2_int_DeallocateBlock(disk, block);
 104                         goto ret;
 105                 }
 106                 // Copy data to the node
 107                 base = block * disk->BlockSize;
 108                 VFS_WriteAt(disk->FD, base, disk->BlockSize, Buffer);
 109                 // Update pointer and size remaining
 110                 inode.i_size += disk->BlockSize;
 111                 Buffer += disk->BlockSize;
 112                 retLen -= disk->BlockSize;
 113         }
 114         // Last block :D
 115         block = Ext2_int_AllocateBlock(disk, base/disk->BlockSize);
 116         if(!block)      goto ret;
 117         if( !Ext2_int_AppendBlock(disk, &inode, block) ) {
 118                 Ext2_int_DeallocateBlock(disk, block);
 119                 goto ret;
 120         }
 121         base = block * disk->BlockSize;
 122         VFS_WriteAt(disk->FD, base, retLen, Buffer);
 123         inode.i_size += retLen;
 124         retLen = 0;
 125
 126 ret:    // Makes sure the changes to the inode are committed
 127         Ext2_int_WriteInode(disk, Node->Inode, &inode);
 128         return Length - retLen;
 129 }
 130
 131 /**
 132  * \fn Uint32 Ext2_int_AllocateBlock(tExt2_Disk *Disk, Uint32 PrevBlock)
 133  * \brief Allocate a block from the best possible location
 134  * \param Disk  EXT2 Disk Information Structure
 135  * \param PrevBlock     Previous block ID in the file
 136  */
 137 Uint32 Ext2_int_AllocateBlock(tExt2_Disk *Disk, Uint32 PrevBlock)
 138 {
 139          int    bpg = Disk->SuperBlock.s_blocks_per_group;
 140         Uint    blockgroup = PrevBlock / bpg;
 141         Uint    bitmap[Disk->BlockSize/sizeof(Uint)];
 142         Uint    bitsperblock = 8*Disk->BlockSize;
 143          int    i, j = 0;
 144         Uint    block;
 145
 146         // Are there any free blocks?
 147         if(Disk->SuperBlock.s_free_blocks_count == 0)   return 0;
 148
 149         if(Disk->Groups[blockgroup].bg_free_blocks_count > 0)
 150         {
 151                 // Search block group's bitmap
 152                 for(i = 0; i < bpg; i++)
 153                 {
 154                         // Get the block in the bitmap block
 155                         j = i & (bitsperblock-1);
 156
 157                         // Read in if needed
 158                         if(j == 0) {
 159                                 VFS_ReadAt(
 160                                         Disk->FD,
 161                                         (Uint64)Disk->Groups[blockgroup].bg_block_bitmap + i / bitsperblock,
 162                                         Disk->BlockSize,
 163                                         bitmap
 164                                         );
 165                         }
 166
 167                         // Fast Check
 168                         if( bitmap[j/32] == 0xFFFFFFFF ) {
 169                                 j = (j + 31) & ~31;
 170                                 continue;
 171                         }
 172
 173                         // Is the bit set?
 174                         if( bitmap[j/32] & (1 << (j%32)) )
 175                                 continue;
 176
 177                         // Ooh! We found one
 178                         break;
 179                 }
 180                 if( i < bpg ) {
 181                         Warning("[EXT2 ] Inconsistency detected, Group Free Block count is non-zero when no free blocks exist");
 182                         goto    checkAll;       // Search the entire filesystem for a free block
 183                         // Goto needed for neatness
 184                 }
 185
 186                 // Mark as used
 187                 bitmap[j/32] |= (1 << (j%32));
 188                 VFS_WriteAt(
 189                         Disk->FD,
 190                         (Uint64)Disk->Groups[blockgroup].bg_block_bitmap + i / bitsperblock,
 191                         Disk->BlockSize,
 192                         bitmap
 193                         );
 194                 block = i;
 195                 Disk->Groups[blockgroup].bg_free_blocks_count --;
 196                 #if EXT2_UPDATE_WRITEBACK
 197                 //Ext2_int_UpdateBlockGroup(Disk, blockgroup);
 198                 #endif
 199         }
 200         else
 201         {
 202         checkAll:
 203                 Log_Warning("EXT2", "TODO - Implement using blocks outside the current block group");
 204                 return 0;
 205         }
 206
 207         // Reduce global count
 208         Disk->SuperBlock.s_free_blocks_count --;
 209         #if EXT2_UPDATE_WRITEBACK
 210         Ext2_int_UpdateSuperblock(Disk);
 211         #endif
 212
 213         return block;
 214 }
 215
 216 /**
 217  * \brief Deallocates a block
 218  */
 219 void Ext2_int_DeallocateBlock(tExt2_Disk *Disk, Uint32 Block)
 220 {
 221 }
 222
 223 /**
 224  * \brief Append a block to an inode
 225  */
 226 int Ext2_int_AppendBlock(tExt2_Disk *Disk, tExt2_Inode *Inode, Uint32 Block)
 227 {
 228          int    nBlocks;
 229          int    dwPerBlock = Disk->BlockSize / 4;
 230         Uint32  *blocks;
 231         Uint32  id1, id2;
 232
 233         nBlocks = (Inode->i_size + Disk->BlockSize - 1) / Disk->BlockSize;
 234
 235         // Direct Blocks
 236         if( nBlocks < 12 ) {
 237                 Inode->i_block[nBlocks] = Block;
 238                 return 0;
 239         }
 240
 241         blocks = malloc( Disk->BlockSize );
 242         if(!blocks)     return 1;
 243
 244         nBlocks -= 12;
 245         // Single Indirect
 246         if( nBlocks < dwPerBlock)
 247         {
 248                 // Allocate/Get Indirect block
 249                 if( nBlocks == 0 ) {
 250                         Inode->i_block[12] = Ext2_int_AllocateBlock(Disk, Inode->i_block[0]);
 251                         if( !Inode->i_block[12] ) {
 252                                 free(blocks);
 253                                 return 1;
 254                         }
 255                         memset(blocks, 0, Disk->BlockSize);
 256                 }
 257                 else
 258                         VFS_ReadAt(Disk->FD, Inode->i_block[12]*Disk->BlockSize, Disk->BlockSize, blocks);
 259
 260                 blocks[nBlocks] = Block;
 261
 262                 VFS_WriteAt(Disk->FD, Inode->i_block[12]*Disk->BlockSize, Disk->BlockSize, blocks);
 263                 free(blocks);
 264                 return 0;
 265         }
 266
 267         nBlocks += dwPerBlock;
 268         // Double Indirect
 269         if( nBlocks < dwPerBlock*dwPerBlock )
 270         {
 271                 // Allocate/Get Indirect block
 272                 if( nBlocks == 0 ) {
 273                         Inode->i_block[13] = Ext2_int_AllocateBlock(Disk, Inode->i_block[0]);
 274                         if( !Inode->i_block[13] ) {
 275                                 free(blocks);
 276                                 return 1;
 277                         }
 278                         memset(blocks, 0, Disk->BlockSize);
 279                 }
 280                 else
 281                         VFS_ReadAt(Disk->FD, Inode->i_block[13]*Disk->BlockSize, Disk->BlockSize, blocks);
 282
 283                 // Allocate / Get Indirect lvl2 Block
 284                 if( nBlocks % dwPerBlock == 0 ) {
 285                         id1 = Ext2_int_AllocateBlock(Disk, Inode->i_block[0]);
 286                         if( !id1 ) {
 287                                 free(blocks);
 288                                 return 1;
 289                         }
 290                         blocks[nBlocks/dwPerBlock] = id1;
 291                         // Write back indirect 1 block
 292                         VFS_WriteAt(Disk->FD, Inode->i_block[13]*Disk->BlockSize, Disk->BlockSize, blocks);
 293                         memset(blocks, 0, Disk->BlockSize);
 294                 }
 295                 else {
 296                         id1 = blocks[nBlocks / dwPerBlock];
 297                         VFS_ReadAt(Disk->FD, id1*Disk->BlockSize, Disk->BlockSize, blocks);
 298                 }
 299
 300                 blocks[nBlocks % dwPerBlock] = Block;
 301
 302                 VFS_WriteAt(Disk->FD, id1*Disk->BlockSize, Disk->BlockSize, blocks);
 303                 free(blocks);
 304                 return 0;
 305         }
 306
 307         nBlocks -= dwPerBlock*dwPerBlock;
 308         // Triple Indirect
 309         if( nBlocks < dwPerBlock*dwPerBlock*dwPerBlock )
 310         {
 311                 // Allocate/Get Indirect block
 312                 if( nBlocks == 0 ) {
 313                         Inode->i_block[14] = Ext2_int_AllocateBlock(Disk, Inode->i_block[0]);
 314                         if( !Inode->i_block[14] ) {
 315                                 free(blocks);
 316                                 return 1;
 317                         }
 318                         memset(blocks, 0, Disk->BlockSize);
 319                 }
 320                 else
 321                         VFS_ReadAt(Disk->FD, Inode->i_block[14]*Disk->BlockSize, Disk->BlockSize, blocks);
 322
 323                 // Allocate / Get Indirect lvl2 Block
 324                 if( (nBlocks/dwPerBlock) % dwPerBlock == 0 && nBlocks % dwPerBlock == 0 )
 325                 {
 326                         id1 = Ext2_int_AllocateBlock(Disk, Inode->i_block[0]);
 327                         if( !id1 ) {
 328                                 free(blocks);
 329                                 return 1;
 330                         }
 331                         blocks[nBlocks/dwPerBlock] = id1;
 332                         // Write back indirect 1 block
 333                         VFS_WriteAt(Disk->FD, Inode->i_block[14]*Disk->BlockSize, Disk->BlockSize, blocks);
 334                         memset(blocks, 0, Disk->BlockSize);
 335                 }
 336                 else {
 337                         id1 = blocks[nBlocks / (dwPerBlock*dwPerBlock)];
 338                         VFS_ReadAt(Disk->FD, id1*Disk->BlockSize, Disk->BlockSize, blocks);
 339                 }
 340
 341                 // Allocate / Get Indirect Level 3 Block
 342                 if( nBlocks % dwPerBlock == 0 ) {
 343                         id2 = Ext2_int_AllocateBlock(Disk, id1);
 344                         if( !id2 ) {
 345                                 free(blocks);
 346                                 return 1;
 347                         }
 348                         blocks[(nBlocks/dwPerBlock)%dwPerBlock] = id2;
 349                         // Write back indirect 1 block
 350                         VFS_WriteAt(Disk->FD, id1*Disk->BlockSize, Disk->BlockSize, blocks);
 351                         memset(blocks, 0, Disk->BlockSize);
 352                 }
 353                 else {
 354                         id2 = blocks[(nBlocks/dwPerBlock)%dwPerBlock];
 355                         VFS_ReadAt(Disk->FD, id2*Disk->BlockSize, Disk->BlockSize, blocks);
 356                 }
 357
 358                 blocks[nBlocks % dwPerBlock] = Block;
 359
 360                 VFS_WriteAt(Disk->FD, id2*Disk->BlockSize, Disk->BlockSize, blocks);
 361                 free(blocks);
 362                 return 0;
 363         }
 364
 365         Warning("[EXT2 ] Inode %i cannot have a block appended to it, all indirects used");
 366         free(blocks);
 367         return 1;
 368 }