servers/ext2/inode.c

   1 /* This file manages the inode table.  There are procedures to allocate and
   2  * deallocate inodes, acquire, erase, and release them, and read and write
   3  * them from the disk.
   4  *
   5  * The entry points into this file are
   6  *   get_inode:       search inode table for a given inode; if not there,
   7  *                 read it
   8  *   put_inode:       indicate that an inode is no longer needed in memory
   9  *   update_times: update atime, ctime, and mtime
  10  *   rw_inode:       read a disk block and extract an inode, or corresp. write
  11  *   dup_inode:       indicate that someone else is using an inode table entry
  12  *   find_inode:   retrieve pointer to inode in inode cache
  13  *
  14  * Created (MFS based):
  15  *   February 2010 (Evgeniy Ivanov)
  16  */
  17
  18 #include "fs.h"
  19 #include <string.h>
  20 #include "buf.h"
  21 #include "inode.h"
  22 #include "super.h"
  23 #include <minix/vfsif.h>
  24
  25 static void icopy(struct inode *rip, d_inode *dip, int direction, int
  26         norm);
  27 static void addhash_inode(struct inode *node);
  28 static void unhash_inode(struct inode *node);
  29
  30
  31 /*===========================================================================*
  32  *                fs_putnode                                                 *
  33  *===========================================================================*/
  34 int fs_putnode(void)
  35 {
  36 /* Find the inode specified by the request message and decrease its counter.*/
  37
  38   struct inode *rip;
  39   int count;
  40
  41   rip = find_inode(fs_dev, (ino_t) fs_m_in.REQ_INODE_NR);
  42
  43   if (!rip) {
  44         printf("%s:%d put_inode: inode #%lu dev: %d not found\n", __FILE__,
  45                 __LINE__, (ino_t) fs_m_in.REQ_INODE_NR, fs_dev);
  46         panic("fs_putnode failed");
  47   }
  48
  49   count = fs_m_in.REQ_COUNT;
  50   if (count <= 0) {
  51         printf("%s:%d put_inode: bad value for count: %d\n", __FILE__,
  52                 __LINE__, count);
  53         panic("fs_putnode failed");
  54   } else if (count > rip->i_count) {
  55         printf("%s:%d put_inode: count too high: %d > %d\n", __FILE__,
  56                 __LINE__, count, rip->i_count);
  57         panic("fs_putnode failed");
  58   }
  59
  60   /* Decrease reference counter, but keep one reference;
  61    * it will be consumed by put_inode().
  62    */
  63   rip->i_count -= count - 1;
  64   put_inode(rip);
  65
  66   return(OK);
  67 }
  68
  69
  70 /*===========================================================================*
  71  *                init_inode_cache                                           *
  72  *===========================================================================*/
  73 void init_inode_cache()
  74 {
  75   struct inode *rip;
  76   struct inodelist *rlp;
  77
  78   inode_cache_hit = 0;
  79   inode_cache_miss = 0;
  80
  81   /* init free/unused list */
  82   TAILQ_INIT(&unused_inodes);
  83
  84   /* init hash lists */
  85   for (rlp = &hash_inodes[0]; rlp < &hash_inodes[INODE_HASH_SIZE]; ++rlp)
  86         LIST_INIT(rlp);
  87
  88   /* add free inodes to unused/free list */
  89   for (rip = &inode[0]; rip < &inode[NR_INODES]; ++rip) {
  90         rip->i_num = NO_ENTRY;
  91         TAILQ_INSERT_HEAD(&unused_inodes, rip, i_unused);
  92   }
  93 }
  94
  95
  96 /*===========================================================================*
  97  *                addhash_inode                                              *
  98  *===========================================================================*/
  99 static void addhash_inode(struct inode *node)
 100 {
 101   int hashi = node->i_num & INODE_HASH_MASK;
 102
 103   /* insert into hash table */
 104   LIST_INSERT_HEAD(&hash_inodes[hashi], node, i_hash);
 105 }
 106
 107
 108 /*===========================================================================*
 109  *                unhash_inode                                               *
 110  *===========================================================================*/
 111 static void unhash_inode(struct inode *node)
 112 {
 113   /* remove from hash table */
 114   LIST_REMOVE(node, i_hash);
 115 }
 116
 117
 118 /*===========================================================================*
 119  *                get_inode                                                  *
 120  *===========================================================================*/
 121 struct inode *get_inode(
 122   dev_t dev,          /* device on which inode resides */
 123   ino_t numb            /* inode number (ANSI: may not be unshort) */
 124 )
 125 {
 126 /* Find the inode in the hash table. If it is not there, get a free inode
 127  * load it from the disk if it's necessary and put on the hash list
 128  */
 129   register struct inode *rip;
 130   int hashi;
 131   int i;
 132
 133   hashi = (int) numb & INODE_HASH_MASK;
 134
 135   /* Search inode in the hash table */
 136   LIST_FOREACH(rip, &hash_inodes[hashi], i_hash) {
 137         if (rip->i_num == numb && rip->i_dev == dev) {
 138                 /* If unused, remove it from the unused/free list */
 139                 if (rip->i_count == 0) {
 140                         inode_cache_hit++;
 141                         TAILQ_REMOVE(&unused_inodes, rip, i_unused);
 142                 }
 143                 ++rip->i_count;
 144                 return(rip);
 145         }
 146   }
 147
 148   inode_cache_miss++;
 149
 150   /* Inode is not on the hash, get a free one */
 151   if (TAILQ_EMPTY(&unused_inodes)) {
 152         err_code = ENFILE;
 153         return(NULL);
 154   }
 155   rip = TAILQ_FIRST(&unused_inodes);
 156
 157   /* If not free unhash it */
 158   if (rip->i_num != NO_ENTRY)
 159         unhash_inode(rip);
 160
 161   /* Inode is not unused any more */
 162   TAILQ_REMOVE(&unused_inodes, rip, i_unused);
 163
 164   /* Load the inode. */
 165   rip->i_dev = dev;
 166   rip->i_num = numb;
 167   rip->i_count = 1;
 168   if (dev != NO_DEV)
 169         rw_inode(rip, READING);    /* get inode from disk */
 170   rip->i_update = 0;        /* all the times are initially up-to-date */
 171   rip->i_last_dpos = 0;     /* no dentries searched for yet */
 172   rip->i_bsearch = NO_BLOCK;
 173   rip->i_last_pos_bl_alloc = 0;
 174   rip->i_last_dentry_size = 0;
 175   rip->i_mountpoint= FALSE;
 176
 177   rip->i_preallocation = opt.use_prealloc;
 178   rip->i_prealloc_count = rip->i_prealloc_index = 0;
 179
 180   for (i = 0; i < EXT2_PREALLOC_BLOCKS; i++) {
 181         if (rip->i_prealloc_blocks[i] != NO_BLOCK) {
 182                 /* Actually this should never happen */
 183                 free_block(rip->i_sp, rip->i_prealloc_blocks[i]);
 184                 rip->i_prealloc_blocks[i] = NO_BLOCK;
 185                 ext2_debug("Warning: Unexpected preallocated block.");
 186         }
 187   }
 188
 189   /* Add to hash */
 190   addhash_inode(rip);
 191
 192   return(rip);
 193 }
 194
 195
 196 /*===========================================================================*
 197  *                find_inode                                                 *
 198  *===========================================================================*/
 199 struct inode *find_inode(
 200   dev_t dev,          /* device on which inode resides */
 201   ino_t numb            /* inode number (ANSI: may not be unshort) */
 202 )
 203 {
 204 /* Find the inode specified by the inode and device number. */
 205   struct inode *rip;
 206   int hashi;
 207
 208   hashi = (int) numb & INODE_HASH_MASK;
 209
 210   /* Search inode in the hash table */
 211   LIST_FOREACH(rip, &hash_inodes[hashi], i_hash) {
 212         if (rip->i_count > 0 && rip->i_num == numb && rip->i_dev == dev) {
 213                 return(rip);
 214         }
 215   }
 216
 217   return(NULL);
 218 }
 219
 220
 221 /*===========================================================================*
 222  *                put_inode                                                  *
 223  *===========================================================================*/
 224 void put_inode(
 225   register struct inode *rip     /* pointer to inode to be released */
 226 )
 227 {
 228 /* The caller is no longer using this inode. If no one else is using it either
 229  * write it back to the disk immediately. If it has no links, truncate it and
 230  * return it to the pool of available inodes.
 231  */
 232
 233   if (rip == NULL)
 234         return;    /* checking here is easier than in caller */
 235
 236   if (rip->i_count < 1)
 237         panic("put_inode: i_count already below 1", rip->i_count);
 238
 239   if (--rip->i_count == 0) {    /* i_count == 0 means no one is using it now */
 240         if (rip->i_links_count == NO_LINK) {
 241                 /* i_nlinks == NO_LINK means free the inode. */
 242                 /* return all the disk blocks */
 243
 244                 /* Ignore errors by truncate_inode in case inode is a block
 245                  * special or character special file.
 246                  */
 247                 (void) truncate_inode(rip, (off_t) 0);
 248                 /* free inode clears I_TYPE field, since it's used there */
 249                 rip->i_dirt = DIRTY;
 250                 free_inode(rip);
 251         }
 252
 253         rip->i_mountpoint = FALSE;
 254         if (rip->i_dirt == DIRTY) rw_inode(rip, WRITING);
 255
 256         discard_preallocated_blocks(rip); /* Return blocks to the filesystem */
 257
 258         if (rip->i_links_count == NO_LINK) {
 259                 /* free, put at the front of the LRU list */
 260                 unhash_inode(rip);
 261                 rip->i_num = NO_ENTRY;
 262                 TAILQ_INSERT_HEAD(&unused_inodes, rip, i_unused);
 263         } else {
 264                 /* unused, put at the back of the LRU (cache it) */
 265                 TAILQ_INSERT_TAIL(&unused_inodes, rip, i_unused);
 266         }
 267   }
 268 }
 269
 270
 271 /*===========================================================================*
 272  *                update_times                                               *
 273  *===========================================================================*/
 274 void update_times(
 275   register struct inode *rip     /* pointer to inode to be read/written */
 276 )
 277 {
 278 /* Various system calls are required by the standard to update atime, ctime,
 279  * or mtime.  Since updating a time requires sending a message to the clock
 280  * task--an expensive business--the times are marked for update by setting
 281  * bits in i_update. When a stat, fstat, or sync is done, or an inode is
 282  * released, update_times() may be called to actually fill in the times.
 283  */
 284
 285   time_t cur_time;
 286   struct super_block *sp;
 287
 288   sp = rip->i_sp;         /* get pointer to super block. */
 289   if (sp->s_rd_only)
 290         return;             /* no updates for read-only file systems */
 291
 292   cur_time = clock_time();
 293   if (rip->i_update & ATIME)
 294         rip->i_atime = cur_time;
 295   if (rip->i_update & CTIME)
 296         rip->i_ctime = cur_time;
 297   if (rip->i_update & MTIME)
 298         rip->i_mtime = cur_time;
 299   rip->i_update = 0;          /* they are all up-to-date now */
 300 }
 301
 302 /*===========================================================================*
 303  *                rw_inode                                                   *
 304  *===========================================================================*/
 305 void rw_inode(
 306   register struct inode *rip,         /* pointer to inode to be read/written */
 307   int rw_flag                         /* READING or WRITING */
 308 )
 309 {
 310 /* An entry in the inode table is to be copied to or from the disk. */
 311
 312   register struct buf *bp;
 313   register struct super_block *sp;
 314   register struct group_desc *gd;
 315   register d_inode *dip;
 316   u32_t block_group_number;
 317   block_t b, offset;
 318
 319   /* Get the block where the inode resides. */
 320   sp = get_super(rip->i_dev);     /* get pointer to super block */
 321   rip->i_sp = sp;        /* inode must contain super block pointer */
 322
 323   block_group_number = (rip->i_num - 1) / sp->s_inodes_per_group;
 324
 325   gd = get_group_desc(block_group_number);
 326
 327   if (gd == NULL)
 328         panic("can't get group_desc to read/write inode");
 329
 330   offset = ((rip->i_num - 1) % sp->s_inodes_per_group) * EXT2_INODE_SIZE(sp);
 331   /* offset requires shifting, since each block contains several inodes,
 332    * e.g. inode 2 is stored in bklock 0.
 333    */
 334   b = (block_t) gd->inode_table + (offset >> sp->s_blocksize_bits);
 335   bp = get_block(rip->i_dev, b, NORMAL);
 336
 337   offset &= (sp->s_block_size - 1);
 338   dip = (d_inode*) (bp->b_data + offset);
 339
 340   /* Do the read or write. */
 341   if (rw_flag == WRITING) {
 342         if (rip->i_update)
 343                 update_times(rip);    /* times need updating */
 344         if (sp->s_rd_only == FALSE)
 345                 bp->b_dirt = DIRTY;
 346   }
 347
 348   icopy(rip, dip, rw_flag, TRUE);
 349
 350   put_block(bp, INODE_BLOCK);
 351   rip->i_dirt = CLEAN;
 352 }
 353
 354
 355 /*===========================================================================*
 356  *                              icopy                                        *
 357  *===========================================================================*/
 358 static void icopy(
 359   register struct inode *rip,   /* pointer to the in-core inode struct */
 360   register d_inode *dip,        /* pointer to the on-disk struct */
 361   int direction,                /* READING (from disk) or WRITING (to disk) */
 362   int norm                      /* TRUE = do not swap bytes; FALSE = swap */
 363 )
 364 {
 365   int i;
 366
 367   if (direction == READING) {
 368         /* Copy inode to the in-core table, swapping bytes if need be. */
 369         rip->i_mode    = conv2(norm,dip->i_mode);
 370         rip->i_uid     = conv2(norm,dip->i_uid);
 371         rip->i_size    = conv4(norm,dip->i_size);
 372         rip->i_atime   = conv4(norm,dip->i_atime);
 373         rip->i_ctime   = conv4(norm,dip->i_ctime);
 374         rip->i_mtime   = conv4(norm,dip->i_mtime);
 375         rip->i_dtime   = conv4(norm,dip->i_dtime);
 376         rip->i_gid     = conv2(norm,dip->i_gid);
 377         rip->i_links_count  = conv2(norm,dip->i_links_count);
 378         rip->i_blocks   = conv4(norm,dip->i_blocks);
 379         rip->i_flags    = conv4(norm,dip->i_flags);
 380         /* Minix doesn't touch osd1 and osd2 either, so just copy. */
 381         memcpy(&rip->osd1, &dip->osd1, sizeof(rip->osd1));
 382         for (i = 0; i < EXT2_N_BLOCKS; i++)
 383                 rip->i_block[i] = conv4(norm, dip->i_block[i]);
 384         rip->i_generation = conv4(norm,dip->i_generation);
 385         rip->i_file_acl = conv4(norm,dip->i_file_acl);
 386         rip->i_dir_acl  = conv4(norm,dip->i_dir_acl);
 387         rip->i_faddr    = conv4(norm,dip->i_faddr);
 388         memcpy(&rip->osd2, &dip->osd2, sizeof(rip->osd2));
 389   } else {
 390         /* Copying inode to disk from the in-core table. */
 391         dip->i_mode    = conv2(norm,rip->i_mode);
 392         dip->i_uid     = conv2(norm,rip->i_uid);
 393         dip->i_size    = conv4(norm,rip->i_size);
 394         dip->i_atime   = conv4(norm,rip->i_atime);
 395         dip->i_ctime   = conv4(norm,rip->i_ctime);
 396         dip->i_mtime   = conv4(norm,rip->i_mtime);
 397         dip->i_dtime   = conv4(norm,rip->i_dtime);
 398         dip->i_gid     = conv2(norm,rip->i_gid);
 399         dip->i_links_count  = conv2(norm,rip->i_links_count);
 400         dip->i_blocks   = conv4(norm,rip->i_blocks);
 401         dip->i_flags    = conv4(norm,rip->i_flags);
 402         /* Minix doesn't touch osd1 and osd2 either, so just copy. */
 403         memcpy(&dip->osd1, &rip->osd1, sizeof(dip->osd1));
 404         for (i = 0; i < EXT2_N_BLOCKS; i++)
 405                 dip->i_block[i] = conv4(norm, rip->i_block[i]);
 406         dip->i_generation  = conv4(norm,rip->i_generation);
 407         dip->i_file_acl = conv4(norm,rip->i_file_acl);
 408         dip->i_dir_acl  = conv4(norm,rip->i_dir_acl);
 409         dip->i_faddr    = conv4(norm,rip->i_faddr);
 410         memcpy(&dip->osd2, &rip->osd2, sizeof(dip->osd2));
 411   }
 412 }
 413
 414
 415 /*===========================================================================*
 416  *                dup_inode                                                  *
 417  *===========================================================================*/
 418 void dup_inode(
 419   struct inode *ip         /* The inode to be duplicated. */
 420 )
 421 {
 422 /* This routine is a simplified form of get_inode() for the case where
 423  * the inode pointer is already known.
 424  */
 425   ip->i_count++;
 426 }