{"id":1634,"date":"2012-04-10T10:00:07","date_gmt":"2012-04-10T01:00:07","guid":{"rendered":"http:\/\/peta.okechan.net\/blog\/?p=1634"},"modified":"2012-04-10T10:00:07","modified_gmt":"2012-04-10T01:00:07","slug":"xv6-62-chapter-5-file-system-code-inodes","status":"publish","type":"post","link":"https:\/\/peta.okechan.net\/blog\/archives\/1634","title":{"rendered":"[xv6 #62] Chapter 5 – File system – Code: Inodes"},"content":{"rendered":"

\u30c6\u30ad\u30b9\u30c8\u306e70\u301c71\u30da\u30fc\u30b8<\/p>\n

\u672c\u6587<\/h3>\n

\u65b0\u3057\u3044inode\u3092\u5272\u308a\u5f53\u3066\u308b\u305f\u3081\u306b\uff08\u4f8b\u3048\u3070\u3001\u30d5\u30a1\u30a4\u30eb\u3092\u4f5c\u308b\u3068\u304d\u306a\u3069\uff09\u3001xv6\u306fialloc\u95a2\u6570\u3092\u547c\u3076\u3002
\nialloc\u95a2\u6570\u306f\u3001balloc\u95a2\u6570\u306b\u4f3c\u3066\u3044\u3066\u3001\u30c7\u30a3\u30b9\u30af\u4e0a\u306einode\u306e\u69cb\u9020\u4f53\u7fa4\u3092\u8d70\u67fb\u3057\u3001\u4e00\u5ea6\u306b\u4e00\u3064\u306e\u30d6\u30ed\u30c3\u30af\u306b\u3064\u3044\u3066\u3001\u305d\u306e\u30d6\u30ed\u30c3\u30af\u304c\u300c\u7a7a\u304d\u300d\u3068\u30de\u30fc\u30af\u3055\u308c\u3066\u3044\u308b\u304b\u3069\u3046\u304b\u8abf\u3079\u308b\u3002
\n\u305d\u306e\u3088\u3046\u306a\u30d6\u30ed\u30c3\u30af\u304c\u898b\u3064\u304b\u3063\u305f\u3089\u3001\u65b0\u3057\u3044type\u5909\u6570\u306e\u5185\u5bb9\u3092\u30c7\u30a3\u30b9\u30af\u306b\u66f8\u304d\u8fbc\u307f\u3001\u305d\u308c\u304b\u3089return\u6587\u3067\u547c\u3070\u308c\u308biget\u95a2\u6570\u306e\u547c\u3073\u51fa\u3057\u306b\u3088\u3063\u3066\u3001inode\u30ad\u30e3\u30c3\u30b7\u30e5\u304b\u3089\u4e00\u3064\u306e\u30a8\u30f3\u30c8\u30ea\u3092\u8fd4\u3059\u3002
\nballoc\u95a2\u6570\u3067\u306e\u51e6\u7406\u306e\u3088\u3046\u306b\u3001ialloc\u95a2\u6570\u306f\u6b63\u3057\u304f\u51e6\u7406\u3092\u884c\u3046\u305f\u3081\u306b\u3001\u5909\u6570bp\u306b\u5bfe\u3059\u308b\u53c2\u7167\u3092\u4fdd\u6301\u3067\u304d\u308b\u306e\u306f\u4e00\u5ea6\u306b\u4e00\u3064\u306e\u30d7\u30ed\u30bb\u30b9\u3060\u3051\u3068\u3044\u3046\u4e8b\u5b9f\u306b\u4f9d\u5b58\u3057\u3066\u3044\u308b\u3002
\nialloc\u95a2\u6570\u306f\u3001\u305d\u306e\u53d6\u5f97\u53ef\u80fd\u306ainode\u3092\u4ed6\u306e\u30d7\u30ed\u30bb\u30b9\u304c\u540c\u6642\u306b\u53c2\u7167\u3057\u3066\u306a\u3044\u4e8b\u3092\u4fdd\u8a3c\u3067\u304d\u3001\u305d\u3057\u3066\u305d\u306e\u53d6\u5f97\u53ef\u80fd\u306ainode\u306e\u8981\u6c42\u3092\u8a66\u307f\u308b\u3002<\/p>\n

fs.c\u306eialloc, iget\u95a2\u6570<\/p>\n

\/\/ Allocate a new inode with the given type on device dev.\r\nstruct inode*\r\nialloc(uint dev, short type)\r\n{\r\n  int inum;\r\n  struct buf *bp;\r\n  struct dinode *dip;\r\n  struct superblock sb;\r\n\r\n  readsb(dev, &sb);\r\n  for(inum = 1; inum < sb.ninodes; inum++){  \/\/ loop over inode blocks\r\n    bp = bread(dev, IBLOCK(inum));\r\n    dip = (struct dinode*)bp->data + inum%IPB;\r\n    if(dip->type == 0){  \/\/ a free inode\r\n      memset(dip, 0, sizeof(*dip));\r\n      dip->type = type;\r\n      log_write(bp);   \/\/ mark it allocated on the disk\r\n      brelse(bp);\r\n      return iget(dev, inum);\r\n    }\r\n    brelse(bp);\r\n  }\r\n  panic("ialloc: no inodes");\r\n}\r\n\r\n\/\/ Find the inode with number inum on device dev\r\n\/\/ and return the in-memory copy.\r\nstatic struct inode*\r\niget(uint dev, uint inum)\r\n{\r\n  struct inode *ip, *empty;\r\n\r\n  acquire(&icache.lock);\r\n\r\n  \/\/ Try for cached inode.\r\n  empty = 0;\r\n  for(ip = &icache.inode[0]; ip < &icache.inode[NINODE]; ip++){\r\n    if(ip->ref > 0 && ip->dev == dev && ip->inum == inum){\r\n      ip->ref++;\r\n      release(&icache.lock);\r\n      return ip;\r\n    }\r\n    if(empty == 0 && ip->ref == 0)    \/\/ Remember empty slot.\r\n      empty = ip;\r\n  }\r\n\r\n  \/\/ Allocate fresh inode.\r\n  if(empty == 0)\r\n    panic("iget: no inodes");\r\n\r\n  ip = empty;\r\n  ip->dev = dev;\r\n  ip->inum = inum;\r\n  ip->ref = 1;\r\n  ip->flags = 0;\r\n  release(&icache.lock);\r\n\r\n  return ip;\r\n}<\/pre>\n
iget\u95a2\u6570\u306f\u3001\u6e21\u3055\u308c\u305f\u30c7\u30d0\u30a4\u30b9\u756a\u53f7\u3068inode\u756a\u53f7\u3092\u5143\u306b\u3001\u30a2\u30af\u30c6\u30a3\u30d6\u306a\u30a8\u30f3\u30c8\u30ea\uff08ip->ref > 0\uff09\u3092\u3001inode\u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u4e2d\u3092\u8d70\u67fb\u3057\u3066\u63a2\u3059\u3002
\n\u305d\u306e\u3088\u3046\u306a\u30a8\u30f3\u30c8\u30ea\u304c\u898b\u3064\u304b\u3063\u305f\u3089\u3001\u305d\u306einode\u306b\u5bfe\u3059\u308b\u65b0\u3057\u3044\u53c2\u7167\u3092\u8fd4\u3059\u3002
\n\u305d\u306eiget\u95a2\u6570\u306e\u8d70\u67fb\u306b\u3088\u3063\u3066\u3001\u6700\u521d\u306e\u7a7a\u304d\u30b9\u30ed\u30c3\u30c8\u306e\u4f4d\u7f6e\u3092\u8a18\u9332\u3057\uff08Remember empty slot.\u3068\u3044\u3046\u30b3\u30e1\u30f3\u30c8\u306e\u90e8\u5206\uff09\u3001\u305d\u306e\u7a7a\u304d\u30b9\u30ed\u30c3\u30c8\u306f\u65b0\u3057\u3044\u30ad\u30e3\u30c3\u30b7\u30e5\u30a8\u30f3\u30c8\u30ea\u3092\u5272\u308a\u5f53\u3066\u308b\u5fc5\u8981\u304c\u3042\u308b\u5834\u5408\u306b\u4f7f\u308f\u308c\u308b\u3002
\n\u3069\u3061\u3089\u306e\u5834\u5408\u3082\uff08inode\u30ad\u30e3\u30c3\u30b7\u30e5\u304b\u3089\u898b\u3064\u304b\u3063\u305f\u5834\u5408\u3068\u305d\u3046\u3067\u306a\u3044\u5834\u5408\uff09\u3001iget\u95a2\u6570\u306f\u3001\u547c\u3073\u51fa\u3057\u5143\u306b\u4e00\u3064\u306e\u53c2\u7167\u3092\u8fd4\u3059\u3002
\n\u547c\u3073\u51fa\u3057\u5074\u306b\u306f\u3001iput\u95a2\u6570\u4e16\u3092\u547c\u3073\u3001\u305d\u306einode\u3092\u89e3\u653e\u3059\u308b\u8cac\u4efb\u304c\u3042\u308b\u3002
\n\u3053\u308c\u306f\u3001\u3044\u304f\u3064\u304b\u306e\u30d7\u30ed\u30bb\u30b9\u304c\u3001\u8907\u6570\u56de\u306eiput\u95a2\u6570\u306e\u547c\u3073\u51fa\u3057\u3092\u914d\u7f6e\u3059\u308b\u5834\u5408\u306b\u4fbf\u5229\u3067\u3042\u308b\u3002
\nidup\u95a2\u6570\u306f\u3001inode\u306e\u53c2\u7167\u30ab\u30a6\u30f3\u30c8\u3092\u5897\u52a0\u3055\u305b\u308b\u306e\u3067\u3001\u305d\u306einode\u306e\u30ad\u30e3\u30c3\u30b7\u30e5\u3092\u3084\u3081\u3055\u305b\u308b\u524d\u306b\u3001\u8ffd\u52a0\u306eiput\u95a2\u6570\u306e\u547c\u3073\u51fa\u3057\u304c\u5fc5\u8981\u3067\u3042\u308b\u3002<\/p>\n
fs.c\u306eidup\u95a2\u6570<\/p>\n
\/\/ Increment reference count for ip.\r\n\/\/ Returns ip to enable ip = idup(ip1) idiom.\r\nstruct inode*\r\nidup(struct inode *ip)\r\n{\r\n  acquire(&icache.lock);\r\n  ip->ref++;\r\n  release(&icache.lock);\r\n  return ip;\r\n}<\/pre>\n
\u547c\u3073\u51fa\u3057\u5074\u306f\u3001inode\u306e\u30e1\u30bf\u30c7\u30fc\u30bf\u3084\u5185\u5bb9\u3092\u8aad\u307f\u66f8\u304d\u3059\u308b\u524d\u306b\u3001ilock\u95a2\u6570\u3092\u4f7f\u3063\u3066\u305d\u306einode\u3092\u30ed\u30c3\u30af\u3057\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002
\nilock\u95a2\u6570\u306f\u3001\u4eca\u306f\u304a\u306a\u3058\u307f\u306esleep\u30eb\u30fc\u30d7\u3092\u4f7f\u3063\u3066\u3001ip->flag\u306eI_BUSY\u30d3\u30c3\u30c8\u304c\u30af\u30ea\u30a2\u3055\u308c\u308b\u306e\u3092\u5f85\u3061\u3001\u305d\u3057\u305f\u3089ip->flag\u306bI_BUSY\u30d3\u30c3\u30c8\u3092\u30bb\u30c3\u30c8\u3059\u308b\u3002
\n\u4e00\u5ea6ilock\u611f\u83c5\u3001inode\u306b\u5bfe\u3059\u308b\u6392\u4ed6\u7684\u306a\u30a2\u30af\u30bb\u30b9\u6a29\u3092\u5f97\u305f\u3089\u3001\u5fc5\u8981\u306b\u5fdc\u3058\u3066\u30c7\u30a3\u30b9\u30af\u304b\u3089\uff08\u30d0\u30c3\u30d5\u30a1\u30ad\u30e3\u30c3\u30b7\u30e5\u304b\u3089\u306e\u53ef\u80fd\u6027\u3082\u9ad8\u3044\uff09\u305d\u306einode\u306e\u30e1\u30bf\u30c7\u30fc\u30bf\u3092\u8aad\u307f\u8fbc\u3080\u3053\u3068\u304c\u51fa\u6765\u308b\u3002
\niunlock\u95a2\u6570\u306f\u3001I_BUSY\u30d3\u30c3\u30c8\u3092\u30af\u30ea\u30a2\u3057\u3001ilock\u3067\u30b9\u30ea\u30fc\u30d7\u3057\u3066\u3044\u308b\u4ed6\u306e\u30d7\u30ed\u30bb\u30b9\u306e\u3044\u305a\u308c\u304b\u3092\u8d77\u3053\u3059\u3002<\/p>\n
fs.c\u306eilock, iunlock\u95a2\u6570<\/p>\n
\/\/ Lock the given inode.\r\nvoid\r\nilock(struct inode *ip)\r\n{\r\n  struct buf *bp;\r\n  struct dinode *dip;\r\n\r\n  if(ip == 0 || ip->ref < 1)\r\n    panic("ilock");\r\n\r\n  acquire(&icache.lock);\r\n  while(ip->flags & I_BUSY)\r\n    sleep(ip, &icache.lock);\r\n  ip->flags |= I_BUSY;\r\n  release(&icache.lock);\r\n\r\n  if(!(ip->flags & I_VALID)){\r\n    bp = bread(ip->dev, IBLOCK(ip->inum));\r\n    dip = (struct dinode*)bp->data + ip->inum%IPB;\r\n    ip->type = dip->type;\r\n    ip->major = dip->major;\r\n    ip->minor = dip->minor;\r\n    ip->nlink = dip->nlink;\r\n    ip->size = dip->size;\r\n    memmove(ip->addrs, dip->addrs, sizeof(ip->addrs));\r\n    brelse(bp);\r\n    ip->flags |= I_VALID;\r\n    if(ip->type == 0)\r\n      panic("ilock: no type");\r\n  }\r\n}\r\n\r\n\/\/ Unlock the given inode.\r\nvoid\r\niunlock(struct inode *ip)\r\n{\r\n  if(ip == 0 || !(ip->flags & I_BUSY) || ip->ref < 1)\r\n    panic("iunlock");\r\n\r\n  acquire(&icache.lock);\r\n  ip->flags &= ~I_BUSY;\r\n  wakeup(ip);\r\n  release(&icache.lock);\r\n}<\/pre>\n
iput\u95a2\u6570\u306f\u3001\u53c2\u7167\u30ab\u30a6\u30f3\u30c8\u3092\u30c7\u30af\u30ea\u30e1\u30f3\u30c8\u3059\u308b\u4e8b\u306b\u3088\u3063\u3066\u3001\u3042\u308binode\u306b\u5bfe\u3059\u308bC\u30dd\u30a4\u30f3\u30bf\u3092\u89e3\u653e\u3059\u308b\u3002
\n\u3082\u3057\u6700\u5f8c\u306e\u53c2\u7167\u3060\u3063\u305f\u5834\u5408\u3001inode\u30ad\u30e3\u30c3\u30b7\u30e5\u306b\u304a\u3051\u308b\u305d\u306einode\u306e\u30b9\u30ed\u30c3\u30c8\u306f\u7a7a\u304d\u3068\u306a\u308a\u3001\u4ed6\u306einode\u306b\u3088\u3063\u3066\u518d\u5229\u7528\u53ef\u80fd\u3068\u306a\u308b\u3002<\/p>\n
fs.c\u306eiput\u95a2\u6570<\/p>\n
\/\/ Caller holds reference to unlocked ip.  Drop reference.\r\nvoid\r\niput(struct inode *ip)\r\n{\r\n  acquire(&icache.lock);\r\n  if(ip->ref == 1 && (ip->flags & I_VALID) && ip->nlink == 0){\r\n    \/\/ inode is no longer used: truncate and free inode.\r\n    if(ip->flags & I_BUSY)\r\n      panic("iput busy");\r\n    ip->flags |= I_BUSY;\r\n    release(&icache.lock);\r\n    itrunc(ip);\r\n    ip->type = 0;\r\n    iupdate(ip);\r\n    acquire(&icache.lock);\r\n    ip->flags = 0;\r\n    wakeup(ip);\r\n  }\r\n  ip->ref--;\r\n  release(&icache.lock);\r\n}<\/pre>\n
\u3082\u3057inode\u306b\u5bfe\u3059\u308bC\u30dd\u30a4\u30f3\u30bf\u304c\u4e00\u3064\u3082\u7121\u304f\u3001\u30ea\u30f3\u30af\u3082\u6301\u305f\u306a\u3044\uff08\u3069\u306e\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u306b\u3082\u5c5e\u3055\u306a\u3044\uff09\u3068\u3044\u3046\u3053\u3068\u3092iput\u95a2\u6570\u304c\u767a\u898b\u3057\u305f\u5834\u5408\u3001\u305d\u306einode\u3068\u305d\u306e\u30c7\u30fc\u30bf\u30d6\u30ed\u30c3\u30af\u306f\u89e3\u653e\u3055\u308c\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002
\niput\u95a2\u6570\u306f\u3001\u305d\u306einode\u3092\u518d\u30ed\u30c3\u30af\u3057\uff08ip->flags |= I_BUSY;\uff09\u3001\u30d5\u30a1\u30a4\u30eb\u30920\u30d0\u30a4\u30c8\u306b\u5207\u308a\u8a70\u3081\u308b\u305f\u3081\u306bitrunc\u95a2\u6570\u3092\u547c\u3073\u3001\u30c7\u30fc\u30bf\u30d6\u30ed\u30c3\u30af\u3092\u89e3\u653e\u3057\u3001\u305d\u306einode\u306e\u30bf\u30a4\u30d7\u30920\uff08\u672a\u5272\u308a\u5f53\u3066\uff09\u306b\u30bb\u30c3\u30c8\u3057\u3001\u3053\u306e\u5909\u66f4\u3092\u30c7\u30a3\u30b9\u30af\u306b\u66f8\u304d\u8fbc\u307f\u3001\u305d\u3057\u3066\u6700\u5f8c\u306b\u305d\u306einode\u306e\u30ed\u30c3\u30af\u3092\u89e3\u653e\uff08ip->flags = 0;\uff09\u3059\u308b\u3002\uff08\u3053\u306e\u4e00\u9023\u306e\u51e6\u7406\u306f\u3001iput\u95a2\u6570\u306eif\u6587\u306e\u30d6\u30ed\u30c3\u30af\u306e\u4e2d\u306e\u8a71\u3002\uff09<\/p>\n
iput\u95a2\u6570\u306b\u304a\u3051\u308b\u30ed\u30c3\u30af\u624b\u6cd5\u306f\u6ce8\u76ee\u306b\u5024\u3059\u308b\u3002
\n\u4fa1\u5024\u3042\u308b\u4f8b\u306e\u307e\u305a\u4e00\u3064\u3081\u306e\u90e8\u5206\u306f\u3001ip\u3092\u30ed\u30c3\u30af\u3059\u308b\u3068\u304d\u3001iput\u95a2\u6570\u306f\u3001sleep\u30eb\u30fc\u30d7\u3092\u4f7f\u308f\u305a\u306b\u3001\u5358\u7d14\u306b\u305d\u308c\u304c\u30ed\u30c3\u30af\u3055\u308c\u3066\u306a\u3044\u3060\u308d\u3046\u3068\u4eee\u5b9a\u3059\u308b\u3002
\n\u3053\u308c\u306f\u3001\u547c\u3073\u51fa\u3057\u5074\u304ciput\u95a2\u6570\u3092\u547c\u3073\u51fa\u3059\u524d\u306bip\u3092\u30ed\u30c3\u30af\u3057\u3066\u306a\u3044\u4e8b\u3092\u8981\u6c42\u3055\u308c\u3001\u305d\u3057\u3066\u547c\u3073\u51fa\u3057\u5074\u304c\u305d\u308c\u306b\u5bfe\u3059\u308b\u552f\u4e00\u306e\u53c2\u7167\u3092\u6301\u3064\uff08ip->ref == 1\uff09\u5834\u5408\u3067\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002
\n\u4fa1\u5024\u3042\u308b\u4f8b\u306e\u4e8c\u3064\u3081\u306e\u90e8\u5206\u306f\u3001iput\u95a2\u6570\u304c\u4e00\u6642\u7684\u306b\u89e3\u653e\u3057\uff08if\u30d6\u30ed\u30c3\u30af\u4e2d\u306erelease(&icache.lock);\u306e\u3068\u3053\u308d\uff09\u3001\u518d\u5ea6\u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u30ed\u30c3\u30af\u3092\u7372\u5f97\u3059\u308b\uff08if\u30d6\u30ed\u30c3\u30af\u4e2d\u306eacquire(&icache.lock);\u306e\u3068\u3053\u308d\uff09\u4e8b\u3067\u3042\u308b\u3002
\n\u3053\u308c\u306f\u3001itrunc\u95a2\u6570\u3068iupdate\u95a2\u6570\u304c\u30c7\u30a3\u30b9\u30afI\/O\u5f85\u3061\u3067\u30b9\u30ea\u30fc\u30d7\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b\u306e\u3067\u3001\u5fc5\u8981\u3068\u3055\u308c\u308b\u306e\u3060\u304c\u3001\u6211\u3005\u306f\u3001\u30ed\u30c3\u30af\u3092\u4fdd\u6301\u3057\u3066\u306a\u3044\u9593\u306b\u4f55\u304c\u8d77\u304d\u3046\u308b\u304b\u306b\u3064\u3044\u3066\u719f\u8003\u3057\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002
\n\u5177\u4f53\u7684\u306b\u8a00\u3046\u3068\u3001\u4e00\u5ea6iupdate\u95a2\u6570\u304c\u5b8c\u4e86\u3057\u305f\u3089\u3001\u30c7\u30a3\u30b9\u30af\u4e0a\u306e\u69cb\u9020\u4f53\u306f\u3001\u5229\u7528\u53ef\u80fd\u3067\u3042\u308b\uff08\u7a7a\u304d\u3067\u3042\u308b\uff09\u3068\u30de\u30fc\u30af\u3055\u308c\u3001\u305d\u3057\u3066iput\u95a2\u6570\u304c\u7d42\u308f\u308b\u524d\u306b\u3001\u540c\u6642\u5b9f\u884c\u3055\u308c\u308bialloc\u306e\u547c\u3073\u51fa\u3057\u304c\u3001\u305d\u308c\u3092\u898b\u3064\u3051\u518d\u5272\u5f53\u3066\u3057\u3066\u3057\u307e\u3046\u304b\u3082\u3057\u308c\u306a\u3044\u3002
\nialloc\u95a2\u6570\u3067\u3001iget\u95a2\u6570\u304c\u547c\u3073\u51fa\u3055\u308c\u3001iget\u95a2\u6570\u304c\u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u4e2d\u304b\u3089ip\u3092\u898b\u3064\u3051\u3001\u6700\u7d42\u7684\u306bialloc\u95a2\u6570\u306f\u305d\u306e\u30d6\u30ed\u30c3\u30af\u3078\u306e\u53c2\u7167\u3092\u8fd4\u3059\u53ef\u80fd\u6027\u304c\u3042\u308b\u3002
\n\u305d\u306e\u5834\u5408\u3001\u305d\u306einode\u306fI_BUSY\u30d5\u30e9\u30b0\u304c\u30bb\u30c3\u30c8\u3055\u308c\u3066\u3044\u308b\u72b6\u614b\u3067\u3042\u308a\u3001ialloc\u95a2\u6570\u306e\u547c\u3073\u51fa\u3057\u5074\u304c\u305d\u306einode\u3092\u8aad\u307f\u66f8\u304d\u3057\u3088\u3046\u3068\u3057\u3066ilock\u95a2\u6570\u3092\u547c\u3073\u51fa\u3059\u3068\u3001\u30b9\u30ea\u30fc\u30d7\u3059\u308b\u3002
\n\u305d\u3046\u306a\u308b\u3068\u30e1\u30e2\u30ea\u4e0a\u306einode\u304c\u30c7\u30a3\u30b9\u30af\u4e0a\u306e\u305d\u308c\u3068\u6bd4\u3079\u3066\u4e00\u81f4\u3057\u3066\u306a\u3044\u72b6\u614b\u306b\u306a\u308b\u3002
\nialloc\u95a2\u6570\u306f\u3001\u30c7\u30a3\u30b9\u30af\u306e\u5074\u3092\u518d\u521d\u671f\u5316\u3057\u305f\u304c\u3001ilock\u95a2\u6570\u306e\u9593\u306b\u547c\u3073\u51fa\u3057\u5074\u304c\u305d\u308c\u3092\u30e1\u30e2\u30ea\u306b\u8aad\u307f\u8fbc\u3080\u3053\u3068\u3092\u5f53\u3066\u306b\u3057\u3066\u3044\u308b\u3002
\n\u3053\u308c\u304c\u8d77\u304d\u308b\u3053\u3068\u3092\u78ba\u5b9f\u306b\u3059\u308b\u305f\u3081\u306b\u3001iput\u95a2\u6570\u306f\u3001inode\u306e\u30ed\u30c3\u30af\u3092\u89e3\u653e\u3059\u308b\u524d\u306b\u3001I_BUSY\u30d5\u30e9\u30b0\u3060\u3051\u3067\u306a\u304fI_VALID\u30d5\u30e9\u30b0\u3082\u30af\u30ea\u30a2\u3057\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002
\n\u3053\u308c\u306f\u3001flags\u306b0\u3092\u30bb\u30c3\u30c8\u3059\u308b\u3053\u3068\u3067\u884c\u308f\u308c\u308b\u3002\uff08iput\u95a2\u6570\u306eif\u30d6\u30ed\u30c3\u30af\u4e2d\u306eip->flags = 0;\u306e\u3068\u3053\u308d\uff09<\/p>\n
\u611f\u60f3<\/h3>\n
inode\u306e\u7ba1\u7406\u306b\u3064\u3044\u3066\u306e\u30b3\u30fc\u30c9\u306e\u8aac\u660e\u3067\u3059\u3002
\n\u3061\u3087\u3063\u3068\u6700\u5f8c\u306e\u6bb5\u843d\u304c\u96e3\u3057\u3044\u3067\u3059\u3002
\n\u91cd\u8981\u306a\u306e\u306f\u591a\u5206\u3001iput\u306b\u304a\u3051\u308b\u6d88\u53bb\u51e6\u7406\u4e2d\u306einode\u3092\u3001\u5076\u7136\u4ed6\u306e\u30d7\u30ed\u30bb\u30b9\u304cialloc\u306b\u3088\u3063\u3066\u3055\u308c\u3066\u3057\u307e\u3063\u305f\u5834\u5408\u3001\u305d\u306einode\u3092\u4f55\u3082\u6c17\u3065\u304b\u305a\u4f7f\u3063\u3066\u3057\u307e\u3046\u306e\u3092\u9632\u3050\u305f\u3081\u306b\u3001\u6700\u5f8c\u306bI_VALID\u3082\u30af\u30ea\u30a2\u3057\u3066\u308b\u90e8\u5206\u3060\u3068\u601d\u3044\u307e\u3059\u3002
\n\u4ed6\u306e\u30d7\u30ed\u30bb\u30b9\u304c\u3059\u3067\u306bilock\u307e\u3067\u5230\u9054\u3057sleep\u4e2d\u304b\u3082\u3057\u308c\u306a\u3044\u306e\u3067\u3001\u3055\u3089\u306b\u76f4\u5f8c\u306bwakeup\u3092\u547c\u3076\u3053\u3068\u3082\u4f55\u6c17\u306b\u91cd\u8981\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u3002<\/p>\n
\u4eca\u307e\u3067\u306f\u306a\u308b\u3079\u304f\u30bd\u30fc\u30b9\u306f\u305d\u306e\u307e\u307e\u63b2\u8f09\u3059\u308b\u3088\u3046\u306b\u3001\u90e8\u5206\u7684\u306b\u63b2\u8f09\u3059\u308b\u5834\u5408\u3082\u95a2\u6570\u306e\u9806\u756a\u306f\u306a\u308b\u3079\u304f\u5143\u306e\u307e\u307e\u306b\u3059\u308b\u3088\u3046\u306b\u3057\u3066\u307e\u3057\u305f\u304c\u3001\u3061\u3087\u3063\u3068\u4eca\u56de\u306f\u53c2\u7167\u3059\u308b\u95a2\u6570\u304c\u591a\u3044\u4e0a\u306b\u3001\u672c\u6587\u3068\u5143\u306e\u30bd\u30fc\u30b9\u306e\u95a2\u6570\u306e\u9806\u756a\u304c\u9055\u3044\u3059\u304e\u308b\u306e\u3067\u3001\u672c\u6587\u306b\u5408\u308f\u305b\u3066\u95a2\u6570\u3092\u629c\u304d\u51fa\u3057\u3064\u3064\u9806\u756a\u3092\u5909\u3048\u3066\u63b2\u8f09\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
\u30c6\u30ad\u30b9\u30c8\u306e70\u301c71\u30da\u30fc\u30b8<\/p>\n
\u672c\u6587<\/h3>\n
\u65b0\u3057\u3044inode\u3092\u5272\u308a\u5f53\u3066\u308b\u305f\u3081\u306b\uff08\u4f8b\u3048\u3070\u3001\u30d5\u30a1\u30a4\u30eb\u3092\u4f5c\u308b\u3068\u304d\u306a\u3069\uff09\u3001xv6\u306fialloc\u95a2\u6570\u3092\u547c\u3076\u3002
\nialloc\u95a2\u6570\u306f\u3001balloc\u95a2\u6570\u306b\u4f3c\u3066\u3044\u3066\u3001\u30c7\u30a3\u30b9\u30af\u4e0a\u306einode\u306e\u69cb\u9020\u4f53\u7fa4\u3092\u8d70\u67fb\u3057\u3001\u4e00\u5ea6\u306b\u4e00\u3064\u306e\u30d6\u30ed\u30c3\u30af\u306b\u3064\u3044\u3066\u3001\u305d\u306e\u30d6\u30ed\u30c3\u30af\u304c\u300c\u7a7a\u304d\u300d\u3068\u30de\u30fc\u30af\u3055\u308c\u3066\u3044\u308b\u304b\u3069\u3046\u304b\u8abf\u3079\u308b\u3002
\n\u305d\u306e\u3088\u3046\u306a\u30d6\u30ed\u30c3\u30af\u304c\u898b\u3064\u304b\u3063\u305f\u3089\u3001\u65b0\u3057\u3044type\u5909\u6570\u306e\u5185\u5bb9\u3092\u30c7\u30a3\u30b9\u30af\u306b\u66f8\u304d\u8fbc\u307f\u3001\u305d\u308c\u304b\u3089return\u6587\u3067\u547c\u3070\u308c\u308biget\u95a2\u6570\u306e\u547c\u3073\u51fa\u3057\u306b\u3088\u3063\u3066\u3001inode\u30ad\u30e3\u30c3\u30b7\u30e5\u304b\u3089\u4e00\u3064\u306e\u30a8\u30f3\u30c8\u30ea\u3092\u8fd4\u3059\u3002
\nballoc\u95a2\u6570\u3067\u306e\u51e6\u7406\u306e\u3088\u3046\u306b\u3001ialloc\u95a2\u6570\u306f\u6b63\u3057\u304f\u51e6\u7406\u3092\u884c\u3046\u305f\u3081\u306b\u3001\u5909\u6570bp\u306b\u5bfe\u3059\u308b\u53c2\u7167\u3092\u4fdd\u6301\u3067\u304d\u308b\u306e\u306f\u4e00\u5ea6\u306b\u4e00\u3064\u306e\u30d7\u30ed\u30bb\u30b9\u3060\u3051\u3068\u3044\u3046\u4e8b\u5b9f\u306b\u4f9d\u5b58\u3057\u3066\u3044\u308b\u3002
\nialloc\u95a2\u6570\u306f\u3001\u305d\u306e\u53d6\u5f97\u53ef\u80fd\u306ainode\u3092\u4ed6\u306e\u30d7\u30ed\u30bb\u30b9\u304c\u540c\u6642\u306b\u53c2\u7167\u3057\u3066\u306a\u3044\u4e8b\u3092\u4fdd\u8a3c\u3067\u304d\u3001\u305d\u3057\u3066\u305d\u306e\u53d6\u5f97\u53ef\u80fd\u306ainode\u306e\u8981\u6c42\u3092\u8a66\u307f\u308b\u3002<\/p>\n
fs.c\u306eialloc, iget\u95a2\u6570<\/p>\n
\/\/ Allocate a new inode with the given type on device dev.\r\nstruct inode*\r\nialloc(uint dev, short type)\r\n{\r\n  int inum;\r\n  struct buf *bp;\r\n  struct dinode *dip;\r\n  struct superblock sb;\r\n\r\n  readsb(dev, &sb);\r\n  for(inum = 1; inum < sb.ninodes; inum++){  \/\/ loop over inode blocks\r\n    bp = bread(dev, IBLOCK(inum));\r\n    dip = (struct dinode*)bp->data + inum%IPB;\r\n    if(dip->type == 0){  \/\/ a free inode\r\n      memset(dip, 0, sizeof(*dip));\r\n      dip->type = type;\r\n      log_write(bp);   \/\/ mark it allocated on the disk\r\n      brelse(bp);\r\n      return iget(dev, inum);\r\n    }\r\n    brelse(bp);\r\n  }\r\n  panic("ialloc: no inodes");\r\n}\r\n\r\n\/\/ Find the inode with number inum on device dev\r\n\/\/ and return the in-memory copy.\r\nstatic struct inode*\r\niget(uint dev, uint inum)\r\n{\r\n  struct inode *ip, *empty;\r\n\r\n  acquire(&icache.lock);\r\n\r\n  \/\/ Try for cached inode.\r\n  empty = 0;\r\n  for(ip = &icache.inode[0]; ip < &icache.inode[NINODE]; ip++){\r\n    if(ip->ref > 0 && ip->dev == dev && ip->inum == inum){\r\n      ip->ref++;\r\n      release(&icache.lock);\r\n      return ip;\r\n    }\r\n    if(empty == 0 && ip->ref == 0)    \/\/ Remember empty slot.\r\n      empty = ip;\r\n  }\r\n\r\n  \/\/ Allocate fresh inode.\r\n  if(empty == 0)\r\n    panic("iget: no inodes");\r\n\r\n  ip = empty;\r\n  ip->dev = dev;\r\n  ip->inum = inum;\r\n  ip->ref = 1;\r\n  ip->flags = 0;\r\n  release(&icache.lock);\r\n\r\n  return ip;\r\n}<\/pre>\n
iget\u95a2\u6570\u306f\u3001\u6e21\u3055\u308c\u305f\u30c7\u30d0\u30a4\u30b9\u756a\u53f7\u3068inode\u756a\u53f7\u3092\u5143\u306b\u3001\u30a2\u30af\u30c6\u30a3\u30d6\u306a\u30a8\u30f3\u30c8\u30ea\uff08ip->ref > 0\uff09\u3092\u3001inode\u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u4e2d\u3092\u8d70\u67fb\u3057\u3066\u63a2\u3059\u3002
\n\u305d\u306e\u3088\u3046\u306a\u30a8\u30f3\u30c8\u30ea\u304c\u898b\u3064\u304b\u3063\u305f\u3089\u3001\u305d\u306einode\u306b\u5bfe\u3059\u308b\u65b0\u3057\u3044\u53c2\u7167\u3092\u8fd4\u3059\u3002
\n\u305d\u306eiget\u95a2\u6570\u306e\u8d70\u67fb\u306b\u3088\u3063\u3066\u3001\u6700\u521d\u306e\u7a7a\u304d\u30b9\u30ed\u30c3\u30c8\u306e\u4f4d\u7f6e\u3092\u8a18\u9332\u3057\uff08Remember empty slot.\u3068\u3044\u3046\u30b3\u30e1\u30f3\u30c8\u306e\u90e8\u5206\uff09\u3001\u305d\u306e\u7a7a\u304d\u30b9\u30ed\u30c3\u30c8\u306f\u65b0\u3057\u3044\u30ad\u30e3\u30c3\u30b7\u30e5\u30a8\u30f3\u30c8\u30ea\u3092\u5272\u308a\u5f53\u3066\u308b\u5fc5\u8981\u304c\u3042\u308b\u5834\u5408\u306b\u4f7f\u308f\u308c\u308b\u3002
\n\u3069\u3061\u3089\u306e\u5834\u5408\u3082\uff08inode\u30ad\u30e3\u30c3\u30b7\u30e5\u304b\u3089\u898b\u3064\u304b\u3063\u305f\u5834\u5408\u3068\u305d\u3046\u3067\u306a\u3044\u5834\u5408\uff09\u3001iget\u95a2\u6570\u306f\u3001\u547c\u3073\u51fa\u3057\u5143\u306b\u4e00\u3064\u306e\u53c2\u7167\u3092\u8fd4\u3059\u3002
\n\u547c\u3073\u51fa\u3057\u5074\u306b\u306f\u3001iput\u95a2\u6570\u4e16\u3092\u547c\u3073\u3001\u305d\u306einode\u3092\u89e3\u653e\u3059\u308b\u8cac\u4efb\u304c\u3042\u308b\u3002
\n\u3053\u308c\u306f\u3001\u3044\u304f\u3064\u304b\u306e\u30d7\u30ed\u30bb\u30b9\u304c\u3001\u8907\u6570\u56de\u306eiput\u95a2\u6570\u306e\u547c\u3073\u51fa\u3057\u3092\u914d\u7f6e\u3059\u308b\u5834\u5408\u306b\u4fbf\u5229\u3067\u3042\u308b\u3002
\nidup\u95a2\u6570\u306f\u3001inode\u306e\u53c2\u7167\u30ab\u30a6\u30f3\u30c8\u3092\u5897\u52a0\u3055\u305b\u308b\u306e\u3067\u3001\u305d\u306einode\u306e\u30ad\u30e3\u30c3\u30b7\u30e5\u3092\u3084\u3081\u3055\u305b\u308b\u524d\u306b\u3001\u8ffd\u52a0\u306eiput\u95a2\u6570\u306e\u547c\u3073\u51fa\u3057\u304c\u5fc5\u8981\u3067\u3042\u308b\u3002<\/p>\n
fs.c\u306eidup\u95a2\u6570<\/p>\n
\/\/ Increment reference count for ip.\r\n\/\/ Returns ip to enable ip = idup(ip1) idiom.\r\nstruct inode*\r\nidup(struct inode *ip)\r\n{\r\n  acquire(&icache.lock);\r\n  ip->ref++;\r\n  release(&icache.lock);\r\n  return ip;\r\n}<\/pre>\n
\u547c\u3073\u51fa\u3057\u5074\u306f\u3001inode\u306e\u30e1\u30bf\u30c7\u30fc\u30bf\u3084\u5185\u5bb9\u3092\u8aad\u307f\u66f8\u304d\u3059\u308b\u524d\u306b\u3001ilock\u95a2\u6570\u3092\u4f7f\u3063\u3066\u305d\u306einode\u3092\u30ed\u30c3\u30af\u3057\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002
\nilock\u95a2\u6570\u306f\u3001\u4eca\u306f\u304a\u306a\u3058\u307f\u306esleep\u30eb\u30fc\u30d7\u3092\u4f7f\u3063\u3066\u3001ip->flag\u306eI_BUSY\u30d3\u30c3\u30c8\u304c\u30af\u30ea\u30a2\u3055\u308c\u308b\u306e\u3092\u5f85\u3061\u3001\u305d\u3057\u305f\u3089ip->flag\u306bI_BUSY\u30d3\u30c3\u30c8\u3092\u30bb\u30c3\u30c8\u3059\u308b\u3002
\n\u4e00\u5ea6ilock\u611f\u83c5\u3001inode\u306b\u5bfe\u3059\u308b\u6392\u4ed6\u7684\u306a\u30a2\u30af\u30bb\u30b9\u6a29\u3092\u5f97\u305f\u3089\u3001\u5fc5\u8981\u306b\u5fdc\u3058\u3066\u30c7\u30a3\u30b9\u30af\u304b\u3089\uff08\u30d0\u30c3\u30d5\u30a1\u30ad\u30e3\u30c3\u30b7\u30e5\u304b\u3089\u306e\u53ef\u80fd\u6027\u3082\u9ad8\u3044\uff09\u305d\u306einode\u306e\u30e1\u30bf\u30c7\u30fc\u30bf\u3092\u8aad\u307f\u8fbc\u3080\u3053\u3068\u304c\u51fa\u6765\u308b\u3002
\niunlock\u95a2\u6570\u306f\u3001I_BUSY\u30d3\u30c3\u30c8\u3092\u30af\u30ea\u30a2\u3057\u3001ilock\u3067\u30b9\u30ea\u30fc\u30d7\u3057\u3066\u3044\u308b\u4ed6\u306e\u30d7\u30ed\u30bb\u30b9\u306e\u3044\u305a\u308c\u304b\u3092\u8d77\u3053\u3059\u3002<\/p>\n
fs.c\u306eilock, iunlock\u95a2\u6570<\/p>\n
\/\/ Lock the given inode.\r\nvoid\r\nilock(struct inode *ip)\r\n{\r\n  struct buf *bp;\r\n  struct dinode *dip;\r\n\r\n  if(ip == 0 || ip->ref < 1)\r\n    panic("ilock");\r\n\r\n  acquire(&icache.lock);\r\n  while(ip->flags & I_BUSY)\r\n    sleep(ip, &icache.lock);\r\n  ip->flags |= I_BUSY;\r\n  release(&icache.lock);\r\n\r\n  if(!(ip->flags & I_VALID)){\r\n    bp = bread(ip->dev, IBLOCK(ip->inum));\r\n    dip = (struct dinode*)bp->data + ip->inum%IPB;\r\n    ip->type = dip->type;\r\n    ip->major = dip->major;\r\n    ip->minor = dip->minor;\r\n    ip->nlink = dip->nlink;\r\n    ip->size = dip->size;\r\n    memmove(ip->addrs, dip->addrs, sizeof(ip->addrs));\r\n    brelse(bp);\r\n    ip->flags |= I_VALID;\r\n    if(ip->type == 0)\r\n      panic("ilock: no type");\r\n  }\r\n}\r\n\r\n\/\/ Unlock the given inode.\r\nvoid\r\niunlock(struct inode *ip)\r\n{\r\n  if(ip == 0 || !(ip->flags & I_BUSY) || ip->ref < 1)\r\n    panic("iunlock");\r\n\r\n  acquire(&icache.lock);\r\n  ip->flags &= ~I_BUSY;\r\n  wakeup(ip);\r\n  release(&icache.lock);\r\n}<\/pre>\n
iput\u95a2\u6570\u306f\u3001\u53c2\u7167\u30ab\u30a6\u30f3\u30c8\u3092\u30c7\u30af\u30ea\u30e1\u30f3\u30c8\u3059\u308b\u4e8b\u306b\u3088\u3063\u3066\u3001\u3042\u308binode\u306b\u5bfe\u3059\u308bC\u30dd\u30a4\u30f3\u30bf\u3092\u89e3\u653e\u3059\u308b\u3002
\n\u3082\u3057\u6700\u5f8c\u306e\u53c2\u7167\u3060\u3063\u305f\u5834\u5408\u3001inode\u30ad\u30e3\u30c3\u30b7\u30e5\u306b\u304a\u3051\u308b\u305d\u306einode\u306e\u30b9\u30ed\u30c3\u30c8\u306f\u7a7a\u304d\u3068\u306a\u308a\u3001\u4ed6\u306einode\u306b\u3088\u3063\u3066\u518d\u5229\u7528\u53ef\u80fd\u3068\u306a\u308b\u3002<\/p>\n
fs.c\u306eiput\u95a2\u6570<\/p>\n
\/\/ Caller holds reference to unlocked ip.  Drop reference.\r\nvoid\r\niput(struct inode *ip)\r\n{\r\n  acquire(&icache.lock);\r\n  if(ip->ref == 1 && (ip->flags & I_VALID) && ip->nlink == 0){\r\n    \/\/ inode is no longer used: truncate and free inode.\r\n    if(ip->flags & I_BUSY)\r\n      panic("iput busy");\r\n    ip->flags |= I_BUSY;\r\n    release(&icache.lock);\r\n    itrunc(ip);\r\n    ip->type = 0;\r\n    iupdate(ip);\r\n    acquire(&icache.lock);\r\n    ip->flags = 0;\r\n    wakeup(ip);\r\n  }\r\n  ip->ref--;\r\n  release(&icache.lock);\r\n}<\/pre>\n
\u3082\u3057inode\u306b\u5bfe\u3059\u308bC\u30dd\u30a4\u30f3\u30bf\u304c\u4e00\u3064\u3082\u7121\u304f\u3001\u30ea\u30f3\u30af\u3082\u6301\u305f\u306a\u3044\uff08\u3069\u306e\u30c7\u30a3\u30ec\u30af\u30c8\u30ea\u306b\u3082\u5c5e\u3055\u306a\u3044\uff09\u3068\u3044\u3046\u3053\u3068\u3092iput\u95a2\u6570\u304c\u767a\u898b\u3057\u305f\u5834\u5408\u3001\u305d\u306einode\u3068\u305d\u306e\u30c7\u30fc\u30bf\u30d6\u30ed\u30c3\u30af\u306f\u89e3\u653e\u3055\u308c\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002
\niput\u95a2\u6570\u306f\u3001\u305d\u306einode\u3092\u518d\u30ed\u30c3\u30af\u3057\uff08ip->flags |= I_BUSY;\uff09\u3001\u30d5\u30a1\u30a4\u30eb\u30920\u30d0\u30a4\u30c8\u306b\u5207\u308a\u8a70\u3081\u308b\u305f\u3081\u306bitrunc\u95a2\u6570\u3092\u547c\u3073\u3001\u30c7\u30fc\u30bf\u30d6\u30ed\u30c3\u30af\u3092\u89e3\u653e\u3057\u3001\u305d\u306einode\u306e\u30bf\u30a4\u30d7\u30920\uff08\u672a\u5272\u308a\u5f53\u3066\uff09\u306b\u30bb\u30c3\u30c8\u3057\u3001\u3053\u306e\u5909\u66f4\u3092\u30c7\u30a3\u30b9\u30af\u306b\u66f8\u304d\u8fbc\u307f\u3001\u305d\u3057\u3066\u6700\u5f8c\u306b\u305d\u306einode\u306e\u30ed\u30c3\u30af\u3092\u89e3\u653e\uff08ip->flags = 0;\uff09\u3059\u308b\u3002\uff08\u3053\u306e\u4e00\u9023\u306e\u51e6\u7406\u306f\u3001iput\u95a2\u6570\u306eif\u6587\u306e\u30d6\u30ed\u30c3\u30af\u306e\u4e2d\u306e\u8a71\u3002\uff09<\/p>\n
iput\u95a2\u6570\u306b\u304a\u3051\u308b\u30ed\u30c3\u30af\u624b\u6cd5\u306f\u6ce8\u76ee\u306b\u5024\u3059\u308b\u3002
\n\u4fa1\u5024\u3042\u308b\u4f8b\u306e\u307e\u305a\u4e00\u3064\u3081\u306e\u90e8\u5206\u306f\u3001ip\u3092\u30ed\u30c3\u30af\u3059\u308b\u3068\u304d\u3001iput\u95a2\u6570\u306f\u3001sleep\u30eb\u30fc\u30d7\u3092\u4f7f\u308f\u305a\u306b\u3001\u5358\u7d14\u306b\u305d\u308c\u304c\u30ed\u30c3\u30af\u3055\u308c\u3066\u306a\u3044\u3060\u308d\u3046\u3068\u4eee\u5b9a\u3059\u308b\u3002
\n\u3053\u308c\u306f\u3001\u547c\u3073\u51fa\u3057\u5074\u304ciput\u95a2\u6570\u3092\u547c\u3073\u51fa\u3059\u524d\u306bip\u3092\u30ed\u30c3\u30af\u3057\u3066\u306a\u3044\u4e8b\u3092\u8981\u6c42\u3055\u308c\u3001\u305d\u3057\u3066\u547c\u3073\u51fa\u3057\u5074\u304c\u305d\u308c\u306b\u5bfe\u3059\u308b\u552f\u4e00\u306e\u53c2\u7167\u3092\u6301\u3064\uff08ip->ref == 1\uff09\u5834\u5408\u3067\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002
\n\u4fa1\u5024\u3042\u308b\u4f8b\u306e\u4e8c\u3064\u3081\u306e\u90e8\u5206\u306f\u3001iput\u95a2\u6570\u304c\u4e00\u6642\u7684\u306b\u89e3\u653e\u3057\uff08if\u30d6\u30ed\u30c3\u30af\u4e2d\u306erelease(&icache.lock);\u306e\u3068\u3053\u308d\uff09\u3001\u518d\u5ea6\u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u30ed\u30c3\u30af\u3092\u7372\u5f97\u3059\u308b\uff08if\u30d6\u30ed\u30c3\u30af\u4e2d\u306eacquire(&icache.lock);\u306e\u3068\u3053\u308d\uff09\u4e8b\u3067\u3042\u308b\u3002
\n\u3053\u308c\u306f\u3001itrunc\u95a2\u6570\u3068iupdate\u95a2\u6570\u304c\u30c7\u30a3\u30b9\u30afI\/O\u5f85\u3061\u3067\u30b9\u30ea\u30fc\u30d7\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b\u306e\u3067\u3001\u5fc5\u8981\u3068\u3055\u308c\u308b\u306e\u3060\u304c\u3001\u6211\u3005\u306f\u3001\u30ed\u30c3\u30af\u3092\u4fdd\u6301\u3057\u3066\u306a\u3044\u9593\u306b\u4f55\u304c\u8d77\u304d\u3046\u308b\u304b\u306b\u3064\u3044\u3066\u719f\u8003\u3057\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002
\n\u5177\u4f53\u7684\u306b\u8a00\u3046\u3068\u3001\u4e00\u5ea6iupdate\u95a2\u6570\u304c\u5b8c\u4e86\u3057\u305f\u3089\u3001\u30c7\u30a3\u30b9\u30af\u4e0a\u306e\u69cb\u9020\u4f53\u306f\u3001\u5229\u7528\u53ef\u80fd\u3067\u3042\u308b\uff08\u7a7a\u304d\u3067\u3042\u308b\uff09\u3068\u30de\u30fc\u30af\u3055\u308c\u3001\u305d\u3057\u3066iput\u95a2\u6570\u304c\u7d42\u308f\u308b\u524d\u306b\u3001\u540c\u6642\u5b9f\u884c\u3055\u308c\u308bialloc\u306e\u547c\u3073\u51fa\u3057\u304c\u3001\u305d\u308c\u3092\u898b\u3064\u3051\u518d\u5272\u5f53\u3066\u3057\u3066\u3057\u307e\u3046\u304b\u3082\u3057\u308c\u306a\u3044\u3002
\nialloc\u95a2\u6570\u3067\u3001iget\u95a2\u6570\u304c\u547c\u3073\u51fa\u3055\u308c\u3001iget\u95a2\u6570\u304c\u30ad\u30e3\u30c3\u30b7\u30e5\u306e\u4e2d\u304b\u3089ip\u3092\u898b\u3064\u3051\u3001\u6700\u7d42\u7684\u306bialloc\u95a2\u6570\u306f\u305d\u306e\u30d6\u30ed\u30c3\u30af\u3078\u306e\u53c2\u7167\u3092\u8fd4\u3059\u53ef\u80fd\u6027\u304c\u3042\u308b\u3002
\n\u305d\u306e\u5834\u5408\u3001\u305d\u306einode\u306fI_BUSY\u30d5\u30e9\u30b0\u304c\u30bb\u30c3\u30c8\u3055\u308c\u3066\u3044\u308b\u72b6\u614b\u3067\u3042\u308a\u3001ialloc\u95a2\u6570\u306e\u547c\u3073\u51fa\u3057\u5074\u304c\u305d\u306einode\u3092\u8aad\u307f\u66f8\u304d\u3057\u3088\u3046\u3068\u3057\u3066ilock\u95a2\u6570\u3092\u547c\u3073\u51fa\u3059\u3068\u3001\u30b9\u30ea\u30fc\u30d7\u3059\u308b\u3002
\n\u305d\u3046\u306a\u308b\u3068\u30e1\u30e2\u30ea\u4e0a\u306einode\u304c\u30c7\u30a3\u30b9\u30af\u4e0a\u306e\u305d\u308c\u3068\u6bd4\u3079\u3066\u4e00\u81f4\u3057\u3066\u306a\u3044\u72b6\u614b\u306b\u306a\u308b\u3002
\nialloc\u95a2\u6570\u306f\u3001\u30c7\u30a3\u30b9\u30af\u306e\u5074\u3092\u518d\u521d\u671f\u5316\u3057\u305f\u304c\u3001ilock\u95a2\u6570\u306e\u9593\u306b\u547c\u3073\u51fa\u3057\u5074\u304c\u305d\u308c\u3092\u30e1\u30e2\u30ea\u306b\u8aad\u307f\u8fbc\u3080\u3053\u3068\u3092\u5f53\u3066\u306b\u3057\u3066\u3044\u308b\u3002
\n\u3053\u308c\u304c\u8d77\u304d\u308b\u3053\u3068\u3092\u78ba\u5b9f\u306b\u3059\u308b\u305f\u3081\u306b\u3001iput\u95a2\u6570\u306f\u3001inode\u306e\u30ed\u30c3\u30af\u3092\u89e3\u653e\u3059\u308b\u524d\u306b\u3001I_BUSY\u30d5\u30e9\u30b0\u3060\u3051\u3067\u306a\u304fI_VALID\u30d5\u30e9\u30b0\u3082\u30af\u30ea\u30a2\u3057\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002
\n\u3053\u308c\u306f\u3001flags\u306b0\u3092\u30bb\u30c3\u30c8\u3059\u308b\u3053\u3068\u3067\u884c\u308f\u308c\u308b\u3002\uff08iput\u95a2\u6570\u306eif\u30d6\u30ed\u30c3\u30af\u4e2d\u306eip->flags = 0;\u306e\u3068\u3053\u308d\uff09<\/p>\n
\u611f\u60f3<\/h3>\n
inode\u306e\u7ba1\u7406\u306b\u3064\u3044\u3066\u306e\u30b3\u30fc\u30c9\u306e\u8aac\u660e\u3067\u3059\u3002
\n\u3061\u3087\u3063\u3068\u6700\u5f8c\u306e\u6bb5\u843d\u304c\u96e3\u3057\u3044\u3067\u3059\u3002
\n\u91cd\u8981\u306a\u306e\u306f\u591a\u5206\u3001iput\u306b\u304a\u3051\u308b\u6d88\u53bb\u51e6\u7406\u4e2d\u306einode\u3092\u3001\u5076\u7136\u4ed6\u306e\u30d7\u30ed\u30bb\u30b9\u304cialloc\u306b\u3088\u3063\u3066\u3055\u308c\u3066\u3057\u307e\u3063\u305f\u5834\u5408\u3001\u305d\u306einode\u3092\u4f55\u3082\u6c17\u3065\u304b\u305a\u4f7f\u3063\u3066\u3057\u307e\u3046\u306e\u3092\u9632\u3050\u305f\u3081\u306b\u3001\u6700\u5f8c\u306bI_VALID\u3082\u30af\u30ea\u30a2\u3057\u3066\u308b\u90e8\u5206\u3060\u3068\u601d\u3044\u307e\u3059\u3002
\n\u4ed6\u306e\u30d7\u30ed\u30bb\u30b9\u304c\u3059\u3067\u306bilock\u307e\u3067\u5230\u9054\u3057sleep\u4e2d\u304b\u3082\u3057\u308c\u306a\u3044\u306e\u3067\u3001\u3055\u3089\u306b\u76f4\u5f8c\u306bwakeup\u3092\u547c\u3076\u3053\u3068\u3082\u4f55\u6c17\u306b\u91cd\u8981\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u3002<\/p>\n
\u4eca\u307e\u3067\u306f\u306a\u308b\u3079\u304f\u30bd\u30fc\u30b9\u306f\u305d\u306e\u307e\u307e\u63b2\u8f09\u3059\u308b\u3088\u3046\u306b\u3001\u90e8\u5206\u7684\u306b\u63b2\u8f09\u3059\u308b\u5834\u5408\u3082\u95a2\u6570\u306e\u9806\u756a\u306f\u306a\u308b\u3079\u304f\u5143\u306e\u307e\u307e\u306b\u3059\u308b\u3088\u3046\u306b\u3057\u3066\u307e\u3057\u305f\u304c\u3001\u3061\u3087\u3063\u3068\u4eca\u56de\u306f\u53c2\u7167\u3059\u308b\u95a2\u6570\u304c\u591a\u3044\u4e0a\u306b\u3001\u672c\u6587\u3068\u5143\u306e\u30bd\u30fc\u30b9\u306e\u95a2\u6570\u306e\u9806\u756a\u304c\u9055\u3044\u3059\u304e\u308b\u306e\u3067\u3001\u672c\u6587\u306b\u5408\u308f\u305b\u3066\u95a2\u6570\u3092\u629c\u304d\u51fa\u3057\u3064\u3064\u9806\u756a\u3092\u5909\u3048\u3066\u63b2\u8f09\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[32],"tags":[405],"class_list":["post-1634","post","type-post","status-publish","format-standard","hentry","category-tech","tag-xv6"],"_links":{"self":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/posts\/1634","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/comments?post=1634"}],"version-history":[{"count":0,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/posts\/1634\/revisions"}],"wp:attachment":[{"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/media?parent=1634"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/categories?post=1634"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/peta.okechan.net\/blog\/wp-json\/wp\/v2\/tags?post=1634"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}