fs/sysv/namei.c

   1 /*
   2  *  linux/fs/sysv/namei.c
   3  *
   4  *  minix/namei.c
   5  *  Copyright (C) 1991, 1992  Linus Torvalds
   6  *
   7  *  coh/namei.c
   8  *  Copyright (C) 1993  Pascal Haible, Bruno Haible
   9  *
  10  *  sysv/namei.c
  11  *  Copyright (C) 1993  Bruno Haible
  12  *  Copyright (C) 1997, 1998  Krzysztof G. Baranowski
  13  */
  14
  15 #include <linux/pagemap.h>
  16 #include "sysv.h"
  17
  18 static int add_nondir(struct dentry *dentry, struct inode *inode)
  19 {
  20         int err = sysv_add_link(dentry, inode);
  21         if (!err) {
  22                 d_instantiate(dentry, inode);
  23                 return 0;
  24         }
  25         inode_dec_link_count(inode);
  26         iput(inode);
  27         return err;
  28 }
  29
  30 static int sysv_hash(struct dentry *dentry, struct qstr *qstr)
  31 {
  32         /* Truncate the name in place, avoids having to define a compare
  33            function. */
  34         if (qstr->len > SYSV_NAMELEN) {
  35                 qstr->len = SYSV_NAMELEN;
  36                 qstr->hash = full_name_hash(qstr->name, qstr->len);
  37         }
  38         return 0;
  39 }
  40
  41 struct dentry_operations sysv_dentry_operations = {
  42         .d_hash         = sysv_hash,
  43 };
  44
  45 static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
  46 {
  47         struct inode * inode = NULL;
  48         ino_t ino;
  49
  50         dentry->d_op = dir->i_sb->s_root->d_op;
  51         if (dentry->d_name.len > SYSV_NAMELEN)
  52                 return ERR_PTR(-ENAMETOOLONG);
  53         ino = sysv_inode_by_name(dentry);
  54
  55         if (ino) {
  56                 inode = iget(dir->i_sb, ino);
  57                 if (!inode)
  58                         return ERR_PTR(-EACCES);
  59         }
  60         d_add(dentry, inode);
  61         return NULL;
  62 }
  63
  64 static int sysv_mknod(struct inode * dir, struct dentry * dentry, int mode, dev_t rdev)
  65 {
  66         struct inode * inode;
  67         int err;
  68
  69         if (!old_valid_dev(rdev))
  70                 return -EINVAL;
  71
  72         inode = sysv_new_inode(dir, mode);
  73         err = PTR_ERR(inode);
  74
  75         if (!IS_ERR(inode)) {
  76                 sysv_set_inode(inode, rdev);
  77                 mark_inode_dirty(inode);
  78                 err = add_nondir(dentry, inode);
  79         }
  80         return err;
  81 }
  82
  83 static int sysv_create(struct inode * dir, struct dentry * dentry, int mode, struct nameidata *nd)
  84 {
  85         return sysv_mknod(dir, dentry, mode, 0);
  86 }
  87
  88 static int sysv_symlink(struct inode * dir, struct dentry * dentry,
  89         const char * symname)
  90 {
  91         int err = -ENAMETOOLONG;
  92         int l = strlen(symname)+1;
  93         struct inode * inode;
  94
  95         if (l > dir->i_sb->s_blocksize)
  96                 goto out;
  97
  98         inode = sysv_new_inode(dir, S_IFLNK|0777);
  99         err = PTR_ERR(inode);
 100         if (IS_ERR(inode))
 101                 goto out;
 102
 103         sysv_set_inode(inode, 0);
 104         err = page_symlink(inode, symname, l);
 105         if (err)
 106                 goto out_fail;
 107
 108         mark_inode_dirty(inode);
 109         err = add_nondir(dentry, inode);
 110 out:
 111         return err;
 112
 113 out_fail:
 114         inode_dec_link_count(inode);
 115         iput(inode);
 116         goto out;
 117 }
 118
 119 static int sysv_link(struct dentry * old_dentry, struct inode * dir,
 120         struct dentry * dentry)
 121 {
 122         struct inode *inode = old_dentry->d_inode;
 123
 124         if (inode->i_nlink >= SYSV_SB(inode->i_sb)->s_link_max)
 125                 return -EMLINK;
 126
 127         inode->i_ctime = CURRENT_TIME_SEC;
 128         inode_inc_link_count(inode);
 129         atomic_inc(&inode->i_count);
 130
 131         return add_nondir(dentry, inode);
 132 }
 133
 134 static int sysv_mkdir(struct inode * dir, struct dentry *dentry, int mode)
 135 {
 136         struct inode * inode;
 137         int err = -EMLINK;
 138
 139         if (dir->i_nlink >= SYSV_SB(dir->i_sb)->s_link_max)
 140                 goto out;
 141         inode_inc_link_count(dir);
 142
 143         inode = sysv_new_inode(dir, S_IFDIR|mode);
 144         err = PTR_ERR(inode);
 145         if (IS_ERR(inode))
 146                 goto out_dir;
 147
 148         sysv_set_inode(inode, 0);
 149
 150         inode_inc_link_count(inode);
 151
 152         err = sysv_make_empty(inode, dir);
 153         if (err)
 154                 goto out_fail;
 155
 156         err = sysv_add_link(dentry, inode);
 157         if (err)
 158                 goto out_fail;
 159
 160         d_instantiate(dentry, inode);
 161 out:
 162         return err;
 163
 164 out_fail:
 165         inode_dec_link_count(inode);
 166         inode_dec_link_count(inode);
 167         iput(inode);
 168 out_dir:
 169         inode_dec_link_count(dir);
 170         goto out;
 171 }
 172
 173 static int sysv_unlink(struct inode * dir, struct dentry * dentry)
 174 {
 175         struct inode * inode = dentry->d_inode;
 176         struct page * page;
 177         struct sysv_dir_entry * de;
 178         int err = -ENOENT;
 179
 180         de = sysv_find_entry(dentry, &page);
 181         if (!de)
 182                 goto out;
 183
 184         err = sysv_delete_entry (de, page);
 185         if (err)
 186                 goto out;
 187
 188         inode->i_ctime = dir->i_ctime;
 189         inode_dec_link_count(inode);
 190 out:
 191         return err;
 192 }
 193
 194 static int sysv_rmdir(struct inode * dir, struct dentry * dentry)
 195 {
 196         struct inode *inode = dentry->d_inode;
 197         int err = -ENOTEMPTY;
 198
 199         if (sysv_empty_dir(inode)) {
 200                 err = sysv_unlink(dir, dentry);
 201                 if (!err) {
 202                         inode->i_size = 0;
 203                         inode_dec_link_count(inode);
 204                         inode_dec_link_count(dir);
 205                 }
 206         }
 207         return err;
 208 }
 209
 210 /*
 211  * Anybody can rename anything with this: the permission checks are left to the
 212  * higher-level routines.
 213  */
 214 static int sysv_rename(struct inode * old_dir, struct dentry * old_dentry,
 215                   struct inode * new_dir, struct dentry * new_dentry)
 216 {
 217         struct inode * old_inode = old_dentry->d_inode;
 218         struct inode * new_inode = new_dentry->d_inode;
 219         struct page * dir_page = NULL;
 220         struct sysv_dir_entry * dir_de = NULL;
 221         struct page * old_page;
 222         struct sysv_dir_entry * old_de;
 223         int err = -ENOENT;
 224
 225         old_de = sysv_find_entry(old_dentry, &old_page);
 226         if (!old_de)
 227                 goto out;
 228
 229         if (S_ISDIR(old_inode->i_mode)) {
 230                 err = -EIO;
 231                 dir_de = sysv_dotdot(old_inode, &dir_page);
 232                 if (!dir_de)
 233                         goto out_old;
 234         }
 235
 236         if (new_inode) {
 237                 struct page * new_page;
 238                 struct sysv_dir_entry * new_de;
 239
 240                 err = -ENOTEMPTY;
 241                 if (dir_de && !sysv_empty_dir(new_inode))
 242                         goto out_dir;
 243
 244                 err = -ENOENT;
 245                 new_de = sysv_find_entry(new_dentry, &new_page);
 246                 if (!new_de)
 247                         goto out_dir;
 248                 inode_inc_link_count(old_inode);
 249                 sysv_set_link(new_de, new_page, old_inode);
 250                 new_inode->i_ctime = CURRENT_TIME_SEC;
 251                 if (dir_de)
 252                         drop_nlink(new_inode);
 253                 inode_dec_link_count(new_inode);
 254         } else {
 255                 if (dir_de) {
 256                         err = -EMLINK;
 257                         if (new_dir->i_nlink >= SYSV_SB(new_dir->i_sb)->s_link_max)
 258                                 goto out_dir;
 259                 }
 260                 inode_inc_link_count(old_inode);
 261                 err = sysv_add_link(new_dentry, old_inode);
 262                 if (err) {
 263                         inode_dec_link_count(old_inode);
 264                         goto out_dir;
 265                 }
 266                 if (dir_de)
 267                         inode_inc_link_count(new_dir);
 268         }
 269
 270         sysv_delete_entry(old_de, old_page);
 271         inode_dec_link_count(old_inode);
 272
 273         if (dir_de) {
 274                 sysv_set_link(dir_de, dir_page, new_dir);
 275                 inode_dec_link_count(old_dir);
 276         }
 277         return 0;
 278
 279 out_dir:
 280         if (dir_de) {
 281                 kunmap(dir_page);
 282                 page_cache_release(dir_page);
 283         }
 284 out_old:
 285         kunmap(old_page);
 286         page_cache_release(old_page);
 287 out:
 288         return err;
 289 }
 290
 291 /*
 292  * directories can handle most operations...
 293  */
 294 const struct inode_operations sysv_dir_inode_operations = {
 295         .create         = sysv_create,
 296         .lookup         = sysv_lookup,
 297         .link           = sysv_link,
 298         .unlink         = sysv_unlink,
 299         .symlink        = sysv_symlink,
 300         .mkdir          = sysv_mkdir,
 301         .rmdir          = sysv_rmdir,
 302         .mknod          = sysv_mknod,
 303         .rename         = sysv_rename,
 304         .getattr        = sysv_getattr,
 305 };