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 <linux/smp_lock.h>
  17 #include "sysv.h"
  18
  19 static inline void inc_count(struct inode *inode)
  20 {
  21         inode->i_nlink++;
  22         mark_inode_dirty(inode);
  23 }
  24
  25 static inline void dec_count(struct inode *inode)
  26 {
  27         inode->i_nlink--;
  28         mark_inode_dirty(inode);
  29 }
  30
  31 static int add_nondir(struct dentry *dentry, struct inode *inode)
  32 {
  33         int err = sysv_add_link(dentry, inode);
  34         if (!err) {
  35                 d_instantiate(dentry, inode);
  36                 return 0;
  37         }
  38         dec_count(inode);
  39         iput(inode);
  40         return err;
  41 }
  42
  43 static int sysv_hash(struct dentry *dentry, struct qstr *qstr)
  44 {
  45         /* Truncate the name in place, avoids having to define a compare
  46            function. */
  47         if (qstr->len > SYSV_NAMELEN) {
  48                 qstr->len = SYSV_NAMELEN;
  49                 qstr->hash = full_name_hash(qstr->name, qstr->len);
  50         }
  51         return 0;
  52 }
  53
  54 struct dentry_operations sysv_dentry_operations = {
  55         .d_hash         = sysv_hash,
  56 };
  57
  58 static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry, struct nameidata *nd)
  59 {
  60         struct inode * inode = NULL;
  61         ino_t ino;
  62
  63         dentry->d_op = dir->i_sb->s_root->d_op;
  64         if (dentry->d_name.len > SYSV_NAMELEN)
  65                 return ERR_PTR(-ENAMETOOLONG);
  66         ino = sysv_inode_by_name(dentry);
  67
  68         if (ino) {
  69                 inode = iget(dir->i_sb, ino);
  70                 if (!inode)
  71                         return ERR_PTR(-EACCES);
  72         }
  73         d_add(dentry, inode);
  74         return NULL;
  75 }
  76
  77 static int sysv_mknod(struct inode * dir, struct dentry * dentry, int mode, dev_t rdev)
  78 {
  79         struct inode * inode;
  80         int err;
  81
  82         if (!old_valid_dev(rdev))
  83                 return -EINVAL;
  84
  85         inode = sysv_new_inode(dir, mode);
  86         err = PTR_ERR(inode);
  87
  88         if (!IS_ERR(inode)) {
  89                 sysv_set_inode(inode, rdev);
  90                 mark_inode_dirty(inode);
  91                 err = add_nondir(dentry, inode);
  92         }
  93         return err;
  94 }
  95
  96 static int sysv_create(struct inode * dir, struct dentry * dentry, int mode, struct nameidata *nd)
  97 {
  98         return sysv_mknod(dir, dentry, mode, 0);
  99 }
 100
 101 static int sysv_symlink(struct inode * dir, struct dentry * dentry,
 102         const char * symname)
 103 {
 104         int err = -ENAMETOOLONG;
 105         int l = strlen(symname)+1;
 106         struct inode * inode;
 107
 108         if (l > dir->i_sb->s_blocksize)
 109                 goto out;
 110
 111         inode = sysv_new_inode(dir, S_IFLNK|0777);
 112         err = PTR_ERR(inode);
 113         if (IS_ERR(inode))
 114                 goto out;
 115
 116         sysv_set_inode(inode, 0);
 117         err = page_symlink(inode, symname, l);
 118         if (err)
 119                 goto out_fail;
 120
 121         mark_inode_dirty(inode);
 122         err = add_nondir(dentry, inode);
 123 out:
 124         return err;
 125
 126 out_fail:
 127         dec_count(inode);
 128         iput(inode);
 129         goto out;
 130 }
 131
 132 static int sysv_link(struct dentry * old_dentry, struct inode * dir,
 133         struct dentry * dentry)
 134 {
 135         struct inode *inode = old_dentry->d_inode;
 136
 137         if (inode->i_nlink >= SYSV_SB(inode->i_sb)->s_link_max)
 138                 return -EMLINK;
 139
 140         inode->i_ctime = CURRENT_TIME;
 141         inc_count(inode);
 142         atomic_inc(&inode->i_count);
 143
 144         return add_nondir(dentry, inode);
 145 }
 146
 147 static int sysv_mkdir(struct inode * dir, struct dentry *dentry, int mode)
 148 {
 149         struct inode * inode;
 150         int err = -EMLINK;
 151
 152         if (dir->i_nlink >= SYSV_SB(dir->i_sb)->s_link_max)
 153                 goto out;
 154         inc_count(dir);
 155
 156         inode = sysv_new_inode(dir, S_IFDIR|mode);
 157         err = PTR_ERR(inode);
 158         if (IS_ERR(inode))
 159                 goto out_dir;
 160
 161         sysv_set_inode(inode, 0);
 162
 163         inc_count(inode);
 164
 165         err = sysv_make_empty(inode, dir);
 166         if (err)
 167                 goto out_fail;
 168
 169         err = sysv_add_link(dentry, inode);
 170         if (err)
 171                 goto out_fail;
 172
 173         d_instantiate(dentry, inode);
 174 out:
 175         return err;
 176
 177 out_fail:
 178         dec_count(inode);
 179         dec_count(inode);
 180         iput(inode);
 181 out_dir:
 182         dec_count(dir);
 183         goto out;
 184 }
 185
 186 static int sysv_unlink(struct inode * dir, struct dentry * dentry)
 187 {
 188         struct inode * inode = dentry->d_inode;
 189         struct page * page;
 190         struct sysv_dir_entry * de;
 191         int err = -ENOENT;
 192
 193         de = sysv_find_entry(dentry, &page);
 194         if (!de)
 195                 goto out;
 196
 197         err = sysv_delete_entry (de, page);
 198         if (err)
 199                 goto out;
 200
 201         inode->i_ctime = dir->i_ctime;
 202         dec_count(inode);
 203 out:
 204         return err;
 205 }
 206
 207 static int sysv_rmdir(struct inode * dir, struct dentry * dentry)
 208 {
 209         struct inode *inode = dentry->d_inode;
 210         int err = -ENOTEMPTY;
 211
 212         if (sysv_empty_dir(inode)) {
 213                 err = sysv_unlink(dir, dentry);
 214                 if (!err) {
 215                         inode->i_size = 0;
 216                         dec_count(inode);
 217                         dec_count(dir);
 218                 }
 219         }
 220         return err;
 221 }
 222
 223 /*
 224  * Anybody can rename anything with this: the permission checks are left to the
 225  * higher-level routines.
 226  */
 227 static int sysv_rename(struct inode * old_dir, struct dentry * old_dentry,
 228                   struct inode * new_dir, struct dentry * new_dentry)
 229 {
 230         struct inode * old_inode = old_dentry->d_inode;
 231         struct inode * new_inode = new_dentry->d_inode;
 232         struct page * dir_page = NULL;
 233         struct sysv_dir_entry * dir_de = NULL;
 234         struct page * old_page;
 235         struct sysv_dir_entry * old_de;
 236         int err = -ENOENT;
 237
 238         old_de = sysv_find_entry(old_dentry, &old_page);
 239         if (!old_de)
 240                 goto out;
 241
 242         if (S_ISDIR(old_inode->i_mode)) {
 243                 err = -EIO;
 244                 dir_de = sysv_dotdot(old_inode, &dir_page);
 245                 if (!dir_de)
 246                         goto out_old;
 247         }
 248
 249         if (new_inode) {
 250                 struct page * new_page;
 251                 struct sysv_dir_entry * new_de;
 252
 253                 err = -ENOTEMPTY;
 254                 if (dir_de && !sysv_empty_dir(new_inode))
 255                         goto out_dir;
 256
 257                 err = -ENOENT;
 258                 new_de = sysv_find_entry(new_dentry, &new_page);
 259                 if (!new_de)
 260                         goto out_dir;
 261                 inc_count(old_inode);
 262                 sysv_set_link(new_de, new_page, old_inode);
 263                 new_inode->i_ctime = CURRENT_TIME;
 264                 if (dir_de)
 265                         new_inode->i_nlink--;
 266                 dec_count(new_inode);
 267         } else {
 268                 if (dir_de) {
 269                         err = -EMLINK;
 270                         if (new_dir->i_nlink >= SYSV_SB(new_dir->i_sb)->s_link_max)
 271                                 goto out_dir;
 272                 }
 273                 inc_count(old_inode);
 274                 err = sysv_add_link(new_dentry, old_inode);
 275                 if (err) {
 276                         dec_count(old_inode);
 277                         goto out_dir;
 278                 }
 279                 if (dir_de)
 280                         inc_count(new_dir);
 281         }
 282
 283         sysv_delete_entry(old_de, old_page);
 284         dec_count(old_inode);
 285
 286         if (dir_de) {
 287                 sysv_set_link(dir_de, dir_page, new_dir);
 288                 dec_count(old_dir);
 289         }
 290         return 0;
 291
 292 out_dir:
 293         if (dir_de) {
 294                 kunmap(dir_page);
 295                 page_cache_release(dir_page);
 296         }
 297 out_old:
 298         kunmap(old_page);
 299         page_cache_release(old_page);
 300 out:
 301         return err;
 302 }
 303
 304 /*
 305  * directories can handle most operations...
 306  */
 307 struct inode_operations sysv_dir_inode_operations = {
 308         .create         = sysv_create,
 309         .lookup         = sysv_lookup,
 310         .link           = sysv_link,
 311         .unlink         = sysv_unlink,
 312         .symlink        = sysv_symlink,
 313         .mkdir          = sysv_mkdir,
 314         .rmdir          = sysv_rmdir,
 315         .mknod          = sysv_mknod,
 316         .rename         = sysv_rename,
 317         .getattr        = sysv_getattr,
 318 };