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