arch/ia64/sn/io/hwgfs/interface.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (c) 2003 Silicon Graphics, Inc.  All Rights Reserved.
   7  *
   8  *  Portions based on Adam Richter's smalldevfs and thus
   9  *  Copyright 2002-2003  Yggdrasil Computing, Inc.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/kernel.h>
  14 #include <linux/fs.h>
  15 #include <linux/mount.h>
  16 #include <linux/namei.h>
  17 #include <linux/string.h>
  18 #include <linux/slab.h>
  19 #include <asm/sn/hwgfs.h>
  20
  21
  22 extern struct vfsmount *hwgfs_vfsmount;
  23
  24 static int
  25 walk_parents_mkdir(
  26         const char              **path,
  27         struct nameidata        *nd,
  28         int                     is_dir)
  29 {
  30         char                    *slash;
  31         char                    buf[strlen(*path)+1];
  32         int                     error;
  33
  34         while ((slash = strchr(*path, '/')) != NULL) {
  35                 int len = slash - *path;
  36                 memcpy(buf, *path, len);
  37                 buf[len] = '\0';
  38
  39                 error = path_walk(buf, nd);
  40                 if (unlikely(error))
  41                         return error;
  42
  43                 nd->dentry = lookup_create(nd, is_dir);
  44                 nd->flags |= LOOKUP_PARENT;
  45                 if (unlikely(IS_ERR(nd->dentry)))
  46                         return PTR_ERR(nd->dentry);
  47
  48                 if (!nd->dentry->d_inode)
  49                         error = vfs_mkdir(nd->dentry->d_parent->d_inode,
  50                                         nd->dentry, 0755);
  51
  52                 up(&nd->dentry->d_parent->d_inode->i_sem);
  53                 if (unlikely(error))
  54                         return error;
  55
  56                 *path += len + 1;
  57         }
  58
  59         return 0;
  60 }
  61
  62 /* On success, returns with parent_inode->i_sem taken. */
  63 static int
  64 hwgfs_decode(
  65         hwgfs_handle_t          dir,
  66         const char              *name,
  67         int                     is_dir,
  68         struct inode            **parent_inode,
  69         struct dentry           **dentry)
  70 {
  71         struct nameidata        nd;
  72         int                     error;
  73
  74         if (!dir)
  75                 dir = hwgfs_vfsmount->mnt_sb->s_root;
  76
  77         memset(&nd, 0, sizeof(nd));
  78         nd.flags = LOOKUP_PARENT;
  79         nd.mnt = mntget(hwgfs_vfsmount);
  80         nd.dentry = dget(dir);
  81
  82         error = walk_parents_mkdir(&name, &nd, is_dir);
  83         if (unlikely(error))
  84                 return error;
  85
  86         error = path_walk(name, &nd);
  87         if (unlikely(error))
  88                 return error;
  89
  90         *dentry = lookup_create(&nd, is_dir);
  91
  92         if (unlikely(IS_ERR(*dentry)))
  93                 return PTR_ERR(*dentry);
  94         *parent_inode = (*dentry)->d_parent->d_inode;
  95         return 0;
  96 }
  97
  98 static int
  99 path_len(
 100         struct dentry           *de,
 101         struct dentry           *root)
 102 {
 103         int                     len = 0;
 104
 105         while (de != root) {
 106                 len += de->d_name.len + 1;      /* count the '/' */
 107                 de = de->d_parent;
 108         }
 109         return len;             /* -1 because we omit the leading '/',
 110                                    +1 because we include trailing '\0' */
 111 }
 112
 113 int
 114 hwgfs_generate_path(
 115         hwgfs_handle_t          de,
 116         char                    *path,
 117         int                     buflen)
 118 {
 119         struct dentry           *hwgfs_root;
 120         int                     len;
 121         char                    *path_orig = path;
 122
 123         if (unlikely(de == NULL))
 124                 return -EINVAL;
 125
 126         hwgfs_root = hwgfs_vfsmount->mnt_sb->s_root;
 127         if (unlikely(de == hwgfs_root))
 128                 return -EINVAL;
 129
 130         spin_lock(&dcache_lock);
 131         len = path_len(de, hwgfs_root);
 132         if (len > buflen) {
 133                 spin_unlock(&dcache_lock);
 134                 return -ENAMETOOLONG;
 135         }
 136
 137         path += len - 1;
 138         *path = '\0';
 139
 140         for (;;) {
 141                 path -= de->d_name.len;
 142                 memcpy(path, de->d_name.name, de->d_name.len);
 143                 de = de->d_parent;
 144                 if (de == hwgfs_root)
 145                         break;
 146                 *(--path) = '/';
 147         }
 148
 149         spin_unlock(&dcache_lock);
 150         BUG_ON(path != path_orig);
 151         return 0;
 152 }
 153
 154 hwgfs_handle_t
 155 hwgfs_register(
 156         hwgfs_handle_t          dir,
 157         const char              *name,
 158         unsigned int            flags,
 159         unsigned int            major,
 160         unsigned int            minor,
 161         umode_t                 mode,
 162         void                    *ops,
 163         void                    *info)
 164 {
 165         dev_t                   devnum = MKDEV(major, minor);
 166         struct inode            *parent_inode;
 167         struct dentry           *dentry;
 168         int                     error;
 169
 170         error = hwgfs_decode(dir, name, 0, &parent_inode, &dentry);
 171         if (likely(!error)) {
 172                 error = vfs_mknod(parent_inode, dentry, mode, devnum);
 173                 if (likely(!error)) {
 174                         /*
 175                          * Do this inside parents i_sem to avoid racing
 176                          * with lookups.
 177                          */
 178                         if (S_ISCHR(mode))
 179                                 dentry->d_inode->i_fop = ops;
 180                         dentry->d_fsdata = info;
 181                         up(&parent_inode->i_sem);
 182                 } else {
 183                         up(&parent_inode->i_sem);
 184                         dput(dentry);
 185                         dentry = NULL;
 186                 }
 187         }
 188
 189         return dentry;
 190 }
 191
 192 int
 193 hwgfs_mk_symlink(
 194         hwgfs_handle_t          dir,
 195         const char              *name,
 196         unsigned int            flags,
 197         const char              *link,
 198         hwgfs_handle_t          *handle,
 199         void                    *info)
 200 {
 201         struct inode            *parent_inode;
 202         struct dentry           *dentry;
 203         int                     error;
 204
 205         error = hwgfs_decode(dir, name, 0, &parent_inode, &dentry);
 206         if (likely(!error)) {
 207                 error = vfs_symlink(parent_inode, dentry, link, S_IALLUGO);
 208                 dentry->d_fsdata = info;
 209                 if (handle)
 210                         *handle = dentry;
 211                 up(&parent_inode->i_sem);
 212                 /* dput(dentry); */
 213         }
 214         return error;
 215 }
 216
 217 hwgfs_handle_t
 218 hwgfs_mk_dir(
 219         hwgfs_handle_t          dir,
 220         const char              *name,
 221         void                    *info)
 222 {
 223         struct inode            *parent_inode;
 224         struct dentry           *dentry;
 225         int                     error;
 226
 227         error = hwgfs_decode(dir, name, 1, &parent_inode, &dentry);
 228         if (likely(!error)) {
 229                 error = vfs_mkdir(parent_inode, dentry, 0755);
 230                 up(&parent_inode->i_sem);
 231
 232                 if (unlikely(error)) {
 233                         dput(dentry);
 234                         dentry = NULL;
 235                 } else {
 236                         dentry->d_fsdata = info;
 237                 }
 238         }
 239         return dentry;
 240 }
 241
 242 void
 243 hwgfs_unregister(
 244         hwgfs_handle_t          de)
 245 {
 246         struct inode            *parent_inode = de->d_parent->d_inode;
 247
 248         if (S_ISDIR(de->d_inode->i_mode))
 249                 vfs_rmdir(parent_inode, de);
 250         else
 251                 vfs_unlink(parent_inode, de);
 252 }
 253
 254 /* XXX: this function is utterly bogus.  Every use of it is racy and the
 255         prototype is stupid.  You have been warned.  --hch.  */
 256 hwgfs_handle_t
 257 hwgfs_find_handle(
 258         hwgfs_handle_t          base,
 259         const char              *name,
 260         unsigned int            major,          /* IGNORED */
 261         unsigned int            minor,          /* IGNORED */
 262         char                    type,           /* IGNORED */
 263         int                     traverse_symlinks)
 264 {
 265         struct dentry           *dentry = NULL;
 266         struct nameidata        nd;
 267         int                     error;
 268
 269         BUG_ON(*name=='/');
 270
 271         memset(&nd, 0, sizeof(nd));
 272
 273         nd.mnt = mntget(hwgfs_vfsmount);
 274         nd.dentry = dget(base ? base : hwgfs_vfsmount->mnt_sb->s_root);
 275         nd.flags = (traverse_symlinks ? LOOKUP_FOLLOW : 0);
 276
 277         error = path_walk(name, &nd);
 278         if (likely(!error)) {
 279                 dentry = nd.dentry;
 280                 path_release(&nd);              /* stale data from here! */
 281         }
 282
 283         return dentry;
 284 }
 285
 286 hwgfs_handle_t
 287 hwgfs_get_parent(
 288         hwgfs_handle_t          de)
 289 {
 290         struct dentry           *parent;
 291
 292         spin_lock(&de->d_lock);
 293         parent = de->d_parent;
 294         spin_unlock(&de->d_lock);
 295
 296         return parent;
 297 }
 298
 299 int
 300 hwgfs_set_info(
 301         hwgfs_handle_t          de,
 302         void                    *info)
 303 {
 304         if (unlikely(de == NULL))
 305                 return -EINVAL;
 306         de->d_fsdata = info;
 307         return 0;
 308 }
 309
 310 void *
 311 hwgfs_get_info(
 312         hwgfs_handle_t          de)
 313 {
 314         return de->d_fsdata;
 315 }
 316
 317 EXPORT_SYMBOL(hwgfs_generate_path);
 318 EXPORT_SYMBOL(hwgfs_register);
 319 EXPORT_SYMBOL(hwgfs_unregister);
 320 EXPORT_SYMBOL(hwgfs_mk_symlink);
 321 EXPORT_SYMBOL(hwgfs_mk_dir);
 322 EXPORT_SYMBOL(hwgfs_find_handle);
 323 EXPORT_SYMBOL(hwgfs_get_parent);
 324 EXPORT_SYMBOL(hwgfs_set_info);
 325 EXPORT_SYMBOL(hwgfs_get_info);