fs/umsdos/rdir.c

   1 /*
   2  *  linux/fs/umsdos/rdir.c
   3  *
   4  *  Written 1994 by Jacques Gelinas
   5  *
   6  *  Extended MS-DOS directory pure MS-DOS handling functions
   7  *  (For directory without EMD file).
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/fs.h>
  12 #include <linux/msdos_fs.h>
  13 #include <linux/errno.h>
  14 #include <linux/stat.h>
  15 #include <linux/limits.h>
  16 #include <linux/umsdos_fs.h>
  17 #include <linux/malloc.h>
  18
  19 #include <asm/uaccess.h>
  20
  21
  22 extern struct dentry *saved_root;
  23 extern struct inode *pseudo_root;
  24 extern struct dentry_operations umsdos_dentry_operations;
  25
  26 struct RDIR_FILLDIR {
  27         void *dirbuf;
  28         filldir_t filldir;
  29         int real_root;
  30 };
  31
  32 static int rdir_filldir (       void *buf,
  33                                 const char *name,
  34                                 int name_len,
  35                                 off_t offset,
  36                                 ino_t ino)
  37 {
  38         int ret = 0;
  39         struct RDIR_FILLDIR *d = (struct RDIR_FILLDIR *) buf;
  40
  41         if (d->real_root) {
  42                 PRINTK ((KERN_DEBUG "rdir_filldir /mn/: real root!\n"));
  43                 /* real root of a pseudo_rooted partition */
  44                 if (name_len != UMSDOS_PSDROOT_LEN
  45                     || memcmp (name, UMSDOS_PSDROOT_NAME, UMSDOS_PSDROOT_LEN) != 0) {
  46                         /* So it is not the /linux directory */
  47                         if (name_len == 2 && name[0] == '.' && name[1] == '.') {
  48                                 /* Make sure the .. entry points back to the pseudo_root */
  49                                 ino = pseudo_root->i_ino;
  50                         }
  51                         ret = d->filldir (d->dirbuf, name, name_len, offset, ino);
  52                 }
  53         } else {
  54                 /* Any DOS directory */
  55                 ret = d->filldir (d->dirbuf, name, name_len, offset, ino);
  56         }
  57         return ret;
  58 }
  59
  60
  61 static int UMSDOS_rreaddir (struct file *filp, void *dirbuf, filldir_t filldir)
  62 {
  63         struct inode *dir = filp->f_dentry->d_inode;
  64         struct RDIR_FILLDIR bufk;
  65
  66         bufk.filldir = filldir;
  67         bufk.dirbuf = dirbuf;
  68         bufk.real_root = pseudo_root && (dir == saved_root->d_inode);
  69         return fat_readdir (filp, &bufk, rdir_filldir);
  70 }
  71
  72
  73 /*
  74  * Lookup into a non promoted directory.
  75  * If the result is a directory, make sure we find out if it is
  76  * a promoted one or not (calling umsdos_setup_dir_inode(inode)).
  77  */
  78 /* #Specification: pseudo root / DOS/..
  79  * In the real root directory (c:\), the directory ..
  80  * is the pseudo root (c:\linux).
  81  */
  82 struct dentry *umsdos_rlookup_x ( struct inode *dir, struct dentry *dentry, int nopseudo)
  83 {
  84         struct dentry *ret;
  85
  86         if (saved_root && dir == saved_root->d_inode && !nopseudo &&
  87             dentry->d_name.len == UMSDOS_PSDROOT_LEN &&
  88             memcmp (dentry->d_name.name, UMSDOS_PSDROOT_NAME, UMSDOS_PSDROOT_LEN) == 0) {
  89                 /* #Specification: pseudo root / DOS/linux
  90                  * Even in the real root directory (c:\), the directory
  91                  * /linux won't show
  92                  */
  93
  94                 ret = ERR_PTR(-ENOENT);
  95                 goto out;
  96         }
  97
  98         ret = msdos_lookup (dir, dentry);
  99         if (ret) {
 100                 printk(KERN_WARNING
 101                         "umsdos_rlookup_x: %s/%s failed, ret=%ld\n",
 102                         dentry->d_parent->d_name.name, dentry->d_name.name,
 103                         PTR_ERR(ret));
 104                 goto out;
 105         }
 106         if (dentry->d_inode) {
 107                 /* We must install the proper function table
 108                  * depending on whether this is an MS-DOS or
 109                  * a UMSDOS directory
 110                  */
 111 Printk ((KERN_DEBUG "umsdos_rlookup_x: patch_dentry_inode %s/%s\n",
 112 dentry->d_parent->d_name.name, dentry->d_name.name));
 113                 umsdos_patch_dentry_inode(dentry, 0);
 114
 115         }
 116 out:
 117         /* always install our dentry ops ... */
 118         dentry->d_op = &umsdos_dentry_operations;
 119         return ret;
 120 }
 121
 122
 123 struct dentry *UMSDOS_rlookup ( struct inode *dir, struct dentry *dentry)
 124 {
 125         return umsdos_rlookup_x (dir, dentry, 0);
 126 }
 127
 128
 129 /* #Specification: dual mode / rmdir in a DOS directory
 130  * In a DOS (not EMD in it) directory, we use a reverse strategy
 131  * compared with a UMSDOS directory. We assume that a subdirectory
 132  * of a DOS directory is also a DOS directory. This is not always
 133  * true (umssync may be used anywhere), but makes sense.
 134  *
 135  * So we call msdos_rmdir() directly. If it failed with a -ENOTEMPTY
 136  * then we check if it is a Umsdos directory. We check if it is
 137  * really empty (only . .. and --linux-.--- in it). If it is true
 138  * we remove the EMD and do a msdos_rmdir() again.
 139  *
 140  * In a Umsdos directory, we assume all subdirectories are also
 141  * Umsdos directories, so we check the EMD file first.
 142  */
 143 /* #Specification: pseudo root / rmdir /DOS
 144  * The pseudo sub-directory /DOS can't be removed!
 145  * This is done even if the pseudo root is not a Umsdos
 146  * directory anymore (very unlikely), but an accident (under
 147  * MS-DOS) is always possible.
 148  *
 149  * EPERM is returned.
 150  */
 151 static int UMSDOS_rrmdir ( struct inode *dir, struct dentry *dentry)
 152 {
 153         int ret, empty;
 154
 155         ret = -EPERM;
 156         if (umsdos_is_pseudodos (dir, dentry))
 157                 goto out;
 158
 159         ret = -EBUSY;
 160         if (!list_empty(&dentry->d_hash))
 161                 goto out;
 162
 163         ret = msdos_rmdir (dir, dentry);
 164         if (ret != -ENOTEMPTY)
 165                 goto out;
 166
 167         empty = umsdos_isempty (dentry);
 168         if (empty == 1) {
 169                 struct dentry *demd;
 170                 /* We have to remove the EMD file. */
 171                 demd = umsdos_get_emd_dentry(dentry);
 172                 ret = PTR_ERR(demd);
 173                 if (!IS_ERR(demd)) {
 174                         ret = 0;
 175                         if (demd->d_inode)
 176                                 ret = msdos_unlink (dentry->d_inode, demd);
 177                         dput(demd);
 178                 }
 179         }
 180         if (ret)
 181                 goto out;
 182
 183         /* now retry the original ... */
 184         ret = msdos_rmdir (dir, dentry);
 185
 186 out:
 187         return ret;
 188 }
 189
 190 /* #Specification: dual mode / introduction
 191  * One goal of UMSDOS is to allow a practical and simple coexistence
 192  * between MS-DOS and Linux in a single partition. Using the EMD file
 193  * in each directory, UMSDOS adds Unix semantics and capabilities to
 194  * a normal DOS filesystem. To help and simplify coexistence, here is
 195  * the logic related to the EMD file.
 196  *
 197  * If it is missing, then the directory is managed by the MS-DOS driver.
 198  * The names are limited to DOS limits (8.3). No links, no device special
 199  * and pipe and so on.
 200  *
 201  * If it is there, it is the directory. If it is there but empty, then
 202  * the directory looks empty. The utility umssync allows synchronisation
 203  * of the real DOS directory and the EMD.
 204  *
 205  * Whenever umssync is applied to a directory without EMD, one is
 206  * created on the fly.  The directory is promoted to full Unix semantics.
 207  * Of course, the ls command will show exactly the same content as before
 208  * the umssync session.
 209  *
 210  * It is believed that the user/admin will promote directories to Unix
 211  * semantics as needed.
 212  *
 213  * The strategy to implement this is to use two function table (struct
 214  * inode_operations). One for true UMSDOS directory and one for directory
 215  * with missing EMD.
 216  *
 217  * Functions related to the DOS semantic (but aware of UMSDOS) generally
 218  * have a "r" prefix (r for real) such as UMSDOS_rlookup, to differentiate
 219  * from the one with full UMSDOS semantics.
 220  */
 221 static struct file_operations umsdos_rdir_operations =
 222 {
 223         NULL,                   /* lseek - default */
 224         dummy_dir_read,         /* read */
 225         NULL,                   /* write - bad */
 226         UMSDOS_rreaddir,        /* readdir */
 227         NULL,                   /* poll - default */
 228         UMSDOS_ioctl_dir,       /* ioctl - default */
 229         NULL,                   /* mmap */
 230         NULL,                   /* no special open code */
 231         NULL,                   /* flush */
 232         NULL,                   /* no special release code */
 233         NULL                    /* fsync */
 234 };
 235
 236 struct inode_operations umsdos_rdir_inode_operations =
 237 {
 238         &umsdos_rdir_operations,        /* default directory file-ops */
 239         msdos_create,           /* create */
 240         UMSDOS_rlookup,         /* lookup */
 241         NULL,                   /* link */
 242         msdos_unlink,           /* unlink */
 243         NULL,                   /* symlink */
 244         msdos_mkdir,            /* mkdir */
 245         UMSDOS_rrmdir,          /* rmdir */
 246         NULL,                   /* mknod */
 247         msdos_rename,           /* rename */
 248         NULL,                   /* readlink */
 249         NULL,                   /* followlink */
 250         NULL,                   /* readpage */
 251         NULL,                   /* writepage */
 252         NULL,                   /* get_block */
 253         NULL,                   /* truncate */
 254         NULL,                   /* permission */
 255         NULL,                   /* smap */
 256         NULL,                   /* revalidate */
 257 };