fs/bfs/dir.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *      fs/bfs/dir.c
   4  *      BFS directory operations.
   5  *      Copyright (C) 1999-2018  Tigran Aivazian <aivazian.tigran@gmail.com>
   6  *  Made endianness-clean by Andrew Stribblehill <ads@wompom.org> 2005
   7  */
   8
   9 #include <linux/time.h>
  10 #include <linux/string.h>
  11 #include <linux/fs.h>
  12 #include <linux/buffer_head.h>
  13 #include <linux/sched.h>
  14 #include "bfs.h"
  15
  16 #undef DEBUG
  17
  18 #ifdef DEBUG
  19 #define dprintf(x...)   printf(x)
  20 #else
  21 #define dprintf(x...)
  22 #endif
  23
  24 static int bfs_add_entry(struct inode *dir, const struct qstr *child, int ino);
  25 static struct buffer_head *bfs_find_entry(struct inode *dir,
  26                                 const struct qstr *child,
  27                                 struct bfs_dirent **res_dir);
  28
  29 static int bfs_readdir(struct file *f, struct dir_context *ctx)
  30 {
  31         struct inode *dir = file_inode(f);
  32         struct buffer_head *bh;
  33         struct bfs_dirent *de;
  34         unsigned int offset;
  35         int block;
  36
  37         if (ctx->pos & (BFS_DIRENT_SIZE - 1)) {
  38                 printf("Bad f_pos=%08lx for %s:%08lx\n",
  39                                         (unsigned long)ctx->pos,
  40                                         dir->i_sb->s_id, dir->i_ino);
  41                 return -EINVAL;
  42         }
  43
  44         while (ctx->pos < dir->i_size) {
  45                 offset = ctx->pos & (BFS_BSIZE - 1);
  46                 block = BFS_I(dir)->i_sblock + (ctx->pos >> BFS_BSIZE_BITS);
  47                 bh = sb_bread(dir->i_sb, block);
  48                 if (!bh) {
  49                         ctx->pos += BFS_BSIZE - offset;
  50                         continue;
  51                 }
  52                 do {
  53                         de = (struct bfs_dirent *)(bh->b_data + offset);
  54                         if (de->ino) {
  55                                 int size = strnlen(de->name, BFS_NAMELEN);
  56                                 if (!dir_emit(ctx, de->name, size,
  57                                                 le16_to_cpu(de->ino),
  58                                                 DT_UNKNOWN)) {
  59                                         brelse(bh);
  60                                         return 0;
  61                                 }
  62                         }
  63                         offset += BFS_DIRENT_SIZE;
  64                         ctx->pos += BFS_DIRENT_SIZE;
  65                 } while ((offset < BFS_BSIZE) && (ctx->pos < dir->i_size));
  66                 brelse(bh);
  67         }
  68         return 0;
  69 }
  70
  71 const struct file_operations bfs_dir_operations = {
  72         .read           = generic_read_dir,
  73         .iterate_shared = bfs_readdir,
  74         .fsync          = generic_file_fsync,
  75         .llseek         = generic_file_llseek,
  76 };
  77
  78 static int bfs_create(struct user_namespace *mnt_userns, struct inode *dir,
  79                       struct dentry *dentry, umode_t mode, bool excl)
  80 {
  81         int err;
  82         struct inode *inode;
  83         struct super_block *s = dir->i_sb;
  84         struct bfs_sb_info *info = BFS_SB(s);
  85         unsigned long ino;
  86
  87         inode = new_inode(s);
  88         if (!inode)
  89                 return -ENOMEM;
  90         mutex_lock(&info->bfs_lock);
  91         ino = find_first_zero_bit(info->si_imap, info->si_lasti + 1);
  92         if (ino > info->si_lasti) {
  93                 mutex_unlock(&info->bfs_lock);
  94                 iput(inode);
  95                 return -ENOSPC;
  96         }
  97         set_bit(ino, info->si_imap);
  98         info->si_freei--;
  99         inode_init_owner(&init_user_ns, inode, dir, mode);
 100         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 101         inode->i_blocks = 0;
 102         inode->i_op = &bfs_file_inops;
 103         inode->i_fop = &bfs_file_operations;
 104         inode->i_mapping->a_ops = &bfs_aops;
 105         inode->i_ino = ino;
 106         BFS_I(inode)->i_dsk_ino = ino;
 107         BFS_I(inode)->i_sblock = 0;
 108         BFS_I(inode)->i_eblock = 0;
 109         insert_inode_hash(inode);
 110         mark_inode_dirty(inode);
 111         bfs_dump_imap("create", s);
 112
 113         err = bfs_add_entry(dir, &dentry->d_name, inode->i_ino);
 114         if (err) {
 115                 inode_dec_link_count(inode);
 116                 mutex_unlock(&info->bfs_lock);
 117                 iput(inode);
 118                 return err;
 119         }
 120         mutex_unlock(&info->bfs_lock);
 121         d_instantiate(dentry, inode);
 122         return 0;
 123 }
 124
 125 static struct dentry *bfs_lookup(struct inode *dir, struct dentry *dentry,
 126                                                 unsigned int flags)
 127 {
 128         struct inode *inode = NULL;
 129         struct buffer_head *bh;
 130         struct bfs_dirent *de;
 131         struct bfs_sb_info *info = BFS_SB(dir->i_sb);
 132
 133         if (dentry->d_name.len > BFS_NAMELEN)
 134                 return ERR_PTR(-ENAMETOOLONG);
 135
 136         mutex_lock(&info->bfs_lock);
 137         bh = bfs_find_entry(dir, &dentry->d_name, &de);
 138         if (bh) {
 139                 unsigned long ino = (unsigned long)le16_to_cpu(de->ino);
 140                 brelse(bh);
 141                 inode = bfs_iget(dir->i_sb, ino);
 142         }
 143         mutex_unlock(&info->bfs_lock);
 144         return d_splice_alias(inode, dentry);
 145 }
 146
 147 static int bfs_link(struct dentry *old, struct inode *dir,
 148                                                 struct dentry *new)
 149 {
 150         struct inode *inode = d_inode(old);
 151         struct bfs_sb_info *info = BFS_SB(inode->i_sb);
 152         int err;
 153
 154         mutex_lock(&info->bfs_lock);
 155         err = bfs_add_entry(dir, &new->d_name, inode->i_ino);
 156         if (err) {
 157                 mutex_unlock(&info->bfs_lock);
 158                 return err;
 159         }
 160         inc_nlink(inode);
 161         inode->i_ctime = current_time(inode);
 162         mark_inode_dirty(inode);
 163         ihold(inode);
 164         d_instantiate(new, inode);
 165         mutex_unlock(&info->bfs_lock);
 166         return 0;
 167 }
 168
 169 static int bfs_unlink(struct inode *dir, struct dentry *dentry)
 170 {
 171         int error = -ENOENT;
 172         struct inode *inode = d_inode(dentry);
 173         struct buffer_head *bh;
 174         struct bfs_dirent *de;
 175         struct bfs_sb_info *info = BFS_SB(inode->i_sb);
 176
 177         mutex_lock(&info->bfs_lock);
 178         bh = bfs_find_entry(dir, &dentry->d_name, &de);
 179         if (!bh || (le16_to_cpu(de->ino) != inode->i_ino))
 180                 goto out_brelse;
 181
 182         if (!inode->i_nlink) {
 183                 printf("unlinking non-existent file %s:%lu (nlink=%d)\n",
 184                                         inode->i_sb->s_id, inode->i_ino,
 185                                         inode->i_nlink);
 186                 set_nlink(inode, 1);
 187         }
 188         de->ino = 0;
 189         mark_buffer_dirty_inode(bh, dir);
 190         dir->i_ctime = dir->i_mtime = current_time(dir);
 191         mark_inode_dirty(dir);
 192         inode->i_ctime = dir->i_ctime;
 193         inode_dec_link_count(inode);
 194         error = 0;
 195
 196 out_brelse:
 197         brelse(bh);
 198         mutex_unlock(&info->bfs_lock);
 199         return error;
 200 }
 201
 202 static int bfs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 203                       struct dentry *old_dentry, struct inode *new_dir,
 204                       struct dentry *new_dentry, unsigned int flags)
 205 {
 206         struct inode *old_inode, *new_inode;
 207         struct buffer_head *old_bh, *new_bh;
 208         struct bfs_dirent *old_de, *new_de;
 209         struct bfs_sb_info *info;
 210         int error = -ENOENT;
 211
 212         if (flags & ~RENAME_NOREPLACE)
 213                 return -EINVAL;
 214
 215         old_bh = new_bh = NULL;
 216         old_inode = d_inode(old_dentry);
 217         if (S_ISDIR(old_inode->i_mode))
 218                 return -EINVAL;
 219
 220         info = BFS_SB(old_inode->i_sb);
 221
 222         mutex_lock(&info->bfs_lock);
 223         old_bh = bfs_find_entry(old_dir, &old_dentry->d_name, &old_de);
 224
 225         if (!old_bh || (le16_to_cpu(old_de->ino) != old_inode->i_ino))
 226                 goto end_rename;
 227
 228         error = -EPERM;
 229         new_inode = d_inode(new_dentry);
 230         new_bh = bfs_find_entry(new_dir, &new_dentry->d_name, &new_de);
 231
 232         if (new_bh && !new_inode) {
 233                 brelse(new_bh);
 234                 new_bh = NULL;
 235         }
 236         if (!new_bh) {
 237                 error = bfs_add_entry(new_dir, &new_dentry->d_name,
 238                                         old_inode->i_ino);
 239                 if (error)
 240                         goto end_rename;
 241         }
 242         old_de->ino = 0;
 243         old_dir->i_ctime = old_dir->i_mtime = current_time(old_dir);
 244         mark_inode_dirty(old_dir);
 245         if (new_inode) {
 246                 new_inode->i_ctime = current_time(new_inode);
 247                 inode_dec_link_count(new_inode);
 248         }
 249         mark_buffer_dirty_inode(old_bh, old_dir);
 250         error = 0;
 251
 252 end_rename:
 253         mutex_unlock(&info->bfs_lock);
 254         brelse(old_bh);
 255         brelse(new_bh);
 256         return error;
 257 }
 258
 259 const struct inode_operations bfs_dir_inops = {
 260         .create                 = bfs_create,
 261         .lookup                 = bfs_lookup,
 262         .link                   = bfs_link,
 263         .unlink                 = bfs_unlink,
 264         .rename                 = bfs_rename,
 265 };
 266
 267 static int bfs_add_entry(struct inode *dir, const struct qstr *child, int ino)
 268 {
 269         const unsigned char *name = child->name;
 270         int namelen = child->len;
 271         struct buffer_head *bh;
 272         struct bfs_dirent *de;
 273         int block, sblock, eblock, off, pos;
 274         int i;
 275
 276         dprintf("name=%s, namelen=%d\n", name, namelen);
 277
 278         if (!namelen)
 279                 return -ENOENT;
 280         if (namelen > BFS_NAMELEN)
 281                 return -ENAMETOOLONG;
 282
 283         sblock = BFS_I(dir)->i_sblock;
 284         eblock = BFS_I(dir)->i_eblock;
 285         for (block = sblock; block <= eblock; block++) {
 286                 bh = sb_bread(dir->i_sb, block);
 287                 if (!bh)
 288                         return -EIO;
 289                 for (off = 0; off < BFS_BSIZE; off += BFS_DIRENT_SIZE) {
 290                         de = (struct bfs_dirent *)(bh->b_data + off);
 291                         if (!de->ino) {
 292                                 pos = (block - sblock) * BFS_BSIZE + off;
 293                                 if (pos >= dir->i_size) {
 294                                         dir->i_size += BFS_DIRENT_SIZE;
 295                                         dir->i_ctime = current_time(dir);
 296                                 }
 297                                 dir->i_mtime = current_time(dir);
 298                                 mark_inode_dirty(dir);
 299                                 de->ino = cpu_to_le16((u16)ino);
 300                                 for (i = 0; i < BFS_NAMELEN; i++)
 301                                         de->name[i] =
 302                                                 (i < namelen) ? name[i] : 0;
 303                                 mark_buffer_dirty_inode(bh, dir);
 304                                 brelse(bh);
 305                                 return 0;
 306                         }
 307                 }
 308                 brelse(bh);
 309         }
 310         return -ENOSPC;
 311 }
 312
 313 static inline int bfs_namecmp(int len, const unsigned char *name,
 314                                                         const char *buffer)
 315 {
 316         if ((len < BFS_NAMELEN) && buffer[len])
 317                 return 0;
 318         return !memcmp(name, buffer, len);
 319 }
 320
 321 static struct buffer_head *bfs_find_entry(struct inode *dir,
 322                         const struct qstr *child,
 323                         struct bfs_dirent **res_dir)
 324 {
 325         unsigned long block = 0, offset = 0;
 326         struct buffer_head *bh = NULL;
 327         struct bfs_dirent *de;
 328         const unsigned char *name = child->name;
 329         int namelen = child->len;
 330
 331         *res_dir = NULL;
 332         if (namelen > BFS_NAMELEN)
 333                 return NULL;
 334
 335         while (block * BFS_BSIZE + offset < dir->i_size) {
 336                 if (!bh) {
 337                         bh = sb_bread(dir->i_sb, BFS_I(dir)->i_sblock + block);
 338                         if (!bh) {
 339                                 block++;
 340                                 continue;
 341                         }
 342                 }
 343                 de = (struct bfs_dirent *)(bh->b_data + offset);
 344                 offset += BFS_DIRENT_SIZE;
 345                 if (le16_to_cpu(de->ino) &&
 346                                 bfs_namecmp(namelen, name, de->name)) {
 347                         *res_dir = de;
 348                         return bh;
 349                 }
 350                 if (offset < bh->b_size)
 351                         continue;
 352                 brelse(bh);
 353                 bh = NULL;
 354                 offset = 0;
 355                 block++;
 356         }
 357         brelse(bh);
 358         return NULL;
 359 }