fs/efs/super.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * super.c
   4  *
   5  * Copyright (c) 1999 Al Smith
   6  *
   7  * Portions derived from work (c) 1995,1996 Christian Vogelgsang.
   8  */
   9
  10 #include <linux/init.h>
  11 #include <linux/module.h>
  12 #include <linux/exportfs.h>
  13 #include <linux/slab.h>
  14 #include <linux/buffer_head.h>
  15 #include <linux/vfs.h>
  16 #include <linux/blkdev.h>
  17 #include <linux/fs_context.h>
  18 #include "efs.h"
  19 #include <linux/efs_vh.h>
  20 #include <linux/efs_fs_sb.h>
  21
  22 static int efs_statfs(struct dentry *dentry, struct kstatfs *buf);
  23 static int efs_init_fs_context(struct fs_context *fc);
  24
  25 static void efs_kill_sb(struct super_block *s)
  26 {
  27         struct efs_sb_info *sbi = SUPER_INFO(s);
  28         kill_block_super(s);
  29         kfree(sbi);
  30 }
  31
  32 static struct pt_types sgi_pt_types[] = {
  33         {0x00,          "SGI vh"},
  34         {0x01,          "SGI trkrepl"},
  35         {0x02,          "SGI secrepl"},
  36         {0x03,          "SGI raw"},
  37         {0x04,          "SGI bsd"},
  38         {SGI_SYSV,      "SGI sysv"},
  39         {0x06,          "SGI vol"},
  40         {SGI_EFS,       "SGI efs"},
  41         {0x08,          "SGI lv"},
  42         {0x09,          "SGI rlv"},
  43         {0x0A,          "SGI xfs"},
  44         {0x0B,          "SGI xfslog"},
  45         {0x0C,          "SGI xlv"},
  46         {0x82,          "Linux swap"},
  47         {0x83,          "Linux native"},
  48         {0,             NULL}
  49 };
  50
  51 /*
  52  * File system definition and registration.
  53  */
  54 static struct file_system_type efs_fs_type = {
  55         .owner                  = THIS_MODULE,
  56         .name                   = "efs",
  57         .kill_sb                = efs_kill_sb,
  58         .fs_flags               = FS_REQUIRES_DEV,
  59         .init_fs_context        = efs_init_fs_context,
  60 };
  61 MODULE_ALIAS_FS("efs");
  62
  63 static struct kmem_cache * efs_inode_cachep;
  64
  65 static struct inode *efs_alloc_inode(struct super_block *sb)
  66 {
  67         struct efs_inode_info *ei;
  68         ei = alloc_inode_sb(sb, efs_inode_cachep, GFP_KERNEL);
  69         if (!ei)
  70                 return NULL;
  71         return &ei->vfs_inode;
  72 }
  73
  74 static void efs_free_inode(struct inode *inode)
  75 {
  76         kmem_cache_free(efs_inode_cachep, INODE_INFO(inode));
  77 }
  78
  79 static void init_once(void *foo)
  80 {
  81         struct efs_inode_info *ei = (struct efs_inode_info *) foo;
  82
  83         inode_init_once(&ei->vfs_inode);
  84 }
  85
  86 static int __init init_inodecache(void)
  87 {
  88         efs_inode_cachep = kmem_cache_create("efs_inode_cache",
  89                                 sizeof(struct efs_inode_info), 0,
  90                                 SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
  91                                 init_once);
  92         if (efs_inode_cachep == NULL)
  93                 return -ENOMEM;
  94         return 0;
  95 }
  96
  97 static void destroy_inodecache(void)
  98 {
  99         /*
 100          * Make sure all delayed rcu free inodes are flushed before we
 101          * destroy cache.
 102          */
 103         rcu_barrier();
 104         kmem_cache_destroy(efs_inode_cachep);
 105 }
 106
 107 static const struct super_operations efs_superblock_operations = {
 108         .alloc_inode    = efs_alloc_inode,
 109         .free_inode     = efs_free_inode,
 110         .statfs         = efs_statfs,
 111 };
 112
 113 static const struct export_operations efs_export_ops = {
 114         .encode_fh      = generic_encode_ino32_fh,
 115         .fh_to_dentry   = efs_fh_to_dentry,
 116         .fh_to_parent   = efs_fh_to_parent,
 117         .get_parent     = efs_get_parent,
 118 };
 119
 120 static int __init init_efs_fs(void) {
 121         int err;
 122         pr_info(EFS_VERSION" - http://aeschi.ch.eu.org/efs/\n");
 123         err = init_inodecache();
 124         if (err)
 125                 goto out1;
 126         err = register_filesystem(&efs_fs_type);
 127         if (err)
 128                 goto out;
 129         return 0;
 130 out:
 131         destroy_inodecache();
 132 out1:
 133         return err;
 134 }
 135
 136 static void __exit exit_efs_fs(void) {
 137         unregister_filesystem(&efs_fs_type);
 138         destroy_inodecache();
 139 }
 140
 141 module_init(init_efs_fs)
 142 module_exit(exit_efs_fs)
 143
 144 static efs_block_t efs_validate_vh(struct volume_header *vh) {
 145         int             i;
 146         __be32          cs, *ui;
 147         int             csum;
 148         efs_block_t     sblock = 0; /* shuts up gcc */
 149         struct pt_types *pt_entry;
 150         int             pt_type, slice = -1;
 151
 152         if (be32_to_cpu(vh->vh_magic) != VHMAGIC) {
 153                 /*
 154                  * assume that we're dealing with a partition and allow
 155                  * read_super() to try and detect a valid superblock
 156                  * on the next block.
 157                  */
 158                 return 0;
 159         }
 160
 161         ui = ((__be32 *) (vh + 1)) - 1;
 162         for(csum = 0; ui >= ((__be32 *) vh);) {
 163                 cs = *ui--;
 164                 csum += be32_to_cpu(cs);
 165         }
 166         if (csum) {
 167                 pr_warn("SGI disklabel: checksum bad, label corrupted\n");
 168                 return 0;
 169         }
 170
 171 #ifdef DEBUG
 172         pr_debug("bf: \"%16s\"\n", vh->vh_bootfile);
 173
 174         for(i = 0; i < NVDIR; i++) {
 175                 int     j;
 176                 char    name[VDNAMESIZE+1];
 177
 178                 for(j = 0; j < VDNAMESIZE; j++) {
 179                         name[j] = vh->vh_vd[i].vd_name[j];
 180                 }
 181                 name[j] = (char) 0;
 182
 183                 if (name[0]) {
 184                         pr_debug("vh: %8s block: 0x%08x size: 0x%08x\n",
 185                                 name, (int) be32_to_cpu(vh->vh_vd[i].vd_lbn),
 186                                 (int) be32_to_cpu(vh->vh_vd[i].vd_nbytes));
 187                 }
 188         }
 189 #endif
 190
 191         for(i = 0; i < NPARTAB; i++) {
 192                 pt_type = (int) be32_to_cpu(vh->vh_pt[i].pt_type);
 193                 for(pt_entry = sgi_pt_types; pt_entry->pt_name; pt_entry++) {
 194                         if (pt_type == pt_entry->pt_type) break;
 195                 }
 196 #ifdef DEBUG
 197                 if (be32_to_cpu(vh->vh_pt[i].pt_nblks)) {
 198                         pr_debug("pt %2d: start: %08d size: %08d type: 0x%02x (%s)\n",
 199                                  i, (int)be32_to_cpu(vh->vh_pt[i].pt_firstlbn),
 200                                  (int)be32_to_cpu(vh->vh_pt[i].pt_nblks),
 201                                  pt_type, (pt_entry->pt_name) ?
 202                                  pt_entry->pt_name : "unknown");
 203                 }
 204 #endif
 205                 if (IS_EFS(pt_type)) {
 206                         sblock = be32_to_cpu(vh->vh_pt[i].pt_firstlbn);
 207                         slice = i;
 208                 }
 209         }
 210
 211         if (slice == -1) {
 212                 pr_notice("partition table contained no EFS partitions\n");
 213 #ifdef DEBUG
 214         } else {
 215                 pr_info("using slice %d (type %s, offset 0x%x)\n", slice,
 216                         (pt_entry->pt_name) ? pt_entry->pt_name : "unknown",
 217                         sblock);
 218 #endif
 219         }
 220         return sblock;
 221 }
 222
 223 static int efs_validate_super(struct efs_sb_info *sb, struct efs_super *super) {
 224
 225         if (!IS_EFS_MAGIC(be32_to_cpu(super->fs_magic)))
 226                 return -1;
 227
 228         sb->fs_magic     = be32_to_cpu(super->fs_magic);
 229         sb->total_blocks = be32_to_cpu(super->fs_size);
 230         sb->first_block  = be32_to_cpu(super->fs_firstcg);
 231         sb->group_size   = be32_to_cpu(super->fs_cgfsize);
 232         sb->data_free    = be32_to_cpu(super->fs_tfree);
 233         sb->inode_free   = be32_to_cpu(super->fs_tinode);
 234         sb->inode_blocks = be16_to_cpu(super->fs_cgisize);
 235         sb->total_groups = be16_to_cpu(super->fs_ncg);
 236
 237         return 0;
 238 }
 239
 240 static int efs_fill_super(struct super_block *s, struct fs_context *fc)
 241 {
 242         struct efs_sb_info *sb;
 243         struct buffer_head *bh;
 244         struct inode *root;
 245
 246         sb = kzalloc(sizeof(struct efs_sb_info), GFP_KERNEL);
 247         if (!sb)
 248                 return -ENOMEM;
 249         s->s_fs_info = sb;
 250         s->s_time_min = 0;
 251         s->s_time_max = U32_MAX;
 252
 253         s->s_magic              = EFS_SUPER_MAGIC;
 254         if (!sb_set_blocksize(s, EFS_BLOCKSIZE)) {
 255                 pr_err("device does not support %d byte blocks\n",
 256                         EFS_BLOCKSIZE);
 257                 return invalf(fc, "device does not support %d byte blocks\n",
 258                               EFS_BLOCKSIZE);
 259         }
 260
 261         /* read the vh (volume header) block */
 262         bh = sb_bread(s, 0);
 263
 264         if (!bh) {
 265                 pr_err("cannot read volume header\n");
 266                 return -EIO;
 267         }
 268
 269         /*
 270          * if this returns zero then we didn't find any partition table.
 271          * this isn't (yet) an error - just assume for the moment that
 272          * the device is valid and go on to search for a superblock.
 273          */
 274         sb->fs_start = efs_validate_vh((struct volume_header *) bh->b_data);
 275         brelse(bh);
 276
 277         if (sb->fs_start == -1) {
 278                 return -EINVAL;
 279         }
 280
 281         bh = sb_bread(s, sb->fs_start + EFS_SUPER);
 282         if (!bh) {
 283                 pr_err("cannot read superblock\n");
 284                 return -EIO;
 285         }
 286
 287         if (efs_validate_super(sb, (struct efs_super *) bh->b_data)) {
 288 #ifdef DEBUG
 289                 pr_warn("invalid superblock at block %u\n",
 290                         sb->fs_start + EFS_SUPER);
 291 #endif
 292                 brelse(bh);
 293                 return -EINVAL;
 294         }
 295         brelse(bh);
 296
 297         if (!sb_rdonly(s)) {
 298 #ifdef DEBUG
 299                 pr_info("forcing read-only mode\n");
 300 #endif
 301                 s->s_flags |= SB_RDONLY;
 302         }
 303         s->s_op   = &efs_superblock_operations;
 304         s->s_export_op = &efs_export_ops;
 305         root = efs_iget(s, EFS_ROOTINODE);
 306         if (IS_ERR(root)) {
 307                 pr_err("get root inode failed\n");
 308                 return PTR_ERR(root);
 309         }
 310
 311         s->s_root = d_make_root(root);
 312         if (!(s->s_root)) {
 313                 pr_err("get root dentry failed\n");
 314                 return -ENOMEM;
 315         }
 316
 317         return 0;
 318 }
 319
 320 static int efs_get_tree(struct fs_context *fc)
 321 {
 322         return get_tree_bdev(fc, efs_fill_super);
 323 }
 324
 325 static int efs_reconfigure(struct fs_context *fc)
 326 {
 327         sync_filesystem(fc->root->d_sb);
 328         fc->sb_flags |= SB_RDONLY;
 329
 330         return 0;
 331 }
 332
 333 static const struct fs_context_operations efs_context_opts = {
 334         .get_tree       = efs_get_tree,
 335         .reconfigure    = efs_reconfigure,
 336 };
 337
 338 /*
 339  * Set up the filesystem mount context.
 340  */
 341 static int efs_init_fs_context(struct fs_context *fc)
 342 {
 343         fc->ops = &efs_context_opts;
 344
 345         return 0;
 346 }
 347
 348 static int efs_statfs(struct dentry *dentry, struct kstatfs *buf) {
 349         struct super_block *sb = dentry->d_sb;
 350         struct efs_sb_info *sbi = SUPER_INFO(sb);
 351         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 352
 353         buf->f_type    = EFS_SUPER_MAGIC;       /* efs magic number */
 354         buf->f_bsize   = EFS_BLOCKSIZE;         /* blocksize */
 355         buf->f_blocks  = sbi->total_groups *    /* total data blocks */
 356                         (sbi->group_size - sbi->inode_blocks);
 357         buf->f_bfree   = sbi->data_free;        /* free data blocks */
 358         buf->f_bavail  = sbi->data_free;        /* free blocks for non-root */
 359         buf->f_files   = sbi->total_groups *    /* total inodes */
 360                         sbi->inode_blocks *
 361                         (EFS_BLOCKSIZE / sizeof(struct efs_dinode));
 362         buf->f_ffree   = sbi->inode_free;       /* free inodes */
 363         buf->f_fsid    = u64_to_fsid(id);
 364         buf->f_namelen = EFS_MAXNAMELEN;        /* max filename length */
 365
 366         return 0;
 367 }
 368