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
  17 #include "efs.h"
  18 #include <linux/efs_vh.h>
  19 #include <linux/efs_fs_sb.h>
  20
  21 static int efs_statfs(struct dentry *dentry, struct kstatfs *buf);
  22 static int efs_fill_super(struct super_block *s, void *d, int silent);
  23
  24 static struct dentry *efs_mount(struct file_system_type *fs_type,
  25         int flags, const char *dev_name, void *data)
  26 {
  27         return mount_bdev(fs_type, flags, dev_name, data, efs_fill_super);
  28 }
  29
  30 static void efs_kill_sb(struct super_block *s)
  31 {
  32         struct efs_sb_info *sbi = SUPER_INFO(s);
  33         kill_block_super(s);
  34         kfree(sbi);
  35 }
  36
  37 static struct file_system_type efs_fs_type = {
  38         .owner          = THIS_MODULE,
  39         .name           = "efs",
  40         .mount          = efs_mount,
  41         .kill_sb        = efs_kill_sb,
  42         .fs_flags       = FS_REQUIRES_DEV,
  43 };
  44 MODULE_ALIAS_FS("efs");
  45
  46 static struct pt_types sgi_pt_types[] = {
  47         {0x00,          "SGI vh"},
  48         {0x01,          "SGI trkrepl"},
  49         {0x02,          "SGI secrepl"},
  50         {0x03,          "SGI raw"},
  51         {0x04,          "SGI bsd"},
  52         {SGI_SYSV,      "SGI sysv"},
  53         {0x06,          "SGI vol"},
  54         {SGI_EFS,       "SGI efs"},
  55         {0x08,          "SGI lv"},
  56         {0x09,          "SGI rlv"},
  57         {0x0A,          "SGI xfs"},
  58         {0x0B,          "SGI xfslog"},
  59         {0x0C,          "SGI xlv"},
  60         {0x82,          "Linux swap"},
  61         {0x83,          "Linux native"},
  62         {0,             NULL}
  63 };
  64
  65
  66 static struct kmem_cache * efs_inode_cachep;
  67
  68 static struct inode *efs_alloc_inode(struct super_block *sb)
  69 {
  70         struct efs_inode_info *ei;
  71         ei = kmem_cache_alloc(efs_inode_cachep, GFP_KERNEL);
  72         if (!ei)
  73                 return NULL;
  74         return &ei->vfs_inode;
  75 }
  76
  77 static void efs_free_inode(struct inode *inode)
  78 {
  79         kmem_cache_free(efs_inode_cachep, INODE_INFO(inode));
  80 }
  81
  82 static void init_once(void *foo)
  83 {
  84         struct efs_inode_info *ei = (struct efs_inode_info *) foo;
  85
  86         inode_init_once(&ei->vfs_inode);
  87 }
  88
  89 static int __init init_inodecache(void)
  90 {
  91         efs_inode_cachep = kmem_cache_create("efs_inode_cache",
  92                                 sizeof(struct efs_inode_info), 0,
  93                                 SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD|
  94                                 SLAB_ACCOUNT, init_once);
  95         if (efs_inode_cachep == NULL)
  96                 return -ENOMEM;
  97         return 0;
  98 }
  99
 100 static void destroy_inodecache(void)
 101 {
 102         /*
 103          * Make sure all delayed rcu free inodes are flushed before we
 104          * destroy cache.
 105          */
 106         rcu_barrier();
 107         kmem_cache_destroy(efs_inode_cachep);
 108 }
 109
 110 static int efs_remount(struct super_block *sb, int *flags, char *data)
 111 {
 112         sync_filesystem(sb);
 113         *flags |= SB_RDONLY;
 114         return 0;
 115 }
 116
 117 static const struct super_operations efs_superblock_operations = {
 118         .alloc_inode    = efs_alloc_inode,
 119         .free_inode     = efs_free_inode,
 120         .statfs         = efs_statfs,
 121         .remount_fs     = efs_remount,
 122 };
 123
 124 static const struct export_operations efs_export_ops = {
 125         .fh_to_dentry   = efs_fh_to_dentry,
 126         .fh_to_parent   = efs_fh_to_parent,
 127         .get_parent     = efs_get_parent,
 128 };
 129
 130 static int __init init_efs_fs(void) {
 131         int err;
 132         pr_info(EFS_VERSION" - http://aeschi.ch.eu.org/efs/\n");
 133         err = init_inodecache();
 134         if (err)
 135                 goto out1;
 136         err = register_filesystem(&efs_fs_type);
 137         if (err)
 138                 goto out;
 139         return 0;
 140 out:
 141         destroy_inodecache();
 142 out1:
 143         return err;
 144 }
 145
 146 static void __exit exit_efs_fs(void) {
 147         unregister_filesystem(&efs_fs_type);
 148         destroy_inodecache();
 149 }
 150
 151 module_init(init_efs_fs)
 152 module_exit(exit_efs_fs)
 153
 154 static efs_block_t efs_validate_vh(struct volume_header *vh) {
 155         int             i;
 156         __be32          cs, *ui;
 157         int             csum;
 158         efs_block_t     sblock = 0; /* shuts up gcc */
 159         struct pt_types *pt_entry;
 160         int             pt_type, slice = -1;
 161
 162         if (be32_to_cpu(vh->vh_magic) != VHMAGIC) {
 163                 /*
 164                  * assume that we're dealing with a partition and allow
 165                  * read_super() to try and detect a valid superblock
 166                  * on the next block.
 167                  */
 168                 return 0;
 169         }
 170
 171         ui = ((__be32 *) (vh + 1)) - 1;
 172         for(csum = 0; ui >= ((__be32 *) vh);) {
 173                 cs = *ui--;
 174                 csum += be32_to_cpu(cs);
 175         }
 176         if (csum) {
 177                 pr_warn("SGI disklabel: checksum bad, label corrupted\n");
 178                 return 0;
 179         }
 180
 181 #ifdef DEBUG
 182         pr_debug("bf: \"%16s\"\n", vh->vh_bootfile);
 183
 184         for(i = 0; i < NVDIR; i++) {
 185                 int     j;
 186                 char    name[VDNAMESIZE+1];
 187
 188                 for(j = 0; j < VDNAMESIZE; j++) {
 189                         name[j] = vh->vh_vd[i].vd_name[j];
 190                 }
 191                 name[j] = (char) 0;
 192
 193                 if (name[0]) {
 194                         pr_debug("vh: %8s block: 0x%08x size: 0x%08x\n",
 195                                 name, (int) be32_to_cpu(vh->vh_vd[i].vd_lbn),
 196                                 (int) be32_to_cpu(vh->vh_vd[i].vd_nbytes));
 197                 }
 198         }
 199 #endif
 200
 201         for(i = 0; i < NPARTAB; i++) {
 202                 pt_type = (int) be32_to_cpu(vh->vh_pt[i].pt_type);
 203                 for(pt_entry = sgi_pt_types; pt_entry->pt_name; pt_entry++) {
 204                         if (pt_type == pt_entry->pt_type) break;
 205                 }
 206 #ifdef DEBUG
 207                 if (be32_to_cpu(vh->vh_pt[i].pt_nblks)) {
 208                         pr_debug("pt %2d: start: %08d size: %08d type: 0x%02x (%s)\n",
 209                                  i, (int)be32_to_cpu(vh->vh_pt[i].pt_firstlbn),
 210                                  (int)be32_to_cpu(vh->vh_pt[i].pt_nblks),
 211                                  pt_type, (pt_entry->pt_name) ?
 212                                  pt_entry->pt_name : "unknown");
 213                 }
 214 #endif
 215                 if (IS_EFS(pt_type)) {
 216                         sblock = be32_to_cpu(vh->vh_pt[i].pt_firstlbn);
 217                         slice = i;
 218                 }
 219         }
 220
 221         if (slice == -1) {
 222                 pr_notice("partition table contained no EFS partitions\n");
 223 #ifdef DEBUG
 224         } else {
 225                 pr_info("using slice %d (type %s, offset 0x%x)\n", slice,
 226                         (pt_entry->pt_name) ? pt_entry->pt_name : "unknown",
 227                         sblock);
 228 #endif
 229         }
 230         return sblock;
 231 }
 232
 233 static int efs_validate_super(struct efs_sb_info *sb, struct efs_super *super) {
 234
 235         if (!IS_EFS_MAGIC(be32_to_cpu(super->fs_magic)))
 236                 return -1;
 237
 238         sb->fs_magic     = be32_to_cpu(super->fs_magic);
 239         sb->total_blocks = be32_to_cpu(super->fs_size);
 240         sb->first_block  = be32_to_cpu(super->fs_firstcg);
 241         sb->group_size   = be32_to_cpu(super->fs_cgfsize);
 242         sb->data_free    = be32_to_cpu(super->fs_tfree);
 243         sb->inode_free   = be32_to_cpu(super->fs_tinode);
 244         sb->inode_blocks = be16_to_cpu(super->fs_cgisize);
 245         sb->total_groups = be16_to_cpu(super->fs_ncg);
 246
 247         return 0;
 248 }
 249
 250 static int efs_fill_super(struct super_block *s, void *d, int silent)
 251 {
 252         struct efs_sb_info *sb;
 253         struct buffer_head *bh;
 254         struct inode *root;
 255
 256         sb = kzalloc(sizeof(struct efs_sb_info), GFP_KERNEL);
 257         if (!sb)
 258                 return -ENOMEM;
 259         s->s_fs_info = sb;
 260         s->s_time_min = 0;
 261         s->s_time_max = U32_MAX;
 262
 263         s->s_magic              = EFS_SUPER_MAGIC;
 264         if (!sb_set_blocksize(s, EFS_BLOCKSIZE)) {
 265                 pr_err("device does not support %d byte blocks\n",
 266                         EFS_BLOCKSIZE);
 267                 return -EINVAL;
 268         }
 269
 270         /* read the vh (volume header) block */
 271         bh = sb_bread(s, 0);
 272
 273         if (!bh) {
 274                 pr_err("cannot read volume header\n");
 275                 return -EIO;
 276         }
 277
 278         /*
 279          * if this returns zero then we didn't find any partition table.
 280          * this isn't (yet) an error - just assume for the moment that
 281          * the device is valid and go on to search for a superblock.
 282          */
 283         sb->fs_start = efs_validate_vh((struct volume_header *) bh->b_data);
 284         brelse(bh);
 285
 286         if (sb->fs_start == -1) {
 287                 return -EINVAL;
 288         }
 289
 290         bh = sb_bread(s, sb->fs_start + EFS_SUPER);
 291         if (!bh) {
 292                 pr_err("cannot read superblock\n");
 293                 return -EIO;
 294         }
 295
 296         if (efs_validate_super(sb, (struct efs_super *) bh->b_data)) {
 297 #ifdef DEBUG
 298                 pr_warn("invalid superblock at block %u\n",
 299                         sb->fs_start + EFS_SUPER);
 300 #endif
 301                 brelse(bh);
 302                 return -EINVAL;
 303         }
 304         brelse(bh);
 305
 306         if (!sb_rdonly(s)) {
 307 #ifdef DEBUG
 308                 pr_info("forcing read-only mode\n");
 309 #endif
 310                 s->s_flags |= SB_RDONLY;
 311         }
 312         s->s_op   = &efs_superblock_operations;
 313         s->s_export_op = &efs_export_ops;
 314         root = efs_iget(s, EFS_ROOTINODE);
 315         if (IS_ERR(root)) {
 316                 pr_err("get root inode failed\n");
 317                 return PTR_ERR(root);
 318         }
 319
 320         s->s_root = d_make_root(root);
 321         if (!(s->s_root)) {
 322                 pr_err("get root dentry failed\n");
 323                 return -ENOMEM;
 324         }
 325
 326         return 0;
 327 }
 328
 329 static int efs_statfs(struct dentry *dentry, struct kstatfs *buf) {
 330         struct super_block *sb = dentry->d_sb;
 331         struct efs_sb_info *sbi = SUPER_INFO(sb);
 332         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 333
 334         buf->f_type    = EFS_SUPER_MAGIC;       /* efs magic number */
 335         buf->f_bsize   = EFS_BLOCKSIZE;         /* blocksize */
 336         buf->f_blocks  = sbi->total_groups *    /* total data blocks */
 337                         (sbi->group_size - sbi->inode_blocks);
 338         buf->f_bfree   = sbi->data_free;        /* free data blocks */
 339         buf->f_bavail  = sbi->data_free;        /* free blocks for non-root */
 340         buf->f_files   = sbi->total_groups *    /* total inodes */
 341                         sbi->inode_blocks *
 342                         (EFS_BLOCKSIZE / sizeof(struct efs_dinode));
 343         buf->f_ffree   = sbi->inode_free;       /* free inodes */
 344         buf->f_fsid.val[0] = (u32)id;
 345         buf->f_fsid.val[1] = (u32)(id >> 32);
 346         buf->f_namelen = EFS_MAXNAMELEN;        /* max filename length */
 347
 348         return 0;
 349 }
 350