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_i_callback(struct rcu_head *head)
  78 {
  79         struct inode *inode = container_of(head, struct inode, i_rcu);
  80         kmem_cache_free(efs_inode_cachep, INODE_INFO(inode));
  81 }
  82
  83 static void efs_destroy_inode(struct inode *inode)
  84 {
  85         call_rcu(&inode->i_rcu, efs_i_callback);
  86 }
  87
  88 static void init_once(void *foo)
  89 {
  90         struct efs_inode_info *ei = (struct efs_inode_info *) foo;
  91
  92         inode_init_once(&ei->vfs_inode);
  93 }
  94
  95 static int __init init_inodecache(void)
  96 {
  97         efs_inode_cachep = kmem_cache_create("efs_inode_cache",
  98                                 sizeof(struct efs_inode_info), 0,
  99                                 SLAB_RECLAIM_ACCOUNT|SLAB_MEM_SPREAD|
 100                                 SLAB_ACCOUNT, init_once);
 101         if (efs_inode_cachep == NULL)
 102                 return -ENOMEM;
 103         return 0;
 104 }
 105
 106 static void destroy_inodecache(void)
 107 {
 108         /*
 109          * Make sure all delayed rcu free inodes are flushed before we
 110          * destroy cache.
 111          */
 112         rcu_barrier();
 113         kmem_cache_destroy(efs_inode_cachep);
 114 }
 115
 116 static int efs_remount(struct super_block *sb, int *flags, char *data)
 117 {
 118         sync_filesystem(sb);
 119         *flags |= SB_RDONLY;
 120         return 0;
 121 }
 122
 123 static const struct super_operations efs_superblock_operations = {
 124         .alloc_inode    = efs_alloc_inode,
 125         .destroy_inode  = efs_destroy_inode,
 126         .statfs         = efs_statfs,
 127         .remount_fs     = efs_remount,
 128 };
 129
 130 static const struct export_operations efs_export_ops = {
 131         .fh_to_dentry   = efs_fh_to_dentry,
 132         .fh_to_parent   = efs_fh_to_parent,
 133         .get_parent     = efs_get_parent,
 134 };
 135
 136 static int __init init_efs_fs(void) {
 137         int err;
 138         pr_info(EFS_VERSION" - http://aeschi.ch.eu.org/efs/\n");
 139         err = init_inodecache();
 140         if (err)
 141                 goto out1;
 142         err = register_filesystem(&efs_fs_type);
 143         if (err)
 144                 goto out;
 145         return 0;
 146 out:
 147         destroy_inodecache();
 148 out1:
 149         return err;
 150 }
 151
 152 static void __exit exit_efs_fs(void) {
 153         unregister_filesystem(&efs_fs_type);
 154         destroy_inodecache();
 155 }
 156
 157 module_init(init_efs_fs)
 158 module_exit(exit_efs_fs)
 159
 160 static efs_block_t efs_validate_vh(struct volume_header *vh) {
 161         int             i;
 162         __be32          cs, *ui;
 163         int             csum;
 164         efs_block_t     sblock = 0; /* shuts up gcc */
 165         struct pt_types *pt_entry;
 166         int             pt_type, slice = -1;
 167
 168         if (be32_to_cpu(vh->vh_magic) != VHMAGIC) {
 169                 /*
 170                  * assume that we're dealing with a partition and allow
 171                  * read_super() to try and detect a valid superblock
 172                  * on the next block.
 173                  */
 174                 return 0;
 175         }
 176
 177         ui = ((__be32 *) (vh + 1)) - 1;
 178         for(csum = 0; ui >= ((__be32 *) vh);) {
 179                 cs = *ui--;
 180                 csum += be32_to_cpu(cs);
 181         }
 182         if (csum) {
 183                 pr_warn("SGI disklabel: checksum bad, label corrupted\n");
 184                 return 0;
 185         }
 186
 187 #ifdef DEBUG
 188         pr_debug("bf: \"%16s\"\n", vh->vh_bootfile);
 189
 190         for(i = 0; i < NVDIR; i++) {
 191                 int     j;
 192                 char    name[VDNAMESIZE+1];
 193
 194                 for(j = 0; j < VDNAMESIZE; j++) {
 195                         name[j] = vh->vh_vd[i].vd_name[j];
 196                 }
 197                 name[j] = (char) 0;
 198
 199                 if (name[0]) {
 200                         pr_debug("vh: %8s block: 0x%08x size: 0x%08x\n",
 201                                 name, (int) be32_to_cpu(vh->vh_vd[i].vd_lbn),
 202                                 (int) be32_to_cpu(vh->vh_vd[i].vd_nbytes));
 203                 }
 204         }
 205 #endif
 206
 207         for(i = 0; i < NPARTAB; i++) {
 208                 pt_type = (int) be32_to_cpu(vh->vh_pt[i].pt_type);
 209                 for(pt_entry = sgi_pt_types; pt_entry->pt_name; pt_entry++) {
 210                         if (pt_type == pt_entry->pt_type) break;
 211                 }
 212 #ifdef DEBUG
 213                 if (be32_to_cpu(vh->vh_pt[i].pt_nblks)) {
 214                         pr_debug("pt %2d: start: %08d size: %08d type: 0x%02x (%s)\n",
 215                                  i, (int)be32_to_cpu(vh->vh_pt[i].pt_firstlbn),
 216                                  (int)be32_to_cpu(vh->vh_pt[i].pt_nblks),
 217                                  pt_type, (pt_entry->pt_name) ?
 218                                  pt_entry->pt_name : "unknown");
 219                 }
 220 #endif
 221                 if (IS_EFS(pt_type)) {
 222                         sblock = be32_to_cpu(vh->vh_pt[i].pt_firstlbn);
 223                         slice = i;
 224                 }
 225         }
 226
 227         if (slice == -1) {
 228                 pr_notice("partition table contained no EFS partitions\n");
 229 #ifdef DEBUG
 230         } else {
 231                 pr_info("using slice %d (type %s, offset 0x%x)\n", slice,
 232                         (pt_entry->pt_name) ? pt_entry->pt_name : "unknown",
 233                         sblock);
 234 #endif
 235         }
 236         return sblock;
 237 }
 238
 239 static int efs_validate_super(struct efs_sb_info *sb, struct efs_super *super) {
 240
 241         if (!IS_EFS_MAGIC(be32_to_cpu(super->fs_magic)))
 242                 return -1;
 243
 244         sb->fs_magic     = be32_to_cpu(super->fs_magic);
 245         sb->total_blocks = be32_to_cpu(super->fs_size);
 246         sb->first_block  = be32_to_cpu(super->fs_firstcg);
 247         sb->group_size   = be32_to_cpu(super->fs_cgfsize);
 248         sb->data_free    = be32_to_cpu(super->fs_tfree);
 249         sb->inode_free   = be32_to_cpu(super->fs_tinode);
 250         sb->inode_blocks = be16_to_cpu(super->fs_cgisize);
 251         sb->total_groups = be16_to_cpu(super->fs_ncg);
 252
 253         return 0;
 254 }
 255
 256 static int efs_fill_super(struct super_block *s, void *d, int silent)
 257 {
 258         struct efs_sb_info *sb;
 259         struct buffer_head *bh;
 260         struct inode *root;
 261
 262         sb = kzalloc(sizeof(struct efs_sb_info), GFP_KERNEL);
 263         if (!sb)
 264                 return -ENOMEM;
 265         s->s_fs_info = sb;
 266
 267         s->s_magic              = EFS_SUPER_MAGIC;
 268         if (!sb_set_blocksize(s, EFS_BLOCKSIZE)) {
 269                 pr_err("device does not support %d byte blocks\n",
 270                         EFS_BLOCKSIZE);
 271                 return -EINVAL;
 272         }
 273
 274         /* read the vh (volume header) block */
 275         bh = sb_bread(s, 0);
 276
 277         if (!bh) {
 278                 pr_err("cannot read volume header\n");
 279                 return -EIO;
 280         }
 281
 282         /*
 283          * if this returns zero then we didn't find any partition table.
 284          * this isn't (yet) an error - just assume for the moment that
 285          * the device is valid and go on to search for a superblock.
 286          */
 287         sb->fs_start = efs_validate_vh((struct volume_header *) bh->b_data);
 288         brelse(bh);
 289
 290         if (sb->fs_start == -1) {
 291                 return -EINVAL;
 292         }
 293
 294         bh = sb_bread(s, sb->fs_start + EFS_SUPER);
 295         if (!bh) {
 296                 pr_err("cannot read superblock\n");
 297                 return -EIO;
 298         }
 299
 300         if (efs_validate_super(sb, (struct efs_super *) bh->b_data)) {
 301 #ifdef DEBUG
 302                 pr_warn("invalid superblock at block %u\n",
 303                         sb->fs_start + EFS_SUPER);
 304 #endif
 305                 brelse(bh);
 306                 return -EINVAL;
 307         }
 308         brelse(bh);
 309
 310         if (!sb_rdonly(s)) {
 311 #ifdef DEBUG
 312                 pr_info("forcing read-only mode\n");
 313 #endif
 314                 s->s_flags |= SB_RDONLY;
 315         }
 316         s->s_op   = &efs_superblock_operations;
 317         s->s_export_op = &efs_export_ops;
 318         root = efs_iget(s, EFS_ROOTINODE);
 319         if (IS_ERR(root)) {
 320                 pr_err("get root inode failed\n");
 321                 return PTR_ERR(root);
 322         }
 323
 324         s->s_root = d_make_root(root);
 325         if (!(s->s_root)) {
 326                 pr_err("get root dentry failed\n");
 327                 return -ENOMEM;
 328         }
 329
 330         return 0;
 331 }
 332
 333 static int efs_statfs(struct dentry *dentry, struct kstatfs *buf) {
 334         struct super_block *sb = dentry->d_sb;
 335         struct efs_sb_info *sbi = SUPER_INFO(sb);
 336         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 337
 338         buf->f_type    = EFS_SUPER_MAGIC;       /* efs magic number */
 339         buf->f_bsize   = EFS_BLOCKSIZE;         /* blocksize */
 340         buf->f_blocks  = sbi->total_groups *    /* total data blocks */
 341                         (sbi->group_size - sbi->inode_blocks);
 342         buf->f_bfree   = sbi->data_free;        /* free data blocks */
 343         buf->f_bavail  = sbi->data_free;        /* free blocks for non-root */
 344         buf->f_files   = sbi->total_groups *    /* total inodes */
 345                         sbi->inode_blocks *
 346                         (EFS_BLOCKSIZE / sizeof(struct efs_dinode));
 347         buf->f_ffree   = sbi->inode_free;       /* free inodes */
 348         buf->f_fsid.val[0] = (u32)id;
 349         buf->f_fsid.val[1] = (u32)(id >> 32);
 350         buf->f_namelen = EFS_MAXNAMELEN;        /* max filename length */
 351
 352         return 0;
 353 }
 354