fs/btrfs/super.c

   1 #include <linux/module.h>
   2 #include <linux/buffer_head.h>
   3 #include <linux/fs.h>
   4 #include <linux/pagemap.h>
   5 #include <linux/highmem.h>
   6 #include <linux/time.h>
   7 #include <linux/init.h>
   8 #include <linux/string.h>
   9 #include <linux/smp_lock.h>
  10 #include <linux/backing-dev.h>
  11 #include "ctree.h"
  12 #include "disk-io.h"
  13
  14 #define BTRFS_SUPER_MAGIC 0x9123682E
  15
  16 static struct inode_operations btrfs_dir_inode_operations;
  17 static struct super_operations btrfs_super_ops;
  18 static struct file_operations btrfs_dir_file_operations;
  19
  20 #if 0
  21 /* some random number */
  22
  23 static struct super_operations ramfs_ops;
  24
  25 static struct backing_dev_info ramfs_backing_dev_info = {
  26         .ra_pages       = 0,    /* No readahead */
  27         .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK |
  28                           BDI_CAP_MAP_DIRECT | BDI_CAP_MAP_COPY |
  29                           BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP,
  30 };
  31
  32 struct inode *ramfs_get_inode(struct super_block *sb, int mode, dev_t dev)
  33 {
  34         struct inode * inode = new_inode(sb);
  35
  36         if (inode) {
  37                 inode->i_mode = mode;
  38                 inode->i_uid = current->fsuid;
  39                 inode->i_gid = current->fsgid;
  40                 inode->i_blocks = 0;
  41                 inode->i_mapping->a_ops = &ramfs_aops;
  42                 inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info;
  43                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  44                 switch (mode & S_IFMT) {
  45                 default:
  46                         init_special_inode(inode, mode, dev);
  47                         break;
  48                 case S_IFREG:
  49                         inode->i_op = &ramfs_file_inode_operations;
  50                         inode->i_fop = &ramfs_file_operations;
  51                         break;
  52                 case S_IFDIR:
  53                         inode->i_op = &ramfs_dir_inode_operations;
  54                         inode->i_fop = &simple_dir_operations;
  55
  56                         /* directory inodes start off with i_nlink == 2 (for "." entry) */
  57                         inc_nlink(inode);
  58                         break;
  59                 case S_IFLNK:
  60                         inode->i_op = &page_symlink_inode_operations;
  61                         break;
  62                 }
  63         }
  64         return inode;
  65 }
  66
  67 /*
  68  * File creation. Allocate an inode, and we're done..
  69  */
  70 /* SMP-safe */
  71 static int
  72 ramfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
  73 {
  74         struct inode * inode = ramfs_get_inode(dir->i_sb, mode, dev);
  75         int error = -ENOSPC;
  76
  77         if (inode) {
  78                 if (dir->i_mode & S_ISGID) {
  79                         inode->i_gid = dir->i_gid;
  80                         if (S_ISDIR(mode))
  81                                 inode->i_mode |= S_ISGID;
  82                 }
  83                 d_instantiate(dentry, inode);
  84                 dget(dentry);   /* Extra count - pin the dentry in core */
  85                 error = 0;
  86                 dir->i_mtime = dir->i_ctime = CURRENT_TIME;
  87         }
  88         return error;
  89 }
  90
  91 static int ramfs_mkdir(struct inode * dir, struct dentry * dentry, int mode)
  92 {
  93         int retval = ramfs_mknod(dir, dentry, mode | S_IFDIR, 0);
  94         if (!retval)
  95                 inc_nlink(dir);
  96         return retval;
  97 }
  98
  99 static int ramfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)
 100 {
 101         return ramfs_mknod(dir, dentry, mode | S_IFREG, 0);
 102 }
 103
 104 static int ramfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
 105 {
 106         struct inode *inode;
 107         int error = -ENOSPC;
 108
 109         inode = ramfs_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
 110         if (inode) {
 111                 int l = strlen(symname)+1;
 112                 error = page_symlink(inode, symname, l);
 113                 if (!error) {
 114                         if (dir->i_mode & S_ISGID)
 115                                 inode->i_gid = dir->i_gid;
 116                         d_instantiate(dentry, inode);
 117                         dget(dentry);
 118                         dir->i_mtime = dir->i_ctime = CURRENT_TIME;
 119                 } else
 120                         iput(inode);
 121         }
 122         return error;
 123 }
 124
 125 static struct inode_operations ramfs_dir_inode_operations = {
 126         .create         = ramfs_create,
 127         .lookup         = simple_lookup,
 128         .link           = simple_link,
 129         .unlink         = simple_unlink,
 130         .symlink        = ramfs_symlink,
 131         .mkdir          = ramfs_mkdir,
 132         .rmdir          = simple_rmdir,
 133         .mknod          = ramfs_mknod,
 134         .rename         = simple_rename,
 135 };
 136 #endif
 137
 138 static void btrfs_read_locked_inode(struct inode *inode)
 139 {
 140         struct btrfs_path path;
 141         struct btrfs_inode_item *inode_item;
 142         struct btrfs_root *root = btrfs_sb(inode->i_sb);
 143         int ret;
 144         btrfs_init_path(&path);
 145         ret = btrfs_lookup_inode(NULL, root, &path, inode->i_ino, 0);
 146         if (ret) {
 147                 make_bad_inode(inode);
 148                 return;
 149         }
 150         inode_item = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]),
 151                                   path.slots[0],
 152                                   struct btrfs_inode_item);
 153
 154         inode->i_mode = btrfs_inode_mode(inode_item);
 155         inode->i_nlink = btrfs_inode_nlink(inode_item);
 156         inode->i_uid = btrfs_inode_uid(inode_item);
 157         inode->i_gid = btrfs_inode_gid(inode_item);
 158         inode->i_size = btrfs_inode_size(inode_item);
 159         inode->i_atime.tv_sec = btrfs_timespec_sec(&inode_item->atime);
 160         inode->i_atime.tv_nsec = btrfs_timespec_nsec(&inode_item->atime);
 161         inode->i_mtime.tv_sec = btrfs_timespec_sec(&inode_item->mtime);
 162         inode->i_mtime.tv_nsec = btrfs_timespec_nsec(&inode_item->mtime);
 163         inode->i_ctime.tv_sec = btrfs_timespec_sec(&inode_item->ctime);
 164         inode->i_ctime.tv_nsec = btrfs_timespec_nsec(&inode_item->ctime);
 165         inode->i_blocks = btrfs_inode_nblocks(inode_item);
 166         inode->i_generation = btrfs_inode_generation(inode_item);
 167         btrfs_release_path(root, &path);
 168         switch (inode->i_mode & S_IFMT) {
 169 #if 0
 170         default:
 171                 init_special_inode(inode, inode->i_mode,
 172                                    btrfs_inode_rdev(inode_item));
 173                 break;
 174 #endif
 175         case S_IFREG:
 176                 break;
 177         case S_IFDIR:
 178                 inode->i_op = &btrfs_dir_inode_operations;
 179                 inode->i_fop = &btrfs_dir_file_operations;
 180                 break;
 181         case S_IFLNK:
 182                 // inode->i_op = &page_symlink_inode_operations;
 183                 break;
 184         }
 185         return;
 186 }
 187
 188 static int btrfs_inode_by_name(struct inode *dir, struct dentry *dentry,
 189                               ino_t *ino)
 190 {
 191         const char *name = dentry->d_name.name;
 192         int namelen = dentry->d_name.len;
 193         struct btrfs_dir_item *di;
 194         struct btrfs_path path;
 195         struct btrfs_root *root = btrfs_sb(dir->i_sb);
 196         int ret;
 197
 198         btrfs_init_path(&path);
 199         ret = btrfs_lookup_dir_item(NULL, root, &path, dir->i_ino, name,
 200                                     namelen, 0);
 201         if (ret) {
 202                 *ino = 0;
 203                 goto out;
 204         }
 205         di = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]), path.slots[0],
 206                             struct btrfs_dir_item);
 207         *ino = btrfs_dir_objectid(di);
 208 out:
 209         btrfs_release_path(root, &path);
 210         return ret;
 211 }
 212
 213 static struct dentry *btrfs_lookup(struct inode *dir, struct dentry *dentry,
 214                                    struct nameidata *nd)
 215 {
 216         struct inode * inode;
 217         ino_t ino;
 218         int ret;
 219
 220         if (dentry->d_name.len > BTRFS_NAME_LEN)
 221                 return ERR_PTR(-ENAMETOOLONG);
 222
 223         ret = btrfs_inode_by_name(dir, dentry, &ino);
 224         if (ret < 0)
 225                 return ERR_PTR(ret);
 226         inode = NULL;
 227         if (ino) {
 228                 inode = iget(dir->i_sb, ino);
 229                 if (!inode)
 230                         return ERR_PTR(-EACCES);
 231         }
 232         return d_splice_alias(inode, dentry);
 233 }
 234
 235 static int btrfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
 236 {
 237         struct inode *inode = filp->f_path.dentry->d_inode;
 238         struct btrfs_root *root = btrfs_sb(inode->i_sb);
 239         struct btrfs_item *item;
 240         struct btrfs_dir_item *di;
 241         struct btrfs_key key;
 242         struct btrfs_path path;
 243         int ret;
 244         u32 nritems;
 245         struct btrfs_leaf *leaf;
 246         int slot;
 247         int advance;
 248         unsigned char d_type = DT_UNKNOWN;
 249         int over;
 250
 251         key.objectid = inode->i_ino;
 252         key.flags = 0;
 253         btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
 254         key.offset = filp->f_pos;
 255         btrfs_init_path(&path);
 256         ret = btrfs_search_slot(NULL, root, &key, &path, 0, 0);
 257         if (ret < 0) {
 258                 goto err;
 259         }
 260         advance = filp->f_pos > 0 && ret != 0;
 261         while(1) {
 262                 leaf = btrfs_buffer_leaf(path.nodes[0]);
 263                 nritems = btrfs_header_nritems(&leaf->header);
 264                 slot = path.slots[0];
 265                 if (advance) {
 266                         if (slot == nritems -1) {
 267                                 ret = btrfs_next_leaf(root, &path);
 268                                 if (ret)
 269                                         break;
 270                                 leaf = btrfs_buffer_leaf(path.nodes[0]);
 271                                 nritems = btrfs_header_nritems(&leaf->header);
 272                                 slot = path.slots[0];
 273                         } else {
 274                                 slot++;
 275                                 path.slots[0]++;
 276                         }
 277                 }
 278                 advance = 1;
 279                 item = leaf->items + slot;
 280                 if (btrfs_disk_key_objectid(&item->key) != key.objectid)
 281                         break;
 282                 if (btrfs_disk_key_type(&item->key) != BTRFS_DIR_ITEM_KEY)
 283                         continue;
 284                 di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
 285                 over = filldir(dirent, (const char *)(di + 1),
 286                                btrfs_dir_name_len(di),
 287                                btrfs_disk_key_offset(&item->key),
 288                                btrfs_dir_objectid(di), d_type);
 289                 if (over)
 290                         break;
 291                 filp->f_pos = btrfs_disk_key_offset(&item->key) + 1;
 292         }
 293         ret = 0;
 294 err:
 295         btrfs_release_path(root, &path);
 296         return ret;
 297 }
 298
 299 static void btrfs_put_super (struct super_block * sb)
 300 {
 301         struct btrfs_root *root = btrfs_sb(sb);
 302         int ret;
 303
 304         ret = close_ctree(root);
 305         if (ret) {
 306                 printk("close ctree returns %d\n", ret);
 307         }
 308         sb->s_fs_info = NULL;
 309 }
 310
 311 static int btrfs_fill_super(struct super_block * sb, void * data, int silent)
 312 {
 313         struct inode * inode;
 314         struct dentry * root_dentry;
 315         struct btrfs_super_block *disk_super;
 316         struct buffer_head *bh;
 317         struct btrfs_root *root;
 318
 319         sb->s_maxbytes = MAX_LFS_FILESIZE;
 320         sb->s_blocksize = PAGE_CACHE_SIZE;
 321         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 322         sb->s_magic = BTRFS_SUPER_MAGIC;
 323         sb->s_op = &btrfs_super_ops;
 324         sb->s_time_gran = 1;
 325
 326         bh = sb_bread(sb, BTRFS_SUPER_INFO_OFFSET / sb->s_blocksize);
 327         if (!bh) {
 328                 printk("btrfs: unable to read on disk super\n");
 329                 return -EIO;
 330         }
 331         disk_super = (struct btrfs_super_block *)bh->b_data;
 332         root = open_ctree(sb, bh, disk_super);
 333         sb->s_fs_info = root;
 334         if (!root) {
 335                 printk("btrfs: open_ctree failed\n");
 336                 return -EIO;
 337         }
 338         printk("read in super total blocks %Lu root %Lu\n",
 339                btrfs_super_total_blocks(disk_super),
 340                btrfs_super_root_dir(disk_super));
 341
 342         inode = iget_locked(sb, btrfs_super_root_dir(disk_super));
 343         if (!inode)
 344                 return -ENOMEM;
 345         if (inode->i_state & I_NEW) {
 346                 btrfs_read_locked_inode(inode);
 347                 unlock_new_inode(inode);
 348         }
 349
 350         root_dentry = d_alloc_root(inode);
 351         if (!root_dentry) {
 352                 iput(inode);
 353                 return -ENOMEM;
 354         }
 355         sb->s_root = root_dentry;
 356
 357         return 0;
 358 }
 359
 360 static int btrfs_get_sb(struct file_system_type *fs_type,
 361         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 362 {
 363         return get_sb_bdev(fs_type, flags, dev_name, data,
 364                            btrfs_fill_super, mnt);
 365 }
 366
 367 static struct file_system_type btrfs_fs_type = {
 368         .owner          = THIS_MODULE,
 369         .name           = "btrfs",
 370         .get_sb         = btrfs_get_sb,
 371         .kill_sb        = kill_block_super,
 372         .fs_flags       = FS_REQUIRES_DEV,
 373 };
 374
 375 static struct super_operations btrfs_super_ops = {
 376         .statfs         = simple_statfs,
 377         .drop_inode     = generic_delete_inode,
 378         .put_super      = btrfs_put_super,
 379         .read_inode     = btrfs_read_locked_inode,
 380 };
 381
 382 static struct inode_operations btrfs_dir_inode_operations = {
 383         .lookup         = btrfs_lookup,
 384 };
 385
 386 static struct file_operations btrfs_dir_file_operations = {
 387         .llseek         = generic_file_llseek,
 388         .read           = generic_read_dir,
 389         .readdir        = btrfs_readdir,
 390 };
 391
 392
 393 static int __init init_btrfs_fs(void)
 394 {
 395         printk("btrfs loaded!\n");
 396         return register_filesystem(&btrfs_fs_type);
 397 }
 398
 399 static void __exit exit_btrfs_fs(void)
 400 {
 401         unregister_filesystem(&btrfs_fs_type);
 402         printk("btrfs unloaded\n");
 403 }
 404
 405 module_init(init_btrfs_fs)
 406 module_exit(exit_btrfs_fs)
 407
 408 MODULE_LICENSE("GPL");