fs/btrfs/super.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/blkdev.h>
  20 #include <linux/module.h>
  21 #include <linux/buffer_head.h>
  22 #include <linux/fs.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/highmem.h>
  25 #include <linux/time.h>
  26 #include <linux/init.h>
  27 #include <linux/string.h>
  28 #include <linux/smp_lock.h>
  29 #include <linux/backing-dev.h>
  30 #include <linux/mount.h>
  31 #include <linux/mpage.h>
  32 #include <linux/swap.h>
  33 #include <linux/writeback.h>
  34 #include <linux/statfs.h>
  35 #include <linux/compat.h>
  36 #include <linux/parser.h>
  37 #include <linux/ctype.h>
  38 #include <linux/namei.h>
  39 #include "ctree.h"
  40 #include "disk-io.h"
  41 #include "transaction.h"
  42 #include "btrfs_inode.h"
  43 #include "ioctl.h"
  44 #include "print-tree.h"
  45 #include "xattr.h"
  46
  47 #define BTRFS_SUPER_MAGIC 0x9123683E
  48
  49 static struct super_operations btrfs_super_ops;
  50
  51 static void btrfs_put_super (struct super_block * sb)
  52 {
  53         struct btrfs_root *root = btrfs_sb(sb);
  54         struct btrfs_fs_info *fs = root->fs_info;
  55         int ret;
  56
  57         ret = close_ctree(root);
  58         if (ret) {
  59                 printk("close ctree returns %d\n", ret);
  60         }
  61         btrfs_sysfs_del_super(fs);
  62         sb->s_fs_info = NULL;
  63 }
  64
  65 enum {
  66         Opt_subvol, Opt_nodatasum, Opt_nodatacow, Opt_max_extent,
  67         Opt_alloc_start, Opt_err,
  68 };
  69
  70 static match_table_t tokens = {
  71         {Opt_subvol, "subvol=%s"},
  72         {Opt_nodatasum, "nodatasum"},
  73         {Opt_nodatacow, "nodatacow"},
  74         {Opt_max_extent, "max_extent=%s"},
  75         {Opt_alloc_start, "alloc_start=%s"},
  76         {Opt_err, NULL}
  77 };
  78
  79 u64 btrfs_parse_size(char *str)
  80 {
  81         u64 res;
  82         int mult = 1;
  83         char *end;
  84         char last;
  85
  86         res = simple_strtoul(str, &end, 10);
  87
  88         last = end[0];
  89         if (isalpha(last)) {
  90                 last = tolower(last);
  91                 switch (last) {
  92                 case 'g':
  93                         mult *= 1024;
  94                 case 'm':
  95                         mult *= 1024;
  96                 case 'k':
  97                         mult *= 1024;
  98                 }
  99                 res = res * mult;
 100         }
 101         return res;
 102 }
 103
 104 static int parse_options (char * options,
 105                           struct btrfs_root *root,
 106                           char **subvol_name)
 107 {
 108         char * p;
 109         struct btrfs_fs_info *info = NULL;
 110         substring_t args[MAX_OPT_ARGS];
 111
 112         if (!options)
 113                 return 1;
 114
 115         /*
 116          * strsep changes the string, duplicate it because parse_options
 117          * gets called twice
 118          */
 119         options = kstrdup(options, GFP_NOFS);
 120         if (!options)
 121                 return -ENOMEM;
 122
 123         if (root)
 124                 info = root->fs_info;
 125
 126         while ((p = strsep (&options, ",")) != NULL) {
 127                 int token;
 128                 if (!*p)
 129                         continue;
 130
 131                 token = match_token(p, tokens, args);
 132                 switch (token) {
 133                 case Opt_subvol:
 134                         if (subvol_name) {
 135                                 *subvol_name = match_strdup(&args[0]);
 136                         }
 137                         break;
 138                 case Opt_nodatasum:
 139                         if (info) {
 140                                 printk("btrfs: setting nodatacsum\n");
 141                                 btrfs_set_opt(info->mount_opt, NODATASUM);
 142                         }
 143                         break;
 144                 case Opt_nodatacow:
 145                         if (info) {
 146                                 printk("btrfs: setting nodatacow\n");
 147                                 btrfs_set_opt(info->mount_opt, NODATACOW);
 148                                 btrfs_set_opt(info->mount_opt, NODATASUM);
 149                         }
 150                         break;
 151                 case Opt_max_extent:
 152                         if (info) {
 153                                 char *num = match_strdup(&args[0]);
 154                                 if (num) {
 155                                         info->max_extent =
 156                                                 btrfs_parse_size(num);
 157                                         kfree(num);
 158
 159                                         info->max_extent = max_t(u64,
 160                                                          info->max_extent,
 161                                                          root->sectorsize);
 162                                         printk("btrfs: max_extent at %Lu\n",
 163                                                info->max_extent);
 164                                 }
 165                         }
 166                         break;
 167                 case Opt_alloc_start:
 168                         if (info) {
 169                                 char *num = match_strdup(&args[0]);
 170                                 if (num) {
 171                                         info->alloc_start =
 172                                                 btrfs_parse_size(num);
 173                                         kfree(num);
 174                                         printk("btrfs: allocations start at "
 175                                                "%Lu\n", info->alloc_start);
 176                                 }
 177                         }
 178                         break;
 179                 default:
 180                         break;
 181                 }
 182         }
 183         kfree(options);
 184         return 1;
 185 }
 186
 187 static int btrfs_fill_super(struct super_block * sb, void * data, int silent)
 188 {
 189         struct inode * inode;
 190         struct dentry * root_dentry;
 191         struct btrfs_super_block *disk_super;
 192         struct btrfs_root *tree_root;
 193         struct btrfs_inode *bi;
 194         int err;
 195
 196         sb->s_maxbytes = MAX_LFS_FILESIZE;
 197         sb->s_magic = BTRFS_SUPER_MAGIC;
 198         sb->s_op = &btrfs_super_ops;
 199         sb->s_xattr = btrfs_xattr_handlers;
 200         sb->s_time_gran = 1;
 201
 202         tree_root = open_ctree(sb);
 203
 204         if (!tree_root || IS_ERR(tree_root)) {
 205                 printk("btrfs: open_ctree failed\n");
 206                 return -EIO;
 207         }
 208         sb->s_fs_info = tree_root;
 209         disk_super = &tree_root->fs_info->super_copy;
 210         inode = btrfs_iget_locked(sb, btrfs_super_root_dir(disk_super),
 211                                   tree_root);
 212         bi = BTRFS_I(inode);
 213         bi->location.objectid = inode->i_ino;
 214         bi->location.offset = 0;
 215         bi->root = tree_root;
 216
 217         btrfs_set_key_type(&bi->location, BTRFS_INODE_ITEM_KEY);
 218
 219         if (!inode) {
 220                 err = -ENOMEM;
 221                 goto fail_close;
 222         }
 223         if (inode->i_state & I_NEW) {
 224                 btrfs_read_locked_inode(inode);
 225                 unlock_new_inode(inode);
 226         }
 227
 228         root_dentry = d_alloc_root(inode);
 229         if (!root_dentry) {
 230                 iput(inode);
 231                 err = -ENOMEM;
 232                 goto fail_close;
 233         }
 234
 235         parse_options((char *)data, tree_root, NULL);
 236
 237         /* this does the super kobj at the same time */
 238         err = btrfs_sysfs_add_super(tree_root->fs_info);
 239         if (err)
 240                 goto fail_close;
 241
 242         sb->s_root = root_dentry;
 243         btrfs_transaction_queue_work(tree_root, HZ * 30);
 244         return 0;
 245
 246 fail_close:
 247         close_ctree(tree_root);
 248         return err;
 249 }
 250
 251 static int btrfs_sync_fs(struct super_block *sb, int wait)
 252 {
 253         struct btrfs_trans_handle *trans;
 254         struct btrfs_root *root;
 255         int ret;
 256         root = btrfs_sb(sb);
 257
 258         sb->s_dirt = 0;
 259         if (!wait) {
 260                 filemap_flush(root->fs_info->btree_inode->i_mapping);
 261                 return 0;
 262         }
 263         btrfs_clean_old_snapshots(root);
 264         mutex_lock(&root->fs_info->fs_mutex);
 265         btrfs_defrag_dirty_roots(root->fs_info);
 266         trans = btrfs_start_transaction(root, 1);
 267         ret = btrfs_commit_transaction(trans, root);
 268         sb->s_dirt = 0;
 269         mutex_unlock(&root->fs_info->fs_mutex);
 270         return ret;
 271 }
 272
 273 static void btrfs_write_super(struct super_block *sb)
 274 {
 275         sb->s_dirt = 0;
 276 }
 277
 278 /*
 279  * This is almost a copy of get_sb_bdev in fs/super.c.
 280  * We need the local copy to allow direct mounting of
 281  * subvolumes, but this could be easily integrated back
 282  * into the generic version.  --hch
 283  */
 284
 285 /* start copy & paste */
 286 static int set_bdev_super(struct super_block *s, void *data)
 287 {
 288         s->s_bdev = data;
 289         s->s_dev = s->s_bdev->bd_dev;
 290         return 0;
 291 }
 292
 293 static int test_bdev_super(struct super_block *s, void *data)
 294 {
 295         return (void *)s->s_bdev == data;
 296 }
 297
 298 int btrfs_get_sb_bdev(struct file_system_type *fs_type,
 299         int flags, const char *dev_name, void *data,
 300         int (*fill_super)(struct super_block *, void *, int),
 301         struct vfsmount *mnt, const char *subvol)
 302 {
 303         struct block_device *bdev = NULL;
 304         struct super_block *s;
 305         struct dentry *root;
 306         int error = 0;
 307
 308         bdev = open_bdev_excl(dev_name, flags, fs_type);
 309         if (IS_ERR(bdev))
 310                 return PTR_ERR(bdev);
 311
 312         /*
 313          * once the super is inserted into the list by sget, s_umount
 314          * will protect the lockfs code from trying to start a snapshot
 315          * while we are mounting
 316          */
 317         down(&bdev->bd_mount_sem);
 318         s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
 319         up(&bdev->bd_mount_sem);
 320         if (IS_ERR(s))
 321                 goto error_s;
 322
 323         if (s->s_root) {
 324                 if ((flags ^ s->s_flags) & MS_RDONLY) {
 325                         up_write(&s->s_umount);
 326                         deactivate_super(s);
 327                         error = -EBUSY;
 328                         goto error_bdev;
 329                 }
 330
 331                 close_bdev_excl(bdev);
 332         } else {
 333                 char b[BDEVNAME_SIZE];
 334
 335                 s->s_flags = flags;
 336                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 337                 sb_set_blocksize(s, block_size(bdev));
 338                 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
 339                 if (error) {
 340                         up_write(&s->s_umount);
 341                         deactivate_super(s);
 342                         goto error;
 343                 }
 344
 345                 s->s_flags |= MS_ACTIVE;
 346         }
 347
 348         if (subvol) {
 349                 root = lookup_one_len(subvol, s->s_root, strlen(subvol));
 350                 if (IS_ERR(root)) {
 351                         up_write(&s->s_umount);
 352                         deactivate_super(s);
 353                         error = PTR_ERR(root);
 354                         goto error;
 355                 }
 356                 if (!root->d_inode) {
 357                         dput(root);
 358                         up_write(&s->s_umount);
 359                         deactivate_super(s);
 360                         error = -ENXIO;
 361                         goto error;
 362                 }
 363         } else {
 364                 root = dget(s->s_root);
 365         }
 366
 367         mnt->mnt_sb = s;
 368         mnt->mnt_root = root;
 369         return 0;
 370
 371 error_s:
 372         error = PTR_ERR(s);
 373 error_bdev:
 374         close_bdev_excl(bdev);
 375 error:
 376         return error;
 377 }
 378 /* end copy & paste */
 379
 380 static int btrfs_get_sb(struct file_system_type *fs_type,
 381         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 382 {
 383         int ret;
 384         char *subvol_name = NULL;
 385
 386         parse_options((char *)data, NULL, &subvol_name);
 387         ret = btrfs_get_sb_bdev(fs_type, flags, dev_name, data,
 388                         btrfs_fill_super, mnt,
 389                         subvol_name ? subvol_name : "default");
 390         if (subvol_name)
 391                 kfree(subvol_name);
 392         return ret;
 393 }
 394
 395 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 396 {
 397         struct btrfs_root *root = btrfs_sb(dentry->d_sb);
 398         struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
 399         int bits = dentry->d_sb->s_blocksize_bits;
 400
 401         buf->f_namelen = BTRFS_NAME_LEN;
 402         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
 403         buf->f_bfree = buf->f_blocks -
 404                 (btrfs_super_bytes_used(disk_super) >> bits);
 405         buf->f_bavail = buf->f_bfree;
 406         buf->f_bsize = dentry->d_sb->s_blocksize;
 407         buf->f_type = BTRFS_SUPER_MAGIC;
 408         return 0;
 409 }
 410
 411 static struct file_system_type btrfs_fs_type = {
 412         .owner          = THIS_MODULE,
 413         .name           = "btrfs",
 414         .get_sb         = btrfs_get_sb,
 415         .kill_sb        = kill_block_super,
 416         .fs_flags       = FS_REQUIRES_DEV,
 417 };
 418
 419 static struct super_operations btrfs_super_ops = {
 420         .delete_inode   = btrfs_delete_inode,
 421         .put_super      = btrfs_put_super,
 422         .read_inode     = btrfs_read_locked_inode,
 423         .write_super    = btrfs_write_super,
 424         .sync_fs        = btrfs_sync_fs,
 425         .write_inode    = btrfs_write_inode,
 426         .dirty_inode    = btrfs_dirty_inode,
 427         .alloc_inode    = btrfs_alloc_inode,
 428         .destroy_inode  = btrfs_destroy_inode,
 429         .statfs         = btrfs_statfs,
 430 };
 431
 432 static int __init init_btrfs_fs(void)
 433 {
 434         int err;
 435
 436         err = btrfs_init_sysfs();
 437         if (err)
 438                 return err;
 439
 440         btrfs_init_transaction_sys();
 441         err = btrfs_init_cachep();
 442         if (err)
 443                 goto free_transaction_sys;
 444         err = extent_map_init();
 445         if (err)
 446                 goto free_cachep;
 447
 448         err = register_filesystem(&btrfs_fs_type);
 449         if (err)
 450                 goto free_extent_map;
 451         return 0;
 452
 453 free_extent_map:
 454         extent_map_exit();
 455 free_cachep:
 456         btrfs_destroy_cachep();
 457 free_transaction_sys:
 458         btrfs_exit_transaction_sys();
 459         btrfs_exit_sysfs();
 460         return err;
 461 }
 462
 463 static void __exit exit_btrfs_fs(void)
 464 {
 465         btrfs_exit_transaction_sys();
 466         btrfs_destroy_cachep();
 467         extent_map_exit();
 468         unregister_filesystem(&btrfs_fs_type);
 469         btrfs_exit_sysfs();
 470 }
 471
 472 module_init(init_btrfs_fs)
 473 module_exit(exit_btrfs_fs)
 474
 475 MODULE_LICENSE("GPL");