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_nobarrier, 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_nobarrier, "nobarrier"},
  75         {Opt_max_extent, "max_extent=%s"},
  76         {Opt_alloc_start, "alloc_start=%s"},
  77         {Opt_err, NULL}
  78 };
  79
  80 u64 btrfs_parse_size(char *str)
  81 {
  82         u64 res;
  83         int mult = 1;
  84         char *end;
  85         char last;
  86
  87         res = simple_strtoul(str, &end, 10);
  88
  89         last = end[0];
  90         if (isalpha(last)) {
  91                 last = tolower(last);
  92                 switch (last) {
  93                 case 'g':
  94                         mult *= 1024;
  95                 case 'm':
  96                         mult *= 1024;
  97                 case 'k':
  98                         mult *= 1024;
  99                 }
 100                 res = res * mult;
 101         }
 102         return res;
 103 }
 104
 105 static int parse_options (char * options,
 106                           struct btrfs_root *root,
 107                           char **subvol_name)
 108 {
 109         char * p;
 110         struct btrfs_fs_info *info = NULL;
 111         substring_t args[MAX_OPT_ARGS];
 112
 113         if (!options)
 114                 return 1;
 115
 116         /*
 117          * strsep changes the string, duplicate it because parse_options
 118          * gets called twice
 119          */
 120         options = kstrdup(options, GFP_NOFS);
 121         if (!options)
 122                 return -ENOMEM;
 123
 124         if (root)
 125                 info = root->fs_info;
 126
 127         while ((p = strsep (&options, ",")) != NULL) {
 128                 int token;
 129                 if (!*p)
 130                         continue;
 131
 132                 token = match_token(p, tokens, args);
 133                 switch (token) {
 134                 case Opt_subvol:
 135                         if (subvol_name) {
 136                                 *subvol_name = match_strdup(&args[0]);
 137                         }
 138                         break;
 139                 case Opt_nodatasum:
 140                         if (info) {
 141                                 printk("btrfs: setting nodatacsum\n");
 142                                 btrfs_set_opt(info->mount_opt, NODATASUM);
 143                         }
 144                         break;
 145                 case Opt_nodatacow:
 146                         if (info) {
 147                                 printk("btrfs: setting nodatacow\n");
 148                                 btrfs_set_opt(info->mount_opt, NODATACOW);
 149                                 btrfs_set_opt(info->mount_opt, NODATASUM);
 150                         }
 151                         break;
 152                 case Opt_nobarrier:
 153                         if (info) {
 154                                 printk("btrfs: turning off barriers\n");
 155                                 btrfs_set_opt(info->mount_opt, NOBARRIER);
 156                         }
 157                         break;
 158                 case Opt_max_extent:
 159                         if (info) {
 160                                 char *num = match_strdup(&args[0]);
 161                                 if (num) {
 162                                         info->max_extent =
 163                                                 btrfs_parse_size(num);
 164                                         kfree(num);
 165
 166                                         info->max_extent = max_t(u64,
 167                                                          info->max_extent,
 168                                                          root->sectorsize);
 169                                         printk("btrfs: max_extent at %Lu\n",
 170                                                info->max_extent);
 171                                 }
 172                         }
 173                         break;
 174                 case Opt_alloc_start:
 175                         if (info) {
 176                                 char *num = match_strdup(&args[0]);
 177                                 if (num) {
 178                                         info->alloc_start =
 179                                                 btrfs_parse_size(num);
 180                                         kfree(num);
 181                                         printk("btrfs: allocations start at "
 182                                                "%Lu\n", info->alloc_start);
 183                                 }
 184                         }
 185                         break;
 186                 default:
 187                         break;
 188                 }
 189         }
 190         kfree(options);
 191         return 1;
 192 }
 193
 194 static int btrfs_fill_super(struct super_block * sb, void * data, int silent)
 195 {
 196         struct inode * inode;
 197         struct dentry * root_dentry;
 198         struct btrfs_super_block *disk_super;
 199         struct btrfs_root *tree_root;
 200         struct btrfs_inode *bi;
 201         int err;
 202
 203         sb->s_maxbytes = MAX_LFS_FILESIZE;
 204         sb->s_magic = BTRFS_SUPER_MAGIC;
 205         sb->s_op = &btrfs_super_ops;
 206         sb->s_xattr = btrfs_xattr_handlers;
 207         sb->s_time_gran = 1;
 208
 209         tree_root = open_ctree(sb);
 210
 211         if (!tree_root || IS_ERR(tree_root)) {
 212                 printk("btrfs: open_ctree failed\n");
 213                 return -EIO;
 214         }
 215         sb->s_fs_info = tree_root;
 216         disk_super = &tree_root->fs_info->super_copy;
 217         inode = btrfs_iget_locked(sb, btrfs_super_root_dir(disk_super),
 218                                   tree_root);
 219         bi = BTRFS_I(inode);
 220         bi->location.objectid = inode->i_ino;
 221         bi->location.offset = 0;
 222         bi->root = tree_root;
 223
 224         btrfs_set_key_type(&bi->location, BTRFS_INODE_ITEM_KEY);
 225
 226         if (!inode) {
 227                 err = -ENOMEM;
 228                 goto fail_close;
 229         }
 230         if (inode->i_state & I_NEW) {
 231                 btrfs_read_locked_inode(inode);
 232                 unlock_new_inode(inode);
 233         }
 234
 235         root_dentry = d_alloc_root(inode);
 236         if (!root_dentry) {
 237                 iput(inode);
 238                 err = -ENOMEM;
 239                 goto fail_close;
 240         }
 241
 242         parse_options((char *)data, tree_root, NULL);
 243
 244         /* this does the super kobj at the same time */
 245         err = btrfs_sysfs_add_super(tree_root->fs_info);
 246         if (err)
 247                 goto fail_close;
 248
 249         sb->s_root = root_dentry;
 250         btrfs_transaction_queue_work(tree_root, HZ * 30);
 251         return 0;
 252
 253 fail_close:
 254         close_ctree(tree_root);
 255         return err;
 256 }
 257
 258 static int btrfs_sync_fs(struct super_block *sb, int wait)
 259 {
 260         struct btrfs_trans_handle *trans;
 261         struct btrfs_root *root;
 262         int ret;
 263         root = btrfs_sb(sb);
 264
 265         sb->s_dirt = 0;
 266         if (!wait) {
 267                 filemap_flush(root->fs_info->btree_inode->i_mapping);
 268                 return 0;
 269         }
 270         btrfs_clean_old_snapshots(root);
 271         mutex_lock(&root->fs_info->fs_mutex);
 272         btrfs_defrag_dirty_roots(root->fs_info);
 273         trans = btrfs_start_transaction(root, 1);
 274         ret = btrfs_commit_transaction(trans, root);
 275         sb->s_dirt = 0;
 276         mutex_unlock(&root->fs_info->fs_mutex);
 277         return ret;
 278 }
 279
 280 static void btrfs_write_super(struct super_block *sb)
 281 {
 282         sb->s_dirt = 0;
 283 }
 284
 285 /*
 286  * This is almost a copy of get_sb_bdev in fs/super.c.
 287  * We need the local copy to allow direct mounting of
 288  * subvolumes, but this could be easily integrated back
 289  * into the generic version.  --hch
 290  */
 291
 292 /* start copy & paste */
 293 static int set_bdev_super(struct super_block *s, void *data)
 294 {
 295         s->s_bdev = data;
 296         s->s_dev = s->s_bdev->bd_dev;
 297         return 0;
 298 }
 299
 300 static int test_bdev_super(struct super_block *s, void *data)
 301 {
 302         return (void *)s->s_bdev == data;
 303 }
 304
 305 int btrfs_get_sb_bdev(struct file_system_type *fs_type,
 306         int flags, const char *dev_name, void *data,
 307         int (*fill_super)(struct super_block *, void *, int),
 308         struct vfsmount *mnt, const char *subvol)
 309 {
 310         struct block_device *bdev = NULL;
 311         struct super_block *s;
 312         struct dentry *root;
 313         int error = 0;
 314
 315         bdev = open_bdev_excl(dev_name, flags, fs_type);
 316         if (IS_ERR(bdev))
 317                 return PTR_ERR(bdev);
 318
 319         /*
 320          * once the super is inserted into the list by sget, s_umount
 321          * will protect the lockfs code from trying to start a snapshot
 322          * while we are mounting
 323          */
 324         down(&bdev->bd_mount_sem);
 325         s = sget(fs_type, test_bdev_super, set_bdev_super, bdev);
 326         up(&bdev->bd_mount_sem);
 327         if (IS_ERR(s))
 328                 goto error_s;
 329
 330         if (s->s_root) {
 331                 if ((flags ^ s->s_flags) & MS_RDONLY) {
 332                         up_write(&s->s_umount);
 333                         deactivate_super(s);
 334                         error = -EBUSY;
 335                         goto error_bdev;
 336                 }
 337
 338                 close_bdev_excl(bdev);
 339         } else {
 340                 char b[BDEVNAME_SIZE];
 341
 342                 s->s_flags = flags;
 343                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
 344                 sb_set_blocksize(s, block_size(bdev));
 345                 error = fill_super(s, data, flags & MS_SILENT ? 1 : 0);
 346                 if (error) {
 347                         up_write(&s->s_umount);
 348                         deactivate_super(s);
 349                         goto error;
 350                 }
 351
 352                 s->s_flags |= MS_ACTIVE;
 353         }
 354
 355         if (subvol) {
 356                 root = lookup_one_len(subvol, s->s_root, strlen(subvol));
 357                 if (IS_ERR(root)) {
 358                         up_write(&s->s_umount);
 359                         deactivate_super(s);
 360                         error = PTR_ERR(root);
 361                         goto error;
 362                 }
 363                 if (!root->d_inode) {
 364                         dput(root);
 365                         up_write(&s->s_umount);
 366                         deactivate_super(s);
 367                         error = -ENXIO;
 368                         goto error;
 369                 }
 370         } else {
 371                 root = dget(s->s_root);
 372         }
 373
 374         mnt->mnt_sb = s;
 375         mnt->mnt_root = root;
 376         return 0;
 377
 378 error_s:
 379         error = PTR_ERR(s);
 380 error_bdev:
 381         close_bdev_excl(bdev);
 382 error:
 383         return error;
 384 }
 385 /* end copy & paste */
 386
 387 static int btrfs_get_sb(struct file_system_type *fs_type,
 388         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 389 {
 390         int ret;
 391         char *subvol_name = NULL;
 392
 393         parse_options((char *)data, NULL, &subvol_name);
 394         ret = btrfs_get_sb_bdev(fs_type, flags, dev_name, data,
 395                         btrfs_fill_super, mnt,
 396                         subvol_name ? subvol_name : "default");
 397         if (subvol_name)
 398                 kfree(subvol_name);
 399         return ret;
 400 }
 401
 402 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 403 {
 404         struct btrfs_root *root = btrfs_sb(dentry->d_sb);
 405         struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
 406         int bits = dentry->d_sb->s_blocksize_bits;
 407
 408         buf->f_namelen = BTRFS_NAME_LEN;
 409         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
 410         buf->f_bfree = buf->f_blocks -
 411                 (btrfs_super_bytes_used(disk_super) >> bits);
 412         buf->f_bavail = buf->f_bfree;
 413         buf->f_bsize = dentry->d_sb->s_blocksize;
 414         buf->f_type = BTRFS_SUPER_MAGIC;
 415         return 0;
 416 }
 417
 418 static struct file_system_type btrfs_fs_type = {
 419         .owner          = THIS_MODULE,
 420         .name           = "btrfs",
 421         .get_sb         = btrfs_get_sb,
 422         .kill_sb        = kill_block_super,
 423         .fs_flags       = FS_REQUIRES_DEV,
 424 };
 425
 426 static struct super_operations btrfs_super_ops = {
 427         .delete_inode   = btrfs_delete_inode,
 428         .put_super      = btrfs_put_super,
 429         .read_inode     = btrfs_read_locked_inode,
 430         .write_super    = btrfs_write_super,
 431         .sync_fs        = btrfs_sync_fs,
 432         .write_inode    = btrfs_write_inode,
 433         .dirty_inode    = btrfs_dirty_inode,
 434         .alloc_inode    = btrfs_alloc_inode,
 435         .destroy_inode  = btrfs_destroy_inode,
 436         .statfs         = btrfs_statfs,
 437 };
 438
 439 static int __init init_btrfs_fs(void)
 440 {
 441         int err;
 442
 443         err = btrfs_init_sysfs();
 444         if (err)
 445                 return err;
 446
 447         btrfs_init_transaction_sys();
 448         err = btrfs_init_cachep();
 449         if (err)
 450                 goto free_transaction_sys;
 451         err = extent_map_init();
 452         if (err)
 453                 goto free_cachep;
 454
 455         err = register_filesystem(&btrfs_fs_type);
 456         if (err)
 457                 goto free_extent_map;
 458         return 0;
 459
 460 free_extent_map:
 461         extent_map_exit();
 462 free_cachep:
 463         btrfs_destroy_cachep();
 464 free_transaction_sys:
 465         btrfs_exit_transaction_sys();
 466         btrfs_exit_sysfs();
 467         return err;
 468 }
 469
 470 static void __exit exit_btrfs_fs(void)
 471 {
 472         btrfs_exit_transaction_sys();
 473         btrfs_destroy_cachep();
 474         extent_map_exit();
 475         unregister_filesystem(&btrfs_fs_type);
 476         btrfs_exit_sysfs();
 477 }
 478
 479 module_init(init_btrfs_fs)
 480 module_exit(exit_btrfs_fs)
 481
 482 MODULE_LICENSE("GPL");