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