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