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