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