linux/fs/btrfs/transaction.c
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   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/fs.h>
  20#include <linux/slab.h>
  21#include <linux/sched.h>
  22#include <linux/writeback.h>
  23#include <linux/pagemap.h>
  24#include <linux/blkdev.h>
  25#include <linux/uuid.h>
  26#include "ctree.h"
  27#include "disk-io.h"
  28#include "transaction.h"
  29#include "locking.h"
  30#include "tree-log.h"
  31#include "inode-map.h"
  32#include "volumes.h"
  33
  34#define BTRFS_ROOT_TRANS_TAG 0
  35
  36void put_transaction(struct btrfs_transaction *transaction)
  37{
  38        WARN_ON(atomic_read(&transaction->use_count) == 0);
  39        if (atomic_dec_and_test(&transaction->use_count)) {
  40                BUG_ON(!list_empty(&transaction->list));
  41                WARN_ON(transaction->delayed_refs.root.rb_node);
  42                memset(transaction, 0, sizeof(*transaction));
  43                kmem_cache_free(btrfs_transaction_cachep, transaction);
  44        }
  45}
  46
  47static noinline void switch_commit_root(struct btrfs_root *root)
  48{
  49        free_extent_buffer(root->commit_root);
  50        root->commit_root = btrfs_root_node(root);
  51}
  52
  53/*
  54 * either allocate a new transaction or hop into the existing one
  55 */
  56static noinline int join_transaction(struct btrfs_root *root, int type)
  57{
  58        struct btrfs_transaction *cur_trans;
  59        struct btrfs_fs_info *fs_info = root->fs_info;
  60
  61        spin_lock(&fs_info->trans_lock);
  62loop:
  63        /* The file system has been taken offline. No new transactions. */
  64        if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
  65                spin_unlock(&fs_info->trans_lock);
  66                return -EROFS;
  67        }
  68
  69        if (fs_info->trans_no_join) {
  70                /* 
  71                 * If we are JOIN_NOLOCK we're already committing a current
  72                 * transaction, we just need a handle to deal with something
  73                 * when committing the transaction, such as inode cache and
  74                 * space cache. It is a special case.
  75                 */
  76                if (type != TRANS_JOIN_NOLOCK) {
  77                        spin_unlock(&fs_info->trans_lock);
  78                        return -EBUSY;
  79                }
  80        }
  81
  82        cur_trans = fs_info->running_transaction;
  83        if (cur_trans) {
  84                if (cur_trans->aborted) {
  85                        spin_unlock(&fs_info->trans_lock);
  86                        return cur_trans->aborted;
  87                }
  88                atomic_inc(&cur_trans->use_count);
  89                atomic_inc(&cur_trans->num_writers);
  90                cur_trans->num_joined++;
  91                spin_unlock(&fs_info->trans_lock);
  92                return 0;
  93        }
  94        spin_unlock(&fs_info->trans_lock);
  95
  96        /*
  97         * If we are ATTACH, we just want to catch the current transaction,
  98         * and commit it. If there is no transaction, just return ENOENT.
  99         */
 100        if (type == TRANS_ATTACH)
 101                return -ENOENT;
 102
 103        cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
 104        if (!cur_trans)
 105                return -ENOMEM;
 106
 107        spin_lock(&fs_info->trans_lock);
 108        if (fs_info->running_transaction) {
 109                /*
 110                 * someone started a transaction after we unlocked.  Make sure
 111                 * to redo the trans_no_join checks above
 112                 */
 113                kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 114                cur_trans = fs_info->running_transaction;
 115                goto loop;
 116        } else if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 117                spin_unlock(&fs_info->trans_lock);
 118                kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 119                return -EROFS;
 120        }
 121
 122        atomic_set(&cur_trans->num_writers, 1);
 123        cur_trans->num_joined = 0;
 124        init_waitqueue_head(&cur_trans->writer_wait);
 125        init_waitqueue_head(&cur_trans->commit_wait);
 126        cur_trans->in_commit = 0;
 127        cur_trans->blocked = 0;
 128        /*
 129         * One for this trans handle, one so it will live on until we
 130         * commit the transaction.
 131         */
 132        atomic_set(&cur_trans->use_count, 2);
 133        cur_trans->commit_done = 0;
 134        cur_trans->start_time = get_seconds();
 135
 136        cur_trans->delayed_refs.root = RB_ROOT;
 137        cur_trans->delayed_refs.num_entries = 0;
 138        cur_trans->delayed_refs.num_heads_ready = 0;
 139        cur_trans->delayed_refs.num_heads = 0;
 140        cur_trans->delayed_refs.flushing = 0;
 141        cur_trans->delayed_refs.run_delayed_start = 0;
 142
 143        /*
 144         * although the tree mod log is per file system and not per transaction,
 145         * the log must never go across transaction boundaries.
 146         */
 147        smp_mb();
 148        if (!list_empty(&fs_info->tree_mod_seq_list)) {
 149                printk(KERN_ERR "btrfs: tree_mod_seq_list not empty when "
 150                        "creating a fresh transaction\n");
 151                WARN_ON(1);
 152        }
 153        if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log)) {
 154                printk(KERN_ERR "btrfs: tree_mod_log rb tree not empty when "
 155                        "creating a fresh transaction\n");
 156                WARN_ON(1);
 157        }
 158        atomic_set(&fs_info->tree_mod_seq, 0);
 159
 160        spin_lock_init(&cur_trans->commit_lock);
 161        spin_lock_init(&cur_trans->delayed_refs.lock);
 162
 163        INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 164        list_add_tail(&cur_trans->list, &fs_info->trans_list);
 165        extent_io_tree_init(&cur_trans->dirty_pages,
 166                             fs_info->btree_inode->i_mapping);
 167        fs_info->generation++;
 168        cur_trans->transid = fs_info->generation;
 169        fs_info->running_transaction = cur_trans;
 170        cur_trans->aborted = 0;
 171        spin_unlock(&fs_info->trans_lock);
 172
 173        return 0;
 174}
 175
 176/*
 177 * this does all the record keeping required to make sure that a reference
 178 * counted root is properly recorded in a given transaction.  This is required
 179 * to make sure the old root from before we joined the transaction is deleted
 180 * when the transaction commits
 181 */
 182static int record_root_in_trans(struct btrfs_trans_handle *trans,
 183                               struct btrfs_root *root)
 184{
 185        if (root->ref_cows && root->last_trans < trans->transid) {
 186                WARN_ON(root == root->fs_info->extent_root);
 187                WARN_ON(root->commit_root != root->node);
 188
 189                /*
 190                 * see below for in_trans_setup usage rules
 191                 * we have the reloc mutex held now, so there
 192                 * is only one writer in this function
 193                 */
 194                root->in_trans_setup = 1;
 195
 196                /* make sure readers find in_trans_setup before
 197                 * they find our root->last_trans update
 198                 */
 199                smp_wmb();
 200
 201                spin_lock(&root->fs_info->fs_roots_radix_lock);
 202                if (root->last_trans == trans->transid) {
 203                        spin_unlock(&root->fs_info->fs_roots_radix_lock);
 204                        return 0;
 205                }
 206                radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 207                           (unsigned long)root->root_key.objectid,
 208                           BTRFS_ROOT_TRANS_TAG);
 209                spin_unlock(&root->fs_info->fs_roots_radix_lock);
 210                root->last_trans = trans->transid;
 211
 212                /* this is pretty tricky.  We don't want to
 213                 * take the relocation lock in btrfs_record_root_in_trans
 214                 * unless we're really doing the first setup for this root in
 215                 * this transaction.
 216                 *
 217                 * Normally we'd use root->last_trans as a flag to decide
 218                 * if we want to take the expensive mutex.
 219                 *
 220                 * But, we have to set root->last_trans before we
 221                 * init the relocation root, otherwise, we trip over warnings
 222                 * in ctree.c.  The solution used here is to flag ourselves
 223                 * with root->in_trans_setup.  When this is 1, we're still
 224                 * fixing up the reloc trees and everyone must wait.
 225                 *
 226                 * When this is zero, they can trust root->last_trans and fly
 227                 * through btrfs_record_root_in_trans without having to take the
 228                 * lock.  smp_wmb() makes sure that all the writes above are
 229                 * done before we pop in the zero below
 230                 */
 231                btrfs_init_reloc_root(trans, root);
 232                smp_wmb();
 233                root->in_trans_setup = 0;
 234        }
 235        return 0;
 236}
 237
 238
 239int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 240                               struct btrfs_root *root)
 241{
 242        if (!root->ref_cows)
 243                return 0;
 244
 245        /*
 246         * see record_root_in_trans for comments about in_trans_setup usage
 247         * and barriers
 248         */
 249        smp_rmb();
 250        if (root->last_trans == trans->transid &&
 251            !root->in_trans_setup)
 252                return 0;
 253
 254        mutex_lock(&root->fs_info->reloc_mutex);
 255        record_root_in_trans(trans, root);
 256        mutex_unlock(&root->fs_info->reloc_mutex);
 257
 258        return 0;
 259}
 260
 261/* wait for commit against the current transaction to become unblocked
 262 * when this is done, it is safe to start a new transaction, but the current
 263 * transaction might not be fully on disk.
 264 */
 265static void wait_current_trans(struct btrfs_root *root)
 266{
 267        struct btrfs_transaction *cur_trans;
 268
 269        spin_lock(&root->fs_info->trans_lock);
 270        cur_trans = root->fs_info->running_transaction;
 271        if (cur_trans && cur_trans->blocked) {
 272                atomic_inc(&cur_trans->use_count);
 273                spin_unlock(&root->fs_info->trans_lock);
 274
 275                wait_event(root->fs_info->transaction_wait,
 276                           !cur_trans->blocked);
 277                put_transaction(cur_trans);
 278        } else {
 279                spin_unlock(&root->fs_info->trans_lock);
 280        }
 281}
 282
 283static int may_wait_transaction(struct btrfs_root *root, int type)
 284{
 285        if (root->fs_info->log_root_recovering)
 286                return 0;
 287
 288        if (type == TRANS_USERSPACE)
 289                return 1;
 290
 291        if (type == TRANS_START &&
 292            !atomic_read(&root->fs_info->open_ioctl_trans))
 293                return 1;
 294
 295        return 0;
 296}
 297
 298static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 299                                                    u64 num_items, int type,
 300                                                    int noflush)
 301{
 302        struct btrfs_trans_handle *h;
 303        struct btrfs_transaction *cur_trans;
 304        u64 num_bytes = 0;
 305        int ret;
 306        u64 qgroup_reserved = 0;
 307
 308        if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 309                return ERR_PTR(-EROFS);
 310
 311        if (current->journal_info) {
 312                WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
 313                h = current->journal_info;
 314                h->use_count++;
 315                h->orig_rsv = h->block_rsv;
 316                h->block_rsv = NULL;
 317                goto got_it;
 318        }
 319
 320        /*
 321         * Do the reservation before we join the transaction so we can do all
 322         * the appropriate flushing if need be.
 323         */
 324        if (num_items > 0 && root != root->fs_info->chunk_root) {
 325                if (root->fs_info->quota_enabled &&
 326                    is_fstree(root->root_key.objectid)) {
 327                        qgroup_reserved = num_items * root->leafsize;
 328                        ret = btrfs_qgroup_reserve(root, qgroup_reserved);
 329                        if (ret)
 330                                return ERR_PTR(ret);
 331                }
 332
 333                num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
 334                if (noflush)
 335                        ret = btrfs_block_rsv_add_noflush(root,
 336                                                &root->fs_info->trans_block_rsv,
 337                                                num_bytes);
 338                else
 339                        ret = btrfs_block_rsv_add(root,
 340                                                &root->fs_info->trans_block_rsv,
 341                                                num_bytes);
 342                if (ret)
 343                        return ERR_PTR(ret);
 344        }
 345again:
 346        h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 347        if (!h)
 348                return ERR_PTR(-ENOMEM);
 349
 350        /*
 351         * If we are JOIN_NOLOCK we're already committing a transaction and
 352         * waiting on this guy, so we don't need to do the sb_start_intwrite
 353         * because we're already holding a ref.  We need this because we could
 354         * have raced in and did an fsync() on a file which can kick a commit
 355         * and then we deadlock with somebody doing a freeze.
 356         *
 357         * If we are ATTACH, it means we just want to catch the current
 358         * transaction and commit it, so we needn't do sb_start_intwrite(). 
 359         */
 360        if (type < TRANS_JOIN_NOLOCK)
 361                sb_start_intwrite(root->fs_info->sb);
 362
 363        if (may_wait_transaction(root, type))
 364                wait_current_trans(root);
 365
 366        do {
 367                ret = join_transaction(root, type);
 368                if (ret == -EBUSY)
 369                        wait_current_trans(root);
 370        } while (ret == -EBUSY);
 371
 372        if (ret < 0) {
 373                /* We must get the transaction if we are JOIN_NOLOCK. */
 374                BUG_ON(type == TRANS_JOIN_NOLOCK);
 375
 376                if (type < TRANS_JOIN_NOLOCK)
 377                        sb_end_intwrite(root->fs_info->sb);
 378                kmem_cache_free(btrfs_trans_handle_cachep, h);
 379                return ERR_PTR(ret);
 380        }
 381
 382        cur_trans = root->fs_info->running_transaction;
 383
 384        h->transid = cur_trans->transid;
 385        h->transaction = cur_trans;
 386        h->blocks_used = 0;
 387        h->bytes_reserved = 0;
 388        h->root = root;
 389        h->delayed_ref_updates = 0;
 390        h->use_count = 1;
 391        h->adding_csums = 0;
 392        h->block_rsv = NULL;
 393        h->orig_rsv = NULL;
 394        h->aborted = 0;
 395        h->qgroup_reserved = qgroup_reserved;
 396        h->delayed_ref_elem.seq = 0;
 397        h->type = type;
 398        INIT_LIST_HEAD(&h->qgroup_ref_list);
 399        INIT_LIST_HEAD(&h->new_bgs);
 400
 401        smp_mb();
 402        if (cur_trans->blocked && may_wait_transaction(root, type)) {
 403                btrfs_commit_transaction(h, root);
 404                goto again;
 405        }
 406
 407        if (num_bytes) {
 408                trace_btrfs_space_reservation(root->fs_info, "transaction",
 409                                              h->transid, num_bytes, 1);
 410                h->block_rsv = &root->fs_info->trans_block_rsv;
 411                h->bytes_reserved = num_bytes;
 412        }
 413
 414got_it:
 415        btrfs_record_root_in_trans(h, root);
 416
 417        if (!current->journal_info && type != TRANS_USERSPACE)
 418                current->journal_info = h;
 419        return h;
 420}
 421
 422struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 423                                                   int num_items)
 424{
 425        return start_transaction(root, num_items, TRANS_START, 0);
 426}
 427
 428struct btrfs_trans_handle *btrfs_start_transaction_noflush(
 429                                        struct btrfs_root *root, int num_items)
 430{
 431        return start_transaction(root, num_items, TRANS_START, 1);
 432}
 433
 434struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 435{
 436        return start_transaction(root, 0, TRANS_JOIN, 0);
 437}
 438
 439struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 440{
 441        return start_transaction(root, 0, TRANS_JOIN_NOLOCK, 0);
 442}
 443
 444struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 445{
 446        return start_transaction(root, 0, TRANS_USERSPACE, 0);
 447}
 448
 449struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
 450{
 451        return start_transaction(root, 0, TRANS_ATTACH, 0);
 452}
 453
 454/* wait for a transaction commit to be fully complete */
 455static noinline void wait_for_commit(struct btrfs_root *root,
 456                                    struct btrfs_transaction *commit)
 457{
 458        wait_event(commit->commit_wait, commit->commit_done);
 459}
 460
 461int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 462{
 463        struct btrfs_transaction *cur_trans = NULL, *t;
 464        int ret;
 465
 466        ret = 0;
 467        if (transid) {
 468                if (transid <= root->fs_info->last_trans_committed)
 469                        goto out;
 470
 471                /* find specified transaction */
 472                spin_lock(&root->fs_info->trans_lock);
 473                list_for_each_entry(t, &root->fs_info->trans_list, list) {
 474                        if (t->transid == transid) {
 475                                cur_trans = t;
 476                                atomic_inc(&cur_trans->use_count);
 477                                break;
 478                        }
 479                        if (t->transid > transid)
 480                                break;
 481                }
 482                spin_unlock(&root->fs_info->trans_lock);
 483                ret = -EINVAL;
 484                if (!cur_trans)
 485                        goto out;  /* bad transid */
 486        } else {
 487                /* find newest transaction that is committing | committed */
 488                spin_lock(&root->fs_info->trans_lock);
 489                list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 490                                            list) {
 491                        if (t->in_commit) {
 492                                if (t->commit_done)
 493                                        break;
 494                                cur_trans = t;
 495                                atomic_inc(&cur_trans->use_count);
 496                                break;
 497                        }
 498                }
 499                spin_unlock(&root->fs_info->trans_lock);
 500                if (!cur_trans)
 501                        goto out;  /* nothing committing|committed */
 502        }
 503
 504        wait_for_commit(root, cur_trans);
 505
 506        put_transaction(cur_trans);
 507        ret = 0;
 508out:
 509        return ret;
 510}
 511
 512void btrfs_throttle(struct btrfs_root *root)
 513{
 514        if (!atomic_read(&root->fs_info->open_ioctl_trans))
 515                wait_current_trans(root);
 516}
 517
 518static int should_end_transaction(struct btrfs_trans_handle *trans,
 519                                  struct btrfs_root *root)
 520{
 521        int ret;
 522
 523        ret = btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
 524        return ret ? 1 : 0;
 525}
 526
 527int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 528                                 struct btrfs_root *root)
 529{
 530        struct btrfs_transaction *cur_trans = trans->transaction;
 531        int updates;
 532        int err;
 533
 534        smp_mb();
 535        if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
 536                return 1;
 537
 538        updates = trans->delayed_ref_updates;
 539        trans->delayed_ref_updates = 0;
 540        if (updates) {
 541                err = btrfs_run_delayed_refs(trans, root, updates);
 542                if (err) /* Error code will also eval true */
 543                        return err;
 544        }
 545
 546        return should_end_transaction(trans, root);
 547}
 548
 549static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 550                          struct btrfs_root *root, int throttle)
 551{
 552        struct btrfs_transaction *cur_trans = trans->transaction;
 553        struct btrfs_fs_info *info = root->fs_info;
 554        int count = 0;
 555        int lock = (trans->type != TRANS_JOIN_NOLOCK);
 556        int err = 0;
 557
 558        if (--trans->use_count) {
 559                trans->block_rsv = trans->orig_rsv;
 560                return 0;
 561        }
 562
 563        /*
 564         * do the qgroup accounting as early as possible
 565         */
 566        err = btrfs_delayed_refs_qgroup_accounting(trans, info);
 567
 568        btrfs_trans_release_metadata(trans, root);
 569        trans->block_rsv = NULL;
 570        /*
 571         * the same root has to be passed to start_transaction and
 572         * end_transaction. Subvolume quota depends on this.
 573         */
 574        WARN_ON(trans->root != root);
 575
 576        if (trans->qgroup_reserved) {
 577                btrfs_qgroup_free(root, trans->qgroup_reserved);
 578                trans->qgroup_reserved = 0;
 579        }
 580
 581        if (!list_empty(&trans->new_bgs))
 582                btrfs_create_pending_block_groups(trans, root);
 583
 584        while (count < 2) {
 585                unsigned long cur = trans->delayed_ref_updates;
 586                trans->delayed_ref_updates = 0;
 587                if (cur &&
 588                    trans->transaction->delayed_refs.num_heads_ready > 64) {
 589                        trans->delayed_ref_updates = 0;
 590                        btrfs_run_delayed_refs(trans, root, cur);
 591                } else {
 592                        break;
 593                }
 594                count++;
 595        }
 596        btrfs_trans_release_metadata(trans, root);
 597        trans->block_rsv = NULL;
 598
 599        if (!list_empty(&trans->new_bgs))
 600                btrfs_create_pending_block_groups(trans, root);
 601
 602        if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
 603            should_end_transaction(trans, root)) {
 604                trans->transaction->blocked = 1;
 605                smp_wmb();
 606        }
 607
 608        if (lock && cur_trans->blocked && !cur_trans->in_commit) {
 609                if (throttle) {
 610                        /*
 611                         * We may race with somebody else here so end up having
 612                         * to call end_transaction on ourselves again, so inc
 613                         * our use_count.
 614                         */
 615                        trans->use_count++;
 616                        return btrfs_commit_transaction(trans, root);
 617                } else {
 618                        wake_up_process(info->transaction_kthread);
 619                }
 620        }
 621
 622        if (trans->type < TRANS_JOIN_NOLOCK)
 623                sb_end_intwrite(root->fs_info->sb);
 624
 625        WARN_ON(cur_trans != info->running_transaction);
 626        WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 627        atomic_dec(&cur_trans->num_writers);
 628
 629        smp_mb();
 630        if (waitqueue_active(&cur_trans->writer_wait))
 631                wake_up(&cur_trans->writer_wait);
 632        put_transaction(cur_trans);
 633
 634        if (current->journal_info == trans)
 635                current->journal_info = NULL;
 636
 637        if (throttle)
 638                btrfs_run_delayed_iputs(root);
 639
 640        if (trans->aborted ||
 641            root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 642                err = -EIO;
 643        }
 644        assert_qgroups_uptodate(trans);
 645
 646        memset(trans, 0, sizeof(*trans));
 647        kmem_cache_free(btrfs_trans_handle_cachep, trans);
 648        return err;
 649}
 650
 651int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 652                          struct btrfs_root *root)
 653{
 654        int ret;
 655
 656        ret = __btrfs_end_transaction(trans, root, 0);
 657        if (ret)
 658                return ret;
 659        return 0;
 660}
 661
 662int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 663                                   struct btrfs_root *root)
 664{
 665        int ret;
 666
 667        ret = __btrfs_end_transaction(trans, root, 1);
 668        if (ret)
 669                return ret;
 670        return 0;
 671}
 672
 673int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans,
 674                                struct btrfs_root *root)
 675{
 676        return __btrfs_end_transaction(trans, root, 1);
 677}
 678
 679/*
 680 * when btree blocks are allocated, they have some corresponding bits set for
 681 * them in one of two extent_io trees.  This is used to make sure all of
 682 * those extents are sent to disk but does not wait on them
 683 */
 684int btrfs_write_marked_extents(struct btrfs_root *root,
 685                               struct extent_io_tree *dirty_pages, int mark)
 686{
 687        int err = 0;
 688        int werr = 0;
 689        struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 690        struct extent_state *cached_state = NULL;
 691        u64 start = 0;
 692        u64 end;
 693
 694        while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 695                                      mark, &cached_state)) {
 696                convert_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT,
 697                                   mark, &cached_state, GFP_NOFS);
 698                cached_state = NULL;
 699                err = filemap_fdatawrite_range(mapping, start, end);
 700                if (err)
 701                        werr = err;
 702                cond_resched();
 703                start = end + 1;
 704        }
 705        if (err)
 706                werr = err;
 707        return werr;
 708}
 709
 710/*
 711 * when btree blocks are allocated, they have some corresponding bits set for
 712 * them in one of two extent_io trees.  This is used to make sure all of
 713 * those extents are on disk for transaction or log commit.  We wait
 714 * on all the pages and clear them from the dirty pages state tree
 715 */
 716int btrfs_wait_marked_extents(struct btrfs_root *root,
 717                              struct extent_io_tree *dirty_pages, int mark)
 718{
 719        int err = 0;
 720        int werr = 0;
 721        struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 722        struct extent_state *cached_state = NULL;
 723        u64 start = 0;
 724        u64 end;
 725
 726        while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 727                                      EXTENT_NEED_WAIT, &cached_state)) {
 728                clear_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT,
 729                                 0, 0, &cached_state, GFP_NOFS);
 730                err = filemap_fdatawait_range(mapping, start, end);
 731                if (err)
 732                        werr = err;
 733                cond_resched();
 734                start = end + 1;
 735        }
 736        if (err)
 737                werr = err;
 738        return werr;
 739}
 740
 741/*
 742 * when btree blocks are allocated, they have some corresponding bits set for
 743 * them in one of two extent_io trees.  This is used to make sure all of
 744 * those extents are on disk for transaction or log commit
 745 */
 746int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 747                                struct extent_io_tree *dirty_pages, int mark)
 748{
 749        int ret;
 750        int ret2;
 751
 752        ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 753        ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 754
 755        if (ret)
 756                return ret;
 757        if (ret2)
 758                return ret2;
 759        return 0;
 760}
 761
 762int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 763                                     struct btrfs_root *root)
 764{
 765        if (!trans || !trans->transaction) {
 766                struct inode *btree_inode;
 767                btree_inode = root->fs_info->btree_inode;
 768                return filemap_write_and_wait(btree_inode->i_mapping);
 769        }
 770        return btrfs_write_and_wait_marked_extents(root,
 771                                           &trans->transaction->dirty_pages,
 772                                           EXTENT_DIRTY);
 773}
 774
 775/*
 776 * this is used to update the root pointer in the tree of tree roots.
 777 *
 778 * But, in the case of the extent allocation tree, updating the root
 779 * pointer may allocate blocks which may change the root of the extent
 780 * allocation tree.
 781 *
 782 * So, this loops and repeats and makes sure the cowonly root didn't
 783 * change while the root pointer was being updated in the metadata.
 784 */
 785static int update_cowonly_root(struct btrfs_trans_handle *trans,
 786                               struct btrfs_root *root)
 787{
 788        int ret;
 789        u64 old_root_bytenr;
 790        u64 old_root_used;
 791        struct btrfs_root *tree_root = root->fs_info->tree_root;
 792
 793        old_root_used = btrfs_root_used(&root->root_item);
 794        btrfs_write_dirty_block_groups(trans, root);
 795
 796        while (1) {
 797                old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 798                if (old_root_bytenr == root->node->start &&
 799                    old_root_used == btrfs_root_used(&root->root_item))
 800                        break;
 801
 802                btrfs_set_root_node(&root->root_item, root->node);
 803                ret = btrfs_update_root(trans, tree_root,
 804                                        &root->root_key,
 805                                        &root->root_item);
 806                if (ret)
 807                        return ret;
 808
 809                old_root_used = btrfs_root_used(&root->root_item);
 810                ret = btrfs_write_dirty_block_groups(trans, root);
 811                if (ret)
 812                        return ret;
 813        }
 814
 815        if (root != root->fs_info->extent_root)
 816                switch_commit_root(root);
 817
 818        return 0;
 819}
 820
 821/*
 822 * update all the cowonly tree roots on disk
 823 *
 824 * The error handling in this function may not be obvious. Any of the
 825 * failures will cause the file system to go offline. We still need
 826 * to clean up the delayed refs.
 827 */
 828static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 829                                         struct btrfs_root *root)
 830{
 831        struct btrfs_fs_info *fs_info = root->fs_info;
 832        struct list_head *next;
 833        struct extent_buffer *eb;
 834        int ret;
 835
 836        ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 837        if (ret)
 838                return ret;
 839
 840        eb = btrfs_lock_root_node(fs_info->tree_root);
 841        ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
 842                              0, &eb);
 843        btrfs_tree_unlock(eb);
 844        free_extent_buffer(eb);
 845
 846        if (ret)
 847                return ret;
 848
 849        ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 850        if (ret)
 851                return ret;
 852
 853        ret = btrfs_run_dev_stats(trans, root->fs_info);
 854        BUG_ON(ret);
 855
 856        ret = btrfs_run_qgroups(trans, root->fs_info);
 857        BUG_ON(ret);
 858
 859        /* run_qgroups might have added some more refs */
 860        ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 861        BUG_ON(ret);
 862
 863        while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 864                next = fs_info->dirty_cowonly_roots.next;
 865                list_del_init(next);
 866                root = list_entry(next, struct btrfs_root, dirty_list);
 867
 868                ret = update_cowonly_root(trans, root);
 869                if (ret)
 870                        return ret;
 871        }
 872
 873        down_write(&fs_info->extent_commit_sem);
 874        switch_commit_root(fs_info->extent_root);
 875        up_write(&fs_info->extent_commit_sem);
 876
 877        return 0;
 878}
 879
 880/*
 881 * dead roots are old snapshots that need to be deleted.  This allocates
 882 * a dirty root struct and adds it into the list of dead roots that need to
 883 * be deleted
 884 */
 885int btrfs_add_dead_root(struct btrfs_root *root)
 886{
 887        spin_lock(&root->fs_info->trans_lock);
 888        list_add(&root->root_list, &root->fs_info->dead_roots);
 889        spin_unlock(&root->fs_info->trans_lock);
 890        return 0;
 891}
 892
 893/*
 894 * update all the cowonly tree roots on disk
 895 */
 896static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 897                                    struct btrfs_root *root)
 898{
 899        struct btrfs_root *gang[8];
 900        struct btrfs_fs_info *fs_info = root->fs_info;
 901        int i;
 902        int ret;
 903        int err = 0;
 904
 905        spin_lock(&fs_info->fs_roots_radix_lock);
 906        while (1) {
 907                ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 908                                                 (void **)gang, 0,
 909                                                 ARRAY_SIZE(gang),
 910                                                 BTRFS_ROOT_TRANS_TAG);
 911                if (ret == 0)
 912                        break;
 913                for (i = 0; i < ret; i++) {
 914                        root = gang[i];
 915                        radix_tree_tag_clear(&fs_info->fs_roots_radix,
 916                                        (unsigned long)root->root_key.objectid,
 917                                        BTRFS_ROOT_TRANS_TAG);
 918                        spin_unlock(&fs_info->fs_roots_radix_lock);
 919
 920                        btrfs_free_log(trans, root);
 921                        btrfs_update_reloc_root(trans, root);
 922                        btrfs_orphan_commit_root(trans, root);
 923
 924                        btrfs_save_ino_cache(root, trans);
 925
 926                        /* see comments in should_cow_block() */
 927                        root->force_cow = 0;
 928                        smp_wmb();
 929
 930                        if (root->commit_root != root->node) {
 931                                mutex_lock(&root->fs_commit_mutex);
 932                                switch_commit_root(root);
 933                                btrfs_unpin_free_ino(root);
 934                                mutex_unlock(&root->fs_commit_mutex);
 935
 936                                btrfs_set_root_node(&root->root_item,
 937                                                    root->node);
 938                        }
 939
 940                        err = btrfs_update_root(trans, fs_info->tree_root,
 941                                                &root->root_key,
 942                                                &root->root_item);
 943                        spin_lock(&fs_info->fs_roots_radix_lock);
 944                        if (err)
 945                                break;
 946                }
 947        }
 948        spin_unlock(&fs_info->fs_roots_radix_lock);
 949        return err;
 950}
 951
 952/*
 953 * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 954 * otherwise every leaf in the btree is read and defragged.
 955 */
 956int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 957{
 958        struct btrfs_fs_info *info = root->fs_info;
 959        struct btrfs_trans_handle *trans;
 960        int ret;
 961        unsigned long nr;
 962
 963        if (xchg(&root->defrag_running, 1))
 964                return 0;
 965
 966        while (1) {
 967                trans = btrfs_start_transaction(root, 0);
 968                if (IS_ERR(trans))
 969                        return PTR_ERR(trans);
 970
 971                ret = btrfs_defrag_leaves(trans, root, cacheonly);
 972
 973                nr = trans->blocks_used;
 974                btrfs_end_transaction(trans, root);
 975                btrfs_btree_balance_dirty(info->tree_root, nr);
 976                cond_resched();
 977
 978                if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
 979                        break;
 980        }
 981        root->defrag_running = 0;
 982        return ret;
 983}
 984
 985/*
 986 * new snapshots need to be created at a very specific time in the
 987 * transaction commit.  This does the actual creation
 988 */
 989static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 990                                   struct btrfs_fs_info *fs_info,
 991                                   struct btrfs_pending_snapshot *pending)
 992{
 993        struct btrfs_key key;
 994        struct btrfs_root_item *new_root_item;
 995        struct btrfs_root *tree_root = fs_info->tree_root;
 996        struct btrfs_root *root = pending->root;
 997        struct btrfs_root *parent_root;
 998        struct btrfs_block_rsv *rsv;
 999        struct inode *parent_inode;
1000        struct btrfs_path *path;
1001        struct btrfs_dir_item *dir_item;
1002        struct dentry *parent;
1003        struct dentry *dentry;
1004        struct extent_buffer *tmp;
1005        struct extent_buffer *old;
1006        struct timespec cur_time = CURRENT_TIME;
1007        int ret;
1008        u64 to_reserve = 0;
1009        u64 index = 0;
1010        u64 objectid;
1011        u64 root_flags;
1012        uuid_le new_uuid;
1013
1014        path = btrfs_alloc_path();
1015        if (!path) {
1016                ret = pending->error = -ENOMEM;
1017                goto path_alloc_fail;
1018        }
1019
1020        new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
1021        if (!new_root_item) {
1022                ret = pending->error = -ENOMEM;
1023                goto root_item_alloc_fail;
1024        }
1025
1026        ret = btrfs_find_free_objectid(tree_root, &objectid);
1027        if (ret) {
1028                pending->error = ret;
1029                goto no_free_objectid;
1030        }
1031
1032        btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
1033
1034        if (to_reserve > 0) {
1035                ret = btrfs_block_rsv_add_noflush(root, &pending->block_rsv,
1036                                                  to_reserve);
1037                if (ret) {
1038                        pending->error = ret;
1039                        goto no_free_objectid;
1040                }
1041        }
1042
1043        ret = btrfs_qgroup_inherit(trans, fs_info, root->root_key.objectid,
1044                                   objectid, pending->inherit);
1045        if (ret) {
1046                pending->error = ret;
1047                goto no_free_objectid;
1048        }
1049
1050        key.objectid = objectid;
1051        key.offset = (u64)-1;
1052        key.type = BTRFS_ROOT_ITEM_KEY;
1053
1054        rsv = trans->block_rsv;
1055        trans->block_rsv = &pending->block_rsv;
1056
1057        dentry = pending->dentry;
1058        parent = dget_parent(dentry);
1059        parent_inode = parent->d_inode;
1060        parent_root = BTRFS_I(parent_inode)->root;
1061        record_root_in_trans(trans, parent_root);
1062
1063        /*
1064         * insert the directory item
1065         */
1066        ret = btrfs_set_inode_index(parent_inode, &index);
1067        BUG_ON(ret); /* -ENOMEM */
1068
1069        /* check if there is a file/dir which has the same name. */
1070        dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1071                                         btrfs_ino(parent_inode),
1072                                         dentry->d_name.name,
1073                                         dentry->d_name.len, 0);
1074        if (dir_item != NULL && !IS_ERR(dir_item)) {
1075                pending->error = -EEXIST;
1076                goto fail;
1077        } else if (IS_ERR(dir_item)) {
1078                ret = PTR_ERR(dir_item);
1079                btrfs_abort_transaction(trans, root, ret);
1080                goto fail;
1081        }
1082        btrfs_release_path(path);
1083
1084        /*
1085         * pull in the delayed directory update
1086         * and the delayed inode item
1087         * otherwise we corrupt the FS during
1088         * snapshot
1089         */
1090        ret = btrfs_run_delayed_items(trans, root);
1091        if (ret) {      /* Transaction aborted */
1092                btrfs_abort_transaction(trans, root, ret);
1093                goto fail;
1094        }
1095
1096        record_root_in_trans(trans, root);
1097        btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1098        memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1099        btrfs_check_and_init_root_item(new_root_item);
1100
1101        root_flags = btrfs_root_flags(new_root_item);
1102        if (pending->readonly)
1103                root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1104        else
1105                root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1106        btrfs_set_root_flags(new_root_item, root_flags);
1107
1108        btrfs_set_root_generation_v2(new_root_item,
1109                        trans->transid);
1110        uuid_le_gen(&new_uuid);
1111        memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
1112        memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1113                        BTRFS_UUID_SIZE);
1114        new_root_item->otime.sec = cpu_to_le64(cur_time.tv_sec);
1115        new_root_item->otime.nsec = cpu_to_le32(cur_time.tv_nsec);
1116        btrfs_set_root_otransid(new_root_item, trans->transid);
1117        memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1118        memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1119        btrfs_set_root_stransid(new_root_item, 0);
1120        btrfs_set_root_rtransid(new_root_item, 0);
1121
1122        old = btrfs_lock_root_node(root);
1123        ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1124        if (ret) {
1125                btrfs_tree_unlock(old);
1126                free_extent_buffer(old);
1127                btrfs_abort_transaction(trans, root, ret);
1128                goto fail;
1129        }
1130
1131        btrfs_set_lock_blocking(old);
1132
1133        ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1134        /* clean up in any case */
1135        btrfs_tree_unlock(old);
1136        free_extent_buffer(old);
1137        if (ret) {
1138                btrfs_abort_transaction(trans, root, ret);
1139                goto fail;
1140        }
1141
1142        /* see comments in should_cow_block() */
1143        root->force_cow = 1;
1144        smp_wmb();
1145
1146        btrfs_set_root_node(new_root_item, tmp);
1147        /* record when the snapshot was created in key.offset */
1148        key.offset = trans->transid;
1149        ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1150        btrfs_tree_unlock(tmp);
1151        free_extent_buffer(tmp);
1152        if (ret) {
1153                btrfs_abort_transaction(trans, root, ret);
1154                goto fail;
1155        }
1156
1157        /*
1158         * insert root back/forward references
1159         */
1160        ret = btrfs_add_root_ref(trans, tree_root, objectid,
1161                                 parent_root->root_key.objectid,
1162                                 btrfs_ino(parent_inode), index,
1163                                 dentry->d_name.name, dentry->d_name.len);
1164        if (ret) {
1165                btrfs_abort_transaction(trans, root, ret);
1166                goto fail;
1167        }
1168
1169        key.offset = (u64)-1;
1170        pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1171        if (IS_ERR(pending->snap)) {
1172                ret = PTR_ERR(pending->snap);
1173                btrfs_abort_transaction(trans, root, ret);
1174                goto fail;
1175        }
1176
1177        ret = btrfs_reloc_post_snapshot(trans, pending);
1178        if (ret) {
1179                btrfs_abort_transaction(trans, root, ret);
1180                goto fail;
1181        }
1182
1183        ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1184        if (ret) {
1185                btrfs_abort_transaction(trans, root, ret);
1186                goto fail;
1187        }
1188
1189        ret = btrfs_insert_dir_item(trans, parent_root,
1190                                    dentry->d_name.name, dentry->d_name.len,
1191                                    parent_inode, &key,
1192                                    BTRFS_FT_DIR, index);
1193        /* We have check then name at the beginning, so it is impossible. */
1194        BUG_ON(ret == -EEXIST);
1195        if (ret) {
1196                btrfs_abort_transaction(trans, root, ret);
1197                goto fail;
1198        }
1199
1200        btrfs_i_size_write(parent_inode, parent_inode->i_size +
1201                                         dentry->d_name.len * 2);
1202        parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
1203        ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
1204        if (ret)
1205                btrfs_abort_transaction(trans, root, ret);
1206fail:
1207        dput(parent);
1208        trans->block_rsv = rsv;
1209no_free_objectid:
1210        kfree(new_root_item);
1211root_item_alloc_fail:
1212        btrfs_free_path(path);
1213path_alloc_fail:
1214        btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
1215        return ret;
1216}
1217
1218/*
1219 * create all the snapshots we've scheduled for creation
1220 */
1221static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1222                                             struct btrfs_fs_info *fs_info)
1223{
1224        struct btrfs_pending_snapshot *pending;
1225        struct list_head *head = &trans->transaction->pending_snapshots;
1226
1227        list_for_each_entry(pending, head, list)
1228                create_pending_snapshot(trans, fs_info, pending);
1229        return 0;
1230}
1231
1232static void update_super_roots(struct btrfs_root *root)
1233{
1234        struct btrfs_root_item *root_item;
1235        struct btrfs_super_block *super;
1236
1237        super = root->fs_info->super_copy;
1238
1239        root_item = &root->fs_info->chunk_root->root_item;
1240        super->chunk_root = root_item->bytenr;
1241        super->chunk_root_generation = root_item->generation;
1242        super->chunk_root_level = root_item->level;
1243
1244        root_item = &root->fs_info->tree_root->root_item;
1245        super->root = root_item->bytenr;
1246        super->generation = root_item->generation;
1247        super->root_level = root_item->level;
1248        if (btrfs_test_opt(root, SPACE_CACHE))
1249                super->cache_generation = root_item->generation;
1250}
1251
1252int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1253{
1254        int ret = 0;
1255        spin_lock(&info->trans_lock);
1256        if (info->running_transaction)
1257                ret = info->running_transaction->in_commit;
1258        spin_unlock(&info->trans_lock);
1259        return ret;
1260}
1261
1262int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1263{
1264        int ret = 0;
1265        spin_lock(&info->trans_lock);
1266        if (info->running_transaction)
1267                ret = info->running_transaction->blocked;
1268        spin_unlock(&info->trans_lock);
1269        return ret;
1270}
1271
1272/*
1273 * wait for the current transaction commit to start and block subsequent
1274 * transaction joins
1275 */
1276static void wait_current_trans_commit_start(struct btrfs_root *root,
1277                                            struct btrfs_transaction *trans)
1278{
1279        wait_event(root->fs_info->transaction_blocked_wait, trans->in_commit);
1280}
1281
1282/*
1283 * wait for the current transaction to start and then become unblocked.
1284 * caller holds ref.
1285 */
1286static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1287                                         struct btrfs_transaction *trans)
1288{
1289        wait_event(root->fs_info->transaction_wait,
1290                   trans->commit_done || (trans->in_commit && !trans->blocked));
1291}
1292
1293/*
1294 * commit transactions asynchronously. once btrfs_commit_transaction_async
1295 * returns, any subsequent transaction will not be allowed to join.
1296 */
1297struct btrfs_async_commit {
1298        struct btrfs_trans_handle *newtrans;
1299        struct btrfs_root *root;
1300        struct delayed_work work;
1301};
1302
1303static void do_async_commit(struct work_struct *work)
1304{
1305        struct btrfs_async_commit *ac =
1306                container_of(work, struct btrfs_async_commit, work.work);
1307
1308        /*
1309         * We've got freeze protection passed with the transaction.
1310         * Tell lockdep about it.
1311         */
1312        rwsem_acquire_read(
1313                &ac->root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1314                0, 1, _THIS_IP_);
1315
1316        current->journal_info = ac->newtrans;
1317
1318        btrfs_commit_transaction(ac->newtrans, ac->root);
1319        kfree(ac);
1320}
1321
1322int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1323                                   struct btrfs_root *root,
1324                                   int wait_for_unblock)
1325{
1326        struct btrfs_async_commit *ac;
1327        struct btrfs_transaction *cur_trans;
1328
1329        ac = kmalloc(sizeof(*ac), GFP_NOFS);
1330        if (!ac)
1331                return -ENOMEM;
1332
1333        INIT_DELAYED_WORK(&ac->work, do_async_commit);
1334        ac->root = root;
1335        ac->newtrans = btrfs_join_transaction(root);
1336        if (IS_ERR(ac->newtrans)) {
1337                int err = PTR_ERR(ac->newtrans);
1338                kfree(ac);
1339                return err;
1340        }
1341
1342        /* take transaction reference */
1343        cur_trans = trans->transaction;
1344        atomic_inc(&cur_trans->use_count);
1345
1346        btrfs_end_transaction(trans, root);
1347
1348        /*
1349         * Tell lockdep we've released the freeze rwsem, since the
1350         * async commit thread will be the one to unlock it.
1351         */
1352        rwsem_release(&root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1353                      1, _THIS_IP_);
1354
1355        schedule_delayed_work(&ac->work, 0);
1356
1357        /* wait for transaction to start and unblock */
1358        if (wait_for_unblock)
1359                wait_current_trans_commit_start_and_unblock(root, cur_trans);
1360        else
1361                wait_current_trans_commit_start(root, cur_trans);
1362
1363        if (current->journal_info == trans)
1364                current->journal_info = NULL;
1365
1366        put_transaction(cur_trans);
1367        return 0;
1368}
1369
1370
1371static void cleanup_transaction(struct btrfs_trans_handle *trans,
1372                                struct btrfs_root *root, int err)
1373{
1374        struct btrfs_transaction *cur_trans = trans->transaction;
1375
1376        WARN_ON(trans->use_count > 1);
1377
1378        btrfs_abort_transaction(trans, root, err);
1379
1380        spin_lock(&root->fs_info->trans_lock);
1381        list_del_init(&cur_trans->list);
1382        if (cur_trans == root->fs_info->running_transaction) {
1383                root->fs_info->running_transaction = NULL;
1384                root->fs_info->trans_no_join = 0;
1385        }
1386        spin_unlock(&root->fs_info->trans_lock);
1387
1388        btrfs_cleanup_one_transaction(trans->transaction, root);
1389
1390        put_transaction(cur_trans);
1391        put_transaction(cur_trans);
1392
1393        trace_btrfs_transaction_commit(root);
1394
1395        btrfs_scrub_continue(root);
1396
1397        if (current->journal_info == trans)
1398                current->journal_info = NULL;
1399
1400        kmem_cache_free(btrfs_trans_handle_cachep, trans);
1401}
1402
1403/*
1404 * btrfs_transaction state sequence:
1405 *    in_commit = 0, blocked = 0  (initial)
1406 *    in_commit = 1, blocked = 1
1407 *    blocked = 0
1408 *    commit_done = 1
1409 */
1410int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1411                             struct btrfs_root *root)
1412{
1413        unsigned long joined = 0;
1414        struct btrfs_transaction *cur_trans = trans->transaction;
1415        struct btrfs_transaction *prev_trans = NULL;
1416        DEFINE_WAIT(wait);
1417        int ret = -EIO;
1418        int should_grow = 0;
1419        unsigned long now = get_seconds();
1420        int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1421
1422        btrfs_run_ordered_operations(root, 0);
1423
1424        if (cur_trans->aborted)
1425                goto cleanup_transaction;
1426
1427        /* make a pass through all the delayed refs we have so far
1428         * any runnings procs may add more while we are here
1429         */
1430        ret = btrfs_run_delayed_refs(trans, root, 0);
1431        if (ret)
1432                goto cleanup_transaction;
1433
1434        btrfs_trans_release_metadata(trans, root);
1435        trans->block_rsv = NULL;
1436
1437        cur_trans = trans->transaction;
1438
1439        /*
1440         * set the flushing flag so procs in this transaction have to
1441         * start sending their work down.
1442         */
1443        cur_trans->delayed_refs.flushing = 1;
1444
1445        if (!list_empty(&trans->new_bgs))
1446                btrfs_create_pending_block_groups(trans, root);
1447
1448        ret = btrfs_run_delayed_refs(trans, root, 0);
1449        if (ret)
1450                goto cleanup_transaction;
1451
1452        spin_lock(&cur_trans->commit_lock);
1453        if (cur_trans->in_commit) {
1454                spin_unlock(&cur_trans->commit_lock);
1455                atomic_inc(&cur_trans->use_count);
1456                ret = btrfs_end_transaction(trans, root);
1457
1458                wait_for_commit(root, cur_trans);
1459
1460                put_transaction(cur_trans);
1461
1462                return ret;
1463        }
1464
1465        trans->transaction->in_commit = 1;
1466        trans->transaction->blocked = 1;
1467        spin_unlock(&cur_trans->commit_lock);
1468        wake_up(&root->fs_info->transaction_blocked_wait);
1469
1470        spin_lock(&root->fs_info->trans_lock);
1471        if (cur_trans->list.prev != &root->fs_info->trans_list) {
1472                prev_trans = list_entry(cur_trans->list.prev,
1473                                        struct btrfs_transaction, list);
1474                if (!prev_trans->commit_done) {
1475                        atomic_inc(&prev_trans->use_count);
1476                        spin_unlock(&root->fs_info->trans_lock);
1477
1478                        wait_for_commit(root, prev_trans);
1479
1480                        put_transaction(prev_trans);
1481                } else {
1482                        spin_unlock(&root->fs_info->trans_lock);
1483                }
1484        } else {
1485                spin_unlock(&root->fs_info->trans_lock);
1486        }
1487
1488        if (!btrfs_test_opt(root, SSD) &&
1489            (now < cur_trans->start_time || now - cur_trans->start_time < 1))
1490                should_grow = 1;
1491
1492        do {
1493                int snap_pending = 0;
1494
1495                joined = cur_trans->num_joined;
1496                if (!list_empty(&trans->transaction->pending_snapshots))
1497                        snap_pending = 1;
1498
1499                WARN_ON(cur_trans != trans->transaction);
1500
1501                if (flush_on_commit || snap_pending) {
1502                        btrfs_start_delalloc_inodes(root, 1);
1503                        btrfs_wait_ordered_extents(root, 1);
1504                }
1505
1506                ret = btrfs_run_delayed_items(trans, root);
1507                if (ret)
1508                        goto cleanup_transaction;
1509
1510                /*
1511                 * running the delayed items may have added new refs. account
1512                 * them now so that they hinder processing of more delayed refs
1513                 * as little as possible.
1514                 */
1515                btrfs_delayed_refs_qgroup_accounting(trans, root->fs_info);
1516
1517                /*
1518                 * rename don't use btrfs_join_transaction, so, once we
1519                 * set the transaction to blocked above, we aren't going
1520                 * to get any new ordered operations.  We can safely run
1521                 * it here and no for sure that nothing new will be added
1522                 * to the list
1523                 */
1524                btrfs_run_ordered_operations(root, 1);
1525
1526                prepare_to_wait(&cur_trans->writer_wait, &wait,
1527                                TASK_UNINTERRUPTIBLE);
1528
1529                if (atomic_read(&cur_trans->num_writers) > 1)
1530                        schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1531                else if (should_grow)
1532                        schedule_timeout(1);
1533
1534                finish_wait(&cur_trans->writer_wait, &wait);
1535        } while (atomic_read(&cur_trans->num_writers) > 1 ||
1536                 (should_grow && cur_trans->num_joined != joined));
1537
1538        /*
1539         * Ok now we need to make sure to block out any other joins while we
1540         * commit the transaction.  We could have started a join before setting
1541         * no_join so make sure to wait for num_writers to == 1 again.
1542         */
1543        spin_lock(&root->fs_info->trans_lock);
1544        root->fs_info->trans_no_join = 1;
1545        spin_unlock(&root->fs_info->trans_lock);
1546        wait_event(cur_trans->writer_wait,
1547                   atomic_read(&cur_trans->num_writers) == 1);
1548
1549        /*
1550         * the reloc mutex makes sure that we stop
1551         * the balancing code from coming in and moving
1552         * extents around in the middle of the commit
1553         */
1554        mutex_lock(&root->fs_info->reloc_mutex);
1555
1556        /*
1557         * We needn't worry about the delayed items because we will
1558         * deal with them in create_pending_snapshot(), which is the
1559         * core function of the snapshot creation.
1560         */
1561        ret = create_pending_snapshots(trans, root->fs_info);
1562        if (ret) {
1563                mutex_unlock(&root->fs_info->reloc_mutex);
1564                goto cleanup_transaction;
1565        }
1566
1567        /*
1568         * We insert the dir indexes of the snapshots and update the inode
1569         * of the snapshots' parents after the snapshot creation, so there
1570         * are some delayed items which are not dealt with. Now deal with
1571         * them.
1572         *
1573         * We needn't worry that this operation will corrupt the snapshots,
1574         * because all the tree which are snapshoted will be forced to COW
1575         * the nodes and leaves.
1576         */
1577        ret = btrfs_run_delayed_items(trans, root);
1578        if (ret) {
1579                mutex_unlock(&root->fs_info->reloc_mutex);
1580                goto cleanup_transaction;
1581        }
1582
1583        ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1584        if (ret) {
1585                mutex_unlock(&root->fs_info->reloc_mutex);
1586                goto cleanup_transaction;
1587        }
1588
1589        /*
1590         * make sure none of the code above managed to slip in a
1591         * delayed item
1592         */
1593        btrfs_assert_delayed_root_empty(root);
1594
1595        WARN_ON(cur_trans != trans->transaction);
1596
1597        btrfs_scrub_pause(root);
1598        /* btrfs_commit_tree_roots is responsible for getting the
1599         * various roots consistent with each other.  Every pointer
1600         * in the tree of tree roots has to point to the most up to date
1601         * root for every subvolume and other tree.  So, we have to keep
1602         * the tree logging code from jumping in and changing any
1603         * of the trees.
1604         *
1605         * At this point in the commit, there can't be any tree-log
1606         * writers, but a little lower down we drop the trans mutex
1607         * and let new people in.  By holding the tree_log_mutex
1608         * from now until after the super is written, we avoid races
1609         * with the tree-log code.
1610         */
1611        mutex_lock(&root->fs_info->tree_log_mutex);
1612
1613        ret = commit_fs_roots(trans, root);
1614        if (ret) {
1615                mutex_unlock(&root->fs_info->tree_log_mutex);
1616                mutex_unlock(&root->fs_info->reloc_mutex);
1617                goto cleanup_transaction;
1618        }
1619
1620        /* commit_fs_roots gets rid of all the tree log roots, it is now
1621         * safe to free the root of tree log roots
1622         */
1623        btrfs_free_log_root_tree(trans, root->fs_info);
1624
1625        ret = commit_cowonly_roots(trans, root);
1626        if (ret) {
1627                mutex_unlock(&root->fs_info->tree_log_mutex);
1628                mutex_unlock(&root->fs_info->reloc_mutex);
1629                goto cleanup_transaction;
1630        }
1631
1632        btrfs_prepare_extent_commit(trans, root);
1633
1634        cur_trans = root->fs_info->running_transaction;
1635
1636        btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1637                            root->fs_info->tree_root->node);
1638        switch_commit_root(root->fs_info->tree_root);
1639
1640        btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1641                            root->fs_info->chunk_root->node);
1642        switch_commit_root(root->fs_info->chunk_root);
1643
1644        assert_qgroups_uptodate(trans);
1645        update_super_roots(root);
1646
1647        if (!root->fs_info->log_root_recovering) {
1648                btrfs_set_super_log_root(root->fs_info->super_copy, 0);
1649                btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
1650        }
1651
1652        memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
1653               sizeof(*root->fs_info->super_copy));
1654
1655        trans->transaction->blocked = 0;
1656        spin_lock(&root->fs_info->trans_lock);
1657        root->fs_info->running_transaction = NULL;
1658        root->fs_info->trans_no_join = 0;
1659        spin_unlock(&root->fs_info->trans_lock);
1660        mutex_unlock(&root->fs_info->reloc_mutex);
1661
1662        wake_up(&root->fs_info->transaction_wait);
1663
1664        ret = btrfs_write_and_wait_transaction(trans, root);
1665        if (ret) {
1666                btrfs_error(root->fs_info, ret,
1667                            "Error while writing out transaction.");
1668                mutex_unlock(&root->fs_info->tree_log_mutex);
1669                goto cleanup_transaction;
1670        }
1671
1672        ret = write_ctree_super(trans, root, 0);
1673        if (ret) {
1674                mutex_unlock(&root->fs_info->tree_log_mutex);
1675                goto cleanup_transaction;
1676        }
1677
1678        /*
1679         * the super is written, we can safely allow the tree-loggers
1680         * to go about their business
1681         */
1682        mutex_unlock(&root->fs_info->tree_log_mutex);
1683
1684        btrfs_finish_extent_commit(trans, root);
1685
1686        cur_trans->commit_done = 1;
1687
1688        root->fs_info->last_trans_committed = cur_trans->transid;
1689
1690        wake_up(&cur_trans->commit_wait);
1691
1692        spin_lock(&root->fs_info->trans_lock);
1693        list_del_init(&cur_trans->list);
1694        spin_unlock(&root->fs_info->trans_lock);
1695
1696        put_transaction(cur_trans);
1697        put_transaction(cur_trans);
1698
1699        if (trans->type < TRANS_JOIN_NOLOCK)
1700                sb_end_intwrite(root->fs_info->sb);
1701
1702        trace_btrfs_transaction_commit(root);
1703
1704        btrfs_scrub_continue(root);
1705
1706        if (current->journal_info == trans)
1707                current->journal_info = NULL;
1708
1709        kmem_cache_free(btrfs_trans_handle_cachep, trans);
1710
1711        if (current != root->fs_info->transaction_kthread)
1712                btrfs_run_delayed_iputs(root);
1713
1714        return ret;
1715
1716cleanup_transaction:
1717        btrfs_trans_release_metadata(trans, root);
1718        trans->block_rsv = NULL;
1719        btrfs_printk(root->fs_info, "Skipping commit of aborted transaction.\n");
1720//      WARN_ON(1);
1721        if (current->journal_info == trans)
1722                current->journal_info = NULL;
1723        cleanup_transaction(trans, root, ret);
1724
1725        return ret;
1726}
1727
1728/*
1729 * interface function to delete all the snapshots we have scheduled for deletion
1730 */
1731int btrfs_clean_old_snapshots(struct btrfs_root *root)
1732{
1733        LIST_HEAD(list);
1734        struct btrfs_fs_info *fs_info = root->fs_info;
1735
1736        spin_lock(&fs_info->trans_lock);
1737        list_splice_init(&fs_info->dead_roots, &list);
1738        spin_unlock(&fs_info->trans_lock);
1739
1740        while (!list_empty(&list)) {
1741                int ret;
1742
1743                root = list_entry(list.next, struct btrfs_root, root_list);
1744                list_del(&root->root_list);
1745
1746                btrfs_kill_all_delayed_nodes(root);
1747
1748                if (btrfs_header_backref_rev(root->node) <
1749                    BTRFS_MIXED_BACKREF_REV)
1750                        ret = btrfs_drop_snapshot(root, NULL, 0, 0);
1751                else
1752                        ret =btrfs_drop_snapshot(root, NULL, 1, 0);
1753                BUG_ON(ret < 0);
1754        }
1755        return 0;
1756}
1757
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