diff options
Diffstat (limited to 'fs/btrfs/transaction.c')
| -rw-r--r-- | fs/btrfs/transaction.c | 2649 |
1 files changed, 2649 insertions, 0 deletions
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c new file mode 100644 index 000000000..60db4c3b8 --- /dev/null +++ b/fs/btrfs/transaction.c @@ -0,0 +1,2649 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2007 Oracle. All rights reserved. + */ + +#include <linux/fs.h> +#include <linux/slab.h> +#include <linux/sched.h> +#include <linux/sched/mm.h> +#include <linux/writeback.h> +#include <linux/pagemap.h> +#include <linux/blkdev.h> +#include <linux/uuid.h> +#include <linux/timekeeping.h> +#include "misc.h" +#include "ctree.h" +#include "disk-io.h" +#include "transaction.h" +#include "locking.h" +#include "tree-log.h" +#include "volumes.h" +#include "dev-replace.h" +#include "qgroup.h" +#include "block-group.h" +#include "space-info.h" +#include "zoned.h" + +#define BTRFS_ROOT_TRANS_TAG 0 + +/* + * Transaction states and transitions + * + * No running transaction (fs tree blocks are not modified) + * | + * | To next stage: + * | Call start_transaction() variants. Except btrfs_join_transaction_nostart(). + * V + * Transaction N [[TRANS_STATE_RUNNING]] + * | + * | New trans handles can be attached to transaction N by calling all + * | start_transaction() variants. + * | + * | To next stage: + * | Call btrfs_commit_transaction() on any trans handle attached to + * | transaction N + * V + * Transaction N [[TRANS_STATE_COMMIT_START]] + * | + * | Will wait for previous running transaction to completely finish if there + * | is one + * | + * | Then one of the following happes: + * | - Wait for all other trans handle holders to release. + * | The btrfs_commit_transaction() caller will do the commit work. + * | - Wait for current transaction to be committed by others. + * | Other btrfs_commit_transaction() caller will do the commit work. + * | + * | At this stage, only btrfs_join_transaction*() variants can attach + * | to this running transaction. + * | All other variants will wait for current one to finish and attach to + * | transaction N+1. + * | + * | To next stage: + * | Caller is chosen to commit transaction N, and all other trans handle + * | haven been released. + * V + * Transaction N [[TRANS_STATE_COMMIT_DOING]] + * | + * | The heavy lifting transaction work is started. + * | From running delayed refs (modifying extent tree) to creating pending + * | snapshots, running qgroups. + * | In short, modify supporting trees to reflect modifications of subvolume + * | trees. + * | + * | At this stage, all start_transaction() calls will wait for this + * | transaction to finish and attach to transaction N+1. + * | + * | To next stage: + * | Until all supporting trees are updated. + * V + * Transaction N [[TRANS_STATE_UNBLOCKED]] + * | Transaction N+1 + * | All needed trees are modified, thus we only [[TRANS_STATE_RUNNING]] + * | need to write them back to disk and update | + * | super blocks. | + * | | + * | At this stage, new transaction is allowed to | + * | start. | + * | All new start_transaction() calls will be | + * | attached to transid N+1. | + * | | + * | To next stage: | + * | Until all tree blocks are super blocks are | + * | written to block devices | + * V | + * Transaction N [[TRANS_STATE_COMPLETED]] V + * All tree blocks and super blocks are written. Transaction N+1 + * This transaction is finished and all its [[TRANS_STATE_COMMIT_START]] + * data structures will be cleaned up. | Life goes on + */ +static const unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = { + [TRANS_STATE_RUNNING] = 0U, + [TRANS_STATE_COMMIT_START] = (__TRANS_START | __TRANS_ATTACH), + [TRANS_STATE_COMMIT_DOING] = (__TRANS_START | + __TRANS_ATTACH | + __TRANS_JOIN | + __TRANS_JOIN_NOSTART), + [TRANS_STATE_UNBLOCKED] = (__TRANS_START | + __TRANS_ATTACH | + __TRANS_JOIN | + __TRANS_JOIN_NOLOCK | + __TRANS_JOIN_NOSTART), + [TRANS_STATE_SUPER_COMMITTED] = (__TRANS_START | + __TRANS_ATTACH | + __TRANS_JOIN | + __TRANS_JOIN_NOLOCK | + __TRANS_JOIN_NOSTART), + [TRANS_STATE_COMPLETED] = (__TRANS_START | + __TRANS_ATTACH | + __TRANS_JOIN | + __TRANS_JOIN_NOLOCK | + __TRANS_JOIN_NOSTART), +}; + +void btrfs_put_transaction(struct btrfs_transaction *transaction) +{ + WARN_ON(refcount_read(&transaction->use_count) == 0); + if (refcount_dec_and_test(&transaction->use_count)) { + BUG_ON(!list_empty(&transaction->list)); + WARN_ON(!RB_EMPTY_ROOT( + &transaction->delayed_refs.href_root.rb_root)); + WARN_ON(!RB_EMPTY_ROOT( + &transaction->delayed_refs.dirty_extent_root)); + if (transaction->delayed_refs.pending_csums) + btrfs_err(transaction->fs_info, + "pending csums is %llu", + transaction->delayed_refs.pending_csums); + /* + * If any block groups are found in ->deleted_bgs then it's + * because the transaction was aborted and a commit did not + * happen (things failed before writing the new superblock + * and calling btrfs_finish_extent_commit()), so we can not + * discard the physical locations of the block groups. + */ + while (!list_empty(&transaction->deleted_bgs)) { + struct btrfs_block_group *cache; + + cache = list_first_entry(&transaction->deleted_bgs, + struct btrfs_block_group, + bg_list); + list_del_init(&cache->bg_list); + btrfs_unfreeze_block_group(cache); + btrfs_put_block_group(cache); + } + WARN_ON(!list_empty(&transaction->dev_update_list)); + kfree(transaction); + } +} + +static noinline void switch_commit_roots(struct btrfs_trans_handle *trans) +{ + struct btrfs_transaction *cur_trans = trans->transaction; + struct btrfs_fs_info *fs_info = trans->fs_info; + struct btrfs_root *root, *tmp; + + /* + * At this point no one can be using this transaction to modify any tree + * and no one can start another transaction to modify any tree either. + */ + ASSERT(cur_trans->state == TRANS_STATE_COMMIT_DOING); + + down_write(&fs_info->commit_root_sem); + + if (test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags)) + fs_info->last_reloc_trans = trans->transid; + + list_for_each_entry_safe(root, tmp, &cur_trans->switch_commits, + dirty_list) { + list_del_init(&root->dirty_list); + free_extent_buffer(root->commit_root); + root->commit_root = btrfs_root_node(root); + extent_io_tree_release(&root->dirty_log_pages); + btrfs_qgroup_clean_swapped_blocks(root); + } + + /* We can free old roots now. */ + spin_lock(&cur_trans->dropped_roots_lock); + while (!list_empty(&cur_trans->dropped_roots)) { + root = list_first_entry(&cur_trans->dropped_roots, + struct btrfs_root, root_list); + list_del_init(&root->root_list); + spin_unlock(&cur_trans->dropped_roots_lock); + btrfs_free_log(trans, root); + btrfs_drop_and_free_fs_root(fs_info, root); + spin_lock(&cur_trans->dropped_roots_lock); + } + spin_unlock(&cur_trans->dropped_roots_lock); + + up_write(&fs_info->commit_root_sem); +} + +static inline void extwriter_counter_inc(struct btrfs_transaction *trans, + unsigned int type) +{ + if (type & TRANS_EXTWRITERS) + atomic_inc(&trans->num_extwriters); +} + +static inline void extwriter_counter_dec(struct btrfs_transaction *trans, + unsigned int type) +{ + if (type & TRANS_EXTWRITERS) + atomic_dec(&trans->num_extwriters); +} + +static inline void extwriter_counter_init(struct btrfs_transaction *trans, + unsigned int type) +{ + atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0)); +} + +static inline int extwriter_counter_read(struct btrfs_transaction *trans) +{ + return atomic_read(&trans->num_extwriters); +} + +/* + * To be called after doing the chunk btree updates right after allocating a new + * chunk (after btrfs_chunk_alloc_add_chunk_item() is called), when removing a + * chunk after all chunk btree updates and after finishing the second phase of + * chunk allocation (btrfs_create_pending_block_groups()) in case some block + * group had its chunk item insertion delayed to the second phase. + */ +void btrfs_trans_release_chunk_metadata(struct btrfs_trans_handle *trans) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + + if (!trans->chunk_bytes_reserved) + return; + + btrfs_block_rsv_release(fs_info, &fs_info->chunk_block_rsv, + trans->chunk_bytes_reserved, NULL); + trans->chunk_bytes_reserved = 0; +} + +/* + * either allocate a new transaction or hop into the existing one + */ +static noinline int join_transaction(struct btrfs_fs_info *fs_info, + unsigned int type) +{ + struct btrfs_transaction *cur_trans; + + spin_lock(&fs_info->trans_lock); +loop: + /* The file system has been taken offline. No new transactions. */ + if (BTRFS_FS_ERROR(fs_info)) { + spin_unlock(&fs_info->trans_lock); + return -EROFS; + } + + cur_trans = fs_info->running_transaction; + if (cur_trans) { + if (TRANS_ABORTED(cur_trans)) { + spin_unlock(&fs_info->trans_lock); + return cur_trans->aborted; + } + if (btrfs_blocked_trans_types[cur_trans->state] & type) { + spin_unlock(&fs_info->trans_lock); + return -EBUSY; + } + refcount_inc(&cur_trans->use_count); + atomic_inc(&cur_trans->num_writers); + extwriter_counter_inc(cur_trans, type); + spin_unlock(&fs_info->trans_lock); + btrfs_lockdep_acquire(fs_info, btrfs_trans_num_writers); + btrfs_lockdep_acquire(fs_info, btrfs_trans_num_extwriters); + return 0; + } + spin_unlock(&fs_info->trans_lock); + + /* + * If we are ATTACH or TRANS_JOIN_NOSTART, we just want to catch the + * current transaction, and commit it. If there is no transaction, just + * return ENOENT. + */ + if (type == TRANS_ATTACH || type == TRANS_JOIN_NOSTART) + return -ENOENT; + + /* + * JOIN_NOLOCK only happens during the transaction commit, so + * it is impossible that ->running_transaction is NULL + */ + BUG_ON(type == TRANS_JOIN_NOLOCK); + + cur_trans = kmalloc(sizeof(*cur_trans), GFP_NOFS); + if (!cur_trans) + return -ENOMEM; + + btrfs_lockdep_acquire(fs_info, btrfs_trans_num_writers); + btrfs_lockdep_acquire(fs_info, btrfs_trans_num_extwriters); + + spin_lock(&fs_info->trans_lock); + if (fs_info->running_transaction) { + /* + * someone started a transaction after we unlocked. Make sure + * to redo the checks above + */ + btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters); + btrfs_lockdep_release(fs_info, btrfs_trans_num_writers); + kfree(cur_trans); + goto loop; + } else if (BTRFS_FS_ERROR(fs_info)) { + spin_unlock(&fs_info->trans_lock); + btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters); + btrfs_lockdep_release(fs_info, btrfs_trans_num_writers); + kfree(cur_trans); + return -EROFS; + } + + cur_trans->fs_info = fs_info; + atomic_set(&cur_trans->pending_ordered, 0); + init_waitqueue_head(&cur_trans->pending_wait); + atomic_set(&cur_trans->num_writers, 1); + extwriter_counter_init(cur_trans, type); + init_waitqueue_head(&cur_trans->writer_wait); + init_waitqueue_head(&cur_trans->commit_wait); + cur_trans->state = TRANS_STATE_RUNNING; + /* + * One for this trans handle, one so it will live on until we + * commit the transaction. + */ + refcount_set(&cur_trans->use_count, 2); + cur_trans->flags = 0; + cur_trans->start_time = ktime_get_seconds(); + + memset(&cur_trans->delayed_refs, 0, sizeof(cur_trans->delayed_refs)); + + cur_trans->delayed_refs.href_root = RB_ROOT_CACHED; + cur_trans->delayed_refs.dirty_extent_root = RB_ROOT; + atomic_set(&cur_trans->delayed_refs.num_entries, 0); + + /* + * although the tree mod log is per file system and not per transaction, + * the log must never go across transaction boundaries. + */ + smp_mb(); + if (!list_empty(&fs_info->tree_mod_seq_list)) + WARN(1, KERN_ERR "BTRFS: tree_mod_seq_list not empty when creating a fresh transaction\n"); + if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log)) + WARN(1, KERN_ERR "BTRFS: tree_mod_log rb tree not empty when creating a fresh transaction\n"); + atomic64_set(&fs_info->tree_mod_seq, 0); + + spin_lock_init(&cur_trans->delayed_refs.lock); + + INIT_LIST_HEAD(&cur_trans->pending_snapshots); + INIT_LIST_HEAD(&cur_trans->dev_update_list); + INIT_LIST_HEAD(&cur_trans->switch_commits); + INIT_LIST_HEAD(&cur_trans->dirty_bgs); + INIT_LIST_HEAD(&cur_trans->io_bgs); + INIT_LIST_HEAD(&cur_trans->dropped_roots); + mutex_init(&cur_trans->cache_write_mutex); + spin_lock_init(&cur_trans->dirty_bgs_lock); + INIT_LIST_HEAD(&cur_trans->deleted_bgs); + spin_lock_init(&cur_trans->dropped_roots_lock); + INIT_LIST_HEAD(&cur_trans->releasing_ebs); + spin_lock_init(&cur_trans->releasing_ebs_lock); + list_add_tail(&cur_trans->list, &fs_info->trans_list); + extent_io_tree_init(fs_info, &cur_trans->dirty_pages, + IO_TREE_TRANS_DIRTY_PAGES, NULL); + extent_io_tree_init(fs_info, &cur_trans->pinned_extents, + IO_TREE_FS_PINNED_EXTENTS, NULL); + fs_info->generation++; + cur_trans->transid = fs_info->generation; + fs_info->running_transaction = cur_trans; + cur_trans->aborted = 0; + spin_unlock(&fs_info->trans_lock); + + return 0; +} + +/* + * This does all the record keeping required to make sure that a shareable root + * is properly recorded in a given transaction. This is required to make sure + * the old root from before we joined the transaction is deleted when the + * transaction commits. + */ +static int record_root_in_trans(struct btrfs_trans_handle *trans, + struct btrfs_root *root, + int force) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + int ret = 0; + + if ((test_bit(BTRFS_ROOT_SHAREABLE, &root->state) && + root->last_trans < trans->transid) || force) { + WARN_ON(!force && root->commit_root != root->node); + + /* + * see below for IN_TRANS_SETUP usage rules + * we have the reloc mutex held now, so there + * is only one writer in this function + */ + set_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state); + + /* make sure readers find IN_TRANS_SETUP before + * they find our root->last_trans update + */ + smp_wmb(); + + spin_lock(&fs_info->fs_roots_radix_lock); + if (root->last_trans == trans->transid && !force) { + spin_unlock(&fs_info->fs_roots_radix_lock); + return 0; + } + radix_tree_tag_set(&fs_info->fs_roots_radix, + (unsigned long)root->root_key.objectid, + BTRFS_ROOT_TRANS_TAG); + spin_unlock(&fs_info->fs_roots_radix_lock); + root->last_trans = trans->transid; + + /* this is pretty tricky. We don't want to + * take the relocation lock in btrfs_record_root_in_trans + * unless we're really doing the first setup for this root in + * this transaction. + * + * Normally we'd use root->last_trans as a flag to decide + * if we want to take the expensive mutex. + * + * But, we have to set root->last_trans before we + * init the relocation root, otherwise, we trip over warnings + * in ctree.c. The solution used here is to flag ourselves + * with root IN_TRANS_SETUP. When this is 1, we're still + * fixing up the reloc trees and everyone must wait. + * + * When this is zero, they can trust root->last_trans and fly + * through btrfs_record_root_in_trans without having to take the + * lock. smp_wmb() makes sure that all the writes above are + * done before we pop in the zero below + */ + ret = btrfs_init_reloc_root(trans, root); + smp_mb__before_atomic(); + clear_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state); + } + return ret; +} + + +void btrfs_add_dropped_root(struct btrfs_trans_handle *trans, + struct btrfs_root *root) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + struct btrfs_transaction *cur_trans = trans->transaction; + + /* Add ourselves to the transaction dropped list */ + spin_lock(&cur_trans->dropped_roots_lock); + list_add_tail(&root->root_list, &cur_trans->dropped_roots); + spin_unlock(&cur_trans->dropped_roots_lock); + + /* Make sure we don't try to update the root at commit time */ + spin_lock(&fs_info->fs_roots_radix_lock); + radix_tree_tag_clear(&fs_info->fs_roots_radix, + (unsigned long)root->root_key.objectid, + BTRFS_ROOT_TRANS_TAG); + spin_unlock(&fs_info->fs_roots_radix_lock); +} + +int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans, + struct btrfs_root *root) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + int ret; + + if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state)) + return 0; + + /* + * see record_root_in_trans for comments about IN_TRANS_SETUP usage + * and barriers + */ + smp_rmb(); + if (root->last_trans == trans->transid && + !test_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state)) + return 0; + + mutex_lock(&fs_info->reloc_mutex); + ret = record_root_in_trans(trans, root, 0); + mutex_unlock(&fs_info->reloc_mutex); + + return ret; +} + +static inline int is_transaction_blocked(struct btrfs_transaction *trans) +{ + return (trans->state >= TRANS_STATE_COMMIT_START && + trans->state < TRANS_STATE_UNBLOCKED && + !TRANS_ABORTED(trans)); +} + +/* wait for commit against the current transaction to become unblocked + * when this is done, it is safe to start a new transaction, but the current + * transaction might not be fully on disk. + */ +static void wait_current_trans(struct btrfs_fs_info *fs_info) +{ + struct btrfs_transaction *cur_trans; + + spin_lock(&fs_info->trans_lock); + cur_trans = fs_info->running_transaction; + if (cur_trans && is_transaction_blocked(cur_trans)) { + refcount_inc(&cur_trans->use_count); + spin_unlock(&fs_info->trans_lock); + + btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED); + wait_event(fs_info->transaction_wait, + cur_trans->state >= TRANS_STATE_UNBLOCKED || + TRANS_ABORTED(cur_trans)); + btrfs_put_transaction(cur_trans); + } else { + spin_unlock(&fs_info->trans_lock); + } +} + +static int may_wait_transaction(struct btrfs_fs_info *fs_info, int type) +{ + if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags)) + return 0; + + if (type == TRANS_START) + return 1; + + return 0; +} + +static inline bool need_reserve_reloc_root(struct btrfs_root *root) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + + if (!fs_info->reloc_ctl || + !test_bit(BTRFS_ROOT_SHAREABLE, &root->state) || + root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID || + root->reloc_root) + return false; + + return true; +} + +static struct btrfs_trans_handle * +start_transaction(struct btrfs_root *root, unsigned int num_items, + unsigned int type, enum btrfs_reserve_flush_enum flush, + bool enforce_qgroups) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv; + struct btrfs_trans_handle *h; + struct btrfs_transaction *cur_trans; + u64 num_bytes = 0; + u64 qgroup_reserved = 0; + bool reloc_reserved = false; + bool do_chunk_alloc = false; + int ret; + + if (BTRFS_FS_ERROR(fs_info)) + return ERR_PTR(-EROFS); + + if (current->journal_info) { + WARN_ON(type & TRANS_EXTWRITERS); + h = current->journal_info; + refcount_inc(&h->use_count); + WARN_ON(refcount_read(&h->use_count) > 2); + h->orig_rsv = h->block_rsv; + h->block_rsv = NULL; + goto got_it; + } + + /* + * Do the reservation before we join the transaction so we can do all + * the appropriate flushing if need be. + */ + if (num_items && root != fs_info->chunk_root) { + struct btrfs_block_rsv *rsv = &fs_info->trans_block_rsv; + u64 delayed_refs_bytes = 0; + + qgroup_reserved = num_items * fs_info->nodesize; + /* + * Use prealloc for now, as there might be a currently running + * transaction that could free this reserved space prematurely + * by committing. + */ + ret = btrfs_qgroup_reserve_meta_prealloc(root, qgroup_reserved, + enforce_qgroups, false); + if (ret) + return ERR_PTR(ret); + + /* + * We want to reserve all the bytes we may need all at once, so + * we only do 1 enospc flushing cycle per transaction start. We + * accomplish this by simply assuming we'll do 2 x num_items + * worth of delayed refs updates in this trans handle, and + * refill that amount for whatever is missing in the reserve. + */ + num_bytes = btrfs_calc_insert_metadata_size(fs_info, num_items); + if (flush == BTRFS_RESERVE_FLUSH_ALL && + btrfs_block_rsv_full(delayed_refs_rsv) == 0) { + delayed_refs_bytes = num_bytes; + num_bytes <<= 1; + } + + /* + * Do the reservation for the relocation root creation + */ + if (need_reserve_reloc_root(root)) { + num_bytes += fs_info->nodesize; + reloc_reserved = true; + } + + ret = btrfs_reserve_metadata_bytes(fs_info, rsv, num_bytes, flush); + if (ret) + goto reserve_fail; + if (delayed_refs_bytes) { + btrfs_migrate_to_delayed_refs_rsv(fs_info, delayed_refs_bytes); + num_bytes -= delayed_refs_bytes; + } + btrfs_block_rsv_add_bytes(rsv, num_bytes, true); + + if (rsv->space_info->force_alloc) + do_chunk_alloc = true; + } else if (num_items == 0 && flush == BTRFS_RESERVE_FLUSH_ALL && + !btrfs_block_rsv_full(delayed_refs_rsv)) { + /* + * Some people call with btrfs_start_transaction(root, 0) + * because they can be throttled, but have some other mechanism + * for reserving space. We still want these guys to refill the + * delayed block_rsv so just add 1 items worth of reservation + * here. + */ + ret = btrfs_delayed_refs_rsv_refill(fs_info, flush); + if (ret) + goto reserve_fail; + } +again: + h = kmem_cache_zalloc(btrfs_trans_handle_cachep, GFP_NOFS); + if (!h) { + ret = -ENOMEM; + goto alloc_fail; + } + + /* + * If we are JOIN_NOLOCK we're already committing a transaction and + * waiting on this guy, so we don't need to do the sb_start_intwrite + * because we're already holding a ref. We need this because we could + * have raced in and did an fsync() on a file which can kick a commit + * and then we deadlock with somebody doing a freeze. + * + * If we are ATTACH, it means we just want to catch the current + * transaction and commit it, so we needn't do sb_start_intwrite(). + */ + if (type & __TRANS_FREEZABLE) + sb_start_intwrite(fs_info->sb); + + if (may_wait_transaction(fs_info, type)) + wait_current_trans(fs_info); + + do { + ret = join_transaction(fs_info, type); + if (ret == -EBUSY) { + wait_current_trans(fs_info); + if (unlikely(type == TRANS_ATTACH || + type == TRANS_JOIN_NOSTART)) + ret = -ENOENT; + } + } while (ret == -EBUSY); + + if (ret < 0) + goto join_fail; + + cur_trans = fs_info->running_transaction; + + h->transid = cur_trans->transid; + h->transaction = cur_trans; + refcount_set(&h->use_count, 1); + h->fs_info = root->fs_info; + + h->type = type; + INIT_LIST_HEAD(&h->new_bgs); + + smp_mb(); + if (cur_trans->state >= TRANS_STATE_COMMIT_START && + may_wait_transaction(fs_info, type)) { + current->journal_info = h; + btrfs_commit_transaction(h); + goto again; + } + + if (num_bytes) { + trace_btrfs_space_reservation(fs_info, "transaction", + h->transid, num_bytes, 1); + h->block_rsv = &fs_info->trans_block_rsv; + h->bytes_reserved = num_bytes; + h->reloc_reserved = reloc_reserved; + } + + /* + * Now that we have found a transaction to be a part of, convert the + * qgroup reservation from prealloc to pertrans. A different transaction + * can't race in and free our pertrans out from under us. + */ + if (qgroup_reserved) + btrfs_qgroup_convert_reserved_meta(root, qgroup_reserved); + +got_it: + if (!current->journal_info) + current->journal_info = h; + + /* + * If the space_info is marked ALLOC_FORCE then we'll get upgraded to + * ALLOC_FORCE the first run through, and then we won't allocate for + * anybody else who races in later. We don't care about the return + * value here. + */ + if (do_chunk_alloc && num_bytes) { + u64 flags = h->block_rsv->space_info->flags; + + btrfs_chunk_alloc(h, btrfs_get_alloc_profile(fs_info, flags), + CHUNK_ALLOC_NO_FORCE); + } + + /* + * btrfs_record_root_in_trans() needs to alloc new extents, and may + * call btrfs_join_transaction() while we're also starting a + * transaction. + * + * Thus it need to be called after current->journal_info initialized, + * or we can deadlock. + */ + ret = btrfs_record_root_in_trans(h, root); + if (ret) { + /* + * The transaction handle is fully initialized and linked with + * other structures so it needs to be ended in case of errors, + * not just freed. + */ + btrfs_end_transaction(h); + return ERR_PTR(ret); + } + + return h; + +join_fail: + if (type & __TRANS_FREEZABLE) + sb_end_intwrite(fs_info->sb); + kmem_cache_free(btrfs_trans_handle_cachep, h); +alloc_fail: + if (num_bytes) + btrfs_block_rsv_release(fs_info, &fs_info->trans_block_rsv, + num_bytes, NULL); +reserve_fail: + btrfs_qgroup_free_meta_prealloc(root, qgroup_reserved); + return ERR_PTR(ret); +} + +struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root, + unsigned int num_items) +{ + return start_transaction(root, num_items, TRANS_START, + BTRFS_RESERVE_FLUSH_ALL, true); +} + +struct btrfs_trans_handle *btrfs_start_transaction_fallback_global_rsv( + struct btrfs_root *root, + unsigned int num_items) +{ + return start_transaction(root, num_items, TRANS_START, + BTRFS_RESERVE_FLUSH_ALL_STEAL, false); +} + +struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root) +{ + return start_transaction(root, 0, TRANS_JOIN, BTRFS_RESERVE_NO_FLUSH, + true); +} + +struct btrfs_trans_handle *btrfs_join_transaction_spacecache(struct btrfs_root *root) +{ + return start_transaction(root, 0, TRANS_JOIN_NOLOCK, + BTRFS_RESERVE_NO_FLUSH, true); +} + +/* + * Similar to regular join but it never starts a transaction when none is + * running or after waiting for the current one to finish. + */ +struct btrfs_trans_handle *btrfs_join_transaction_nostart(struct btrfs_root *root) +{ + return start_transaction(root, 0, TRANS_JOIN_NOSTART, + BTRFS_RESERVE_NO_FLUSH, true); +} + +/* + * btrfs_attach_transaction() - catch the running transaction + * + * It is used when we want to commit the current the transaction, but + * don't want to start a new one. + * + * Note: If this function return -ENOENT, it just means there is no + * running transaction. But it is possible that the inactive transaction + * is still in the memory, not fully on disk. If you hope there is no + * inactive transaction in the fs when -ENOENT is returned, you should + * invoke + * btrfs_attach_transaction_barrier() + */ +struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root) +{ + return start_transaction(root, 0, TRANS_ATTACH, + BTRFS_RESERVE_NO_FLUSH, true); +} + +/* + * btrfs_attach_transaction_barrier() - catch the running transaction + * + * It is similar to the above function, the difference is this one + * will wait for all the inactive transactions until they fully + * complete. + */ +struct btrfs_trans_handle * +btrfs_attach_transaction_barrier(struct btrfs_root *root) +{ + struct btrfs_trans_handle *trans; + + trans = start_transaction(root, 0, TRANS_ATTACH, + BTRFS_RESERVE_NO_FLUSH, true); + if (trans == ERR_PTR(-ENOENT)) { + int ret; + + ret = btrfs_wait_for_commit(root->fs_info, 0); + if (ret) + return ERR_PTR(ret); + } + + return trans; +} + +/* Wait for a transaction commit to reach at least the given state. */ +static noinline void wait_for_commit(struct btrfs_transaction *commit, + const enum btrfs_trans_state min_state) +{ + struct btrfs_fs_info *fs_info = commit->fs_info; + u64 transid = commit->transid; + bool put = false; + + /* + * At the moment this function is called with min_state either being + * TRANS_STATE_COMPLETED or TRANS_STATE_SUPER_COMMITTED. + */ + if (min_state == TRANS_STATE_COMPLETED) + btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED); + else + btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED); + + while (1) { + wait_event(commit->commit_wait, commit->state >= min_state); + if (put) + btrfs_put_transaction(commit); + + if (min_state < TRANS_STATE_COMPLETED) + break; + + /* + * A transaction isn't really completed until all of the + * previous transactions are completed, but with fsync we can + * end up with SUPER_COMMITTED transactions before a COMPLETED + * transaction. Wait for those. + */ + + spin_lock(&fs_info->trans_lock); + commit = list_first_entry_or_null(&fs_info->trans_list, + struct btrfs_transaction, + list); + if (!commit || commit->transid > transid) { + spin_unlock(&fs_info->trans_lock); + break; + } + refcount_inc(&commit->use_count); + put = true; + spin_unlock(&fs_info->trans_lock); + } +} + +int btrfs_wait_for_commit(struct btrfs_fs_info *fs_info, u64 transid) +{ + struct btrfs_transaction *cur_trans = NULL, *t; + int ret = 0; + + if (transid) { + if (transid <= fs_info->last_trans_committed) + goto out; + + /* find specified transaction */ + spin_lock(&fs_info->trans_lock); + list_for_each_entry(t, &fs_info->trans_list, list) { + if (t->transid == transid) { + cur_trans = t; + refcount_inc(&cur_trans->use_count); + ret = 0; + break; + } + if (t->transid > transid) { + ret = 0; + break; + } + } + spin_unlock(&fs_info->trans_lock); + + /* + * The specified transaction doesn't exist, or we + * raced with btrfs_commit_transaction + */ + if (!cur_trans) { + if (transid > fs_info->last_trans_committed) + ret = -EINVAL; + goto out; + } + } else { + /* find newest transaction that is committing | committed */ + spin_lock(&fs_info->trans_lock); + list_for_each_entry_reverse(t, &fs_info->trans_list, + list) { + if (t->state >= TRANS_STATE_COMMIT_START) { + if (t->state == TRANS_STATE_COMPLETED) + break; + cur_trans = t; + refcount_inc(&cur_trans->use_count); + break; + } + } + spin_unlock(&fs_info->trans_lock); + if (!cur_trans) + goto out; /* nothing committing|committed */ + } + + wait_for_commit(cur_trans, TRANS_STATE_COMPLETED); + ret = cur_trans->aborted; + btrfs_put_transaction(cur_trans); +out: + return ret; +} + +void btrfs_throttle(struct btrfs_fs_info *fs_info) +{ + wait_current_trans(fs_info); +} + +static bool should_end_transaction(struct btrfs_trans_handle *trans) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + + if (btrfs_check_space_for_delayed_refs(fs_info)) + return true; + + return !!btrfs_block_rsv_check(&fs_info->global_block_rsv, 5); +} + +bool btrfs_should_end_transaction(struct btrfs_trans_handle *trans) +{ + struct btrfs_transaction *cur_trans = trans->transaction; + + if (cur_trans->state >= TRANS_STATE_COMMIT_START || + test_bit(BTRFS_DELAYED_REFS_FLUSHING, &cur_trans->delayed_refs.flags)) + return true; + + return should_end_transaction(trans); +} + +static void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans) + +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + + if (!trans->block_rsv) { + ASSERT(!trans->bytes_reserved); + return; + } + + if (!trans->bytes_reserved) + return; + + ASSERT(trans->block_rsv == &fs_info->trans_block_rsv); + trace_btrfs_space_reservation(fs_info, "transaction", + trans->transid, trans->bytes_reserved, 0); + btrfs_block_rsv_release(fs_info, trans->block_rsv, + trans->bytes_reserved, NULL); + trans->bytes_reserved = 0; +} + +static int __btrfs_end_transaction(struct btrfs_trans_handle *trans, + int throttle) +{ + struct btrfs_fs_info *info = trans->fs_info; + struct btrfs_transaction *cur_trans = trans->transaction; + int err = 0; + + if (refcount_read(&trans->use_count) > 1) { + refcount_dec(&trans->use_count); + trans->block_rsv = trans->orig_rsv; + return 0; + } + + btrfs_trans_release_metadata(trans); + trans->block_rsv = NULL; + + btrfs_create_pending_block_groups(trans); + + btrfs_trans_release_chunk_metadata(trans); + + if (trans->type & __TRANS_FREEZABLE) + sb_end_intwrite(info->sb); + + WARN_ON(cur_trans != info->running_transaction); + WARN_ON(atomic_read(&cur_trans->num_writers) < 1); + atomic_dec(&cur_trans->num_writers); + extwriter_counter_dec(cur_trans, trans->type); + + cond_wake_up(&cur_trans->writer_wait); + + btrfs_lockdep_release(info, btrfs_trans_num_extwriters); + btrfs_lockdep_release(info, btrfs_trans_num_writers); + + btrfs_put_transaction(cur_trans); + + if (current->journal_info == trans) + current->journal_info = NULL; + + if (throttle) + btrfs_run_delayed_iputs(info); + + if (TRANS_ABORTED(trans) || BTRFS_FS_ERROR(info)) { + wake_up_process(info->transaction_kthread); + if (TRANS_ABORTED(trans)) + err = trans->aborted; + else + err = -EROFS; + } + + kmem_cache_free(btrfs_trans_handle_cachep, trans); + return err; +} + +int btrfs_end_transaction(struct btrfs_trans_handle *trans) +{ + return __btrfs_end_transaction(trans, 0); +} + +int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans) +{ + return __btrfs_end_transaction(trans, 1); +} + +/* + * when btree blocks are allocated, they have some corresponding bits set for + * them in one of two extent_io trees. This is used to make sure all of + * those extents are sent to disk but does not wait on them + */ +int btrfs_write_marked_extents(struct btrfs_fs_info *fs_info, + struct extent_io_tree *dirty_pages, int mark) +{ + int err = 0; + int werr = 0; + struct address_space *mapping = fs_info->btree_inode->i_mapping; + struct extent_state *cached_state = NULL; + u64 start = 0; + u64 end; + + atomic_inc(&BTRFS_I(fs_info->btree_inode)->sync_writers); + while (!find_first_extent_bit(dirty_pages, start, &start, &end, + mark, &cached_state)) { + bool wait_writeback = false; + + err = convert_extent_bit(dirty_pages, start, end, + EXTENT_NEED_WAIT, + mark, &cached_state); + /* + * convert_extent_bit can return -ENOMEM, which is most of the + * time a temporary error. So when it happens, ignore the error + * and wait for writeback of this range to finish - because we + * failed to set the bit EXTENT_NEED_WAIT for the range, a call + * to __btrfs_wait_marked_extents() would not know that + * writeback for this range started and therefore wouldn't + * wait for it to finish - we don't want to commit a + * superblock that points to btree nodes/leafs for which + * writeback hasn't finished yet (and without errors). + * We cleanup any entries left in the io tree when committing + * the transaction (through extent_io_tree_release()). + */ + if (err == -ENOMEM) { + err = 0; + wait_writeback = true; + } + if (!err) + err = filemap_fdatawrite_range(mapping, start, end); + if (err) + werr = err; + else if (wait_writeback) + werr = filemap_fdatawait_range(mapping, start, end); + free_extent_state(cached_state); + cached_state = NULL; + cond_resched(); + start = end + 1; + } + atomic_dec(&BTRFS_I(fs_info->btree_inode)->sync_writers); + return werr; +} + +/* + * when btree blocks are allocated, they have some corresponding bits set for + * them in one of two extent_io trees. This is used to make sure all of + * those extents are on disk for transaction or log commit. We wait + * on all the pages and clear them from the dirty pages state tree + */ +static int __btrfs_wait_marked_extents(struct btrfs_fs_info *fs_info, + struct extent_io_tree *dirty_pages) +{ + int err = 0; + int werr = 0; + struct address_space *mapping = fs_info->btree_inode->i_mapping; + struct extent_state *cached_state = NULL; + u64 start = 0; + u64 end; + + while (!find_first_extent_bit(dirty_pages, start, &start, &end, + EXTENT_NEED_WAIT, &cached_state)) { + /* + * Ignore -ENOMEM errors returned by clear_extent_bit(). + * When committing the transaction, we'll remove any entries + * left in the io tree. For a log commit, we don't remove them + * after committing the log because the tree can be accessed + * concurrently - we do it only at transaction commit time when + * it's safe to do it (through extent_io_tree_release()). + */ + err = clear_extent_bit(dirty_pages, start, end, + EXTENT_NEED_WAIT, &cached_state); + if (err == -ENOMEM) + err = 0; + if (!err) + err = filemap_fdatawait_range(mapping, start, end); + if (err) + werr = err; + free_extent_state(cached_state); + cached_state = NULL; + cond_resched(); + start = end + 1; + } + if (err) + werr = err; + return werr; +} + +static int btrfs_wait_extents(struct btrfs_fs_info *fs_info, + struct extent_io_tree *dirty_pages) +{ + bool errors = false; + int err; + + err = __btrfs_wait_marked_extents(fs_info, dirty_pages); + if (test_and_clear_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags)) + errors = true; + + if (errors && !err) + err = -EIO; + return err; +} + +int btrfs_wait_tree_log_extents(struct btrfs_root *log_root, int mark) +{ + struct btrfs_fs_info *fs_info = log_root->fs_info; + struct extent_io_tree *dirty_pages = &log_root->dirty_log_pages; + bool errors = false; + int err; + + ASSERT(log_root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID); + + err = __btrfs_wait_marked_extents(fs_info, dirty_pages); + if ((mark & EXTENT_DIRTY) && + test_and_clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags)) + errors = true; + + if ((mark & EXTENT_NEW) && + test_and_clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags)) + errors = true; + + if (errors && !err) + err = -EIO; + return err; +} + +/* + * When btree blocks are allocated the corresponding extents are marked dirty. + * This function ensures such extents are persisted on disk for transaction or + * log commit. + * + * @trans: transaction whose dirty pages we'd like to write + */ +static int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans) +{ + int ret; + int ret2; + struct extent_io_tree *dirty_pages = &trans->transaction->dirty_pages; + struct btrfs_fs_info *fs_info = trans->fs_info; + struct blk_plug plug; + + blk_start_plug(&plug); + ret = btrfs_write_marked_extents(fs_info, dirty_pages, EXTENT_DIRTY); + blk_finish_plug(&plug); + ret2 = btrfs_wait_extents(fs_info, dirty_pages); + + extent_io_tree_release(&trans->transaction->dirty_pages); + + if (ret) + return ret; + else if (ret2) + return ret2; + else + return 0; +} + +/* + * this is used to update the root pointer in the tree of tree roots. + * + * But, in the case of the extent allocation tree, updating the root + * pointer may allocate blocks which may change the root of the extent + * allocation tree. + * + * So, this loops and repeats and makes sure the cowonly root didn't + * change while the root pointer was being updated in the metadata. + */ +static int update_cowonly_root(struct btrfs_trans_handle *trans, + struct btrfs_root *root) +{ + int ret; + u64 old_root_bytenr; + u64 old_root_used; + struct btrfs_fs_info *fs_info = root->fs_info; + struct btrfs_root *tree_root = fs_info->tree_root; + + old_root_used = btrfs_root_used(&root->root_item); + + while (1) { + old_root_bytenr = btrfs_root_bytenr(&root->root_item); + if (old_root_bytenr == root->node->start && + old_root_used == btrfs_root_used(&root->root_item)) + break; + + btrfs_set_root_node(&root->root_item, root->node); + ret = btrfs_update_root(trans, tree_root, + &root->root_key, + &root->root_item); + if (ret) + return ret; + + old_root_used = btrfs_root_used(&root->root_item); + } + + return 0; +} + +/* + * update all the cowonly tree roots on disk + * + * The error handling in this function may not be obvious. Any of the + * failures will cause the file system to go offline. We still need + * to clean up the delayed refs. + */ +static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + struct list_head *dirty_bgs = &trans->transaction->dirty_bgs; + struct list_head *io_bgs = &trans->transaction->io_bgs; + struct list_head *next; + struct extent_buffer *eb; + int ret; + + /* + * At this point no one can be using this transaction to modify any tree + * and no one can start another transaction to modify any tree either. + */ + ASSERT(trans->transaction->state == TRANS_STATE_COMMIT_DOING); + + eb = btrfs_lock_root_node(fs_info->tree_root); + ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, + 0, &eb, BTRFS_NESTING_COW); + btrfs_tree_unlock(eb); + free_extent_buffer(eb); + + if (ret) + return ret; + + ret = btrfs_run_dev_stats(trans); + if (ret) + return ret; + ret = btrfs_run_dev_replace(trans); + if (ret) + return ret; + ret = btrfs_run_qgroups(trans); + if (ret) + return ret; + + ret = btrfs_setup_space_cache(trans); + if (ret) + return ret; + +again: + while (!list_empty(&fs_info->dirty_cowonly_roots)) { + struct btrfs_root *root; + next = fs_info->dirty_cowonly_roots.next; + list_del_init(next); + root = list_entry(next, struct btrfs_root, dirty_list); + clear_bit(BTRFS_ROOT_DIRTY, &root->state); + + list_add_tail(&root->dirty_list, + &trans->transaction->switch_commits); + ret = update_cowonly_root(trans, root); + if (ret) + return ret; + } + + /* Now flush any delayed refs generated by updating all of the roots */ + ret = btrfs_run_delayed_refs(trans, (unsigned long)-1); + if (ret) + return ret; + + while (!list_empty(dirty_bgs) || !list_empty(io_bgs)) { + ret = btrfs_write_dirty_block_groups(trans); + if (ret) + return ret; + + /* + * We're writing the dirty block groups, which could generate + * delayed refs, which could generate more dirty block groups, + * so we want to keep this flushing in this loop to make sure + * everything gets run. + */ + ret = btrfs_run_delayed_refs(trans, (unsigned long)-1); + if (ret) + return ret; + } + + if (!list_empty(&fs_info->dirty_cowonly_roots)) + goto again; + + /* Update dev-replace pointer once everything is committed */ + fs_info->dev_replace.committed_cursor_left = + fs_info->dev_replace.cursor_left_last_write_of_item; + + return 0; +} + +/* + * If we had a pending drop we need to see if there are any others left in our + * dead roots list, and if not clear our bit and wake any waiters. + */ +void btrfs_maybe_wake_unfinished_drop(struct btrfs_fs_info *fs_info) +{ + /* + * We put the drop in progress roots at the front of the list, so if the + * first entry doesn't have UNFINISHED_DROP set we can wake everybody + * up. + */ + spin_lock(&fs_info->trans_lock); + if (!list_empty(&fs_info->dead_roots)) { + struct btrfs_root *root = list_first_entry(&fs_info->dead_roots, + struct btrfs_root, + root_list); + if (test_bit(BTRFS_ROOT_UNFINISHED_DROP, &root->state)) { + spin_unlock(&fs_info->trans_lock); + return; + } + } + spin_unlock(&fs_info->trans_lock); + + btrfs_wake_unfinished_drop(fs_info); +} + +/* + * dead roots are old snapshots that need to be deleted. This allocates + * a dirty root struct and adds it into the list of dead roots that need to + * be deleted + */ +void btrfs_add_dead_root(struct btrfs_root *root) +{ + struct btrfs_fs_info *fs_info = root->fs_info; + + spin_lock(&fs_info->trans_lock); + if (list_empty(&root->root_list)) { + btrfs_grab_root(root); + + /* We want to process the partially complete drops first. */ + if (test_bit(BTRFS_ROOT_UNFINISHED_DROP, &root->state)) + list_add(&root->root_list, &fs_info->dead_roots); + else + list_add_tail(&root->root_list, &fs_info->dead_roots); + } + spin_unlock(&fs_info->trans_lock); +} + +/* + * Update each subvolume root and its relocation root, if it exists, in the tree + * of tree roots. Also free log roots if they exist. + */ +static noinline int commit_fs_roots(struct btrfs_trans_handle *trans) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + struct btrfs_root *gang[8]; + int i; + int ret; + + /* + * At this point no one can be using this transaction to modify any tree + * and no one can start another transaction to modify any tree either. + */ + ASSERT(trans->transaction->state == TRANS_STATE_COMMIT_DOING); + + spin_lock(&fs_info->fs_roots_radix_lock); + while (1) { + ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix, + (void **)gang, 0, + ARRAY_SIZE(gang), + BTRFS_ROOT_TRANS_TAG); + if (ret == 0) + break; + for (i = 0; i < ret; i++) { + struct btrfs_root *root = gang[i]; + int ret2; + + /* + * At this point we can neither have tasks logging inodes + * from a root nor trying to commit a log tree. + */ + ASSERT(atomic_read(&root->log_writers) == 0); + ASSERT(atomic_read(&root->log_commit[0]) == 0); + ASSERT(atomic_read(&root->log_commit[1]) == 0); + + radix_tree_tag_clear(&fs_info->fs_roots_radix, + (unsigned long)root->root_key.objectid, + BTRFS_ROOT_TRANS_TAG); + spin_unlock(&fs_info->fs_roots_radix_lock); + + btrfs_free_log(trans, root); + ret2 = btrfs_update_reloc_root(trans, root); + if (ret2) + return ret2; + + /* see comments in should_cow_block() */ + clear_bit(BTRFS_ROOT_FORCE_COW, &root->state); + smp_mb__after_atomic(); + + if (root->commit_root != root->node) { + list_add_tail(&root->dirty_list, + &trans->transaction->switch_commits); + btrfs_set_root_node(&root->root_item, + root->node); + } + + ret2 = btrfs_update_root(trans, fs_info->tree_root, + &root->root_key, + &root->root_item); + if (ret2) + return ret2; + spin_lock(&fs_info->fs_roots_radix_lock); + btrfs_qgroup_free_meta_all_pertrans(root); + } + } + spin_unlock(&fs_info->fs_roots_radix_lock); + return 0; +} + +/* + * defrag a given btree. + * Every leaf in the btree is read and defragged. + */ +int btrfs_defrag_root(struct btrfs_root *root) +{ + struct btrfs_fs_info *info = root->fs_info; + struct btrfs_trans_handle *trans; + int ret; + + if (test_and_set_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state)) + return 0; + + while (1) { + trans = btrfs_start_transaction(root, 0); + if (IS_ERR(trans)) { + ret = PTR_ERR(trans); + break; + } + + ret = btrfs_defrag_leaves(trans, root); + + btrfs_end_transaction(trans); + btrfs_btree_balance_dirty(info); + cond_resched(); + + if (btrfs_fs_closing(info) || ret != -EAGAIN) + break; + + if (btrfs_defrag_cancelled(info)) { + btrfs_debug(info, "defrag_root cancelled"); + ret = -EAGAIN; + break; + } + } + clear_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state); + return ret; +} + +/* + * Do all special snapshot related qgroup dirty hack. + * + * Will do all needed qgroup inherit and dirty hack like switch commit + * roots inside one transaction and write all btree into disk, to make + * qgroup works. + */ +static int qgroup_account_snapshot(struct btrfs_trans_handle *trans, + struct btrfs_root *src, + struct btrfs_root *parent, + struct btrfs_qgroup_inherit *inherit, + u64 dst_objectid) +{ + struct btrfs_fs_info *fs_info = src->fs_info; + int ret; + + /* + * Save some performance in the case that qgroups are not + * enabled. If this check races with the ioctl, rescan will + * kick in anyway. + */ + if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags)) + return 0; + + /* + * Ensure dirty @src will be committed. Or, after coming + * commit_fs_roots() and switch_commit_roots(), any dirty but not + * recorded root will never be updated again, causing an outdated root + * item. + */ + ret = record_root_in_trans(trans, src, 1); + if (ret) + return ret; + + /* + * btrfs_qgroup_inherit relies on a consistent view of the usage for the + * src root, so we must run the delayed refs here. + * + * However this isn't particularly fool proof, because there's no + * synchronization keeping us from changing the tree after this point + * before we do the qgroup_inherit, or even from making changes while + * we're doing the qgroup_inherit. But that's a problem for the future, + * for now flush the delayed refs to narrow the race window where the + * qgroup counters could end up wrong. + */ + ret = btrfs_run_delayed_refs(trans, (unsigned long)-1); + if (ret) { + btrfs_abort_transaction(trans, ret); + return ret; + } + + ret = commit_fs_roots(trans); + if (ret) + goto out; + ret = btrfs_qgroup_account_extents(trans); + if (ret < 0) + goto out; + + /* Now qgroup are all updated, we can inherit it to new qgroups */ + ret = btrfs_qgroup_inherit(trans, src->root_key.objectid, dst_objectid, + inherit); + if (ret < 0) + goto out; + + /* + * Now we do a simplified commit transaction, which will: + * 1) commit all subvolume and extent tree + * To ensure all subvolume and extent tree have a valid + * commit_root to accounting later insert_dir_item() + * 2) write all btree blocks onto disk + * This is to make sure later btree modification will be cowed + * Or commit_root can be populated and cause wrong qgroup numbers + * In this simplified commit, we don't really care about other trees + * like chunk and root tree, as they won't affect qgroup. + * And we don't write super to avoid half committed status. + */ + ret = commit_cowonly_roots(trans); + if (ret) + goto out; + switch_commit_roots(trans); + ret = btrfs_write_and_wait_transaction(trans); + if (ret) + btrfs_handle_fs_error(fs_info, ret, + "Error while writing out transaction for qgroup"); + +out: + /* + * Force parent root to be updated, as we recorded it before so its + * last_trans == cur_transid. + * Or it won't be committed again onto disk after later + * insert_dir_item() + */ + if (!ret) + ret = record_root_in_trans(trans, parent, 1); + return ret; +} + +/* + * new snapshots need to be created at a very specific time in the + * transaction commit. This does the actual creation. + * + * Note: + * If the error which may affect the commitment of the current transaction + * happens, we should return the error number. If the error which just affect + * the creation of the pending snapshots, just return 0. + */ +static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, + struct btrfs_pending_snapshot *pending) +{ + + struct btrfs_fs_info *fs_info = trans->fs_info; + struct btrfs_key key; + struct btrfs_root_item *new_root_item; + struct btrfs_root *tree_root = fs_info->tree_root; + struct btrfs_root *root = pending->root; + struct btrfs_root *parent_root; + struct btrfs_block_rsv *rsv; + struct inode *parent_inode = pending->dir; + struct btrfs_path *path; + struct btrfs_dir_item *dir_item; + struct extent_buffer *tmp; + struct extent_buffer *old; + struct timespec64 cur_time; + int ret = 0; + u64 to_reserve = 0; + u64 index = 0; + u64 objectid; + u64 root_flags; + unsigned int nofs_flags; + struct fscrypt_name fname; + + ASSERT(pending->path); + path = pending->path; + + ASSERT(pending->root_item); + new_root_item = pending->root_item; + + /* + * We're inside a transaction and must make sure that any potential + * allocations with GFP_KERNEL in fscrypt won't recurse back to + * filesystem. + */ + nofs_flags = memalloc_nofs_save(); + pending->error = fscrypt_setup_filename(parent_inode, + &pending->dentry->d_name, 0, + &fname); + memalloc_nofs_restore(nofs_flags); + if (pending->error) + goto free_pending; + + pending->error = btrfs_get_free_objectid(tree_root, &objectid); + if (pending->error) + goto free_fname; + + /* + * Make qgroup to skip current new snapshot's qgroupid, as it is + * accounted by later btrfs_qgroup_inherit(). + */ + btrfs_set_skip_qgroup(trans, objectid); + + btrfs_reloc_pre_snapshot(pending, &to_reserve); + + if (to_reserve > 0) { + pending->error = btrfs_block_rsv_add(fs_info, + &pending->block_rsv, + to_reserve, + BTRFS_RESERVE_NO_FLUSH); + if (pending->error) + goto clear_skip_qgroup; + } + + key.objectid = objectid; + key.offset = (u64)-1; + key.type = BTRFS_ROOT_ITEM_KEY; + + rsv = trans->block_rsv; + trans->block_rsv = &pending->block_rsv; + trans->bytes_reserved = trans->block_rsv->reserved; + trace_btrfs_space_reservation(fs_info, "transaction", + trans->transid, + trans->bytes_reserved, 1); + parent_root = BTRFS_I(parent_inode)->root; + ret = record_root_in_trans(trans, parent_root, 0); + if (ret) + goto fail; + cur_time = current_time(parent_inode); + + /* + * insert the directory item + */ + ret = btrfs_set_inode_index(BTRFS_I(parent_inode), &index); + BUG_ON(ret); /* -ENOMEM */ + + /* check if there is a file/dir which has the same name. */ + dir_item = btrfs_lookup_dir_item(NULL, parent_root, path, + btrfs_ino(BTRFS_I(parent_inode)), + &fname.disk_name, 0); + if (dir_item != NULL && !IS_ERR(dir_item)) { + pending->error = -EEXIST; + goto dir_item_existed; + } else if (IS_ERR(dir_item)) { + ret = PTR_ERR(dir_item); + btrfs_abort_transaction(trans, ret); + goto fail; + } + btrfs_release_path(path); + + /* + * pull in the delayed directory update + * and the delayed inode item + * otherwise we corrupt the FS during + * snapshot + */ + ret = btrfs_run_delayed_items(trans); + if (ret) { /* Transaction aborted */ + btrfs_abort_transaction(trans, ret); + goto fail; + } + + ret = record_root_in_trans(trans, root, 0); + if (ret) { + btrfs_abort_transaction(trans, ret); + goto fail; + } + btrfs_set_root_last_snapshot(&root->root_item, trans->transid); + memcpy(new_root_item, &root->root_item, sizeof(*new_root_item)); + btrfs_check_and_init_root_item(new_root_item); + + root_flags = btrfs_root_flags(new_root_item); + if (pending->readonly) + root_flags |= BTRFS_ROOT_SUBVOL_RDONLY; + else + root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY; + btrfs_set_root_flags(new_root_item, root_flags); + + btrfs_set_root_generation_v2(new_root_item, + trans->transid); + generate_random_guid(new_root_item->uuid); + memcpy(new_root_item->parent_uuid, root->root_item.uuid, + BTRFS_UUID_SIZE); + if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) { + memset(new_root_item->received_uuid, 0, + sizeof(new_root_item->received_uuid)); + memset(&new_root_item->stime, 0, sizeof(new_root_item->stime)); + memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime)); + btrfs_set_root_stransid(new_root_item, 0); + btrfs_set_root_rtransid(new_root_item, 0); + } + btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec); + btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec); + btrfs_set_root_otransid(new_root_item, trans->transid); + + old = btrfs_lock_root_node(root); + ret = btrfs_cow_block(trans, root, old, NULL, 0, &old, + BTRFS_NESTING_COW); + if (ret) { + btrfs_tree_unlock(old); + free_extent_buffer(old); + btrfs_abort_transaction(trans, ret); + goto fail; + } + + ret = btrfs_copy_root(trans, root, old, &tmp, objectid); + /* clean up in any case */ + btrfs_tree_unlock(old); + free_extent_buffer(old); + if (ret) { + btrfs_abort_transaction(trans, ret); + goto fail; + } + /* see comments in should_cow_block() */ + set_bit(BTRFS_ROOT_FORCE_COW, &root->state); + smp_wmb(); + + btrfs_set_root_node(new_root_item, tmp); + /* record when the snapshot was created in key.offset */ + key.offset = trans->transid; + ret = btrfs_insert_root(trans, tree_root, &key, new_root_item); + btrfs_tree_unlock(tmp); + free_extent_buffer(tmp); + if (ret) { + btrfs_abort_transaction(trans, ret); + goto fail; + } + + /* + * insert root back/forward references + */ + ret = btrfs_add_root_ref(trans, objectid, + parent_root->root_key.objectid, + btrfs_ino(BTRFS_I(parent_inode)), index, + &fname.disk_name); + if (ret) { + btrfs_abort_transaction(trans, ret); + goto fail; + } + + key.offset = (u64)-1; + pending->snap = btrfs_get_new_fs_root(fs_info, objectid, pending->anon_dev); + if (IS_ERR(pending->snap)) { + ret = PTR_ERR(pending->snap); + pending->snap = NULL; + btrfs_abort_transaction(trans, ret); + goto fail; + } + + ret = btrfs_reloc_post_snapshot(trans, pending); + if (ret) { + btrfs_abort_transaction(trans, ret); + goto fail; + } + + /* + * Do special qgroup accounting for snapshot, as we do some qgroup + * snapshot hack to do fast snapshot. + * To co-operate with that hack, we do hack again. + * Or snapshot will be greatly slowed down by a subtree qgroup rescan + */ + ret = qgroup_account_snapshot(trans, root, parent_root, + pending->inherit, objectid); + if (ret < 0) + goto fail; + + ret = btrfs_insert_dir_item(trans, &fname.disk_name, + BTRFS_I(parent_inode), &key, BTRFS_FT_DIR, + index); + /* We have check then name at the beginning, so it is impossible. */ + BUG_ON(ret == -EEXIST || ret == -EOVERFLOW); + if (ret) { + btrfs_abort_transaction(trans, ret); + goto fail; + } + + btrfs_i_size_write(BTRFS_I(parent_inode), parent_inode->i_size + + fname.disk_name.len * 2); + parent_inode->i_mtime = current_time(parent_inode); + parent_inode->i_ctime = parent_inode->i_mtime; + ret = btrfs_update_inode_fallback(trans, parent_root, BTRFS_I(parent_inode)); + if (ret) { + btrfs_abort_transaction(trans, ret); + goto fail; + } + ret = btrfs_uuid_tree_add(trans, new_root_item->uuid, + BTRFS_UUID_KEY_SUBVOL, + objectid); + if (ret) { + btrfs_abort_transaction(trans, ret); + goto fail; + } + if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) { + ret = btrfs_uuid_tree_add(trans, new_root_item->received_uuid, + BTRFS_UUID_KEY_RECEIVED_SUBVOL, + objectid); + if (ret && ret != -EEXIST) { + btrfs_abort_transaction(trans, ret); + goto fail; + } + } + +fail: + pending->error = ret; +dir_item_existed: + trans->block_rsv = rsv; + trans->bytes_reserved = 0; +clear_skip_qgroup: + btrfs_clear_skip_qgroup(trans); +free_fname: + fscrypt_free_filename(&fname); +free_pending: + kfree(new_root_item); + pending->root_item = NULL; + btrfs_free_path(path); + pending->path = NULL; + + return ret; +} + +/* + * create all the snapshots we've scheduled for creation + */ +static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans) +{ + struct btrfs_pending_snapshot *pending, *next; + struct list_head *head = &trans->transaction->pending_snapshots; + int ret = 0; + + list_for_each_entry_safe(pending, next, head, list) { + list_del(&pending->list); + ret = create_pending_snapshot(trans, pending); + if (ret) + break; + } + return ret; +} + +static void update_super_roots(struct btrfs_fs_info *fs_info) +{ + struct btrfs_root_item *root_item; + struct btrfs_super_block *super; + + super = fs_info->super_copy; + + root_item = &fs_info->chunk_root->root_item; + super->chunk_root = root_item->bytenr; + super->chunk_root_generation = root_item->generation; + super->chunk_root_level = root_item->level; + + root_item = &fs_info->tree_root->root_item; + super->root = root_item->bytenr; + super->generation = root_item->generation; + super->root_level = root_item->level; + if (btrfs_test_opt(fs_info, SPACE_CACHE)) + super->cache_generation = root_item->generation; + else if (test_bit(BTRFS_FS_CLEANUP_SPACE_CACHE_V1, &fs_info->flags)) + super->cache_generation = 0; + if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags)) + super->uuid_tree_generation = root_item->generation; +} + +int btrfs_transaction_in_commit(struct btrfs_fs_info *info) +{ + struct btrfs_transaction *trans; + int ret = 0; + + spin_lock(&info->trans_lock); + trans = info->running_transaction; + if (trans) + ret = (trans->state >= TRANS_STATE_COMMIT_START); + spin_unlock(&info->trans_lock); + return ret; +} + +int btrfs_transaction_blocked(struct btrfs_fs_info *info) +{ + struct btrfs_transaction *trans; + int ret = 0; + + spin_lock(&info->trans_lock); + trans = info->running_transaction; + if (trans) + ret = is_transaction_blocked(trans); + spin_unlock(&info->trans_lock); + return ret; +} + +void btrfs_commit_transaction_async(struct btrfs_trans_handle *trans) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + struct btrfs_transaction *cur_trans; + + /* Kick the transaction kthread. */ + set_bit(BTRFS_FS_COMMIT_TRANS, &fs_info->flags); + wake_up_process(fs_info->transaction_kthread); + + /* take transaction reference */ + cur_trans = trans->transaction; + refcount_inc(&cur_trans->use_count); + + btrfs_end_transaction(trans); + + /* + * Wait for the current transaction commit to start and block + * subsequent transaction joins + */ + btrfs_might_wait_for_state(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_START); + wait_event(fs_info->transaction_blocked_wait, + cur_trans->state >= TRANS_STATE_COMMIT_START || + TRANS_ABORTED(cur_trans)); + btrfs_put_transaction(cur_trans); +} + +static void cleanup_transaction(struct btrfs_trans_handle *trans, int err) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + struct btrfs_transaction *cur_trans = trans->transaction; + + WARN_ON(refcount_read(&trans->use_count) > 1); + + btrfs_abort_transaction(trans, err); + + spin_lock(&fs_info->trans_lock); + + /* + * If the transaction is removed from the list, it means this + * transaction has been committed successfully, so it is impossible + * to call the cleanup function. + */ + BUG_ON(list_empty(&cur_trans->list)); + + if (cur_trans == fs_info->running_transaction) { + cur_trans->state = TRANS_STATE_COMMIT_DOING; + spin_unlock(&fs_info->trans_lock); + + /* + * The thread has already released the lockdep map as reader + * already in btrfs_commit_transaction(). + */ + btrfs_might_wait_for_event(fs_info, btrfs_trans_num_writers); + wait_event(cur_trans->writer_wait, + atomic_read(&cur_trans->num_writers) == 1); + + spin_lock(&fs_info->trans_lock); + } + + /* + * Now that we know no one else is still using the transaction we can + * remove the transaction from the list of transactions. This avoids + * the transaction kthread from cleaning up the transaction while some + * other task is still using it, which could result in a use-after-free + * on things like log trees, as it forces the transaction kthread to + * wait for this transaction to be cleaned up by us. + */ + list_del_init(&cur_trans->list); + + spin_unlock(&fs_info->trans_lock); + + btrfs_cleanup_one_transaction(trans->transaction, fs_info); + + spin_lock(&fs_info->trans_lock); + if (cur_trans == fs_info->running_transaction) + fs_info->running_transaction = NULL; + spin_unlock(&fs_info->trans_lock); + + if (trans->type & __TRANS_FREEZABLE) + sb_end_intwrite(fs_info->sb); + btrfs_put_transaction(cur_trans); + btrfs_put_transaction(cur_trans); + + trace_btrfs_transaction_commit(fs_info); + + if (current->journal_info == trans) + current->journal_info = NULL; + + /* + * If relocation is running, we can't cancel scrub because that will + * result in a deadlock. Before relocating a block group, relocation + * pauses scrub, then starts and commits a transaction before unpausing + * scrub. If the transaction commit is being done by the relocation + * task or triggered by another task and the relocation task is waiting + * for the commit, and we end up here due to an error in the commit + * path, then calling btrfs_scrub_cancel() will deadlock, as we are + * asking for scrub to stop while having it asked to be paused higher + * above in relocation code. + */ + if (!test_bit(BTRFS_FS_RELOC_RUNNING, &fs_info->flags)) + btrfs_scrub_cancel(fs_info); + + kmem_cache_free(btrfs_trans_handle_cachep, trans); +} + +/* + * Release reserved delayed ref space of all pending block groups of the + * transaction and remove them from the list + */ +static void btrfs_cleanup_pending_block_groups(struct btrfs_trans_handle *trans) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + struct btrfs_block_group *block_group, *tmp; + + list_for_each_entry_safe(block_group, tmp, &trans->new_bgs, bg_list) { + btrfs_delayed_refs_rsv_release(fs_info, 1); + list_del_init(&block_group->bg_list); + } +} + +static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info) +{ + /* + * We use try_to_writeback_inodes_sb() here because if we used + * btrfs_start_delalloc_roots we would deadlock with fs freeze. + * Currently are holding the fs freeze lock, if we do an async flush + * we'll do btrfs_join_transaction() and deadlock because we need to + * wait for the fs freeze lock. Using the direct flushing we benefit + * from already being in a transaction and our join_transaction doesn't + * have to re-take the fs freeze lock. + * + * Note that try_to_writeback_inodes_sb() will only trigger writeback + * if it can read lock sb->s_umount. It will always be able to lock it, + * except when the filesystem is being unmounted or being frozen, but in + * those cases sync_filesystem() is called, which results in calling + * writeback_inodes_sb() while holding a write lock on sb->s_umount. + * Note that we don't call writeback_inodes_sb() directly, because it + * will emit a warning if sb->s_umount is not locked. + */ + if (btrfs_test_opt(fs_info, FLUSHONCOMMIT)) + try_to_writeback_inodes_sb(fs_info->sb, WB_REASON_SYNC); + return 0; +} + +static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info) +{ + if (btrfs_test_opt(fs_info, FLUSHONCOMMIT)) + btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1); +} + +/* + * Add a pending snapshot associated with the given transaction handle to the + * respective handle. This must be called after the transaction commit started + * and while holding fs_info->trans_lock. + * This serves to guarantee a caller of btrfs_commit_transaction() that it can + * safely free the pending snapshot pointer in case btrfs_commit_transaction() + * returns an error. + */ +static void add_pending_snapshot(struct btrfs_trans_handle *trans) +{ + struct btrfs_transaction *cur_trans = trans->transaction; + + if (!trans->pending_snapshot) + return; + + lockdep_assert_held(&trans->fs_info->trans_lock); + ASSERT(cur_trans->state >= TRANS_STATE_COMMIT_START); + + list_add(&trans->pending_snapshot->list, &cur_trans->pending_snapshots); +} + +static void update_commit_stats(struct btrfs_fs_info *fs_info, ktime_t interval) +{ + fs_info->commit_stats.commit_count++; + fs_info->commit_stats.last_commit_dur = interval; + fs_info->commit_stats.max_commit_dur = + max_t(u64, fs_info->commit_stats.max_commit_dur, interval); + fs_info->commit_stats.total_commit_dur += interval; +} + +int btrfs_commit_transaction(struct btrfs_trans_handle *trans) +{ + struct btrfs_fs_info *fs_info = trans->fs_info; + struct btrfs_transaction *cur_trans = trans->transaction; + struct btrfs_transaction *prev_trans = NULL; + int ret; + ktime_t start_time; + ktime_t interval; + + ASSERT(refcount_read(&trans->use_count) == 1); + btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_START); + + /* Stop the commit early if ->aborted is set */ + if (TRANS_ABORTED(cur_trans)) { + ret = cur_trans->aborted; + goto lockdep_trans_commit_start_release; + } + + btrfs_trans_release_metadata(trans); + trans->block_rsv = NULL; + + /* + * We only want one transaction commit doing the flushing so we do not + * waste a bunch of time on lock contention on the extent root node. + */ + if (!test_and_set_bit(BTRFS_DELAYED_REFS_FLUSHING, + &cur_trans->delayed_refs.flags)) { + /* + * Make a pass through all the delayed refs we have so far. + * Any running threads may add more while we are here. + */ + ret = btrfs_run_delayed_refs(trans, 0); + if (ret) + goto lockdep_trans_commit_start_release; + } + + btrfs_create_pending_block_groups(trans); + + if (!test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &cur_trans->flags)) { + int run_it = 0; + + /* this mutex is also taken before trying to set + * block groups readonly. We need to make sure + * that nobody has set a block group readonly + * after a extents from that block group have been + * allocated for cache files. btrfs_set_block_group_ro + * will wait for the transaction to commit if it + * finds BTRFS_TRANS_DIRTY_BG_RUN set. + * + * The BTRFS_TRANS_DIRTY_BG_RUN flag is also used to make sure + * only one process starts all the block group IO. It wouldn't + * hurt to have more than one go through, but there's no + * real advantage to it either. + */ + mutex_lock(&fs_info->ro_block_group_mutex); + if (!test_and_set_bit(BTRFS_TRANS_DIRTY_BG_RUN, + &cur_trans->flags)) + run_it = 1; + mutex_unlock(&fs_info->ro_block_group_mutex); + + if (run_it) { + ret = btrfs_start_dirty_block_groups(trans); + if (ret) + goto lockdep_trans_commit_start_release; + } + } + + spin_lock(&fs_info->trans_lock); + if (cur_trans->state >= TRANS_STATE_COMMIT_START) { + enum btrfs_trans_state want_state = TRANS_STATE_COMPLETED; + + add_pending_snapshot(trans); + + spin_unlock(&fs_info->trans_lock); + refcount_inc(&cur_trans->use_count); + + if (trans->in_fsync) + want_state = TRANS_STATE_SUPER_COMMITTED; + + btrfs_trans_state_lockdep_release(fs_info, + BTRFS_LOCKDEP_TRANS_COMMIT_START); + ret = btrfs_end_transaction(trans); + wait_for_commit(cur_trans, want_state); + + if (TRANS_ABORTED(cur_trans)) + ret = cur_trans->aborted; + + btrfs_put_transaction(cur_trans); + + return ret; + } + + cur_trans->state = TRANS_STATE_COMMIT_START; + wake_up(&fs_info->transaction_blocked_wait); + btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_START); + + if (cur_trans->list.prev != &fs_info->trans_list) { + enum btrfs_trans_state want_state = TRANS_STATE_COMPLETED; + + if (trans->in_fsync) + want_state = TRANS_STATE_SUPER_COMMITTED; + + prev_trans = list_entry(cur_trans->list.prev, + struct btrfs_transaction, list); + if (prev_trans->state < want_state) { + refcount_inc(&prev_trans->use_count); + spin_unlock(&fs_info->trans_lock); + + wait_for_commit(prev_trans, want_state); + + ret = READ_ONCE(prev_trans->aborted); + + btrfs_put_transaction(prev_trans); + if (ret) + goto lockdep_release; + } else { + spin_unlock(&fs_info->trans_lock); + } + } else { + spin_unlock(&fs_info->trans_lock); + /* + * The previous transaction was aborted and was already removed + * from the list of transactions at fs_info->trans_list. So we + * abort to prevent writing a new superblock that reflects a + * corrupt state (pointing to trees with unwritten nodes/leafs). + */ + if (BTRFS_FS_ERROR(fs_info)) { + ret = -EROFS; + goto lockdep_release; + } + } + + /* + * Get the time spent on the work done by the commit thread and not + * the time spent waiting on a previous commit + */ + start_time = ktime_get_ns(); + + extwriter_counter_dec(cur_trans, trans->type); + + ret = btrfs_start_delalloc_flush(fs_info); + if (ret) + goto lockdep_release; + + ret = btrfs_run_delayed_items(trans); + if (ret) + goto lockdep_release; + + /* + * The thread has started/joined the transaction thus it holds the + * lockdep map as a reader. It has to release it before acquiring the + * lockdep map as a writer. + */ + btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters); + btrfs_might_wait_for_event(fs_info, btrfs_trans_num_extwriters); + wait_event(cur_trans->writer_wait, + extwriter_counter_read(cur_trans) == 0); + + /* some pending stuffs might be added after the previous flush. */ + ret = btrfs_run_delayed_items(trans); + if (ret) { + btrfs_lockdep_release(fs_info, btrfs_trans_num_writers); + goto cleanup_transaction; + } + + btrfs_wait_delalloc_flush(fs_info); + + /* + * Wait for all ordered extents started by a fast fsync that joined this + * transaction. Otherwise if this transaction commits before the ordered + * extents complete we lose logged data after a power failure. + */ + btrfs_might_wait_for_event(fs_info, btrfs_trans_pending_ordered); + wait_event(cur_trans->pending_wait, + atomic_read(&cur_trans->pending_ordered) == 0); + + btrfs_scrub_pause(fs_info); + /* + * Ok now we need to make sure to block out any other joins while we + * commit the transaction. We could have started a join before setting + * COMMIT_DOING so make sure to wait for num_writers to == 1 again. + */ + spin_lock(&fs_info->trans_lock); + add_pending_snapshot(trans); + cur_trans->state = TRANS_STATE_COMMIT_DOING; + spin_unlock(&fs_info->trans_lock); + + /* + * The thread has started/joined the transaction thus it holds the + * lockdep map as a reader. It has to release it before acquiring the + * lockdep map as a writer. + */ + btrfs_lockdep_release(fs_info, btrfs_trans_num_writers); + btrfs_might_wait_for_event(fs_info, btrfs_trans_num_writers); + wait_event(cur_trans->writer_wait, + atomic_read(&cur_trans->num_writers) == 1); + + /* + * Make lockdep happy by acquiring the state locks after + * btrfs_trans_num_writers is released. If we acquired the state locks + * before releasing the btrfs_trans_num_writers lock then lockdep would + * complain because we did not follow the reverse order unlocking rule. + */ + btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED); + btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED); + btrfs_trans_state_lockdep_acquire(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED); + + /* + * We've started the commit, clear the flag in case we were triggered to + * do an async commit but somebody else started before the transaction + * kthread could do the work. + */ + clear_bit(BTRFS_FS_COMMIT_TRANS, &fs_info->flags); + + if (TRANS_ABORTED(cur_trans)) { + ret = cur_trans->aborted; + btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED); + goto scrub_continue; + } + /* + * the reloc mutex makes sure that we stop + * the balancing code from coming in and moving + * extents around in the middle of the commit + */ + mutex_lock(&fs_info->reloc_mutex); + + /* + * We needn't worry about the delayed items because we will + * deal with them in create_pending_snapshot(), which is the + * core function of the snapshot creation. + */ + ret = create_pending_snapshots(trans); + if (ret) + goto unlock_reloc; + + /* + * We insert the dir indexes of the snapshots and update the inode + * of the snapshots' parents after the snapshot creation, so there + * are some delayed items which are not dealt with. Now deal with + * them. + * + * We needn't worry that this operation will corrupt the snapshots, + * because all the tree which are snapshoted will be forced to COW + * the nodes and leaves. + */ + ret = btrfs_run_delayed_items(trans); + if (ret) + goto unlock_reloc; + + ret = btrfs_run_delayed_refs(trans, (unsigned long)-1); + if (ret) + goto unlock_reloc; + + /* + * make sure none of the code above managed to slip in a + * delayed item + */ + btrfs_assert_delayed_root_empty(fs_info); + + WARN_ON(cur_trans != trans->transaction); + + ret = commit_fs_roots(trans); + if (ret) + goto unlock_reloc; + + /* + * Since the transaction is done, we can apply the pending changes + * before the next transaction. + */ + btrfs_apply_pending_changes(fs_info); + + /* commit_fs_roots gets rid of all the tree log roots, it is now + * safe to free the root of tree log roots + */ + btrfs_free_log_root_tree(trans, fs_info); + + /* + * Since fs roots are all committed, we can get a quite accurate + * new_roots. So let's do quota accounting. + */ + ret = btrfs_qgroup_account_extents(trans); + if (ret < 0) + goto unlock_reloc; + + ret = commit_cowonly_roots(trans); + if (ret) + goto unlock_reloc; + + /* + * The tasks which save the space cache and inode cache may also + * update ->aborted, check it. + */ + if (TRANS_ABORTED(cur_trans)) { + ret = cur_trans->aborted; + goto unlock_reloc; + } + + cur_trans = fs_info->running_transaction; + + btrfs_set_root_node(&fs_info->tree_root->root_item, + fs_info->tree_root->node); + list_add_tail(&fs_info->tree_root->dirty_list, + &cur_trans->switch_commits); + + btrfs_set_root_node(&fs_info->chunk_root->root_item, + fs_info->chunk_root->node); + list_add_tail(&fs_info->chunk_root->dirty_list, + &cur_trans->switch_commits); + + if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) { + btrfs_set_root_node(&fs_info->block_group_root->root_item, + fs_info->block_group_root->node); + list_add_tail(&fs_info->block_group_root->dirty_list, + &cur_trans->switch_commits); + } + + switch_commit_roots(trans); + + ASSERT(list_empty(&cur_trans->dirty_bgs)); + ASSERT(list_empty(&cur_trans->io_bgs)); + update_super_roots(fs_info); + + btrfs_set_super_log_root(fs_info->super_copy, 0); + btrfs_set_super_log_root_level(fs_info->super_copy, 0); + memcpy(fs_info->super_for_commit, fs_info->super_copy, + sizeof(*fs_info->super_copy)); + + btrfs_commit_device_sizes(cur_trans); + + clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags); + clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags); + + btrfs_trans_release_chunk_metadata(trans); + + /* + * Before changing the transaction state to TRANS_STATE_UNBLOCKED and + * setting fs_info->running_transaction to NULL, lock tree_log_mutex to + * make sure that before we commit our superblock, no other task can + * start a new transaction and commit a log tree before we commit our + * superblock. Anyone trying to commit a log tree locks this mutex before + * writing its superblock. + */ + mutex_lock(&fs_info->tree_log_mutex); + + spin_lock(&fs_info->trans_lock); + cur_trans->state = TRANS_STATE_UNBLOCKED; + fs_info->running_transaction = NULL; + spin_unlock(&fs_info->trans_lock); + mutex_unlock(&fs_info->reloc_mutex); + + wake_up(&fs_info->transaction_wait); + btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED); + + ret = btrfs_write_and_wait_transaction(trans); + if (ret) { + btrfs_handle_fs_error(fs_info, ret, + "Error while writing out transaction"); + mutex_unlock(&fs_info->tree_log_mutex); + goto scrub_continue; + } + + /* + * At this point, we should have written all the tree blocks allocated + * in this transaction. So it's now safe to free the redirtyied extent + * buffers. + */ + btrfs_free_redirty_list(cur_trans); + + ret = write_all_supers(fs_info, 0); + /* + * the super is written, we can safely allow the tree-loggers + * to go about their business + */ + mutex_unlock(&fs_info->tree_log_mutex); + if (ret) + goto scrub_continue; + + /* + * We needn't acquire the lock here because there is no other task + * which can change it. + */ + cur_trans->state = TRANS_STATE_SUPER_COMMITTED; + wake_up(&cur_trans->commit_wait); + btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED); + + btrfs_finish_extent_commit(trans); + + if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &cur_trans->flags)) + btrfs_clear_space_info_full(fs_info); + + fs_info->last_trans_committed = cur_trans->transid; + /* + * We needn't acquire the lock here because there is no other task + * which can change it. + */ + cur_trans->state = TRANS_STATE_COMPLETED; + wake_up(&cur_trans->commit_wait); + btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED); + + spin_lock(&fs_info->trans_lock); + list_del_init(&cur_trans->list); + spin_unlock(&fs_info->trans_lock); + + btrfs_put_transaction(cur_trans); + btrfs_put_transaction(cur_trans); + + if (trans->type & __TRANS_FREEZABLE) + sb_end_intwrite(fs_info->sb); + + trace_btrfs_transaction_commit(fs_info); + + interval = ktime_get_ns() - start_time; + + btrfs_scrub_continue(fs_info); + + if (current->journal_info == trans) + current->journal_info = NULL; + + kmem_cache_free(btrfs_trans_handle_cachep, trans); + + update_commit_stats(fs_info, interval); + + return ret; + +unlock_reloc: + mutex_unlock(&fs_info->reloc_mutex); + btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_UNBLOCKED); +scrub_continue: + btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_SUPER_COMMITTED); + btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMPLETED); + btrfs_scrub_continue(fs_info); +cleanup_transaction: + btrfs_trans_release_metadata(trans); + btrfs_cleanup_pending_block_groups(trans); + btrfs_trans_release_chunk_metadata(trans); + trans->block_rsv = NULL; + btrfs_warn(fs_info, "Skipping commit of aborted transaction."); + if (current->journal_info == trans) + current->journal_info = NULL; + cleanup_transaction(trans, ret); + + return ret; + +lockdep_release: + btrfs_lockdep_release(fs_info, btrfs_trans_num_extwriters); + btrfs_lockdep_release(fs_info, btrfs_trans_num_writers); + goto cleanup_transaction; + +lockdep_trans_commit_start_release: + btrfs_trans_state_lockdep_release(fs_info, BTRFS_LOCKDEP_TRANS_COMMIT_START); + btrfs_end_transaction(trans); + return ret; +} + +/* + * return < 0 if error + * 0 if there are no more dead_roots at the time of call + * 1 there are more to be processed, call me again + * + * The return value indicates there are certainly more snapshots to delete, but + * if there comes a new one during processing, it may return 0. We don't mind, + * because btrfs_commit_super will poke cleaner thread and it will process it a + * few seconds later. + */ +int btrfs_clean_one_deleted_snapshot(struct btrfs_fs_info *fs_info) +{ + struct btrfs_root *root; + int ret; + + spin_lock(&fs_info->trans_lock); + if (list_empty(&fs_info->dead_roots)) { + spin_unlock(&fs_info->trans_lock); + return 0; + } + root = list_first_entry(&fs_info->dead_roots, + struct btrfs_root, root_list); + list_del_init(&root->root_list); + spin_unlock(&fs_info->trans_lock); + + btrfs_debug(fs_info, "cleaner removing %llu", root->root_key.objectid); + + btrfs_kill_all_delayed_nodes(root); + + if (btrfs_header_backref_rev(root->node) < + BTRFS_MIXED_BACKREF_REV) + ret = btrfs_drop_snapshot(root, 0, 0); + else + ret = btrfs_drop_snapshot(root, 1, 0); + + btrfs_put_root(root); + return (ret < 0) ? 0 : 1; +} + +void btrfs_apply_pending_changes(struct btrfs_fs_info *fs_info) +{ + unsigned long prev; + unsigned long bit; + + prev = xchg(&fs_info->pending_changes, 0); + if (!prev) + return; + + bit = 1 << BTRFS_PENDING_COMMIT; + if (prev & bit) + btrfs_debug(fs_info, "pending commit done"); + prev &= ~bit; + + if (prev) + btrfs_warn(fs_info, + "unknown pending changes left 0x%lx, ignoring", prev); +} |