/* * Copyright (C) 2007 Oracle. All rights reserved. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public * License v2 as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public * License along with this program; if not, write to the * Free Software Foundation, Inc., 59 Temple Place - Suite 330, * Boston, MA 021110-1307, USA. */ #include #include #include #include #include #include #include "ctree.h" #include "disk-io.h" #include "transaction.h" #include "locking.h" #include "tree-log.h" #include "inode-map.h" #define BTRFS_ROOT_TRANS_TAG 0 static noinline void put_transaction(struct btrfs_transaction *transaction) { WARN_ON(atomic_read(&transaction->use_count) == 0); if (atomic_dec_and_test(&transaction->use_count)) { BUG_ON(!list_empty(&transaction->list)); WARN_ON(transaction->delayed_refs.root.rb_node); WARN_ON(!list_empty(&transaction->delayed_refs.seq_head)); memset(transaction, 0, sizeof(*transaction)); kmem_cache_free(btrfs_transaction_cachep, transaction); } } static noinline void switch_commit_root(struct btrfs_root *root) { free_extent_buffer(root->commit_root); root->commit_root = btrfs_root_node(root); } /* * either allocate a new transaction or hop into the existing one */ static noinline int join_transaction(struct btrfs_root *root, int nofail) { struct btrfs_transaction *cur_trans; spin_lock(&root->fs_info->trans_lock); loop: if (root->fs_info->trans_no_join) { if (!nofail) { spin_unlock(&root->fs_info->trans_lock); return -EBUSY; } } cur_trans = root->fs_info->running_transaction; if (cur_trans) { atomic_inc(&cur_trans->use_count); atomic_inc(&cur_trans->num_writers); cur_trans->num_joined++; spin_unlock(&root->fs_info->trans_lock); return 0; } spin_unlock(&root->fs_info->trans_lock); cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS); if (!cur_trans) return -ENOMEM; spin_lock(&root->fs_info->trans_lock); if (root->fs_info->running_transaction) { /* * someone started a transaction after we unlocked. Make sure * to redo the trans_no_join checks above */ kmem_cache_free(btrfs_transaction_cachep, cur_trans); cur_trans = root->fs_info->running_transaction; goto loop; } atomic_set(&cur_trans->num_writers, 1); cur_trans->num_joined = 0; init_waitqueue_head(&cur_trans->writer_wait); init_waitqueue_head(&cur_trans->commit_wait); cur_trans->in_commit = 0; cur_trans->blocked = 0; /* * One for this trans handle, one so it will live on until we * commit the transaction. */ atomic_set(&cur_trans->use_count, 2); cur_trans->commit_done = 0; cur_trans->start_time = get_seconds(); cur_trans->delayed_refs.root = RB_ROOT; cur_trans->delayed_refs.num_entries = 0; cur_trans->delayed_refs.num_heads_ready = 0; cur_trans->delayed_refs.num_heads = 0; cur_trans->delayed_refs.flushing = 0; cur_trans->delayed_refs.run_delayed_start = 0; cur_trans->delayed_refs.seq = 1; init_waitqueue_head(&cur_trans->delayed_refs.seq_wait); spin_lock_init(&cur_trans->commit_lock); spin_lock_init(&cur_trans->delayed_refs.lock); INIT_LIST_HEAD(&cur_trans->delayed_refs.seq_head); INIT_LIST_HEAD(&cur_trans->pending_snapshots); list_add_tail(&cur_trans->list, &root->fs_info->trans_list); extent_io_tree_init(&cur_trans->dirty_pages, root->fs_info->btree_inode->i_mapping); root->fs_info->generation++; cur_trans->transid = root->fs_info->generation; root->fs_info->running_transaction = cur_trans; spin_unlock(&root->fs_info->trans_lock); return 0; } /* * this does all the record keeping required to make sure that a reference * counted 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) { if (root->ref_cows && root->last_trans < trans->transid) { WARN_ON(root == root->fs_info->extent_root); WARN_ON(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 */ root->in_trans_setup = 1; /* make sure readers find in_trans_setup before * they find our root->last_trans update */ smp_wmb(); spin_lock(&root->fs_info->fs_roots_radix_lock); if (root->last_trans == trans->transid) { spin_unlock(&root->fs_info->fs_roots_radix_lock); return 0; } radix_tree_tag_set(&root->fs_info->fs_roots_radix, (unsigned long)root->root_key.objectid, BTRFS_ROOT_TRANS_TAG); spin_unlock(&root->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 */ btrfs_init_reloc_root(trans, root); smp_wmb(); root->in_trans_setup = 0; } return 0; } int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans, struct btrfs_root *root) { if (!root->ref_cows) return 0; /* * see record_root_in_trans for comments about in_trans_setup usage * and barriers */ smp_rmb(); if (root->last_trans == trans->transid && !root->in_trans_setup) return 0; mutex_lock(&root->fs_info->reloc_mutex); record_root_in_trans(trans, root); mutex_unlock(&root->fs_info->reloc_mutex); return 0; } /* 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_root *root) { struct btrfs_transaction *cur_trans; spin_lock(&root->fs_info->trans_lock); cur_trans = root->fs_info->running_transaction; if (cur_trans && cur_trans->blocked) { atomic_inc(&cur_trans->use_count); spin_unlock(&root->fs_info->trans_lock); wait_event(root->fs_info->transaction_wait, !cur_trans->blocked); put_transaction(cur_trans); } else { spin_unlock(&root->fs_info->trans_lock); } } enum btrfs_trans_type { TRANS_START, TRANS_JOIN, TRANS_USERSPACE, TRANS_JOIN_NOLOCK, }; static int may_wait_transaction(struct btrfs_root *root, int type) { if (root->fs_info->log_root_recovering) return 0; if (type == TRANS_USERSPACE) return 1; if (type == TRANS_START && !atomic_read(&root->fs_info->open_ioctl_trans)) return 1; return 0; } static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root, u64 num_items, int type) { struct btrfs_trans_handle *h; struct btrfs_transaction *cur_trans; u64 num_bytes = 0; int ret; if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) return ERR_PTR(-EROFS); if (current->journal_info) { WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK); h = current->journal_info; h->use_count++; 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 > 0 && root != root->fs_info->chunk_root) { num_bytes = btrfs_calc_trans_metadata_size(root, num_items); ret = btrfs_block_rsv_add(root, &root->fs_info->trans_block_rsv, num_bytes); if (ret) return ERR_PTR(ret); } again: h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS); if (!h) return ERR_PTR(-ENOMEM); if (may_wait_transaction(root, type)) wait_current_trans(root); do { ret = join_transaction(root, type == TRANS_JOIN_NOLOCK); if (ret == -EBUSY) wait_current_trans(root); } while (ret == -EBUSY); if (ret < 0) { kmem_cache_free(btrfs_trans_handle_cachep, h); return ERR_PTR(ret); } cur_trans = root->fs_info->running_transaction; h->transid = cur_trans->transid; h->transaction = cur_trans; h->blocks_used = 0; h->bytes_reserved = 0; h->delayed_ref_updates = 0; h->use_count = 1; h->block_rsv = NULL; h->orig_rsv = NULL; smp_mb(); if (cur_trans->blocked && may_wait_transaction(root, type)) { btrfs_commit_transaction(h, root); goto again; } if (num_bytes) { trace_btrfs_space_reservation(root->fs_info, "transaction", (u64)h, num_bytes, 1); h->block_rsv = &root->fs_info->trans_block_rsv; h->bytes_reserved = num_bytes; } got_it: btrfs_record_root_in_trans(h, root); if (!current->journal_info && type != TRANS_USERSPACE) current->journal_info = h; return h; } struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root, int num_items) { return start_transaction(root, num_items, TRANS_START); } struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root) { return start_transaction(root, 0, TRANS_JOIN); } struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root) { return start_transaction(root, 0, TRANS_JOIN_NOLOCK); } struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root) { return start_transaction(root, 0, TRANS_USERSPACE); } /* wait for a transaction commit to be fully complete */ static noinline void wait_for_commit(struct btrfs_root *root, struct btrfs_transaction *commit) { wait_event(commit->commit_wait, commit->commit_done); } int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid) { struct btrfs_transaction *cur_trans = NULL, *t; int ret; ret = 0; if (transid) { if (transid <= root->fs_info->last_trans_committed) goto out; /* find specified transaction */ spin_lock(&root->fs_info->trans_lock); list_for_each_entry(t, &root->fs_info->trans_list, list) { if (t->transid == transid) { cur_trans = t; atomic_inc(&cur_trans->use_count); break; } if (t->transid > transid) break; } spin_unlock(&root->fs_info->trans_lock); ret = -EINVAL; if (!cur_trans) goto out; /* bad transid */ } else { /* find newest transaction that is committing | committed */ spin_lock(&root->fs_info->trans_lock); list_for_each_entry_reverse(t, &root->fs_info->trans_list, list) { if (t->in_commit) { if (t->commit_done) break; cur_trans = t; atomic_inc(&cur_trans->use_count); break; } } spin_unlock(&root->fs_info->trans_lock); if (!cur_trans) goto out; /* nothing committing|committed */ } wait_for_commit(root, cur_trans); put_transaction(cur_trans); ret = 0; out: return ret; } void btrfs_throttle(struct btrfs_root *root) { if (!atomic_read(&root->fs_info->open_ioctl_trans)) wait_current_trans(root); } static int should_end_transaction(struct btrfs_trans_handle *trans, struct btrfs_root *root) { int ret; ret = btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5); return ret ? 1 : 0; } int btrfs_should_end_transaction(struct btrfs_trans_handle *trans, struct btrfs_root *root) { struct btrfs_transaction *cur_trans = trans->transaction; struct btrfs_block_rsv *rsv = trans->block_rsv; int updates; smp_mb(); if (cur_trans->blocked || cur_trans->delayed_refs.flushing) return 1; /* * We need to do this in case we're deleting csums so the global block * rsv get's used instead of the csum block rsv. */ trans->block_rsv = NULL; updates = trans->delayed_ref_updates; trans->delayed_ref_updates = 0; if (updates) btrfs_run_delayed_refs(trans, root, updates); trans->block_rsv = rsv; return should_end_transaction(trans, root); } static int __btrfs_end_transaction(struct btrfs_trans_handle *trans, struct btrfs_root *root, int throttle, int lock) { struct btrfs_transaction *cur_trans = trans->transaction; struct btrfs_fs_info *info = root->fs_info; int count = 0; if (--trans->use_count) { trans->block_rsv = trans->orig_rsv; return 0; } btrfs_trans_release_metadata(trans, root); trans->block_rsv = NULL; while (count < 2) { unsigned long cur = trans->delayed_ref_updates; trans->delayed_ref_updates = 0; if (cur && trans->transaction->delayed_refs.num_heads_ready > 64) { trans->delayed_ref_updates = 0; btrfs_run_delayed_refs(trans, root, cur); } else { break; } count++; } if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) && should_end_transaction(trans, root)) { trans->transaction->blocked = 1; smp_wmb(); } if (lock && cur_trans->blocked && !cur_trans->in_commit) { if (throttle) { /* * We may race with somebody else here so end up having * to call end_transaction on ourselves again, so inc * our use_count. */ trans->use_count++; return btrfs_commit_transaction(trans, root); } else { wake_up_process(info->transaction_kthread); } } WARN_ON(cur_trans != info->running_transaction); WARN_ON(atomic_read(&cur_trans->num_writers) < 1); atomic_dec(&cur_trans->num_writers); smp_mb(); if (waitqueue_active(&cur_trans->writer_wait)) wake_up(&cur_trans->writer_wait); put_transaction(cur_trans); if (current->journal_info == trans) current->journal_info = NULL; memset(trans, 0, sizeof(*trans)); kmem_cache_free(btrfs_trans_handle_cachep, trans); if (throttle) btrfs_run_delayed_iputs(root); return 0; } int btrfs_end_transaction(struct btrfs_trans_handle *trans, struct btrfs_root *root) { int ret; ret = __btrfs_end_transaction(trans, root, 0, 1); if (ret) return ret; return 0; } int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans, struct btrfs_root *root) { int ret; ret = __btrfs_end_transaction(trans, root, 1, 1); if (ret) return ret; return 0; } int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans, struct btrfs_root *root) { int ret; ret = __btrfs_end_transaction(trans, root, 0, 0); if (ret) return ret; return 0; } int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans, struct btrfs_root *root) { return __btrfs_end_transaction(trans, root, 1, 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_root *root, struct extent_io_tree *dirty_pages, int mark) { int err = 0; int werr = 0; struct address_space *mapping = root->fs_info->btree_inode->i_mapping; u64 start = 0; u64 end; while (!find_first_extent_bit(dirty_pages, start, &start, &end, mark)) { convert_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT, mark, GFP_NOFS); err = filemap_fdatawrite_range(mapping, start, end); if (err) werr = err; cond_resched(); start = end + 1; } if (err) werr = err; 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 */ int btrfs_wait_marked_extents(struct btrfs_root *root, struct extent_io_tree *dirty_pages, int mark) { int err = 0; int werr = 0; struct address_space *mapping = root->fs_info->btree_inode->i_mapping; u64 start = 0; u64 end; while (!find_first_extent_bit(dirty_pages, start, &start, &end, EXTENT_NEED_WAIT)) { clear_extent_bits(dirty_pages, start, end, EXTENT_NEED_WAIT, GFP_NOFS); err = filemap_fdatawait_range(mapping, start, end); if (err) werr = err; cond_resched(); start = end + 1; } if (err) werr = err; 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 */ int btrfs_write_and_wait_marked_extents(struct btrfs_root *root, struct extent_io_tree *dirty_pages, int mark) { int ret; int ret2; ret = btrfs_write_marked_extents(root, dirty_pages, mark); ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark); if (ret) return ret; if (ret2) return ret2; return 0; } int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans, struct btrfs_root *root) { if (!trans || !trans->transaction) { struct inode *btree_inode; btree_inode = root->fs_info->btree_inode; return filemap_write_and_wait(btree_inode->i_mapping); } return btrfs_write_and_wait_marked_extents(root, &trans->transaction->dirty_pages, EXTENT_DIRTY); } /* * 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_root *tree_root = root->fs_info->tree_root; old_root_used = btrfs_root_used(&root->root_item); btrfs_write_dirty_block_groups(trans, root); 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); BUG_ON(ret); old_root_used = btrfs_root_used(&root->root_item); ret = btrfs_write_dirty_block_groups(trans, root); BUG_ON(ret); } if (root != root->fs_info->extent_root) switch_commit_root(root); return 0; } /* * update all the cowonly tree roots on disk */ static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans, struct btrfs_root *root) { struct btrfs_fs_info *fs_info = root->fs_info; struct list_head *next; struct extent_buffer *eb; int ret; ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1); BUG_ON(ret); eb = btrfs_lock_root_node(fs_info->tree_root); btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb); btrfs_tree_unlock(eb); free_extent_buffer(eb); ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1); BUG_ON(ret); while (!list_empty(&fs_info->dirty_cowonly_roots)) { next = fs_info->dirty_cowonly_roots.next; list_del_init(next); root = list_entry(next, struct btrfs_root, dirty_list); update_cowonly_root(trans, root); } down_write(&fs_info->extent_commit_sem); switch_commit_root(fs_info->extent_root); up_write(&fs_info->extent_commit_sem); return 0; } /* * 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 */ int btrfs_add_dead_root(struct btrfs_root *root) { spin_lock(&root->fs_info->trans_lock); list_add(&root->root_list, &root->fs_info->dead_roots); spin_unlock(&root->fs_info->trans_lock); return 0; } /* * update all the cowonly tree roots on disk */ static noinline int commit_fs_roots(struct btrfs_trans_handle *trans, struct btrfs_root *root) { struct btrfs_root *gang[8]; struct btrfs_fs_info *fs_info = root->fs_info; int i; int ret; int err = 0; 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++) { root = gang[i]; 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); btrfs_update_reloc_root(trans, root); btrfs_orphan_commit_root(trans, root); btrfs_save_ino_cache(root, trans); /* see comments in should_cow_block() */ root->force_cow = 0; smp_wmb(); if (root->commit_root != root->node) { mutex_lock(&root->fs_commit_mutex); switch_commit_root(root); btrfs_unpin_free_ino(root); mutex_unlock(&root->fs_commit_mutex); btrfs_set_root_node(&root->root_item, root->node); } err = btrfs_update_root(trans, fs_info->tree_root, &root->root_key, &root->root_item); spin_lock(&fs_info->fs_roots_radix_lock); if (err) break; } } spin_unlock(&fs_info->fs_roots_radix_lock); return err; } /* * defrag a given btree. If cacheonly == 1, this won't read from the disk, * otherwise every leaf in the btree is read and defragged. */ int btrfs_defrag_root(struct btrfs_root *root, int cacheonly) { struct btrfs_fs_info *info = root->fs_info; struct btrfs_trans_handle *trans; int ret; unsigned long nr; if (xchg(&root->defrag_running, 1)) return 0; while (1) { trans = btrfs_start_transaction(root, 0); if (IS_ERR(trans)) return PTR_ERR(trans); ret = btrfs_defrag_leaves(trans, root, cacheonly); nr = trans->blocks_used; btrfs_end_transaction(trans, root); btrfs_btree_balance_dirty(info->tree_root, nr); cond_resched(); if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN) break; } root->defrag_running = 0; return ret; } /* * new snapshots need to be created at a very specific time in the * transaction commit. This does the actual creation */ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, struct btrfs_fs_info *fs_info, struct btrfs_pending_snapshot *pending) { 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; struct dentry *parent; struct dentry *dentry; struct extent_buffer *tmp; struct extent_buffer *old; int ret; u64 to_reserve = 0; u64 index = 0; u64 objectid; u64 root_flags; rsv = trans->block_rsv; new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS); if (!new_root_item) { pending->error = -ENOMEM; goto fail; } ret = btrfs_find_free_objectid(tree_root, &objectid); if (ret) { pending->error = ret; goto fail; } btrfs_reloc_pre_snapshot(trans, pending, &to_reserve); if (to_reserve > 0) { ret = btrfs_block_rsv_add_noflush(root, &pending->block_rsv, to_reserve); if (ret) { pending->error = ret; goto fail; } } key.objectid = objectid; key.offset = (u64)-1; key.type = BTRFS_ROOT_ITEM_KEY; trans->block_rsv = &pending->block_rsv; dentry = pending->dentry; parent = dget_parent(dentry); parent_inode = parent->d_inode; parent_root = BTRFS_I(parent_inode)->root; record_root_in_trans(trans, parent_root); /* * insert the directory item */ ret = btrfs_set_inode_index(parent_inode, &index); BUG_ON(ret); ret = btrfs_insert_dir_item(trans, parent_root, dentry->d_name.name, dentry->d_name.len, parent_inode, &key, BTRFS_FT_DIR, index); if (ret) { pending->error = -EEXIST; dput(parent); goto fail; } btrfs_i_size_write(parent_inode, parent_inode->i_size + dentry->d_name.len * 2); ret = btrfs_update_inode(trans, parent_root, parent_inode); BUG_ON(ret); /* * pull in the delayed directory update * and the delayed inode item * otherwise we corrupt the FS during * snapshot */ ret = btrfs_run_delayed_items(trans, root); BUG_ON(ret); record_root_in_trans(trans, root); 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); old = btrfs_lock_root_node(root); btrfs_cow_block(trans, root, old, NULL, 0, &old); btrfs_set_lock_blocking(old); btrfs_copy_root(trans, root, old, &tmp, objectid); btrfs_tree_unlock(old); free_extent_buffer(old); /* see comments in should_cow_block() */ root->force_cow = 1; 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); BUG_ON(ret); /* * insert root back/forward references */ ret = btrfs_add_root_ref(trans, tree_root, objectid, parent_root->root_key.objectid, btrfs_ino(parent_inode), index, dentry->d_name.name, dentry->d_name.len); BUG_ON(ret); dput(parent); key.offset = (u64)-1; pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key); BUG_ON(IS_ERR(pending->snap)); btrfs_reloc_post_snapshot(trans, pending); fail: kfree(new_root_item); trans->block_rsv = rsv; btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1); return 0; } /* * create all the snapshots we've scheduled for creation */ static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans, struct btrfs_fs_info *fs_info) { struct btrfs_pending_snapshot *pending; struct list_head *head = &trans->transaction->pending_snapshots; list_for_each_entry(pending, head, list) create_pending_snapshot(trans, fs_info, pending); return 0; } static void update_super_roots(struct btrfs_root *root) { struct btrfs_root_item *root_item; struct btrfs_super_block *super; super = root->fs_info->super_copy; root_item = &root->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 = &root->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(root, SPACE_CACHE)) super->cache_generation = root_item->generation; } int btrfs_transaction_in_commit(struct btrfs_fs_info *info) { int ret = 0; spin_lock(&info->trans_lock); if (info->running_transaction) ret = info->running_transaction->in_commit; spin_unlock(&info->trans_lock); return ret; } int btrfs_transaction_blocked(struct btrfs_fs_info *info) { int ret = 0; spin_lock(&info->trans_lock); if (info->running_transaction) ret = info->running_transaction->blocked; spin_unlock(&info->trans_lock); return ret; } /* * wait for the current transaction commit to start and block subsequent * transaction joins */ static void wait_current_trans_commit_start(struct btrfs_root *root, struct btrfs_transaction *trans) { wait_event(root->fs_info->transaction_blocked_wait, trans->in_commit); } /* * wait for the current transaction to start and then become unblocked. * caller holds ref. */ static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root, struct btrfs_transaction *trans) { wait_event(root->fs_info->transaction_wait, trans->commit_done || (trans->in_commit && !trans->blocked)); } /* * commit transactions asynchronously. once btrfs_commit_transaction_async * returns, any subsequent transaction will not be allowed to join. */ struct btrfs_async_commit { struct btrfs_trans_handle *newtrans; struct btrfs_root *root; struct delayed_work work; }; static void do_async_commit(struct work_struct *work) { struct btrfs_async_commit *ac = container_of(work, struct btrfs_async_commit, work.work); btrfs_commit_transaction(ac->newtrans, ac->root); kfree(ac); } int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans, struct btrfs_root *root, int wait_for_unblock) { struct btrfs_async_commit *ac; struct btrfs_transaction *cur_trans; ac = kmalloc(sizeof(*ac), GFP_NOFS); if (!ac) return -ENOMEM; INIT_DELAYED_WORK(&ac->work, do_async_commit); ac->root = root; ac->newtrans = btrfs_join_transaction(root); if (IS_ERR(ac->newtrans)) { int err = PTR_ERR(ac->newtrans); kfree(ac); return err; } /* take transaction reference */ cur_trans = trans->transaction; atomic_inc(&cur_trans->use_count); btrfs_end_transaction(trans, root); schedule_delayed_work(&ac->work, 0); /* wait for transaction to start and unblock */ if (wait_for_unblock) wait_current_trans_commit_start_and_unblock(root, cur_trans); else wait_current_trans_commit_start(root, cur_trans); if (current->journal_info == trans) current->journal_info = NULL; put_transaction(cur_trans); return 0; } /* * btrfs_transaction state sequence: * in_commit = 0, blocked = 0 (initial) * in_commit = 1, blocked = 1 * blocked = 0 * commit_done = 1 */ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, struct btrfs_root *root) { unsigned long joined = 0; struct btrfs_transaction *cur_trans; struct btrfs_transaction *prev_trans = NULL; DEFINE_WAIT(wait); int ret; int should_grow = 0; unsigned long now = get_seconds(); int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT); btrfs_run_ordered_operations(root, 0); btrfs_trans_release_metadata(trans, root); trans->block_rsv = NULL; /* make a pass through all the delayed refs we have so far * any runnings procs may add more while we are here */ ret = btrfs_run_delayed_refs(trans, root, 0); BUG_ON(ret); cur_trans = trans->transaction; /* * set the flushing flag so procs in this transaction have to * start sending their work down. */ cur_trans->delayed_refs.flushing = 1; ret = btrfs_run_delayed_refs(trans, root, 0); BUG_ON(ret); spin_lock(&cur_trans->commit_lock); if (cur_trans->in_commit) { spin_unlock(&cur_trans->commit_lock); atomic_inc(&cur_trans->use_count); btrfs_end_transaction(trans, root); wait_for_commit(root, cur_trans); put_transaction(cur_trans); return 0; } trans->transaction->in_commit = 1; trans->transaction->blocked = 1; spin_unlock(&cur_trans->commit_lock); wake_up(&root->fs_info->transaction_blocked_wait); spin_lock(&root->fs_info->trans_lock); if (cur_trans->list.prev != &root->fs_info->trans_list) { prev_trans = list_entry(cur_trans->list.prev, struct btrfs_transaction, list); if (!prev_trans->commit_done) { atomic_inc(&prev_trans->use_count); spin_unlock(&root->fs_info->trans_lock); wait_for_commit(root, prev_trans); put_transaction(prev_trans); } else { spin_unlock(&root->fs_info->trans_lock); } } else { spin_unlock(&root->fs_info->trans_lock); } if (now < cur_trans->start_time || now - cur_trans->start_time < 1) should_grow = 1; do { int snap_pending = 0; joined = cur_trans->num_joined; if (!list_empty(&trans->transaction->pending_snapshots)) snap_pending = 1; WARN_ON(cur_trans != trans->transaction); if (flush_on_commit || snap_pending) { btrfs_start_delalloc_inodes(root, 1); ret = btrfs_wait_ordered_extents(root, 0, 1); BUG_ON(ret); } ret = btrfs_run_delayed_items(trans, root); BUG_ON(ret); /* * rename don't use btrfs_join_transaction, so, once we * set the transaction to blocked above, we aren't going * to get any new ordered operations. We can safely run * it here and no for sure that nothing new will be added * to the list */ btrfs_run_ordered_operations(root, 1); prepare_to_wait(&cur_trans->writer_wait, &wait, TASK_UNINTERRUPTIBLE); if (atomic_read(&cur_trans->num_writers) > 1) schedule_timeout(MAX_SCHEDULE_TIMEOUT); else if (should_grow) schedule_timeout(1); finish_wait(&cur_trans->writer_wait, &wait); } while (atomic_read(&cur_trans->num_writers) > 1 || (should_grow && cur_trans->num_joined != joined)); /* * 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 * no_join so make sure to wait for num_writers to == 1 again. */ spin_lock(&root->fs_info->trans_lock); root->fs_info->trans_no_join = 1; spin_unlock(&root->fs_info->trans_lock); wait_event(cur_trans->writer_wait, atomic_read(&cur_trans->num_writers) == 1); /* * 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(&root->fs_info->reloc_mutex); ret = btrfs_run_delayed_items(trans, root); BUG_ON(ret); ret = create_pending_snapshots(trans, root->fs_info); BUG_ON(ret); ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1); BUG_ON(ret); /* * make sure none of the code above managed to slip in a * delayed item */ btrfs_assert_delayed_root_empty(root); WARN_ON(cur_trans != trans->transaction); btrfs_scrub_pause(root); /* btrfs_commit_tree_roots is responsible for getting the * various roots consistent with each other. Every pointer * in the tree of tree roots has to point to the most up to date * root for every subvolume and other tree. So, we have to keep * the tree logging code from jumping in and changing any * of the trees. * * At this point in the commit, there can't be any tree-log * writers, but a little lower down we drop the trans mutex * and let new people in. By holding the tree_log_mutex * from now until after the super is written, we avoid races * with the tree-log code. */ mutex_lock(&root->fs_info->tree_log_mutex); ret = commit_fs_roots(trans, root); BUG_ON(ret); /* 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, root->fs_info); ret = commit_cowonly_roots(trans, root); BUG_ON(ret); btrfs_prepare_extent_commit(trans, root); cur_trans = root->fs_info->running_transaction; btrfs_set_root_node(&root->fs_info->tree_root->root_item, root->fs_info->tree_root->node); switch_commit_root(root->fs_info->tree_root); btrfs_set_root_node(&root->fs_info->chunk_root->root_item, root->fs_info->chunk_root->node); switch_commit_root(root->fs_info->chunk_root); update_super_roots(root); if (!root->fs_info->log_root_recovering) { btrfs_set_super_log_root(root->fs_info->super_copy, 0); btrfs_set_super_log_root_level(root->fs_info->super_copy, 0); } memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy, sizeof(*root->fs_info->super_copy)); trans->transaction->blocked = 0; spin_lock(&root->fs_info->trans_lock); root->fs_info->running_transaction = NULL; root->fs_info->trans_no_join = 0; spin_unlock(&root->fs_info->trans_lock); mutex_unlock(&root->fs_info->reloc_mutex); wake_up(&root->fs_info->transaction_wait); ret = btrfs_write_and_wait_transaction(trans, root); BUG_ON(ret); write_ctree_super(trans, root, 0); /* * the super is written, we can safely allow the tree-loggers * to go about their business */ mutex_unlock(&root->fs_info->tree_log_mutex); btrfs_finish_extent_commit(trans, root); cur_trans->commit_done = 1; root->fs_info->last_trans_committed = cur_trans->transid; wake_up(&cur_trans->commit_wait); spin_lock(&root->fs_info->trans_lock); list_del_init(&cur_trans->list); spin_unlock(&root->fs_info->trans_lock); put_transaction(cur_trans); put_transaction(cur_trans); trace_btrfs_transaction_commit(root); btrfs_scrub_continue(root); if (current->journal_info == trans) current->journal_info = NULL; kmem_cache_free(btrfs_trans_handle_cachep, trans); if (current != root->fs_info->transaction_kthread) btrfs_run_delayed_iputs(root); return ret; } /* * interface function to delete all the snapshots we have scheduled for deletion */ int btrfs_clean_old_snapshots(struct btrfs_root *root) { LIST_HEAD(list); struct btrfs_fs_info *fs_info = root->fs_info; spin_lock(&fs_info->trans_lock); list_splice_init(&fs_info->dead_roots, &list); spin_unlock(&fs_info->trans_lock); while (!list_empty(&list)) { root = list_entry(list.next, struct btrfs_root, root_list); list_del(&root->root_list); btrfs_kill_all_delayed_nodes(root); if (btrfs_header_backref_rev(root->node) < BTRFS_MIXED_BACKREF_REV) btrfs_drop_snapshot(root, NULL, 0, 0); else btrfs_drop_snapshot(root, NULL, 1, 0); } return 0; }