Btrfs transactions are really just snapshots, but this provides an API
around safely coordinating them.
Signed-off-by: Chris Mason <chris.mason@xxxxxxxxxx>
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
new file mode 100644
index 0000000..8a08f94
--- /dev/null
+++ b/fs/btrfs/transaction.c
@@ -0,0 +1,1097 @@
+/*
+ * 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 <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/writeback.h>
+#include <linux/pagemap.h>
+#include <linux/blkdev.h>
+#include "ctree.h"
+#include "disk-io.h"
+#include "transaction.h"
+#include "locking.h"
+#include "ref-cache.h"
+#include "tree-log.h"
+
+#define BTRFS_ROOT_TRANS_TAG 0
+
+static noinline void put_transaction(struct btrfs_transaction *transaction)
+{
+ WARN_ON(transaction->use_count == 0);
+ transaction->use_count--;
+ if (transaction->use_count == 0) {
+ list_del_init(&transaction->list);
+ memset(transaction, 0, sizeof(*transaction));
+ kmem_cache_free(btrfs_transaction_cachep, transaction);
+ }
+}
+
+/*
+ * either allocate a new transaction or hop into the existing one
+ */
+static noinline int join_transaction(struct btrfs_root *root)
+{
+ struct btrfs_transaction *cur_trans;
+ cur_trans = root->fs_info->running_transaction;
+ if (!cur_trans) {
+ cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
+ GFP_NOFS);
+ BUG_ON(!cur_trans);
+ root->fs_info->generation++;
+ root->fs_info->last_alloc = 0;
+ root->fs_info->last_data_alloc = 0;
+ cur_trans->num_writers = 1;
+ cur_trans->num_joined = 0;
+ cur_trans->transid = root->fs_info->generation;
+ init_waitqueue_head(&cur_trans->writer_wait);
+ init_waitqueue_head(&cur_trans->commit_wait);
+ cur_trans->in_commit = 0;
+ cur_trans->blocked = 0;
+ cur_trans->use_count = 1;
+ cur_trans->commit_done = 0;
+ cur_trans->start_time = get_seconds();
+ 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,
+ GFP_NOFS);
+ spin_lock(&root->fs_info->new_trans_lock);
+ root->fs_info->running_transaction = cur_trans;
+ spin_unlock(&root->fs_info->new_trans_lock);
+ } else {
+ cur_trans->num_writers++;
+ cur_trans->num_joined++;
+ }
+
+ 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
+ */
+noinline int btrfs_record_root_in_trans(struct btrfs_root *root)
+{
+ struct btrfs_dirty_root *dirty;
+ u64 running_trans_id = root->fs_info->running_transaction->transid;
+ if (root->ref_cows && root->last_trans < running_trans_id) {
+ WARN_ON(root == root->fs_info->extent_root);
+ if (root->root_item.refs != 0) {
+ radix_tree_tag_set(&root->fs_info->fs_roots_radix,
+ (unsigned long)root->root_key.objectid,
+ BTRFS_ROOT_TRANS_TAG);
+
+ dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
+ BUG_ON(!dirty);
+ dirty->root = kmalloc(sizeof(*dirty->root), GFP_NOFS);
+ BUG_ON(!dirty->root);
+ dirty->latest_root = root;
+ INIT_LIST_HEAD(&dirty->list);
+
+ root->commit_root = btrfs_root_node(root);
+
+ memcpy(dirty->root, root, sizeof(*root));
+ spin_lock_init(&dirty->root->node_lock);
+ spin_lock_init(&dirty->root->list_lock);
+ mutex_init(&dirty->root->objectid_mutex);
+ mutex_init(&dirty->root->log_mutex);
+ INIT_LIST_HEAD(&dirty->root->dead_list);
+ dirty->root->node = root->commit_root;
+ dirty->root->commit_root = NULL;
+
+ spin_lock(&root->list_lock);
+ list_add(&dirty->root->dead_list, &root->dead_list);
+ spin_unlock(&root->list_lock);
+
+ root->dirty_root = dirty;
+ } else {
+ WARN_ON(1);
+ }
+ root->last_trans = running_trans_id;
+ }
+ 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;
+
+ cur_trans = root->fs_info->running_transaction;
+ if (cur_trans && cur_trans->blocked) {
+ DEFINE_WAIT(wait);
+ cur_trans->use_count++;
+ while (1) {
+ prepare_to_wait(&root->fs_info->transaction_wait, &wait,
+ TASK_UNINTERRUPTIBLE);
+ if (cur_trans->blocked) {
+ mutex_unlock(&root->fs_info->trans_mutex);
+ schedule();
+ mutex_lock(&root->fs_info->trans_mutex);
+ finish_wait(&root->fs_info->transaction_wait,
+ &wait);
+ } else {
+ finish_wait(&root->fs_info->transaction_wait,
+ &wait);
+ break;
+ }
+ }
+ put_transaction(cur_trans);
+ }
+}
+
+static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
+ int num_blocks, int wait)
+{
+ struct btrfs_trans_handle *h =
+ kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
+ int ret;
+
+ mutex_lock(&root->fs_info->trans_mutex);
+ if (!root->fs_info->log_root_recovering &&
+ ((wait == 1 && !root->fs_info->open_ioctl_trans) || wait == 2))
+ wait_current_trans(root);
+ ret = join_transaction(root);
+ BUG_ON(ret);
+
+ btrfs_record_root_in_trans(root);
+ h->transid = root->fs_info->running_transaction->transid;
+ h->transaction = root->fs_info->running_transaction;
+ h->blocks_reserved = num_blocks;
+ h->blocks_used = 0;
+ h->block_group = 0;
+ h->alloc_exclude_nr = 0;
+ h->alloc_exclude_start = 0;
+ root->fs_info->running_transaction->use_count++;
+ mutex_unlock(&root->fs_info->trans_mutex);
+ return h;
+}
+
+struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
+ int num_blocks)
+{
+ return start_transaction(root, num_blocks, 1);
+}
+struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
+ int num_blocks)
+{
+ return start_transaction(root, num_blocks, 0);
+}
+
+struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
+ int num_blocks)
+{
+ return start_transaction(r, num_blocks, 2);
+}
+
+/* wait for a transaction commit to be fully complete */
+static noinline int wait_for_commit(struct btrfs_root *root,
+ struct btrfs_transaction *commit)
+{
+ DEFINE_WAIT(wait);
+ mutex_lock(&root->fs_info->trans_mutex);
+ while (!commit->commit_done) {
+ prepare_to_wait(&commit->commit_wait, &wait,
+ TASK_UNINTERRUPTIBLE);
+ if (commit->commit_done)
+ break;
+ mutex_unlock(&root->fs_info->trans_mutex);
+ schedule();
+ mutex_lock(&root->fs_info->trans_mutex);
+ }
+ mutex_unlock(&root->fs_info->trans_mutex);
+ finish_wait(&commit->commit_wait, &wait);
+ return 0;
+}
+
+/*
+ * rate limit against the drop_snapshot code. This helps to slow down new
+ * operations if the drop_snapshot code isn't able to keep up.
+ */
+static void throttle_on_drops(struct btrfs_root *root)
+{
+ struct btrfs_fs_info *info = root->fs_info;
+ int harder_count = 0;
+
+harder:
+ if (atomic_read(&info->throttles)) {
+ DEFINE_WAIT(wait);
+ int thr;
+ thr = atomic_read(&info->throttle_gen);
+
+ do {
+ prepare_to_wait(&info->transaction_throttle,
+ &wait, TASK_UNINTERRUPTIBLE);
+ if (!atomic_read(&info->throttles)) {
+ finish_wait(&info->transaction_throttle, &wait);
+ break;
+ }
+ schedule();
+ finish_wait(&info->transaction_throttle, &wait);
+ } while (thr == atomic_read(&info->throttle_gen));
+ harder_count++;
+
+ if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
+ harder_count < 2)
+ goto harder;
+
+ if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
+ harder_count < 10)
+ goto harder;
+
+ if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
+ harder_count < 20)
+ goto harder;
+ }
+}
+
+void btrfs_throttle(struct btrfs_root *root)
+{
+ mutex_lock(&root->fs_info->trans_mutex);
+ if (!root->fs_info->open_ioctl_trans)
+ wait_current_trans(root);
+ mutex_unlock(&root->fs_info->trans_mutex);
+
+ throttle_on_drops(root);
+}
+
+static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root, int throttle)
+{
+ struct btrfs_transaction *cur_trans;
+ struct btrfs_fs_info *info = root->fs_info;
+
+ mutex_lock(&info->trans_mutex);
+ cur_trans = info->running_transaction;
+ WARN_ON(cur_trans != trans->transaction);
+ WARN_ON(cur_trans->num_writers < 1);
+ cur_trans->num_writers--;
+
+ if (waitqueue_active(&cur_trans->writer_wait))
+ wake_up(&cur_trans->writer_wait);
+ put_transaction(cur_trans);
+ mutex_unlock(&info->trans_mutex);
+ memset(trans, 0, sizeof(*trans));
+ kmem_cache_free(btrfs_trans_handle_cachep, trans);
+
+ if (throttle)
+ throttle_on_drops(root);
+
+ return 0;
+}
+
+int btrfs_end_transaction(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root)
+{
+ return __btrfs_end_transaction(trans, root, 0);
+}
+
+int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root)
+{
+ return __btrfs_end_transaction(trans, root, 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 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 ret;
+ int err = 0;
+ int werr = 0;
+ struct page *page;
+ struct inode *btree_inode = root->fs_info->btree_inode;
+ u64 start = 0;
+ u64 end;
+ unsigned long index;
+
+ while (1) {
+ ret = find_first_extent_bit(dirty_pages, start, &start, &end,
+ EXTENT_DIRTY);
+ if (ret)
+ break;
+ while (start <= end) {
+ cond_resched();
+
+ index = start >> PAGE_CACHE_SHIFT;
+ start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
+ page = find_get_page(btree_inode->i_mapping, index);
+ if (!page)
+ continue;
+
+ btree_lock_page_hook(page);
+ if (!page->mapping) {
+ unlock_page(page);
+ page_cache_release(page);
+ continue;
+ }
+
+ if (PageWriteback(page)) {
+ if (PageDirty(page))
+ wait_on_page_writeback(page);
+ else {
+ unlock_page(page);
+ page_cache_release(page);
+ continue;
+ }
+ }
+ err = write_one_page(page, 0);
+ if (err)
+ werr = err;
+ page_cache_release(page);
+ }
+ }
+ while (1) {
+ ret = find_first_extent_bit(dirty_pages, 0, &start, &end,
+ EXTENT_DIRTY);
+ if (ret)
+ break;
+
+ clear_extent_dirty(dirty_pages, start, end, GFP_NOFS);
+ while (start <= end) {
+ index = start >> PAGE_CACHE_SHIFT;
+ start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
+ page = find_get_page(btree_inode->i_mapping, index);
+ if (!page)
+ continue;
+ if (PageDirty(page)) {
+ btree_lock_page_hook(page);
+ wait_on_page_writeback(page);
+ err = write_one_page(page, 0);
+ if (err)
+ werr = err;
+ }
+ wait_on_page_writeback(page);
+ page_cache_release(page);
+ cond_resched();
+ }
+ }
+ if (err)
+ werr = err;
+ return werr;
+}
+
+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);
+}
+
+/*
+ * 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;
+ struct btrfs_root *tree_root = root->fs_info->tree_root;
+
+ btrfs_extent_post_op(trans, root);
+ btrfs_write_dirty_block_groups(trans, root);
+ btrfs_extent_post_op(trans, root);
+
+ while (1) {
+ old_root_bytenr = btrfs_root_bytenr(&root->root_item);
+ if (old_root_bytenr == root->node->start)
+ break;
+ btrfs_set_root_bytenr(&root->root_item,
+ root->node->start);
+ btrfs_set_root_level(&root->root_item,
+ btrfs_header_level(root->node));
+ btrfs_set_root_generation(&root->root_item, trans->transid);
+
+ btrfs_extent_post_op(trans, root);
+
+ ret = btrfs_update_root(trans, tree_root,
+ &root->root_key,
+ &root->root_item);
+ BUG_ON(ret);
+ btrfs_write_dirty_block_groups(trans, root);
+ btrfs_extent_post_op(trans, root);
+ }
+ return 0;
+}
+
+/*
+ * update all the cowonly tree roots on disk
+ */
+int btrfs_commit_tree_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;
+
+ btrfs_extent_post_op(trans, fs_info->tree_root);
+
+ eb = btrfs_lock_root_node(fs_info->tree_root);
+ btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb, 0);
+ btrfs_tree_unlock(eb);
+ free_extent_buffer(eb);
+
+ btrfs_extent_post_op(trans, fs_info->tree_root);
+
+ 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);
+ }
+ 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, struct btrfs_root *latest)
+{
+ struct btrfs_dirty_root *dirty;
+
+ dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
+ if (!dirty)
+ return -ENOMEM;
+ dirty->root = root;
+ dirty->latest_root = latest;
+
+ mutex_lock(&root->fs_info->trans_mutex);
+ list_add(&dirty->list, &latest->fs_info->dead_roots);
+ mutex_unlock(&root->fs_info->trans_mutex);
+ return 0;
+}
+
+/*
+ * at transaction commit time we need to schedule the old roots for
+ * deletion via btrfs_drop_snapshot. This runs through all the
+ * reference counted roots that were modified in the current
+ * transaction and puts them into the drop list
+ */
+static noinline int add_dirty_roots(struct btrfs_trans_handle *trans,
+ struct radix_tree_root *radix,
+ struct list_head *list)
+{
+ struct btrfs_dirty_root *dirty;
+ struct btrfs_root *gang[8];
+ struct btrfs_root *root;
+ int i;
+ int ret;
+ int err = 0;
+ u32 refs;
+
+ while (1) {
+ ret = radix_tree_gang_lookup_tag(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(radix,
+ (unsigned long)root->root_key.objectid,
+ BTRFS_ROOT_TRANS_TAG);
+
+ BUG_ON(!root->ref_tree);
+ dirty = root->dirty_root;
+
+ btrfs_free_log(trans, root);
+ btrfs_free_reloc_root(trans, root);
+
+ if (root->commit_root == root->node) {
+ WARN_ON(root->node->start !=
+ btrfs_root_bytenr(&root->root_item));
+
+ free_extent_buffer(root->commit_root);
+ root->commit_root = NULL;
+ root->dirty_root = NULL;
+
+ spin_lock(&root->list_lock);
+ list_del_init(&dirty->root->dead_list);
+ spin_unlock(&root->list_lock);
+
+ kfree(dirty->root);
+ kfree(dirty);
+
+ /* make sure to update the root on disk
+ * so we get any updates to the block used
+ * counts
+ */
+ err = btrfs_update_root(trans,
+ root->fs_info->tree_root,
+ &root->root_key,
+ &root->root_item);
+ continue;
+ }
+
+ memset(&root->root_item.drop_progress, 0,
+ sizeof(struct btrfs_disk_key));
+ root->root_item.drop_level = 0;
+ root->commit_root = NULL;
+ root->dirty_root = NULL;
+ root->root_key.offset = root->fs_info->generation;
+ btrfs_set_root_bytenr(&root->root_item,
+ root->node->start);
+ btrfs_set_root_level(&root->root_item,
+ btrfs_header_level(root->node));
+ btrfs_set_root_generation(&root->root_item,
+ root->root_key.offset);
+
+ err = btrfs_insert_root(trans, root->fs_info->tree_root,
+ &root->root_key,
+ &root->root_item);
+ if (err)
+ break;
+
+ refs = btrfs_root_refs(&dirty->root->root_item);
+ btrfs_set_root_refs(&dirty->root->root_item, refs - 1);
+ err = btrfs_update_root(trans, root->fs_info->tree_root,
+ &dirty->root->root_key,
+ &dirty->root->root_item);
+
+ BUG_ON(err);
+ if (refs == 1) {
+ list_add(&dirty->list, list);
+ } else {
+ WARN_ON(1);
+ free_extent_buffer(dirty->root->node);
+ kfree(dirty->root);
+ kfree(dirty);
+ }
+ }
+ }
+ 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;
+ int ret;
+ struct btrfs_trans_handle *trans;
+ unsigned long nr;
+
+ smp_mb();
+ if (root->defrag_running)
+ return 0;
+ trans = btrfs_start_transaction(root, 1);
+ while (1) {
+ root->defrag_running = 1;
+ 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();
+
+ trans = btrfs_start_transaction(root, 1);
+ if (root->fs_info->closing || ret != -EAGAIN)
+ break;
+ }
+ root->defrag_running = 0;
+ smp_mb();
+ btrfs_end_transaction(trans, root);
+ return 0;
+}
+
+/*
+ * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on
+ * all of them
+ */
+static noinline int drop_dirty_roots(struct btrfs_root *tree_root,
+ struct list_head *list)
+{
+ struct btrfs_dirty_root *dirty;
+ struct btrfs_trans_handle *trans;
+ unsigned long nr;
+ u64 num_bytes;
+ u64 bytes_used;
+ u64 max_useless;
+ int ret = 0;
+ int err;
+
+ while (!list_empty(list)) {
+ struct btrfs_root *root;
+
+ dirty = list_entry(list->prev, struct btrfs_dirty_root, list);
+ list_del_init(&dirty->list);
+
+ num_bytes = btrfs_root_used(&dirty->root->root_item);
+ root = dirty->latest_root;
+ atomic_inc(&root->fs_info->throttles);
+
+ while (1) {
+ trans = btrfs_start_transaction(tree_root, 1);
+ mutex_lock(&root->fs_info->drop_mutex);
+ ret = btrfs_drop_snapshot(trans, dirty->root);
+ if (ret != -EAGAIN)
+ break;
+ mutex_unlock(&root->fs_info->drop_mutex);
+
+ err = btrfs_update_root(trans,
+ tree_root,
+ &dirty->root->root_key,
+ &dirty->root->root_item);
+ if (err)
+ ret = err;
+ nr = trans->blocks_used;
+ ret = btrfs_end_transaction(trans, tree_root);
+ BUG_ON(ret);
+
+ btrfs_btree_balance_dirty(tree_root, nr);
+ cond_resched();
+ }
+ BUG_ON(ret);
+ atomic_dec(&root->fs_info->throttles);
+ wake_up(&root->fs_info->transaction_throttle);
+
+ num_bytes -= btrfs_root_used(&dirty->root->root_item);
+ bytes_used = btrfs_root_used(&root->root_item);
+ if (num_bytes) {
+ btrfs_record_root_in_trans(root);
+ btrfs_set_root_used(&root->root_item,
+ bytes_used - num_bytes);
+ }
+
+ ret = btrfs_del_root(trans, tree_root, &dirty->root->root_key);
+ if (ret) {
+ BUG();
+ break;
+ }
+ mutex_unlock(&root->fs_info->drop_mutex);
+
+ spin_lock(&root->list_lock);
+ list_del_init(&dirty->root->dead_list);
+ if (!list_empty(&root->dead_list)) {
+ struct btrfs_root *oldest;
+ oldest = list_entry(root->dead_list.prev,
+ struct btrfs_root, dead_list);
+ max_useless = oldest->root_key.offset - 1;
+ } else {
+ max_useless = root->root_key.offset - 1;
+ }
+ spin_unlock(&root->list_lock);
+
+ nr = trans->blocks_used;
+ ret = btrfs_end_transaction(trans, tree_root);
+ BUG_ON(ret);
+
+ ret = btrfs_remove_leaf_refs(root, max_useless, 0);
+ BUG_ON(ret);
+
+ free_extent_buffer(dirty->root->node);
+ kfree(dirty->root);
+ kfree(dirty);
+
+ btrfs_btree_balance_dirty(tree_root, nr);
+ cond_resched();
+ }
+ 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 extent_buffer *tmp;
+ struct extent_buffer *old;
+ int ret;
+ u64 objectid;
+
+ new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
+ if (!new_root_item) {
+ ret = -ENOMEM;
+ goto fail;
+ }
+ ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
+ if (ret)
+ goto fail;
+
+ btrfs_record_root_in_trans(root);
+ btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
+ memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
+
+ key.objectid = objectid;
+ key.offset = trans->transid;
+ btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
+
+ old = btrfs_lock_root_node(root);
+ btrfs_cow_block(trans, root, old, NULL, 0, &old, 0);
+
+ btrfs_copy_root(trans, root, old, &tmp, objectid);
+ btrfs_tree_unlock(old);
+ free_extent_buffer(old);
+
+ btrfs_set_root_bytenr(new_root_item, tmp->start);
+ btrfs_set_root_level(new_root_item, btrfs_header_level(tmp));
+ btrfs_set_root_generation(new_root_item, trans->transid);
+ ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
+ new_root_item);
+ btrfs_tree_unlock(tmp);
+ free_extent_buffer(tmp);
+ if (ret)
+ goto fail;
+
+ key.offset = (u64)-1;
+ memcpy(&pending->root_key, &key, sizeof(key));
+fail:
+ kfree(new_root_item);
+ return ret;
+}
+
+static noinline int finish_pending_snapshot(struct btrfs_fs_info *fs_info,
+ struct btrfs_pending_snapshot *pending)
+{
+ int ret;
+ int namelen;
+ u64 index = 0;
+ struct btrfs_trans_handle *trans;
+ struct inode *parent_inode;
+ struct inode *inode;
+ struct btrfs_root *parent_root;
+
+ parent_inode = pending->dentry->d_parent->d_inode;
+ parent_root = BTRFS_I(parent_inode)->root;
+ trans = btrfs_join_transaction(parent_root, 1);
+
+ /*
+ * insert the directory item
+ */
+ namelen = strlen(pending->name);
+ ret = btrfs_set_inode_index(parent_inode, &index);
+ ret = btrfs_insert_dir_item(trans, parent_root,
+ pending->name, namelen,
+ parent_inode->i_ino,
+ &pending->root_key, BTRFS_FT_DIR, index);
+
+ if (ret)
+ goto fail;
+
+ btrfs_i_size_write(parent_inode, parent_inode->i_size + namelen * 2);
+ ret = btrfs_update_inode(trans, parent_root, parent_inode);
+ BUG_ON(ret);
+
+ /* add the backref first */
+ ret = btrfs_add_root_ref(trans, parent_root->fs_info->tree_root,
+ pending->root_key.objectid,
+ BTRFS_ROOT_BACKREF_KEY,
+ parent_root->root_key.objectid,
+ parent_inode->i_ino, index, pending->name,
+ namelen);
+
+ BUG_ON(ret);
+
+ /* now add the forward ref */
+ ret = btrfs_add_root_ref(trans, parent_root->fs_info->tree_root,
+ parent_root->root_key.objectid,
+ BTRFS_ROOT_REF_KEY,
+ pending->root_key.objectid,
+ parent_inode->i_ino, index, pending->name,
+ namelen);
+
+ inode = btrfs_lookup_dentry(parent_inode, pending->dentry);
+ d_instantiate(pending->dentry, inode);
+fail:
+ btrfs_end_transaction(trans, fs_info->fs_root);
+ return ret;
+}
+
+/*
+ * 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;
+ struct list_head *cur;
+ int ret;
+
+ list_for_each(cur, head) {
+ pending = list_entry(cur, struct btrfs_pending_snapshot, list);
+ ret = create_pending_snapshot(trans, fs_info, pending);
+ BUG_ON(ret);
+ }
+ return 0;
+}
+
+static noinline int finish_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;
+ int ret;
+
+ while (!list_empty(head)) {
+ pending = list_entry(head->next,
+ struct btrfs_pending_snapshot, list);
+ ret = finish_pending_snapshot(fs_info, pending);
+ BUG_ON(ret);
+ list_del(&pending->list);
+ kfree(pending->name);
+ kfree(pending);
+ }
+ return 0;
+}
+
+int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root)
+{
+ unsigned long joined = 0;
+ unsigned long timeout = 1;
+ struct btrfs_transaction *cur_trans;
+ struct btrfs_transaction *prev_trans = NULL;
+ struct btrfs_root *chunk_root = root->fs_info->chunk_root;
+ struct list_head dirty_fs_roots;
+ struct extent_io_tree *pinned_copy;
+ DEFINE_WAIT(wait);
+ int ret;
+
+ INIT_LIST_HEAD(&dirty_fs_roots);
+ mutex_lock(&root->fs_info->trans_mutex);
+ if (trans->transaction->in_commit) {
+ cur_trans = trans->transaction;
+ trans->transaction->use_count++;
+ mutex_unlock(&root->fs_info->trans_mutex);
+ btrfs_end_transaction(trans, root);
+
+ ret = wait_for_commit(root, cur_trans);
+ BUG_ON(ret);
+
+ mutex_lock(&root->fs_info->trans_mutex);
+ put_transaction(cur_trans);
+ mutex_unlock(&root->fs_info->trans_mutex);
+
+ return 0;
+ }
+
+ pinned_copy = kmalloc(sizeof(*pinned_copy), GFP_NOFS);
+ if (!pinned_copy)
+ return -ENOMEM;
+
+ extent_io_tree_init(pinned_copy,
+ root->fs_info->btree_inode->i_mapping, GFP_NOFS);
+
+ trans->transaction->in_commit = 1;
+ trans->transaction->blocked = 1;
+ cur_trans = trans->transaction;
+ 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) {
+ prev_trans->use_count++;
+ mutex_unlock(&root->fs_info->trans_mutex);
+
+ wait_for_commit(root, prev_trans);
+
+ mutex_lock(&root->fs_info->trans_mutex);
+ put_transaction(prev_trans);
+ }
+ }
+
+ 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);
+ prepare_to_wait(&cur_trans->writer_wait, &wait,
+ TASK_UNINTERRUPTIBLE);
+
+ if (cur_trans->num_writers > 1)
+ timeout = MAX_SCHEDULE_TIMEOUT;
+ else
+ timeout = 1;
+
+ mutex_unlock(&root->fs_info->trans_mutex);
+
+ if (snap_pending) {
+ ret = btrfs_wait_ordered_extents(root, 1);
+ BUG_ON(ret);
+ }
+
+ schedule_timeout(timeout);
+
+ mutex_lock(&root->fs_info->trans_mutex);
+ finish_wait(&cur_trans->writer_wait, &wait);
+ } while (cur_trans->num_writers > 1 ||
+ (cur_trans->num_joined != joined));
+
+ ret = create_pending_snapshots(trans, root->fs_info);
+ BUG_ON(ret);
+
+ WARN_ON(cur_trans != trans->transaction);
+
+ /* 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);
+ /*
+ * keep tree reloc code from adding new reloc trees
+ */
+ mutex_lock(&root->fs_info->tree_reloc_mutex);
+
+
+ ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
+ &dirty_fs_roots);
+ BUG_ON(ret);
+
+ /* add_dirty_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 = btrfs_commit_tree_roots(trans, root);
+ BUG_ON(ret);
+
+ cur_trans = root->fs_info->running_transaction;
+ spin_lock(&root->fs_info->new_trans_lock);
+ root->fs_info->running_transaction = NULL;
+ spin_unlock(&root->fs_info->new_trans_lock);
+ btrfs_set_super_generation(&root->fs_info->super_copy,
+ cur_trans->transid);
+ btrfs_set_super_root(&root->fs_info->super_copy,
+ root->fs_info->tree_root->node->start);
+ btrfs_set_super_root_level(&root->fs_info->super_copy,
+ btrfs_header_level(root->fs_info->tree_root->node));
+
+ btrfs_set_super_chunk_root(&root->fs_info->super_copy,
+ chunk_root->node->start);
+ btrfs_set_super_chunk_root_level(&root->fs_info->super_copy,
+ btrfs_header_level(chunk_root->node));
+ btrfs_set_super_chunk_root_generation(&root->fs_info->super_copy,
+ btrfs_header_generation(chunk_root->node));
+
+ 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));
+
+ btrfs_copy_pinned(root, pinned_copy);
+
+ trans->transaction->blocked = 0;
+ wake_up(&root->fs_info->transaction_throttle);
+ wake_up(&root->fs_info->transaction_wait);
+
+ mutex_unlock(&root->fs_info->trans_mutex);
+ 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, pinned_copy);
+ kfree(pinned_copy);
+
+ btrfs_drop_dead_reloc_roots(root);
+ mutex_unlock(&root->fs_info->tree_reloc_mutex);
+
+ /* do the directory inserts of any pending snapshot creations */
+ finish_pending_snapshots(trans, root->fs_info);
+
+ mutex_lock(&root->fs_info->trans_mutex);
+
+ cur_trans->commit_done = 1;
+ root->fs_info->last_trans_committed = cur_trans->transid;
+ wake_up(&cur_trans->commit_wait);
+
+ put_transaction(cur_trans);
+ put_transaction(cur_trans);
+
+ list_splice_init(&dirty_fs_roots, &root->fs_info->dead_roots);
+ if (root->fs_info->closing)
+ list_splice_init(&root->fs_info->dead_roots, &dirty_fs_roots);
+
+ mutex_unlock(&root->fs_info->trans_mutex);
+
+ kmem_cache_free(btrfs_trans_handle_cachep, trans);
+
+ if (root->fs_info->closing)
+ drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
+ return ret;
+}
+
+/*
+ * interface function to delete all the snapshots we have scheduled for deletion
+ */
+int btrfs_clean_old_snapshots(struct btrfs_root *root)
+{
+ struct list_head dirty_roots;
+ INIT_LIST_HEAD(&dirty_roots);
+again:
+ mutex_lock(&root->fs_info->trans_mutex);
+ list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
+ mutex_unlock(&root->fs_info->trans_mutex);
+
+ if (!list_empty(&dirty_roots)) {
+ drop_dirty_roots(root, &dirty_roots);
+ goto again;
+ }
+ return 0;
+}
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
new file mode 100644
index 0000000..ea29211
--- /dev/null
+++ b/fs/btrfs/transaction.h
@@ -0,0 +1,106 @@
+/*
+ * 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.
+ */
+
+#ifndef __BTRFS_TRANSACTION__
+#define __BTRFS_TRANSACTION__
+#include "btrfs_inode.h"
+
+struct btrfs_transaction {
+ u64 transid;
+ unsigned long num_writers;
+ unsigned long num_joined;
+ int in_commit;
+ int use_count;
+ int commit_done;
+ int blocked;
+ struct list_head list;
+ struct extent_io_tree dirty_pages;
+ unsigned long start_time;
+ wait_queue_head_t writer_wait;
+ wait_queue_head_t commit_wait;
+ struct list_head pending_snapshots;
+};
+
+struct btrfs_trans_handle {
+ u64 transid;
+ unsigned long blocks_reserved;
+ unsigned long blocks_used;
+ struct btrfs_transaction *transaction;
+ u64 block_group;
+ u64 alloc_exclude_start;
+ u64 alloc_exclude_nr;
+};
+
+struct btrfs_pending_snapshot {
+ struct dentry *dentry;
+ struct btrfs_root *root;
+ char *name;
+ struct btrfs_key root_key;
+ struct list_head list;
+};
+
+struct btrfs_dirty_root {
+ struct list_head list;
+ struct btrfs_root *root;
+ struct btrfs_root *latest_root;
+};
+
+static inline void btrfs_set_trans_block_group(struct btrfs_trans_handle *trans,
+ struct inode *inode)
+{
+ trans->block_group = BTRFS_I(inode)->block_group;
+}
+
+static inline void btrfs_update_inode_block_group(
+ struct btrfs_trans_handle *trans,
+ struct inode *inode)
+{
+ BTRFS_I(inode)->block_group = trans->block_group;
+}
+
+static inline void btrfs_set_inode_last_trans(struct btrfs_trans_handle *trans,
+ struct inode *inode)
+{
+ BTRFS_I(inode)->last_trans = trans->transaction->transid;
+}
+
+int btrfs_end_transaction(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root);
+struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
+ int num_blocks);
+struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
+ int num_blocks);
+struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
+ int num_blocks);
+int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root);
+int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root);
+
+int btrfs_add_dead_root(struct btrfs_root *root, struct btrfs_root *latest);
+int btrfs_defrag_root(struct btrfs_root *root, int cacheonly);
+int btrfs_clean_old_snapshots(struct btrfs_root *root);
+int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root);
+int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
+ struct btrfs_root *root);
+void btrfs_throttle(struct btrfs_root *root);
+int btrfs_record_root_in_trans(struct btrfs_root *root);
+int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
+ struct extent_io_tree *dirty_pages);
+#endif
--
1.6.0.2
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