Btrfs: smarter transaction writeback

Signed-off-by: Chris Mason <chris.mason@oracle.com>

4 files changed, 37 insertions, 3 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index afc5267515e2..652cf305a967 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -762,6 +762,7 @@ struct buffer_head *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
         BUG_ON(ret);
         buf = btrfs_find_create_tree_block(root, ins.objectid);
         set_buffer_uptodate(buf);
+        set_radix_bit(&trans->transaction->dirty_pages, buf->b_page->index);
         return buf;
 }
 
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index a10e902d3102..1890e8648dbd 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -980,7 +980,6 @@ static int btrfs_sync_fs(struct super_block *sb, int wait)
                 filemap_flush(root->fs_info->btree_inode->i_mapping);
                 return 0;
         }
-        filemap_write_and_wait(root->fs_info->btree_inode->i_mapping);
         mutex_lock(&root->fs_info->fs_mutex);
         trans = btrfs_start_transaction(root, 1);
         ret = btrfs_commit_transaction(trans, root);
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 8a2545f6a5b6..f9b8864dcc40 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -45,6 +45,7 @@ static int join_transaction(struct btrfs_root *root)
                 cur_trans->use_count = 1;
                 cur_trans->commit_done = 0;
                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
+                init_bit_radix(&cur_trans->dirty_pages);
         }
         cur_trans->num_writers++;
         return 0;
@@ -106,8 +107,40 @@ int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
                                      struct btrfs_root *root)
 {
-        filemap_write_and_wait(root->fs_info->btree_inode->i_mapping);
-        return 0;
+        unsigned long gang[16];
+        int ret;
+        int i;
+        int err;
+        int werr = 0;
+        struct page *page;
+        struct radix_tree_root *dirty_pages;
+        struct inode *btree_inode = root->fs_info->btree_inode;
+
+        if (!trans || !trans->transaction) {
+                return filemap_write_and_wait(btree_inode->i_mapping);
+        }
+        dirty_pages = &trans->transaction->dirty_pages;
+        while(1) {
+                ret = find_first_radix_bit(dirty_pages, gang, ARRAY_SIZE(gang));
+                if (!ret)
+                        break;
+                for (i = 0; i < ret; i++) {
+                        /* FIXME EIO */
+                        clear_radix_bit(dirty_pages, gang[i]);
+                        page = find_lock_page(btree_inode->i_mapping,
+                                              gang[i]);
+                        if (!page)
+                                continue;
+                        err = write_one_page(page, 0);
+                        if (err)
+                                werr = err;
+                        page_cache_release(page);
+                }
+        }
+        err = filemap_fdatawait(btree_inode->i_mapping);
+        if (err)
+                werr = err;
+        return werr;
 }
 
 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index 3cc29900a074..afe42d167cee 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -9,6 +9,7 @@ struct btrfs_transaction {
         int commit_done;
         int magic;
         struct list_head list;
+        struct radix_tree_root dirty_pages;
         wait_queue_head_t writer_wait;
         wait_queue_head_t commit_wait;
 };