From 257c62e1bce03e5b9f3f069fd52ad73a56de71fd Mon Sep 17 00:00:00 2001 From: Chris Mason Date: Tue, 13 Oct 2009 13:21:08 -0400 Subject: Btrfs: avoid tree log commit when there are no changes rpm has a habit of running fdatasync when the file hasn't changed. We already detect if a file hasn't been changed in the current transaction but it might have been sent to the tree-log in this transaction and not changed since the last call to fsync. In this case, we want to avoid a tree log sync, which includes a number of synchronous writes and barriers. This commit extends the existing tracking of the last transaction to change a file to also track the last sub-transaction. The end result is that rpm -ivh and -Uvh are roughly twice as fast, and on par with ext3. Signed-off-by: Chris Mason --- fs/btrfs/tree-log.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) (limited to 'fs/btrfs/tree-log.c') diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c index 6d9ec285644d..0a1bde268963 100644 --- a/fs/btrfs/tree-log.c +++ b/fs/btrfs/tree-log.c @@ -1980,6 +1980,7 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans, int ret; struct btrfs_root *log = root->log_root; struct btrfs_root *log_root_tree = root->fs_info->log_root_tree; + u64 log_transid = 0; mutex_lock(&root->log_mutex); index1 = root->log_transid % 2; @@ -2018,6 +2019,7 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans, btrfs_set_root_node(&log->root_item, log->node); root->log_batch = 0; + log_transid = root->log_transid; root->log_transid++; log->log_transid = root->log_transid; root->log_start_pid = 0; @@ -2095,6 +2097,11 @@ int btrfs_sync_log(struct btrfs_trans_handle *trans, write_ctree_super(trans, root->fs_info->tree_root, 1); ret = 0; + mutex_lock(&root->log_mutex); + if (root->last_log_commit < log_transid) + root->last_log_commit = log_transid; + mutex_unlock(&root->log_mutex); + out_wake_log_root: atomic_set(&log_root_tree->log_commit[index2], 0); smp_mb(); @@ -2862,6 +2869,21 @@ out: return ret; } +static int inode_in_log(struct btrfs_trans_handle *trans, + struct inode *inode) +{ + struct btrfs_root *root = BTRFS_I(inode)->root; + int ret = 0; + + mutex_lock(&root->log_mutex); + if (BTRFS_I(inode)->logged_trans == trans->transid && + BTRFS_I(inode)->last_sub_trans <= root->last_log_commit) + ret = 1; + mutex_unlock(&root->log_mutex); + return ret; +} + + /* * helper function around btrfs_log_inode to make sure newly created * parent directories also end up in the log. A minimal inode and backref @@ -2901,6 +2923,11 @@ int btrfs_log_inode_parent(struct btrfs_trans_handle *trans, if (ret) goto end_no_trans; + if (inode_in_log(trans, inode)) { + ret = BTRFS_NO_LOG_SYNC; + goto end_no_trans; + } + start_log_trans(trans, root); ret = btrfs_log_inode(trans, root, inode, inode_only); -- cgit v1.2.3