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authorChris Mason <chris.mason@oracle.com>2009-10-13 13:21:08 -0400
committerChris Mason <chris.mason@oracle.com>2009-10-13 13:35:12 -0400
commit257c62e1bce03e5b9f3f069fd52ad73a56de71fd (patch)
treead047fe5796156aa88e3f3600111bf2b8d12759f /fs/btrfs/tree-log.h
parent4722607db6a78bd7748c51fa4c8d7371da797254 (diff)
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 <chris.mason@oracle.com>
Diffstat (limited to 'fs/btrfs/tree-log.h')
-rw-r--r--fs/btrfs/tree-log.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/btrfs/tree-log.h b/fs/btrfs/tree-log.h
index d09c7609e16..0776eacb508 100644
--- a/fs/btrfs/tree-log.h
+++ b/fs/btrfs/tree-log.h
@@ -19,6 +19,9 @@
#ifndef __TREE_LOG_
#define __TREE_LOG_
+/* return value for btrfs_log_dentry_safe that means we don't need to log it at all */
+#define BTRFS_NO_LOG_SYNC 256
+
int btrfs_sync_log(struct btrfs_trans_handle *trans,
struct btrfs_root *root);
int btrfs_free_log(struct btrfs_trans_handle *trans, struct btrfs_root *root);