[PATCH] ext3 fsync() and fdatasync() speedup

ext3's fsync/fdatasync implementation is currently syncing the inode via a
full journal commit even if it was unaltered.

Fix that up by exporting the core VFS's inode sync function to modules and
calling it if the inode is dirty.  We need to do it this way so that the
inode is moved to the appropriate superblock list and so that the i_state
dirty flags are appropriately updated.

This speeds up ext3 fsync() for file overwrites by a factor of four (disk
non-writeback) to forty (disk in writeback mode).

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index e47f6360f74c..3e71560374c0 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -925,6 +925,7 @@ static inline void file_accessed(struct file *file)
 	touch_atime(file->f_vfsmnt, file->f_dentry);
 }
 
+int sync_inode(struct inode *inode, struct writeback_control *wbc);
 
 /**
  * &export_operations - for nfsd to communicate with file systems