From e7ca2d41a029577a8cff453d1445951d4f96bfd8 Mon Sep 17 00:00:00 2001 From: Joern Engel Date: Wed, 6 Feb 2008 01:36:59 -0800 Subject: [PATCH] Document I_SYNC and I_DATASYNC After some archeology (see http://logfs.org/logfs/inode_state_bits) I finally figured out what the three I_DIRTY bits do. Maybe others would prefer less effort to reach this insight. Signed-off-by: Joern Engel Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/fs.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index ed289a9c5ccb..e260d9a32c21 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1279,8 +1279,10 @@ struct super_operations { * * Two bits are used for locking and completion notification, I_LOCK and I_SYNC. * - * I_DIRTY_SYNC Inode itself is dirty. - * I_DIRTY_DATASYNC Data-related inode changes pending + * I_DIRTY_SYNC Inode is dirty, but doesn't have to be written on + * fdatasync(). i_atime is the usual cause. + * I_DIRTY_DATASYNC Inode is dirty and must be written on fdatasync(), f.e. + * because i_size changed. * I_DIRTY_PAGES Inode has dirty pages. Inode itself may be clean. * I_NEW get_new_inode() sets i_state to I_LOCK|I_NEW. Both * are cleared by unlock_new_inode(), called from iget(). @@ -1312,8 +1314,6 @@ struct super_operations { * purpose reduces latency and prevents some filesystem- * specific deadlocks. * - * Q: Why does I_DIRTY_DATASYNC exist? It appears as if it could be replaced - * by (I_DIRTY_SYNC|I_DIRTY_PAGES). * Q: What is the difference between I_WILL_FREE and I_FREEING? * Q: igrab() only checks on (I_FREEING|I_WILL_FREE). Should it also check on * I_CLEAR? If not, why?