Add explanation of I_DIRTY_DATASYNC bit.
Signed-off-by: Jan Kara <[EMAIL PROTECTED]>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 56bd421..475125e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1280,7 +1280,10 @@ 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_DATASYNC Data-related inode changes pending. We keep track of
+ * ` these changes separately from I_DIRTY_SYNC so that we
+ * don't have to write inode on fdatasync() when only
+ * mtime has changed in it.
* 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 +1315,6 @@ 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?
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