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authorJoern Engel <joern@logfs.org>2008-02-06 01:36:59 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-06 10:41:03 -0800
commite7ca2d41a029577a8cff453d1445951d4f96bfd8 (patch)
tree60262e34e937ea9bfae7709a913ca940b928eae3 /include/linux/fs.h
parent20420bba13bf79c86cab1e5bdfc4c938d9e44bc9 (diff)
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 <joern@logfs.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/fs.h')
-rw-r--r--include/linux/fs.h8
1 files 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?