From 2054606ad6dd6fee559fe790f190b15ed9355237 Mon Sep 17 00:00:00 2001
From: Nikita Danilov <nikita@clusterfs.com>
Date: Sun, 1 May 2005 08:58:37 -0700
Subject: [PATCH] [PATCH] doc: Locking update

Make the Locking document truer.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
 Documentation/filesystems/Locking | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index a934baeeb33a28..1045da582b9b83 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -219,8 +219,12 @@ This may also be done to avoid internal deadlocks, but rarely.
 If the filesytem is called for sync then it must wait on any
 in-progress I/O and then start new I/O.
 
-The filesystem should unlock the page synchronously, before returning
-to the caller.
+The filesystem should unlock the page synchronously, before returning to the
+caller, unless ->writepage() returns special WRITEPAGE_ACTIVATE
+value. WRITEPAGE_ACTIVATE means that page cannot really be written out
+currently, and VM should stop calling ->writepage() on this page for some
+time. VM does this by moving page to the head of the active list, hence the
+name.
 
 Unless the filesystem is going to redirty_page_for_writepage(), unlock the page
 and return zero, writepage *must* run set_page_writeback() against the page,
-- 
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