From: Nikita Danilov Make the Locking document truer. Signed-off-by: Andrew Morton --- Documentation/filesystems/Locking | 8 ++++++-- 1 files changed, 6 insertions(+), 2 deletions(-) diff -puN Documentation/filesystems/Locking~doc-locking-update Documentation/filesystems/Locking --- 25/Documentation/filesystems/Locking~doc-locking-update 2005-04-26 20:41:20.744590488 -0700 +++ 25-akpm/Documentation/filesystems/Locking 2005-04-26 20:41:20.748589880 -0700 @@ -219,8 +219,12 @@ This may also be done to avoid internal 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, _