diff options
| -rw-r--r-- | Documentation/filesystems/Locking | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking index a934baeeb33a..1045da582b9b 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, |