[PATCH] add AOP_TRUNCATED_PAGE, prepend AOP_ to WRITEPAGE_ACTIVATE

[net-next-2.6.git] / include / linux / fs.h

diff --git a/include/linux/fs.h b/include/linux/fs.h
index cc35b6ac778d6778f51a5112bc2569b9c1f563f4..ed9a41a71e8b57ff62ea245fbbe46e586d74c5ee 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -302,6 +302,37 @@ struct iattr {
  */
 #include <linux/quota.h>
 
+/** 
+ * enum positive_aop_returns - aop return codes with specific semantics
+ *
+ * @AOP_WRITEPAGE_ACTIVATE: Informs the caller that page writeback has
+ *                         completed, that the page is still locked, and
+ *                         should be considered active.  The VM uses this hint
+ *                         to return the page to the active list -- it won't
+ *                         be a candidate for writeback again in the near
+ *                         future.  Other callers must be careful to unlock
+ *                         the page if they get this return.  Returned by
+ *                         writepage(); 
+ *
+ * @AOP_TRUNCATED_PAGE: The AOP method that was handed a locked page has
+ *                     unlocked it and the page might have been truncated.
+ *                     The caller should back up to acquiring a new page and
+ *                     trying again.  The aop will be taking reasonable
+ *                     precautions not to livelock.  If the caller held a page
+ *                     reference, it should drop it before retrying.  Returned
+ *                     by readpage(), prepare_write(), and commit_write().
+ *
+ * address_space_operation functions return these large constants to indicate
+ * special semantics to the caller.  These are much larger than the bytes in a
+ * page to allow for functions that return the number of bytes operated on in a
+ * given page.
+ */
+
+enum positive_aop_returns {
+       AOP_WRITEPAGE_ACTIVATE  = 0x80000,
+       AOP_TRUNCATED_PAGE      = 0x80001,
+};
+
 /*
  * oh the beauties of C type declarations.
  */