centos man page for enum_positive_aop_returns

ENUM 
POSITIVE_AOP_RE(9) 					   The Linux VFS					   ENUM POSITIVE_AOP_RE(9)

NAME
       enum_positive_aop_returns - aop return codes with specific semantics

SYNOPSIS
       enum positive_aop_returns {
	 AOP_WRITEPAGE_ACTIVATE,
	 AOP_TRUNCATED_PAGE
       };

CONSTANTS
       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.

DESCRIPTION
       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.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						   ENUM POSITIVE_AOP_RE(9)