From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4519273C.3000301@oracle.com> Date: Tue, 26 Sep 2006 09:12:28 -0400 From: Chuck Lever Reply-To: chuck.lever@oracle.com MIME-Version: 1.0 Subject: Re: Checking page_count(page) in invalidate_complete_page References: <4518333E.2060101@oracle.com> <20060925141036.73f1e2b3.akpm@osdl.org> <45185D7E.6070104@yahoo.com.au> <451862C5.1010900@oracle.com> <45186481.1090306@yahoo.com.au> <45186DC3.7000902@oracle.com> <451870C6.6050008@yahoo.com.au> <4518835D.3080702@oracle.com> <4518C7F1.3050809@yahoo.com.au> In-Reply-To: <4518C7F1.3050809@yahoo.com.au> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Andrew Morton , Trond Myklebust , Steve Dickson , linux-mm@kvack.org List-ID: Nick Piggin wrote: > Chuck Lever wrote: > >> Nick Piggin wrote: >> >>> But they're present on the LRU? That's unusual (I guess NFS doesn't >>> have a buffer cache for a backing >>> block device). >> >> >> That is correct -- NFS doesn't use the buffer cache. > > > So that raises another question: how do they get to invalidate_inode_pages2 > if they are not part of the buffer or pagecache? It does use the page cache to cache data pages for files, directories, and symlinks. It does not use buffers, however, since incoming file system data is read from a socket, not from a block device. I believe the client provides a dummy backing device for the few things in the VFS that require it. Invalidate_inode_pages2() is used to remove page cache data that the client has determined is stale. The client detects that the file has changed on the server, and it is not responsible for those changes, by examining the file's attributes and noticing mtime or size changes. When such a change is detected, all pages cached for a file are invalidated, and the page cache is gradually repopulated from the server as applications access parts of the file. I'd like to understand the difference between invalidate_inode_pages2() and truncate_inode_pages() in this scenario. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org