From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 20 Feb 2008 08:30:46 -0800 From: Randy Dunlap Subject: Re: [PATCH 22/28] mm: add support for non block device backed swap files Message-Id: <20080220083046.a3ab16d3.randy.dunlap@oracle.com> In-Reply-To: <20080220150308.142619000@chello.nl> References: <20080220144610.548202000@chello.nl> <20080220150308.142619000@chello.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Peter Zijlstra Cc: Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, trond.myklebust@fys.uio.no List-ID: On Wed, 20 Feb 2008 15:46:32 +0100 Peter Zijlstra wrote: > Signed-off-by: Peter Zijlstra > --- > Documentation/filesystems/Locking | 19 +++++++++++++ > Documentation/filesystems/vfs.txt | 17 ++++++++++++ > include/linux/buffer_head.h | 2 - > include/linux/fs.h | 8 +++++ > include/linux/swap.h | 4 ++ > mm/page_io.c | 52 ++++++++++++++++++++++++++++++++++++++ > mm/swap_state.c | 4 +- > mm/swapfile.c | 26 ++++++++++++++++++- > 8 files changed, 128 insertions(+), 4 deletions(-) > Index: linux-2.6/Documentation/filesystems/Locking > =================================================================== > --- linux-2.6.orig/Documentation/filesystems/Locking > +++ linux-2.6/Documentation/filesystems/Locking > @@ -291,6 +297,19 @@ cleaned, or an error value if not. Note > getting mapped back in and redirtied, it needs to be kept locked > across the entire operation. > > + ->swapfile() will be called with a non zero argument on address spaces non-zero > +backing non block device backed swapfiles. A return value of zero indicates > +success. In which case this address space can be used for backing swapspace. success, in which case > +The swapspace operations will be proxied to the address space operations. > +Swapoff will call this method with a zero argument to release the address > +space. > + > + ->swap_out() when swapfile() returned success, this method is used to > +write the swap page. > + > + ->swap_in() when swapfile() returned success, this method is used to > +read the swap page. > + > Note: currently almost all instances of address_space methods are > using BKL for internal serialization and that's one of the worst sources > of contention. Normally they are calling library functions (in fs/buffer.c) > Index: linux-2.6/Documentation/filesystems/vfs.txt > =================================================================== > --- linux-2.6.orig/Documentation/filesystems/vfs.txt > +++ linux-2.6/Documentation/filesystems/vfs.txt > @@ -728,6 +732,19 @@ struct address_space_operations { > prevent redirtying the page, it is kept locked during the whole > operation. > > + swapfile: Called with a non-zero argument when swapon is used on a file. A > + return value of zero indicates success. In which case this success, in which case this > + address_space can be used to back swapspace. The swapspace operations > + will be proxied to this address space's ->swap_{out,in} methods. > + Swapoff will call this method with a zero argument to release the > + address space. > + > + swap_out: Called to write a swapcache page to a backing store, similar to > + writepage. > + > + swap_in: Called to read a swapcache page from a backing store, similar to > + readpage. > + > The File Object > =============== --- ~Randy -- 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