From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 5 Jan 2016 10:41:01 +0100 From: Jan Kara To: Ross Zwisler Cc: linux-kernel@vger.kernel.org, "H. Peter Anvin" , "J. Bruce Fields" , Theodore Ts'o , Alexander Viro , Andreas Dilger , Dave Chinner , Ingo Molnar , Jan Kara , Jeff Layton , Matthew Wilcox , Thomas Gleixner , linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-nvdimm@lists.01.org, x86@kernel.org, xfs@oss.sgi.com, Andrew Morton , Dan Williams , Matthew Wilcox , Dave Hansen Subject: Re: [PATCH v6 2/7] dax: support dirty DAX entries in radix tree Message-ID: <20160105094101.GB2724@quack.suse.cz> References: <1450899560-26708-1-git-send-email-ross.zwisler@linux.intel.com> <1450899560-26708-3-git-send-email-ross.zwisler@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1450899560-26708-3-git-send-email-ross.zwisler@linux.intel.com> Sender: owner-linux-mm@kvack.org List-ID: On Wed 23-12-15 12:39:15, Ross Zwisler wrote: > Add support for tracking dirty DAX entries in the struct address_space > radix tree. This tree is already used for dirty page writeback, and it > already supports the use of exceptional (non struct page*) entries. > > In order to properly track dirty DAX pages we will insert new exceptional > entries into the radix tree that represent dirty DAX PTE or PMD pages. > These exceptional entries will also contain the writeback sectors for the > PTE or PMD faults that we can use at fsync/msync time. > > There are currently two types of exceptional entries (shmem and shadow) > that can be placed into the radix tree, and this adds a third. We rely on > the fact that only one type of exceptional entry can be found in a given > radix tree based on its usage. This happens for free with DAX vs shmem but > we explicitly prevent shadow entries from being added to radix trees for > DAX mappings. > > The only shadow entries that would be generated for DAX radix trees would > be to track zero page mappings that were created for holes. These pages > would receive minimal benefit from having shadow entries, and the choice > to have only one type of exceptional entry in a given radix tree makes the > logic simpler both in clear_exceptional_entry() and in the rest of DAX. > > Signed-off-by: Ross Zwisler The patch looks good to me. You can add: Reviewed-by: Jan Kara Honza -- Jan Kara SUSE Labs, CR -- 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