From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:51713 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755205AbcCUNWd (ORCPT ); Mon, 21 Mar 2016 09:22:33 -0400 From: Jan Kara To: linux-fsdevel@vger.kernel.org Cc: "Wilcox, Matthew R" , Ross Zwisler , Dan Williams , linux-nvdimm@lists.01.org, NeilBrown , Jan Kara Subject: [PATCH 05/10] dax: Allow DAX code to replace exceptional entries Date: Mon, 21 Mar 2016 14:22:50 +0100 Message-Id: <1458566575-28063-6-git-send-email-jack@suse.cz> In-Reply-To: <1458566575-28063-1-git-send-email-jack@suse.cz> References: <1458566575-28063-1-git-send-email-jack@suse.cz> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Currently we forbid page_cache_tree_insert() to replace exceptional radix tree entries for DAX inodes. However to make DAX faults race free we will lock radix tree entries and when hole is created, we need to replace such locked radix tree entry with a hole page. So modify page_cache_tree_insert() to allow that. Signed-off-by: Jan Kara --- include/linux/dax.h | 6 ++++++ mm/filemap.c | 18 +++++++++++------- 2 files changed, 17 insertions(+), 7 deletions(-) diff --git a/include/linux/dax.h b/include/linux/dax.h index 7c45ac7ea1d1..4b63923e1f8d 100644 --- a/include/linux/dax.h +++ b/include/linux/dax.h @@ -3,8 +3,14 @@ #include #include +#include #include +/* + * Since exceptional entries do not use indirect bit, we reuse it as a lock bit + */ +#define DAX_ENTRY_LOCK RADIX_TREE_INDIRECT_PTR + ssize_t dax_do_io(struct kiocb *, struct inode *, struct iov_iter *, loff_t, get_block_t, dio_iodone_t, int flags); int dax_clear_sectors(struct block_device *bdev, sector_t _sector, long _size); diff --git a/mm/filemap.c b/mm/filemap.c index 7c00f105845e..fbebedaf719e 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -597,14 +597,18 @@ static int page_cache_tree_insert(struct address_space *mapping, if (!radix_tree_exceptional_entry(p)) return -EEXIST; - if (WARN_ON(dax_mapping(mapping))) - return -EINVAL; - - if (shadowp) - *shadowp = p; mapping->nrexceptional--; - if (node) - workingset_node_shadows_dec(node); + if (!dax_mapping(mapping)) { + if (shadowp) + *shadowp = p; + if (node) + workingset_node_shadows_dec(node); + } else { + /* DAX can replace empty locked entry with a hole */ + WARN_ON_ONCE(p != + (void *)(RADIX_TREE_EXCEPTIONAL_ENTRY | + DAX_ENTRY_LOCK)); + } } radix_tree_replace_slot(slot, page); mapping->nrpages++; -- 2.6.2