From: Ross Zwisler Subject: [PATCH v4 1/2] dax: dax_layout_busy_page() warn on !exceptional Date: Tue, 10 Jul 2018 13:10:30 -0600 Message-ID: <20180710191031.17919-2-ross.zwisler@linux.intel.com> References: <20180710191031.17919-1-ross.zwisler@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Jan Kara , Dan Williams , Dave Chinner , "Darrick J. Wong" , Christoph Hellwig , linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, Jeff Moyer , linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Lukas Czerner Return-path: In-Reply-To: <20180710191031.17919-1-ross.zwisler-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" List-Id: linux-ext4.vger.kernel.org Inodes using DAX should only ever have exceptional entries in their page caches. Make this clear by warning if the iteration in dax_layout_busy_page() ever sees a non-exceptional entry, and by adding a comment for the pagevec_release() call which only deals with struct page pointers. Signed-off-by: Ross Zwisler Reviewed-by: Jan Kara --- fs/dax.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/fs/dax.c b/fs/dax.c index 641192808bb6..897b51e41d8f 100644 --- a/fs/dax.c +++ b/fs/dax.c @@ -566,7 +566,8 @@ struct page *dax_layout_busy_page(struct address_space *mapping) if (index >= end) break; - if (!radix_tree_exceptional_entry(pvec_ent)) + if (WARN_ON_ONCE( + !radix_tree_exceptional_entry(pvec_ent))) continue; xa_lock_irq(&mapping->i_pages); @@ -578,6 +579,13 @@ struct page *dax_layout_busy_page(struct address_space *mapping) if (page) break; } + + /* + * We don't expect normal struct page entries to exist in our + * tree, but we keep these pagevec calls so that this code is + * consistent with the common pattern for handling pagevecs + * throughout the kernel. + */ pagevec_remove_exceptionals(&pvec); pagevec_release(&pvec); index++; -- 2.14.4