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From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: Jan Kara <jack@suse.cz>, Dan Williams <dan.j.williams@intel.com>,
	Dave Chinner <david@fromorbit.com>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	Christoph Hellwig <hch@lst.de>,
	linux-nvdimm@lists.01.org, Jeff Moyer <jmoyer@redhat.com>,
	linux-ext4@vger.kernel.org, Lukas Czerner <lczerner@redhat.com>
Subject: [PATCH v4 1/2] dax: dax_layout_busy_page() warn on !exceptional
Date: Tue, 10 Jul 2018 13:10:30 -0600	[thread overview]
Message-ID: <20180710191031.17919-2-ross.zwisler@linux.intel.com> (raw)
In-Reply-To: <20180710191031.17919-1-ross.zwisler@linux.intel.com>

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 <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
---
 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

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  reply	other threads:[~2018-07-10 19:10 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-10 19:10 [PATCH v4 0/2] ext4: fix DAX dma vs truncate/hole-punch Ross Zwisler
2018-07-10 19:10 ` Ross Zwisler [this message]
2018-08-10 19:52   ` [PATCH v4 1/2] dax: dax_layout_busy_page() warn on !exceptional Eric Sandeen
2018-08-10 20:33     ` Theodore Y. Ts'o
2018-08-11  2:10       ` Theodore Y. Ts'o
2018-08-13 10:12         ` Jan Kara
2018-08-13 12:46           ` Theodore Y. Ts'o
2018-08-24 15:44           ` Jan Kara
2018-08-27 16:09           ` Jan Kara
2018-07-10 19:10 ` [PATCH v4 2/2] ext4: handle layout changes to pinned DAX mappings Ross Zwisler
2018-07-11  8:17 ` [PATCH v4 0/2] ext4: fix DAX dma vs truncate/hole-punch Jan Kara
2018-07-11 15:41   ` Ross Zwisler
2018-07-25 22:28   ` Ross Zwisler
2018-07-27 16:28     ` Ross Zwisler
2018-08-06  3:55       ` Dave Chinner
2018-08-06 15:49         ` Christoph Hellwig
2018-08-06 22:25           ` Dave Chinner
2018-08-07  8:45       ` Jan Kara
2018-09-10 22:18         ` Eric Sandeen
2018-09-11 15:14           ` Jan Kara
2018-09-11 15:20             ` Jan Kara
2018-09-11 17:28               ` Theodore Y. Ts'o
2018-09-11 18:21                 ` Eric Sandeen
2018-07-31 19:44 ` Ross Zwisler

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