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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
Subject: [PATCH v2 1/2] dax: dax_layout_busy_page() warn on !exceptional
Date: Wed, 27 Jun 2018 15:22:51 -0600	[thread overview]
Message-ID: <20180627212252.31032-2-ross.zwisler@linux.intel.com> (raw)
In-Reply-To: <20180627212252.31032-1-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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WARNING: multiple messages have this Message-ID (diff)
From: Ross Zwisler <ross.zwisler-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
To: Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>,
	Dan Williams
	<dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	Dave Chinner <david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org>,
	"Darrick J. Wong"
	<darrick.wong-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>,
	Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>,
	linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org,
	Jeff Moyer <jmoyer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	linux-ext4-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: [PATCH v2 1/2] dax: dax_layout_busy_page() warn on !exceptional
Date: Wed, 27 Jun 2018 15:22:51 -0600	[thread overview]
Message-ID: <20180627212252.31032-2-ross.zwisler@linux.intel.com> (raw)
In-Reply-To: <20180627212252.31032-1-ross.zwisler-VuQAYsv1563Yd54FQh9/CA@public.gmane.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 <ross.zwisler-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Reviewed-by: Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>
---
 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

  reply	other threads:[~2018-06-27 21:22 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-27 21:22 [PATCH v2 0/2] ext4: fix DAX dma vs truncate/hole-punch Ross Zwisler
2018-06-27 21:22 ` Ross Zwisler
2018-06-27 21:22 ` Ross Zwisler [this message]
2018-06-27 21:22   ` [PATCH v2 1/2] dax: dax_layout_busy_page() warn on !exceptional Ross Zwisler
2018-07-02 22:15   ` Theodore Y. Ts'o
2018-07-02 22:15     ` Theodore Y. Ts'o
2018-07-03 15:41     ` Ross Zwisler
2018-07-03 15:41       ` Ross Zwisler
2018-07-03 17:44       ` Theodore Y. Ts'o
2018-07-03 17:44         ` Theodore Y. Ts'o
2018-06-27 21:22 ` [PATCH v2 2/2] ext4: handle layout changes to pinned DAX mappings Ross Zwisler
2018-06-27 21:22   ` Ross Zwisler
2018-06-29 12:02   ` Lukas Czerner
2018-06-29 12:02     ` Lukas Czerner
2018-06-29 15:13     ` Ross Zwisler
2018-06-29 15:13       ` Ross Zwisler
2018-07-02  7:34       ` Jan Kara
2018-07-02  7:34         ` Jan Kara
2018-07-02  7:59       ` Lukas Czerner
2018-07-02  7:59         ` Lukas Czerner
2018-07-02 16:27         ` Ross Zwisler
2018-07-02 16:27           ` Ross Zwisler
2018-06-30  1:12     ` Dave Chinner
2018-06-30  1:12       ` Dave Chinner
2018-07-02 17:29   ` [PATCH v3 " Ross Zwisler
2018-07-02 17:29     ` Ross Zwisler
2018-07-04  0:49     ` Dave Chinner
2018-07-04  0:49       ` Dave Chinner
2018-07-04 12:27       ` Jan Kara
2018-07-04 12:27         ` Jan Kara
2018-07-04 23:54         ` Dave Chinner
2018-07-04 23:54           ` Dave Chinner
2018-07-05  3:59           ` Darrick J. Wong
2018-07-05  3:59             ` Darrick J. Wong
2018-07-05 16:53             ` Ross Zwisler
2018-07-05 16:53               ` Ross Zwisler
2018-07-09 12:33               ` Jan Kara
2018-07-09 12:33                 ` Jan Kara
2018-07-09 16:23                 ` Darrick J. Wong
2018-07-09 16:23                   ` Darrick J. Wong
2018-07-09 19:49                   ` Jan Kara
2018-07-09 19:49                     ` Jan Kara
2018-07-05 20:40             ` Dan Williams
2018-07-05 20:40               ` Dan Williams
2018-07-05 23:29               ` Dave Chinner
2018-07-05 23:29                 ` Dave Chinner
2018-07-06  5:08                 ` Dan Williams
2018-07-06  5:08                   ` Dan Williams
2018-07-09  9:59                 ` Lukas Czerner
2018-07-09  9:59                   ` Lukas Czerner
2018-07-09 16:18                   ` Darrick J. Wong
2018-07-09 16:18                     ` Darrick J. Wong

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