linux-kernel - [PATCH v4 03/12] dm: Treat alloc_dax() -EOPNOTSUPP failure as non-fatal

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Message-Id: <20240208184913.484340-4-mathieu.desnoyers@efficios.com>
Date: Thu,  8 Feb 2024 13:49:04 -0500
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Dan Williams <dan.j.williams@...el.com>,
	Arnd Bergmann <arnd@...db.de>,
	Dave Chinner <david@...morbit.com>
Cc: linux-kernel@...r.kernel.org,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Vishal Verma <vishal.l.verma@...el.com>,
	Dave Jiang <dave.jiang@...el.com>,
	Matthew Wilcox <willy@...radead.org>,
	Russell King <linux@...linux.org.uk>,
	linux-arch@...r.kernel.org,
	linux-cxl@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org,
	linux-xfs@...r.kernel.org,
	dm-devel@...ts.linux.dev,
	nvdimm@...ts.linux.dev,
	linux-s390@...r.kernel.org,
	Alasdair Kergon <agk@...hat.com>,
	Mike Snitzer <snitzer@...nel.org>,
	Mikulas Patocka <mpatocka@...hat.com>
Subject: [PATCH v4 03/12] dm: Treat alloc_dax() -EOPNOTSUPP failure as non-fatal

In preparation for checking whether the architecture has data cache
aliasing within alloc_dax(), modify the error handling of dm alloc_dev()
to treat alloc_dax() -EOPNOTSUPP failure as non-fatal.

For the transition, consider that alloc_dax() returning NULL is the
same as returning -EOPNOTSUPP.

Fixes: d92576f1167c ("dax: does not work correctly with virtual aliasing caches")
Suggested-by: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Alasdair Kergon <agk@...hat.com>
Cc: Mike Snitzer <snitzer@...nel.org>
Cc: Mikulas Patocka <mpatocka@...hat.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Vishal Verma <vishal.l.verma@...el.com>
Cc: Dave Jiang <dave.jiang@...el.com>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Russell King <linux@...linux.org.uk>
Cc: linux-arch@...r.kernel.org
Cc: linux-cxl@...r.kernel.org
Cc: linux-fsdevel@...r.kernel.org
Cc: linux-mm@...ck.org
Cc: linux-xfs@...r.kernel.org
Cc: dm-devel@...ts.linux.dev
Cc: nvdimm@...ts.linux.dev
---
 drivers/md/dm.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 23c32cd1f1d8..2fc22cae9089 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2054,6 +2054,7 @@ static void cleanup_mapped_device(struct mapped_device *md)
 static struct mapped_device *alloc_dev(int minor)
 {
 	int r, numa_node_id = dm_get_numa_node();
+	struct dax_device *dax_dev;
 	struct mapped_device *md;
 	void *old_md;
 
@@ -2122,15 +2123,15 @@ static struct mapped_device *alloc_dev(int minor)
 	md->disk->private_data = md;
 	sprintf(md->disk->disk_name, "dm-%d", minor);
 
-	if (IS_ENABLED(CONFIG_FS_DAX)) {
-		md->dax_dev = alloc_dax(md, &dm_dax_ops);
-		if (IS_ERR(md->dax_dev)) {
-			md->dax_dev = NULL;
+	dax_dev = alloc_dax(md, &dm_dax_ops);
+	if (IS_ERR_OR_NULL(dax_dev)) {
+		if (IS_ERR(dax_dev) && PTR_ERR(dax_dev) != -EOPNOTSUPP)
 			goto bad;
-		}
-		set_dax_nocache(md->dax_dev);
-		set_dax_nomc(md->dax_dev);
-		if (dax_add_host(md->dax_dev, md->disk))
+	} else {
+		set_dax_nocache(dax_dev);
+		set_dax_nomc(dax_dev);
+		md->dax_dev = dax_dev;
+		if (dax_add_host(dax_dev, md->disk))
 			goto bad;
 	}
 
-- 
2.39.2