linux-ext4 - [PATCH 5/9] dax: move the dax_read_lock() locking into dax

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Date:   Thu, 26 Aug 2021 15:55:06 +0200
From:   Christoph Hellwig <hch@....de>
To:     Dan Williams <dan.j.williams@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Dave Jiang <dave.jiang@...el.com>
Cc:     Mike Snitzer <snitzer@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        linux-xfs@...r.kernel.org, nvdimm@...ts.linux.dev,
        linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org
Subject: [PATCH 5/9] dax: move the dax_read_lock() locking into dax_supported

Move the dax_read_lock/dax_read_unlock pair from the callers into
dax_supported to make it a little easier to use.

Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Dan Williams <dan.j.williams@...el.com>
---
 drivers/dax/super.c   | 16 +++++++++-------
 drivers/md/dm-table.c |  9 ++-------
 2 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/drivers/dax/super.c b/drivers/dax/super.c
index e13fde57c33e..0f74f83101ab 100644
--- a/drivers/dax/super.c
+++ b/drivers/dax/super.c
@@ -219,7 +219,6 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
 	struct request_queue *q;
 	char buf[BDEVNAME_SIZE];
 	bool ret;
-	int id;
 
 	q = bdev_get_queue(bdev);
 	if (!q || !blk_queue_dax(q)) {
@@ -235,10 +234,8 @@ bool __bdev_dax_supported(struct block_device *bdev, int blocksize)
 		return false;
 	}
 
-	id = dax_read_lock();
 	ret = dax_supported(dax_dev, bdev, blocksize, 0,
 			i_size_read(bdev->bd_inode) / 512);
-	dax_read_unlock(id);
 
 	put_dax(dax_dev);
 
@@ -356,13 +353,18 @@ EXPORT_SYMBOL_GPL(dax_direct_access);
 bool dax_supported(struct dax_device *dax_dev, struct block_device *bdev,
 		int blocksize, sector_t start, sector_t len)
 {
-	if (!dax_dev)
-		return false;
+	bool ret = false;
+	int id;
 
-	if (!dax_alive(dax_dev))
+	if (!dax_dev)
 		return false;
 
-	return dax_dev->ops->dax_supported(dax_dev, bdev, blocksize, start, len);
+	id = dax_read_lock();
+	if (dax_alive(dax_dev))
+		ret = dax_dev->ops->dax_supported(dax_dev, bdev, blocksize,
+						  start, len);
+	dax_read_unlock(id);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(dax_supported);
 
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 0543cdf89e92..b53acca37581 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -809,14 +809,9 @@ EXPORT_SYMBOL_GPL(dm_table_set_type);
 int device_not_dax_capable(struct dm_target *ti, struct dm_dev *dev,
 			sector_t start, sector_t len, void *data)
 {
-	int blocksize = *(int *) data, id;
-	bool rc;
+	int blocksize = *(int *) data;
 
-	id = dax_read_lock();
-	rc = !dax_supported(dev->dax_dev, dev->bdev, blocksize, start, len);
-	dax_read_unlock(id);
-
-	return rc;
+	return !dax_supported(dev->dax_dev, dev->bdev, blocksize, start, len);
 }
 
 /* Check devices support synchronous DAX */
-- 
2.30.2