[PATCH V3 4/9] dax/fsdev: clear dev_dax->pgmap on probe failure

[John Groves]

From: John Groves <John@xxxxxxxxxx>

Clear dev_dax->pgmap on probe failure for dynamic devices. After the dynamic
path sets dev_dax->pgmap, if a later probe step fails, devres frees the
devm_kzalloc'd pgmap but leaves dev_dax->pgmap dangling.  Subsequent probe
attempts would hit the "dynamic-dax with pre-populated page map" check and fail
permanently. Use a goto cleanup to NULL dev_dax->pgmap on error.

Fixes: d5406bd458b0a ("dax: add fsdev.c driver for fs-dax on character dax")
Signed-off-by: John Groves <john@xxxxxxxxxx>
---
 drivers/dax/fsdev.c | 32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

diff --git a/drivers/dax/fsdev.c b/drivers/dax/fsdev.c
index dbd722ed7ab05..42aac7e952516 100644
--- a/drivers/dax/fsdev.c
+++ b/drivers/dax/fsdev.c
@@ -223,6 +223,7 @@ static int fsdev_dax_probe(struct dev_dax *dev_dax)
 {
 	struct dax_device *dax_dev = dev_dax->dax_dev;
 	struct device *dev = &dev_dax->dev;
+	bool pgmap_allocated = false;
 	struct dev_pagemap *pgmap;
 	struct inode *inode;
 	u64 data_offset = 0;
@@ -253,6 +254,7 @@ static int fsdev_dax_probe(struct dev_dax *dev_dax)
 
 		pgmap->nr_range = dev_dax->nr_range;
 		dev_dax->pgmap = pgmap;
+		pgmap_allocated = true;
 
 		for (i = 0; i < dev_dax->nr_range; i++) {
 			struct range *range = &dev_dax->ranges[i].range;
@@ -268,7 +270,8 @@ static int fsdev_dax_probe(struct dev_dax *dev_dax)
 					range_len(range), dev_name(dev))) {
 			dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve range\n",
 				 i, range->start, range->end);
-			return -EBUSY;
+			rc = -EBUSY;
+			goto err_pgmap;
 		}
 	}
 
@@ -288,8 +291,10 @@ static int fsdev_dax_probe(struct dev_dax *dev_dax)
 	pgmap->owner = dev_dax;
 
 	addr = devm_memremap_pages(dev, pgmap);
-	if (IS_ERR(addr))
-		return PTR_ERR(addr);
+	if (IS_ERR(addr)) {
+		rc = PTR_ERR(addr);
+		goto err_pgmap;
+	}
 
 	/*
 	 * Clear any stale compound folio state left over from a previous
@@ -301,7 +306,7 @@ static int fsdev_dax_probe(struct dev_dax *dev_dax)
 	rc = devm_add_action_or_reset(dev, fsdev_clear_folio_state_action,
 				      dev_dax);
 	if (rc)
-		return rc;
+		goto err_pgmap;
 
 	/* Detect whether the data is at a non-zero offset into the memory */
 	if (pgmap->range.start != dev_dax->ranges[0].range.start) {
@@ -323,23 +328,32 @@ static int fsdev_dax_probe(struct dev_dax *dev_dax)
 	cdev_set_parent(cdev, &dev->kobj);
 	rc = cdev_add(cdev, dev->devt, 1);
 	if (rc)
-		return rc;
+		goto err_pgmap;
 
 	rc = devm_add_action_or_reset(dev, fsdev_cdev_del, cdev);
 	if (rc)
-		return rc;
+		goto err_pgmap;
 
 	/* Set the dax operations for fs-dax access path */
 	rc = dax_set_ops(dax_dev, &dev_dax_ops);
 	if (rc)
-		return rc;
+		goto err_pgmap;
 
 	rc = devm_add_action_or_reset(dev, fsdev_clear_ops, dev_dax);
 	if (rc)
-		return rc;
+		goto err_pgmap;
 
 	run_dax(dax_dev);
-	return devm_add_action_or_reset(dev, fsdev_kill, dev_dax);
+	rc = devm_add_action_or_reset(dev, fsdev_kill, dev_dax);
+	if (rc)
+		goto err_pgmap;
+
+	return 0;
+
+err_pgmap:
+	if (pgmap_allocated)
+		dev_dax->pgmap = NULL;
+	return rc;
 }
 
 static struct dax_device_driver fsdev_dax_driver = {
-- 
2.53.0