[PATCH] mm/backing-dev: Check return value of the debugfs_create_dir()

[Alexander Kuleshov <kuleshovmail@gmail.com>]

The debugfs_create_dir() function may fail and return error. If the
root directory not created, we can't create anything inside it. This
patch adds check for this case.

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
---
 mm/backing-dev.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index dac5bf5..518d26a 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -117,15 +117,21 @@ static const struct file_operations bdi_debug_stats_fops = {
 
 static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
 {
-	bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
-	bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir,
-					       bdi, &bdi_debug_stats_fops);
+	if (bdi_debug_root) {
+		bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
+		if (bdi->debug_dir)
+			bdi->debug_stats = debugfs_create_file("stats", 0444,
+							bdi->debug_dir, bdi,
+							&bdi_debug_stats_fops);
+	}
 }
 
 static void bdi_debug_unregister(struct backing_dev_info *bdi)
 {
-	debugfs_remove(bdi->debug_stats);
-	debugfs_remove(bdi->debug_dir);
+	if (bdi_debug_root) {
+		debugfs_remove(bdi->debug_stats);
+		debugfs_remove(bdi->debug_dir);
+	}
 }
 #else
 static inline void bdi_debug_init(void)
-- 
2.5.0

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