[PATCH] nbd: Fix return value check for debugfs_create_*()

[weiyj_lk@163.com]

From: Wei Yongjun <yongjun_wei@trendmicro.com.cn>

In case of error, the function debugfs_create_*() returns NULL
pointer not ERR_PTR() if debugfs is enabled. The IS_ERR() test
in the return value check should be replaced with NULL test.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
---
 drivers/block/nbd.c | 50 ++++++++++++++++++++++++--------------------------
 1 file changed, 24 insertions(+), 26 deletions(-)

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index e4c5cc1..02bc697 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -895,49 +895,47 @@ static int nbd_dev_dbg_init(struct nbd_device *nbd)
 	struct dentry *f;
 
 	dir = debugfs_create_dir(nbd_name(nbd), nbd_dbg_dir);
-	if (IS_ERR_OR_NULL(dir)) {
-		dev_err(nbd_to_dev(nbd), "Failed to create debugfs dir for '%s' (%ld)\n",
-			nbd_name(nbd), PTR_ERR(dir));
-		return PTR_ERR(dir);
+	if (!dir) {
+		dev_err(nbd_to_dev(nbd), "Failed to create debugfs dir for '%s'\n",
+			nbd_name(nbd));
+		return -ENOMEM;
 	}
 	nbd->dbg_dir = dir;
 
 	f = debugfs_create_file("tasks", 0444, dir, nbd, &nbd_dbg_tasks_ops);
-	if (IS_ERR_OR_NULL(f)) {
-		dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'tasks', %ld\n",
-			PTR_ERR(f));
-		return PTR_ERR(f);
+	if (!f) {
+		dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'tasks'\n");
+		goto fail;
 	}
 
 	f = debugfs_create_u64("size_bytes", 0444, dir, &nbd->bytesize);
-	if (IS_ERR_OR_NULL(f)) {
-		dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'size_bytes', %ld\n",
-			PTR_ERR(f));
-		return PTR_ERR(f);
+	if (!f) {
+		dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'size_bytes'\n");
+		goto fail;
 	}
 
 	f = debugfs_create_u32("timeout", 0444, dir, &nbd->xmit_timeout);
-	if (IS_ERR_OR_NULL(f)) {
-		dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'timeout', %ld\n",
-			PTR_ERR(f));
-		return PTR_ERR(f);
+	if (!f) {
+		dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'timeout'\n");
+		goto fail;
 	}
 
 	f = debugfs_create_u32("blocksize", 0444, dir, &nbd->blksize);
-	if (IS_ERR_OR_NULL(f)) {
-		dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'blocksize', %ld\n",
-			PTR_ERR(f));
-		return PTR_ERR(f);
+	if (!f) {
+		dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'blocksize'\n");
+		goto fail;
 	}
 
 	f = debugfs_create_file("flags", 0444, dir, &nbd, &nbd_dbg_flags_ops);
-	if (IS_ERR_OR_NULL(f)) {
-		dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'flags', %ld\n",
-			PTR_ERR(f));
-		return PTR_ERR(f);
+	if (!f) {
+		dev_err(nbd_to_dev(nbd), "Failed to create debugfs file 'flags'\n");
+		goto fail;
 	}
 
 	return 0;
+fail:
+	debugfs_remove_recursive(nbd->dbg_dir);
+	return -ENOMEM;
 }
 
 static void nbd_dev_dbg_close(struct nbd_device *nbd)
@@ -950,8 +948,8 @@ static int nbd_dbg_init(void)
 	struct dentry *dbg_dir;
 
 	dbg_dir = debugfs_create_dir("nbd", NULL);
-	if (IS_ERR(dbg_dir))
-		return PTR_ERR(dbg_dir);
+	if (!dbg_dir)
+		return -ENOMEM;
 
 	nbd_dbg_dir = dbg_dir;