debugfs: Provide a file creation function that also takes an initial size

Provide a file creation function that also takes an initial size so that the
caller doesn't have to set i_size, thus meaning that we don't have to call
deal with ->d_inode in the callers.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

6 files changed, 79 insertions, 42 deletions

diff --git a/drivers/infiniband/hw/cxgb4/device.c b/drivers/infiniband/hw/cxgb4/device.c
index eb5df4e62703..391309a55360 100644
--- a/drivers/infiniband/hw/cxgb4/device.c
+++ b/drivers/infiniband/hw/cxgb4/device.c
@@ -700,37 +700,24 @@ static const struct file_operations ep_debugfs_fops = {
 
 static int setup_debugfs(struct c4iw_dev *devp)
 {
-	struct dentry *de;
-
 	if (!devp->debugfs_root)
 		return -1;
 
-	de = debugfs_create_file("qps", S_IWUSR, devp->debugfs_root,
-				 (void *)devp, &qp_debugfs_fops);
-	if (de && de->d_inode)
-		de->d_inode->i_size = 4096;
+	debugfs_create_file_size("qps", S_IWUSR, devp->debugfs_root,
+				 (void *)devp, &qp_debugfs_fops, 4096);
 
-	de = debugfs_create_file("stags", S_IWUSR, devp->debugfs_root,
-				 (void *)devp, &stag_debugfs_fops);
-	if (de && de->d_inode)
-		de->d_inode->i_size = 4096;
+	debugfs_create_file_size("stags", S_IWUSR, devp->debugfs_root,
+				 (void *)devp, &stag_debugfs_fops, 4096);
 
-	de = debugfs_create_file("stats", S_IWUSR, devp->debugfs_root,
-			(void *)devp, &stats_debugfs_fops);
-	if (de && de->d_inode)
-		de->d_inode->i_size = 4096;
+	debugfs_create_file_size("stats", S_IWUSR, devp->debugfs_root,
+				 (void *)devp, &stats_debugfs_fops, 4096);
 
-	de = debugfs_create_file("eps", S_IWUSR, devp->debugfs_root,
-			(void *)devp, &ep_debugfs_fops);
-	if (de && de->d_inode)
-		de->d_inode->i_size = 4096;
+	debugfs_create_file_size("eps", S_IWUSR, devp->debugfs_root,
+				 (void *)devp, &ep_debugfs_fops, 4096);
 
-	if (c4iw_wr_log) {
-		de = debugfs_create_file("wr_log", S_IWUSR, devp->debugfs_root,
-					 (void *)devp, &wr_log_debugfs_fops);
-		if (de && de->d_inode)
-			de->d_inode->i_size = 4096;
-	}
+	if (c4iw_wr_log)
+		debugfs_create_file_size("wr_log", S_IWUSR, devp->debugfs_root,
+					 (void *)devp, &wr_log_debugfs_fops, 4096);
 	return 0;
 }
 
diff --git a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c
index c98a350d857e..4c7fe447e407 100644
--- a/drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c
+++ b/drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c
@@ -91,12 +91,9 @@ static const struct file_operations mem_debugfs_fops = {
 static void add_debugfs_mem(struct adapter *adap, const char *name,
 			    unsigned int idx, unsigned int size_mb)
 {
-	struct dentry *de;
-
-	de = debugfs_create_file(name, S_IRUSR, adap->debugfs_root,
-				 (void *)adap + idx, &mem_debugfs_fops);
-	if (de && de->d_inode)
-		de->d_inode->i_size = size_mb << 20;
+	debugfs_create_file_size(name, S_IRUSR, adap->debugfs_root,
+				 (void *)adap + idx, &mem_debugfs_fops,
+				 size_mb << 20);
 }
 
 /* Add an array of Debug FS files.
diff --git a/drivers/scsi/csiostor/csio_init.c b/drivers/scsi/csiostor/csio_init.c
index 34d20cc3e110..2617f15eaeeb 100644
--- a/drivers/scsi/csiostor/csio_init.c
+++ b/drivers/scsi/csiostor/csio_init.c
@@ -113,12 +113,9 @@ static const struct file_operations csio_mem_debugfs_fops = {
 void csio_add_debugfs_mem(struct csio_hw *hw, const char *name,
 				 unsigned int idx, unsigned int size_mb)
 {
-	struct dentry *de;
-
-	de = debugfs_create_file(name, S_IRUSR, hw->debugfs_root,
-				 (void *)hw + idx, &csio_mem_debugfs_fops);
-	if (de && de->d_inode)
-		de->d_inode->i_size = size_mb << 20;
+	debugfs_create_file_size(name, S_IRUSR, hw->debugfs_root,
+				 (void *)hw + idx, &csio_mem_debugfs_fops,
+				 size_mb << 20);
 }
 
 static int csio_setup_debugfs(struct csio_hw *hw)
diff --git a/drivers/usb/gadget/udc/atmel_usba_udc.c b/drivers/usb/gadget/udc/atmel_usba_udc.c
index 9f93bed42052..b2239a2d4941 100644
--- a/drivers/usb/gadget/udc/atmel_usba_udc.c
+++ b/drivers/usb/gadget/udc/atmel_usba_udc.c
@@ -264,14 +264,17 @@ static void usba_init_debugfs(struct usba_udc *udc)
 		goto err_root;
 	udc->debugfs_root = root;
 
-	regs = debugfs_create_file("regs", 0400, root, udc, &regs_dbg_fops);
-	if (!regs)
-		goto err_regs;
-
 	regs_resource = platform_get_resource(udc->pdev, IORESOURCE_MEM,
 				CTRL_IOMEM_ID);
-	regs->d_inode->i_size = resource_size(regs_resource);
-	udc->debugfs_regs = regs;
+
+	if (regs_resource) {
+		regs = debugfs_create_file_size("regs", 0400, root, udc,
+						&regs_dbg_fops,
+						resource_size(regs_resource));
+		if (!regs)
+			goto err_regs;
+		udc->debugfs_regs = regs;
+	}
 
 	usba_ep_init_debugfs(udc, to_usba_ep(udc->gadget.ep0));
 
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 957c40ce09f6..45b18a5e225c 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -338,6 +338,46 @@ struct dentry *debugfs_create_file(const char *name, umode_t mode,
 EXPORT_SYMBOL_GPL(debugfs_create_file);
 
 /**
+ * debugfs_create_file_size - create a file in the debugfs filesystem
+ * @name: a pointer to a string containing the name of the file to create.
+ * @mode: the permission that the file should have.
+ * @parent: a pointer to the parent dentry for this file.  This should be a
+ *          directory dentry if set.  If this parameter is NULL, then the
+ *          file will be created in the root of the debugfs filesystem.
+ * @data: a pointer to something that the caller will want to get to later
+ *        on.  The inode.i_private pointer will point to this value on
+ *        the open() call.
+ * @fops: a pointer to a struct file_operations that should be used for
+ *        this file.
+ * @file_size: initial file size
+ *
+ * This is the basic "create a file" function for debugfs.  It allows for a
+ * wide range of flexibility in creating a file, or a directory (if you want
+ * to create a directory, the debugfs_create_dir() function is
+ * recommended to be used instead.)
+ *
+ * This function will return a pointer to a dentry if it succeeds.  This
+ * pointer must be passed to the debugfs_remove() function when the file is
+ * to be removed (no automatic cleanup happens if your module is unloaded,
+ * you are responsible here.)  If an error occurs, %NULL will be returned.
+ *
+ * If debugfs is not enabled in the kernel, the value -%ENODEV will be
+ * returned.
+ */
+struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
+					struct dentry *parent, void *data,
+					const struct file_operations *fops,
+					loff_t file_size)
+{
+	struct dentry *de = debugfs_create_file(name, mode, parent, data, fops);
+
+	if (de)
+		de->d_inode->i_size = file_size;
+	return de;
+}
+EXPORT_SYMBOL_GPL(debugfs_create_file_size);
+
+/**
  * debugfs_create_dir - create a directory in the debugfs filesystem
  * @name: a pointer to a string containing the name of the directory to
  *        create.
diff --git a/include/linux/debugfs.h b/include/linux/debugfs.h
index ea149a24a1f2..cb25af461054 100644
--- a/include/linux/debugfs.h
+++ b/include/linux/debugfs.h
@@ -51,6 +51,11 @@ struct dentry *debugfs_create_file(const char *name, umode_t mode,
 				   struct dentry *parent, void *data,
 				   const struct file_operations *fops);
 
+struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
+					struct dentry *parent, void *data,
+					const struct file_operations *fops,
+					loff_t file_size);
+
 struct dentry *debugfs_create_dir(const char *name, struct dentry *parent);
 
 struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
@@ -129,6 +134,14 @@ static inline struct dentry *debugfs_create_file(const char *name, umode_t mode,
 	return ERR_PTR(-ENODEV);
 }
 
+static inline struct dentry *debugfs_create_file_size(const char *name, umode_t mode,
+					struct dentry *parent, void *data,
+					const struct file_operations *fops,
+					loff_t file_size)
+{
+	return ERR_PTR(-ENODEV);
+}
+
 static inline struct dentry *debugfs_create_dir(const char *name,
 						struct dentry *parent)
 {