configfs: add show and store methods to struct configfs_attribute

Add methods to struct configfs_attribute to directly show and store
attributes without adding boilerplate code to every user.  In addition
to the methods this also adds 3 helper macros to define read/write,
read-only and write-only attributes with a single line of code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nicholas Bellinger <nab@linux-iscsi.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 12 insertions, 5 deletions

diff --git a/fs/configfs/file.c b/fs/configfs/file.c
index 403269ffcdf3..106ca589e90a 100644
--- a/fs/configfs/file.c
+++ b/fs/configfs/file.c
@@ -74,7 +74,11 @@ static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buf
         if (!buffer->page)
                 return -ENOMEM;
 
-        count = ops->show_attribute(item,attr,buffer->page);
+        if (ops->show_attribute)
+                count = ops->show_attribute(item, attr, buffer->page);
+        else
+                count = attr->show(item, buffer->page);
+
         buffer->needs_read_fill = 0;
         BUG_ON(count > (ssize_t)SIMPLE_ATTR_SIZE);
         if (count >= 0)
@@ -173,7 +177,9 @@ flush_write_buffer(struct dentry * dentry, struct configfs_buffer * buffer, size
         struct config_item * item = to_item(dentry->d_parent);
         struct configfs_item_operations * ops = buffer->ops;
 
-        return ops->store_attribute(item,attr,buffer->page,count);
+        if (ops->store_attribute)
+                return ops->store_attribute(item, attr, buffer->page, count);
+        return attr->store(item, buffer->page, count);
 }
 
 
@@ -237,8 +243,8 @@ static int check_perm(struct inode * inode, struct file * file)
          * and we must have a store method.
          */
         if (file->f_mode & FMODE_WRITE) {
-
-                if (!(inode->i_mode & S_IWUGO) || !ops->store_attribute)
+                if (!(inode->i_mode & S_IWUGO) ||
+                    (!ops->store_attribute && !attr->store))
                         goto Eaccess;
 
         }
@@ -248,7 +254,8 @@ static int check_perm(struct inode * inode, struct file * file)
          * must be a show method for it.
          */
         if (file->f_mode & FMODE_READ) {
-                if (!(inode->i_mode & S_IRUGO) || !ops->show_attribute)
+                if (!(inode->i_mode & S_IRUGO) ||
+                    (!ops->show_attribute && !attr->show))
                         goto Eaccess;
         }