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>

diff --git a/fs/configfs/file.c b/fs/configfs/file.c
index 403269ffcdf3518b45f878166270c12e3365c17e..106ca589e90a2b3389db0157190247a7aac5fdcc 100644 (file)
--- 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;
        }
 

diff --git a/include/linux/configfs.h b/include/linux/configfs.h
index 63a36e89d0eb6b3f718d7058b723291662c186d3..85e9956a86de363faf1afe65ef5a474fabe656e1 100644 (file)
--- a/include/linux/configfs.h
+++ b/include/linux/configfs.h
@@ -125,8 +125,35 @@ struct configfs_attribute {
        const char              *ca_name;
        struct module           *ca_owner;
        umode_t                 ca_mode;
+       ssize_t (*show)(struct config_item *, char *);
+       ssize_t (*store)(struct config_item *, const char *, size_t);
 };
 
+#define CONFIGFS_ATTR(_pfx, _name)                     \
+static struct configfs_attribute _pfx##attr_##_name = {        \
+       .ca_name        = __stringify(_name),           \
+       .ca_mode        = S_IRUGO | S_IWUSR,            \
+       .ca_owner       = THIS_MODULE,                  \
+       .show           = _pfx##_name##_show,           \
+       .store          = _pfx##_name##_store,          \
+}
+
+#define CONFIGFS_ATTR_RO(_pfx, _name)                  \
+static struct configfs_attribute _pfx##attr_##_name = {        \
+       .ca_name        = __stringify(_name),           \
+       .ca_mode        = S_IRUGO,                      \
+       .ca_owner       = THIS_MODULE,                  \
+       .show           = _pfx##_name##_show,           \
+}
+
+#define CONFIGFS_ATTR_WO(_pfx, _name)                  \
+static struct configfs_attribute _pfx##attr_##_name = {        \
+       .ca_name        = __stringify(_name),           \
+       .ca_mode        = S_IWUSR,                      \
+       .ca_owner       = THIS_MODULE,                  \
+       .store          = _pfx##_name##_store,          \
+}
+
 /*
  * Users often need to create attribute structures for their configurable
  * attributes, containing a configfs_attribute member and function pointers