diff options
Diffstat (limited to 'Documentation/filesystems/configfs/configfs.txt')
| -rw-r--r-- | Documentation/filesystems/configfs/configfs.txt | 38 |
1 files changed, 11 insertions, 27 deletions
diff --git a/Documentation/filesystems/configfs/configfs.txt b/Documentation/filesystems/configfs/configfs.txt index b40fec9d3..af68efdbb 100644 --- a/Documentation/filesystems/configfs/configfs.txt +++ b/Documentation/filesystems/configfs/configfs.txt @@ -160,12 +160,6 @@ among other things. For that, it needs a type. struct configfs_item_operations { void (*release)(struct config_item *); - ssize_t (*show_attribute)(struct config_item *, - struct configfs_attribute *, - char *); - ssize_t (*store_attribute)(struct config_item *, - struct configfs_attribute *, - const char *, size_t); int (*allow_link)(struct config_item *src, struct config_item *target); int (*drop_link)(struct config_item *src, @@ -183,9 +177,7 @@ The most basic function of a config_item_type is to define what operations can be performed on a config_item. All items that have been allocated dynamically will need to provide the ct_item_ops->release() method. This method is called when the config_item's reference count -reaches zero. Items that wish to display an attribute need to provide -the ct_item_ops->show_attribute() method. Similarly, storing a new -attribute value uses the store_attribute() method. +reaches zero. [struct configfs_attribute] @@ -193,6 +185,8 @@ attribute value uses the store_attribute() method. 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); }; When a config_item wants an attribute to appear as a file in the item's @@ -202,10 +196,10 @@ config_item_type->ct_attrs. When the item appears in configfs, the attribute file will appear with the configfs_attribute->ca_name filename. configfs_attribute->ca_mode specifies the file permissions. -If an attribute is readable and the config_item provides a -ct_item_ops->show_attribute() method, that method will be called -whenever userspace asks for a read(2) on the attribute. The converse -will happen for write(2). +If an attribute is readable and provides a ->show method, that method will +be called whenever userspace asks for a read(2) on the attribute. If an +attribute is writable and provides a ->store method, that method will be +be called whenever userspace asks for a write(2) on the attribute. [struct config_group] @@ -311,20 +305,10 @@ the subsystem must be ready for it. [An Example] The best example of these basic concepts is the simple_children -subsystem/group and the simple_child item in configfs_example_explicit.c -and configfs_example_macros.c. It shows a trivial object displaying and -storing an attribute, and a simple group creating and destroying these -children. - -The only difference between configfs_example_explicit.c and -configfs_example_macros.c is how the attributes of the childless item -are defined. The childless item has extended attributes, each with -their own show()/store() operation. This follows a convention commonly -used in sysfs. configfs_example_explicit.c creates these attributes -by explicitly defining the structures involved. Conversely -configfs_example_macros.c uses some convenience macros from configfs.h -to define the attributes. These macros are similar to their sysfs -counterparts. +subsystem/group and the simple_child item in +samples/configfs/configfs_sample.c. It shows a trivial object displaying +and storing an attribute, and a simple group creating and destroying +these children. [Hierarchy Navigation and the Subsystem Mutex] |