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configfs: remove old API

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Remove the old show_attribute and store_attribute methods and update
the documentation.  Also replace the two C samples with a single new
one in the proper samples directory where people expect to find it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Christoph Hellwig
2015-10-03 15:32:59 +02:00
committed by Nicholas Bellinger
parent 45b997737a
commit 517982229f
10 changed files with 73 additions and 701 deletions
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38
Documentation/filesystems/configfs/configfs.txt
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@@ -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]