Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6

[linux-2.6-omap-h63xx.git] / Documentation / filesystems / sysfs.txt

diff --git a/Documentation/filesystems/sysfs.txt b/Documentation/filesystems/sysfs.txt
index dc276598a65a3784c4dd7d41470c41f288db9529..4598ef7b622bb88711cb22595a9b2f85a5050d9c 100644 (file)
--- a/Documentation/filesystems/sysfs.txt
+++ b/Documentation/filesystems/sysfs.txt
@@ -51,7 +51,7 @@ for the attributes, providing a means to read and write kernel
 attributes.
 
 Attributes should be ASCII text files, preferably with only one value
-per file. It is noted that it may not be efficient to contain only
+per file. It is noted that it may not be efficient to contain only one
 value per file, so it is socially acceptable to express an array of
 values of the same type. 
 
@@ -90,7 +90,7 @@ void device_remove_file(struct device *, struct device_attribute *);
 
 It also defines this helper for defining device attributes: 
 
-#define DEVICE_ATTR(_name,_mode,_show,_store)      \
+#define DEVICE_ATTR(_name, _mode, _show, _store)      \
 struct device_attribute dev_attr_##_name = {            \
         .attr = {.name  = __stringify(_name) , .mode   = _mode },      \
         .show   = _show,                                \
@@ -99,14 +99,14 @@ struct device_attribute dev_attr_##_name = {            \
 
 For example, declaring
 
-static DEVICE_ATTR(foo,0644,show_foo,store_foo);
+static DEVICE_ATTR(foo, S_IWUSR | S_IRUGO, show_foo, store_foo);
 
 is equivalent to doing:
 
 static struct device_attribute dev_attr_foo = {
        .attr   = {
                .name = "foo",
-               .mode = 0644,
+               .mode = S_IWUSR | S_IRUGO,
        },
        .show = show_foo,
        .store = store_foo,
@@ -121,8 +121,8 @@ set of sysfs operations for forwarding read and write calls to the
 show and store methods of the attribute owners. 
 
 struct sysfs_ops {
-        ssize_t (*show)(struct kobject *, struct attribute *,char *);
-        ssize_t (*store)(struct kobject *,struct attribute *,const char *);
+        ssize_t (*show)(struct kobject *, struct attribute *, char *);
+        ssize_t (*store)(struct kobject *, struct attribute *, const char *);
 };
 
 [ Subsystems should have already defined a struct kobj_type as a
@@ -137,7 +137,7 @@ calls the associated methods.
 
 To illustrate:
 
-#define to_dev_attr(_attr) container_of(_attr,struct device_attribute,attr)
+#define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
 #define to_dev(d) container_of(d, struct device, kobj)
 
 static ssize_t
@@ -148,7 +148,7 @@ dev_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
         ssize_t ret = 0;
 
         if (dev_attr->show)
-                ret = dev_attr->show(dev,buf);
+                ret = dev_attr->show(dev, buf);
         return ret;
 }
 
@@ -216,16 +216,16 @@ A very simple (and naive) implementation of a device attribute is:
 
 static ssize_t show_name(struct device *dev, struct device_attribute *attr, char *buf)
 {
-        return sprintf(buf,"%s\n",dev->name);
+       return snprintf(buf, PAGE_SIZE, "%s\n", dev->name);
 }
 
 static ssize_t store_name(struct device * dev, const char * buf)
 {
-       sscanf(buf,"%20s",dev->name);
-       return strlen(buf);
+       sscanf(buf, "%20s", dev->name);
+       return strnlen(buf, PAGE_SIZE);
 }
 
-static DEVICE_ATTR(name,S_IRUGO,show_name,store_name);
+static DEVICE_ATTR(name, S_IRUGO, show_name, store_name);
 
 
 (Note that the real implementation doesn't allow userspace to set the 
@@ -238,7 +238,7 @@ Top Level Directory Layout
 The sysfs directory arrangement exposes the relationship of kernel
 data structures. 
 
-The top level sysfs diretory looks like:
+The top level sysfs directory looks like:
 
 block/
 bus/
@@ -246,6 +246,7 @@ class/
 devices/
 firmware/
 net/
+fs/
 
 devices/ contains a filesystem representation of the device tree. It maps
 directly to the internal kernel device tree, which is a hierarchy of
@@ -264,6 +265,10 @@ drivers/ contains a directory for each device driver that is loaded
 for devices on that particular bus (this assumes that drivers do not
 span multiple bus types).
 
+fs/ contains a directory for some filesystems.  Currently each
+filesystem wanting to export attributes must create its own hierarchy
+below fs/ (see ./fuse.txt for an example).
+
 
 More information can driver-model specific features can be found in
 Documentation/driver-model/. 
@@ -290,7 +295,7 @@ struct device_attribute {
 
 Declaring:
 
-DEVICE_ATTR(_name,_str,_mode,_show,_store);
+DEVICE_ATTR(_name, _str, _mode, _show, _store);
 
 Creation/Removal:
 
@@ -310,7 +315,7 @@ struct bus_attribute {
 
 Declaring:
 
-BUS_ATTR(_name,_mode,_show,_store)
+BUS_ATTR(_name, _mode, _show, _store)
 
 Creation/Removal:
 
@@ -331,7 +336,7 @@ struct driver_attribute {
 
 Declaring:
 
-DRIVER_ATTR(_name,_mode,_show,_store)
+DRIVER_ATTR(_name, _mode, _show, _store)
 
 Creation/Removal: