Merge git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-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 c8bce82ddcacdf22e6a7190c204faf154821a619..7f27b8f840d06210df1511db6ef603cedb8f0e58 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. 
 
@@ -176,8 +176,10 @@ implementations:
   Recall that an attribute should only be exporting one value, or an
   array of similar values, so this shouldn't be that expensive. 
 
-  This allows userspace to do partial reads and seeks arbitrarily over
-  the entire file at will. 
+  This allows userspace to do partial reads and forward seeks
+  arbitrarily over the entire file at will. If userspace seeks back to
+  zero or does a pread(2) with an offset of '0' the show() method will
+  be called again, rearmed, to fill the buffer.
 
 - On write(2), sysfs expects the entire buffer to be passed during the
   first write. Sysfs then passes the entire buffer to the store()
@@ -192,6 +194,9 @@ implementations:
 
 Other notes:
 
+- Writing causes the show() method to be rearmed regardless of current
+  file position.
+
 - The buffer will always be PAGE_SIZE bytes in length. On i386, this
   is 4096. 
 
@@ -238,7 +243,7 @@ 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 +251,7 @@ 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 +270,10 @@ 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/.