9p: Update documentation to add fscache related bits

[safe/jmp/linux-2.6] / Documentation / filesystems / relay.txt

diff --git a/Documentation/filesystems/relay.txt b/Documentation/filesystems/relay.txt
index 7fbb6ff..510b722 100644 (file)
--- a/Documentation/filesystems/relay.txt
+++ b/Documentation/filesystems/relay.txt
@@ -140,7 +140,7 @@ close()     decrements the channel buffer's refcount.  When the refcount
 In order for a user application to make use of relay files, the
 host filesystem must be mounted.  For example,
 
-       mount -t debugfs debugfs /debug
+       mount -t debugfs debugfs /sys/kernel/debug
 
 NOTE:   the host filesystem doesn't need to be mounted for kernel
        clients to create or use channels - it only needs to be
@@ -294,6 +294,16 @@ user-defined data with a channel, and is immediately available
 (including in create_buf_file()) via chan->private_data or
 buf->chan->private_data.
 
+Buffer-only channels
+--------------------
+
+These channels have no files associated and can be created with
+relay_open(NULL, NULL, ...). Such channels are useful in scenarios such
+as when doing early tracing in the kernel, before the VFS is up. In these
+cases, one may open a buffer-only channel and then call
+relay_late_setup_files() when the kernel is ready to handle files,
+to expose the buffered data to the userspace.
+
 Channel 'modes'
 ---------------
 
@@ -351,7 +361,7 @@ If the current buffer is full, i.e. all sub-buffers remain unconsumed,
 the callback returns 0 to indicate that the buffer switch should not
 occur yet, i.e. until the consumer has had a chance to read the
 current set of ready sub-buffers.  For the relay_buf_full() function
-to make sense, the consumer is reponsible for notifying the relay
+to make sense, the consumer is responsible for notifying the relay
 interface when sub-buffers have been consumed via
 relay_subbufs_consumed().  Any subsequent attempts to write into the
 buffer will again invoke the subbuf_start() callback with the same