[PATCH] relayfs: add support for global relay buffers
This patch adds the optional is_global outparam to the create_buf_file()
callback. This can be used by clients to create a single global relayfs
buffer instead of the default per-cpu buffers. This was suggested as being
useful for certain debugging applications where it's more convenient to be
able to get all the data from a single channel without having to go to the
bother of dealing with per-cpu files.
Signed-off-by: Tom Zanussi <zanussi@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/relayfs_fs.h b/include/linux/relayfs_fs.h
index 8c21771..30f4551 100644
--- a/include/linux/relayfs_fs.h
+++ b/include/linux/relayfs_fs.h
@@ -116,6 +116,7 @@
* @parent: the parent of the file to create
* @mode: the mode of the file to create
* @buf: the channel buffer
+ * @is_global: outparam - set non-zero if the buffer should be global
*
* Called during relay_open(), once for each per-cpu buffer,
* to allow the client to create a file to be used to
@@ -126,12 +127,17 @@
* The callback should return the dentry of the file created
* to represent the relay buffer.
*
+ * Setting the is_global outparam to a non-zero value will
+ * cause relay_open() to create a single global buffer rather
+ * than the default set of per-cpu buffers.
+ *
* See Documentation/filesystems/relayfs.txt for more info.
*/
struct dentry *(*create_buf_file)(const char *filename,
struct dentry *parent,
int mode,
- struct rchan_buf *buf);
+ struct rchan_buf *buf,
+ int *is_global);
/*
* remove_buf_file - remove file representing a relayfs channel buffer