Commit 08c541a7 authored by Tom Zanussi's avatar Tom Zanussi Committed by Linus Torvalds
Browse files

[PATCH] relayfs: add support for relay files in other filesystems 



This patch adds a couple of callback functions that allow a client to hook
into relay_open()/close() and supply the files that will be used to represent
the channel buffers; the default implementation if no callbacks are defined is
to create the files in relayfs.  This is to support the creation and use of
relay files in other filesystems such as debugfs, as implied by the fact that
relayfs_file_operations are exported.

Signed-off-by: default avatarTom Zanussi <zanussi@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 925ac8a2

fs/relayfs/buffers.c

+1 −1
Original line number Diff line number Diff line
@@ -185,6 +185,6 @@ void relay_destroy_buf(struct rchan_buf *buf) 
void relay_remove_buf(struct kref *kref)

{

	struct rchan_buf *buf = container_of(kref, struct rchan_buf, kref);

	relayfs_remove(buf->dentry);

	buf->chan->cb->remove_buf_file(buf->dentry);

	relay_destroy_buf(buf);

}

fs/relayfs/relay.c

+28 −2
Original line number Diff line number Diff line
@@ -80,11 +80,33 @@ static void buf_unmapped_default_callback(struct rchan_buf *buf, 
{

}



/*

 * create_buf_file_create() default callback.  Creates file to represent buf.

 */

static struct dentry *create_buf_file_default_callback(const char *filename,

						       struct dentry *parent,

						       int mode,

						       struct rchan_buf *buf)

{

	return relayfs_create_file(filename, parent, mode,

				   &relayfs_file_operations, buf);

}



/*

 * remove_buf_file() default callback.  Removes file representing relay buffer.

 */

static int remove_buf_file_default_callback(struct dentry *dentry)

{

	return relayfs_remove(dentry);

}



/* relay channel default callbacks */

static struct rchan_callbacks default_channel_callbacks = {

	.subbuf_start = subbuf_start_default_callback,

	.buf_mapped = buf_mapped_default_callback,

	.buf_unmapped = buf_unmapped_default_callback,

	.create_buf_file = create_buf_file_default_callback,

	.remove_buf_file = remove_buf_file_default_callback,

};



/**
@@ -176,8 +198,8 @@ static struct rchan_buf *relay_open_buf(struct rchan *chan, 
 		return NULL;



	/* Create file in fs */

	dentry = relayfs_create_file(filename, parent, S_IRUSR,

				     &relayfs_file_operations, buf);

 	dentry = chan->cb->create_buf_file(filename, parent, S_IRUSR,

 					   buf);

 	if (!dentry) {

 		relay_destroy_buf(buf);

		return NULL;
@@ -220,6 +242,10 @@ static inline void setup_callbacks(struct rchan *chan, 
		cb->buf_mapped = buf_mapped_default_callback;

	if (!cb->buf_unmapped)

		cb->buf_unmapped = buf_unmapped_default_callback;

	if (!cb->create_buf_file)

		cb->create_buf_file = create_buf_file_default_callback;

	if (!cb->remove_buf_file)

		cb->remove_buf_file = remove_buf_file_default_callback;

	chan->cb = cb;

}

include/linux/relayfs_fs.h

+34 −0
Original line number Diff line number Diff line
@@ -110,6 +110,40 @@ struct rchan_callbacks 
	 */

        void (*buf_unmapped)(struct rchan_buf *buf,

			     struct file *filp);

	/*

	 * create_buf_file - create file to represent a relayfs channel buffer

	 * @filename: the name of the file to create

	 * @parent: the parent of the file to create

	 * @mode: the mode of the file to create

	 * @buf: the channel buffer

	 *

	 * Called during relay_open(), once for each per-cpu buffer,

	 * to allow the client to create a file to be used to

	 * represent the corresponding channel buffer.  If the file is

	 * created outside of relayfs, the parent must also exist in

	 * that filesystem.

	 *

	 * The callback should return the dentry of the file created

	 * to represent the relay buffer.

	 *

	 * 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);



	/*

	 * remove_buf_file - remove file representing a relayfs channel buffer

	 * @dentry: the dentry of the file to remove

	 *

	 * Called during relay_close(), once for each per-cpu buffer,

	 * to allow the client to remove a file used to represent a

	 * channel buffer.

	 *

	 * The callback should return 0 if successful, negative if not.

	 */

	int (*remove_buf_file)(struct dentry *dentry);

};



/*

CRA Git | Maintained and supported by SUSTech CRA and CCSE