3 files changed, 63 insertions, 3 deletions

diff --git a/fs/relayfs/buffers.c b/fs/relayfs/buffers.c
index 667b529944c5..10187812771e 100644
--- a/fs/relayfs/buffers.c
+++ b/fs/relayfs/buffers.c
@@ -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);
 }
diff --git a/fs/relayfs/relay.c b/fs/relayfs/relay.c
index a9cd5585c45c..b9bb56903272 100644
--- a/fs/relayfs/relay.c
+++ b/fs/relayfs/relay.c
@@ -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;
 }
 
diff --git a/include/linux/relayfs_fs.h b/include/linux/relayfs_fs.h
index 8200ecbe6e0f..8c2177105857 100644
--- a/include/linux/relayfs_fs.h
+++ b/include/linux/relayfs_fs.h
@@ -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);
 };
 
 /*