Add pagewrite_reserve().

index 8ba7094..f5b745d 100644
@@ -35,7 +35,7 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action,
 {
 	struct blk_io_trace *t;
 
-	t = kmalloc(sizeof(*t) + len, GFP_KERNEL);
+	t = pagewriter_reserve(bt->pagewriter, sizeof(*t) + len, sizeof(*t));
 	if (t) {
 		const int cpu = smp_processor_id();
 

@@ -47,8 +47,6 @@ static void trace_note(struct blk_trace *bt, pid_t pid, int action,
 		t->cpu = cpu;
 		t->pdu_len = len;
 		memcpy((void *) t + sizeof(*t), data, len);
-		pagewriter_write(bt->pagewriter, t, sizeof(*t) + len);
-		kfree(t);
 	}
 }
 

@@ -168,7 +166,8 @@ void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 	if (unlikely(tsk->btrace_seq != blktrace_seq))
 		trace_note_tsk(bt, tsk);
 
-	t = kmalloc(sizeof(*t) + pdu_len, GFP_KERNEL);
+	t = pagewriter_reserve(bt->pagewriter, sizeof(*t) + pdu_len,
+			       sizeof(*t));
 	if (t) {
 		cpu = smp_processor_id();
 		sequence = per_cpu_ptr(bt->sequence, cpu);

@@ -187,8 +186,6 @@ void __blk_add_trace(struct blk_trace *bt, sector_t sector, int bytes,
 
 		if (pdu_len)
 			memcpy((void *) t + sizeof(*t), pdu_data, pdu_len);
-		pagewriter_write(bt->pagewriter, t, sizeof(*t) + pdu_len);
-		kfree(t);
 	}
 
 	local_irq_restore(flags);

@@ -335,6 +332,21 @@ static const struct file_operations blk_msg_fops = {
 	.write =	blk_msg_write,
 };
 
+static void blk_write_padding_callback(struct pagewriter_buf *buf,
+				       size_t length,
+				       void *reserved)
+{
+	struct blk_io_trace *t = reserved;
+
+	t->magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION;
+	t->action = BLK_TN_PADDING;
+	t->pdu_len = length - sizeof(*t);
+}
+
+static struct pagewriter_callbacks blk_pagewriter_callbacks = {
+	.write_padding           = blk_write_padding_callback,
+};
+
 /*
  * Setup everything required to start tracing
  */

@@ -392,7 +404,8 @@ int do_blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 	n_pages = (buts->buf_size * buts->buf_nr) / PAGE_SIZE;
 	n_pages_wakeup = buts->buf_size / PAGE_SIZE;
 	bt->pagewriter = pagewriter_open("trace", dir, n_pages, n_pages_wakeup,
-					 NULL, bt, 0UL);
+					 &blk_pagewriter_callbacks, bt,
+					 PAGEWRITER_PAD_WRITES);
 	if (!bt->pagewriter)
 		goto err;
 

index 59461f2..c9857f1 100644
@@ -56,6 +56,7 @@ enum blktrace_notify {
 	__BLK_TN_PROCESS = 0,		/* establish pid/name mapping */
 	__BLK_TN_TIMESTAMP,		/* include system clock */
 	__BLK_TN_MESSAGE,		/* Character string message */
+	__BLK_TN_PADDING,		/* Padding message */
 };
 
 

@@ -81,6 +82,7 @@ enum blktrace_notify {
 #define BLK_TN_PROCESS		(__BLK_TN_PROCESS | BLK_TC_ACT(BLK_TC_NOTIFY))
 #define BLK_TN_TIMESTAMP	(__BLK_TN_TIMESTAMP | BLK_TC_ACT(BLK_TC_NOTIFY))
 #define BLK_TN_MESSAGE		(__BLK_TN_MESSAGE | BLK_TC_ACT(BLK_TC_NOTIFY))
+#define BLK_TN_PADDING		(__BLK_TN_PADDING | BLK_TC_ACT(BLK_TC_NOTIFY))
 
 #define BLK_IO_TRACE_MAGIC	0x65617400
 #define BLK_IO_TRACE_VERSION	0x07

97 lines not on this page · raw message

index 4b79274..d27267f 100644
@@ -54,7 +54,7 @@ static void __pagewriter_reset(struct pagewriter_buf *buf, unsigned int init);
  *	@n_pages_wakeup: wakeup readers after this many pages, 0 means never
  *	@cb: client callback functions
  *	@private_data: user-defined data
- *	@rchan_flags: relay flags, passed on to relay
+ *	@flags: channel flags, top half for pagewriter, bottom half for relay
  *
  *	Returns pagewriter pointer if successful, %NULL otherwise.
  *

@@ -67,7 +67,7 @@ struct pagewriter *pagewriter_open(const char *base_filename,
 				   size_t n_pages_wakeup,
 				   struct pagewriter_callbacks *cb,
 				   void *private_data,
-				   unsigned long rchan_flags)
+				   unsigned long flags)
 {
 	unsigned int i;
 	struct pagewriter *pagewriter;

@@ -77,7 +77,7 @@ struct pagewriter *pagewriter_open(const char *base_filename,
 		return NULL;
 
 	rchan = relay_open(base_filename, parent, n_pages_wakeup, NULL,
-			   private_data, rchan_flags);
+			   private_data, flags);
 	if (!rchan)
 		return NULL;
 

@@ -88,6 +88,7 @@ struct pagewriter *pagewriter_open(const char *base_filename,
 	}
 
 	pagewriter->rchan = rchan;
+	pagewriter->flags = flags;
 	pagewriter->n_pages = n_pages;
 	atomic_set(&pagewriter->dropped, 0);
 

@@ -414,10 +415,20 @@ static void new_page_default_callback(struct pagewriter_buf *buf,
 {
 }
 
+/*
+ * write_padding() default callback.
+ */
+void pagewriter_write_padding_default_callback(struct pagewriter_buf *buf,
+					       size_t length,
+					       void *reserved)
+{
+}
+
 /* pagewriter default callbacks */
 static struct pagewriter_callbacks default_pagewriter_callbacks = {
 	.new_page = new_page_default_callback,
 	.switch_page = pagewriter_switch_page_default_callback,
+	.write_padding = pagewriter_write_padding_default_callback,
 };
 
 static void setup_callbacks(struct pagewriter *pagewriter,

@@ -432,6 +443,9 @@ static void setup_callbacks(struct pagewriter *pagewriter,
 		cb->new_page = new_page_default_callback;
 	if (!cb->switch_page)
 		cb->switch_page = pagewriter_switch_page_default_callback;
+	if (!cb->write_padding)
+		cb->write_padding = pagewriter_write_padding_default_callback;
+
 	pagewriter->cb = cb;
 }
 

@@ -502,7 +516,7 @@ size_t pagewriter_switch_page_default_callback(struct pagewriter_buf *buf,
 					       size_t length,
 					       void **reserved)
 {
-	size_t remainder;
+	size_t remainder = length;
 	struct relay_page *new_page;
 
 	if (unlikely(pagewriter_event_toobig(buf, length)))

@@ -517,7 +531,8 @@ size_t pagewriter_switch_page_default_callback(struct pagewriter_buf *buf,
 		return 0;
 	}
 
-	remainder = length - (PAGE_SIZE - buf->offset);
+	if (!(buf->pagewriter->flags & PAGEWRITER_PAD_WRITES))
+		remainder = length - (PAGE_SIZE - buf->offset);
 
 	relay_add_page(buf->pagewriter->rchan, buf->page->page,
 		       &pagewriter_relay_page_callbacks, (void *)buf);