(2006-08-06) rescue-bootcd

extra/linux-2.6.10/include/linux/backing-dev.h

@@ -0,0 +1,65 @@
+/*
+ * include/linux/backing-dev.h
+ *
+ * low-level device information and state which is propagated up through
+ * to high-level code.
+ */
+
+#ifndef _LINUX_BACKING_DEV_H
+#define _LINUX_BACKING_DEV_H
+
+#include <asm/atomic.h>
+
+/*
+ * Bits in backing_dev_info.state
+ */
+enum bdi_state {
+	BDI_pdflush,		/* A pdflush thread is working this device */
+	BDI_write_congested,	/* The write queue is getting full */
+	BDI_read_congested,	/* The read queue is getting full */
+	BDI_unused,		/* Available bits start here */
+};
+
+typedef int (congested_fn)(void *, int);
+
+struct backing_dev_info {
+	unsigned long ra_pages;	/* max readahead in PAGE_CACHE_SIZE units */
+	unsigned long state;	/* Always use atomic bitops on this */
+	int memory_backed;	/* Cannot clean pages with writepage */
+	congested_fn *congested_fn; /* Function pointer if device is md/dm */
+	void *congested_data;	/* Pointer to aux data for congested func */
+	void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
+	void *unplug_io_data;
+};
+
+extern struct backing_dev_info default_backing_dev_info;
+void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
+
+int writeback_acquire(struct backing_dev_info *bdi);
+int writeback_in_progress(struct backing_dev_info *bdi);
+void writeback_release(struct backing_dev_info *bdi);
+
+static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
+{
+	if (bdi->congested_fn)
+		return bdi->congested_fn(bdi->congested_data, bdi_bits);
+	return (bdi->state & bdi_bits);
+}
+
+static inline int bdi_read_congested(struct backing_dev_info *bdi)
+{
+	return bdi_congested(bdi, 1 << BDI_read_congested);
+}
+
+static inline int bdi_write_congested(struct backing_dev_info *bdi)
+{
+	return bdi_congested(bdi, 1 << BDI_write_congested);
+}
+
+static inline int bdi_rw_congested(struct backing_dev_info *bdi)
+{
+	return bdi_congested(bdi, (1 << BDI_read_congested)|
+				  (1 << BDI_write_congested));
+}
+
+#endif		/* _LINUX_BACKING_DEV_H */