laptop-mode: Make flushes per-device

One of the features of laptop-mode is that it forces a writeout of dirty
pages if something else triggers a physical read or write from a device.
The current implementation flushes pages on all devices, rather than only
the one that triggered the flush. This patch alters the behaviour so that
only the recently accessed block device is flushed, preventing other
disks being spun up for no terribly good reason.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

2 files changed, 6 insertions, 1 deletions

diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index fcbc26af00e4..2742e1adfc30 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -14,6 +14,7 @@
 #include <linux/kernel.h>
 #include <linux/fs.h>
 #include <linux/sched.h>
+#include <linux/timer.h>
 #include <linux/writeback.h>
 #include <asm/atomic.h>
 
@@ -88,6 +89,8 @@ struct backing_dev_info {
 
         struct device *dev;
 
+        struct timer_list laptop_mode_wb_timer;
+
 #ifdef CONFIG_DEBUG_FS
         struct dentry *debug_dir;
         struct dentry *debug_stats;
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 36520ded3e06..eb38a2c645f6 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -96,8 +96,10 @@ static inline void inode_sync_wait(struct inode *inode)
 /*
  * mm/page-writeback.c
  */
-void laptop_io_completion(void);
+void laptop_io_completion(struct backing_dev_info *info);
 void laptop_sync_completion(void);
+void laptop_mode_sync(struct work_struct *work);
+void laptop_mode_timer_fn(unsigned long data);
 void throttle_vm_writeout(gfp_t gfp_mask);
 
 /* These are exported to sysctl. */