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Commit af5feae3 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'writeback-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux 

fix 1 mysterious divide error
fix 3 NULL dereference bugs in writeback tracing, on SD card removal w/o umount

* tag 'writeback-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux:
  writeback: fix dereferencing NULL bdi->dev on trace_writeback_queue
  lib: proportion: lower PROP_MAX_SHIFT to 32 on 64-bit kernel
  writeback: fix NULL bdi->dev in trace writeback_single_inode
  backing-dev: fix wakeup timer races with bdi_unregister()
parents ce2814f2 977b7e3a

fs/fs-writeback.c

+8 −8
Original line number Diff line number Diff line
@@ -52,14 +52,6 @@ struct wb_writeback_work { 
	struct completion *done;	/* set if the caller waits */

};



/*

 * Include the creation of the trace points after defining the

 * wb_writeback_work structure so that the definition remains local to this

 * file.

 */

#define CREATE_TRACE_POINTS

#include <trace/events/writeback.h>



/*

 * We don't actually have pdflush, but this one is exported though /proc...

 */
@@ -92,6 +84,14 @@ static inline struct inode *wb_inode(struct list_head *head) 
	return list_entry(head, struct inode, i_wb_list);

}



/*

 * Include the creation of the trace points after defining the

 * wb_writeback_work structure and inline functions so that the definition

 * remains local to this file.

 */

#define CREATE_TRACE_POINTS

#include <trace/events/writeback.h>



/* Wakeup flusher thread or forker thread to fork it. Requires bdi->wb_lock. */

static void bdi_wakeup_flusher(struct backing_dev_info *bdi)

{

include/linux/proportions.h

+4 −0
Original line number Diff line number Diff line
@@ -81,7 +81,11 @@ void prop_inc_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl) 
 * Limit the time part in order to ensure there are some bits left for the

 * cycle counter and fraction multiply.

 */

#if BITS_PER_LONG == 32

#define PROP_MAX_SHIFT (3*BITS_PER_LONG/4)

#else

#define PROP_MAX_SHIFT (BITS_PER_LONG/2)

#endif



#define PROP_FRAC_SHIFT		(BITS_PER_LONG - PROP_MAX_SHIFT - 1)

#define PROP_FRAC_BASE		(1UL << PROP_FRAC_SHIFT)

include/trace/events/writeback.h

+5 −2
Original line number Diff line number Diff line
@@ -47,7 +47,10 @@ DECLARE_EVENT_CLASS(writeback_work_class, 
		__field(int, reason)

	),

	TP_fast_assign(

		strncpy(__entry->name, dev_name(bdi->dev), 32);

		struct device *dev = bdi->dev;

		if (!dev)

			dev = default_backing_dev_info.dev;

		strncpy(__entry->name, dev_name(dev), 32);

		__entry->nr_pages = work->nr_pages;

		__entry->sb_dev = work->sb ? work->sb->s_dev : 0;

		__entry->sync_mode = work->sync_mode;
@@ -426,7 +429,7 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template, 


	TP_fast_assign(

		strncpy(__entry->name,

			dev_name(inode->i_mapping->backing_dev_info->dev), 32);

			dev_name(inode_to_bdi(inode)->dev), 32);

		__entry->ino		= inode->i_ino;

		__entry->state		= inode->i_state;

		__entry->dirtied_when	= inode->dirtied_when;

mm/backing-dev.c

+18 −5
Original line number Diff line number Diff line
@@ -318,7 +318,7 @@ static void wakeup_timer_fn(unsigned long data) 
	if (bdi->wb.task) {

		trace_writeback_wake_thread(bdi);

		wake_up_process(bdi->wb.task);

	} else {

	} else if (bdi->dev) {

		/*

		 * When bdi tasks are inactive for long time, they are killed.

		 * In this case we have to wake-up the forker thread which
@@ -584,6 +584,8 @@ EXPORT_SYMBOL(bdi_register_dev); 
 */

static void bdi_wb_shutdown(struct backing_dev_info *bdi)

{

	struct task_struct *task;



	if (!bdi_cap_writeback_dirty(bdi))

		return;
@@ -602,8 +604,13 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi) 
	 * Finally, kill the kernel thread. We don't need to be RCU

	 * safe anymore, since the bdi is gone from visibility.

	 */

	if (bdi->wb.task)

		kthread_stop(bdi->wb.task);

	spin_lock_bh(&bdi->wb_lock);

	task = bdi->wb.task;

	bdi->wb.task = NULL;

	spin_unlock_bh(&bdi->wb_lock);



	if (task)

		kthread_stop(task);

}



/*
@@ -623,7 +630,9 @@ static void bdi_prune_sb(struct backing_dev_info *bdi) 


void bdi_unregister(struct backing_dev_info *bdi)

{

	if (bdi->dev) {

	struct device *dev = bdi->dev;



	if (dev) {

		bdi_set_min_ratio(bdi, 0);

		trace_writeback_bdi_unregister(bdi);

		bdi_prune_sb(bdi);
@@ -632,8 +641,12 @@ void bdi_unregister(struct backing_dev_info *bdi) 
		if (!bdi_cap_flush_forker(bdi))

			bdi_wb_shutdown(bdi);

		bdi_debug_unregister(bdi);

		device_unregister(bdi->dev);



		spin_lock_bh(&bdi->wb_lock);

		bdi->dev = NULL;

		spin_unlock_bh(&bdi->wb_lock);



		device_unregister(dev);

	}

}

EXPORT_SYMBOL(bdi_unregister);