Commit b09acf1a authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Alasdair G Kergon
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dm raid1: split touched state into two 



Split the variable "touched" into two, "touched_dirtied" and
"touched_cleaned", set when some region was dirtied or cleaned.

This will be used to optimize flushes.

After a transition from "dirty" to "clean" state we don't have flush hardware
cache on the log device. After a transition from "clean" to "dirty" the cache
must be flushed.

Before a transition from "clean" to "dirty" state we don't have to flush all
the raid legs. Before a transition from "dirty" to "clean" we must flush all
the legs to make sure that they are really in sync.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 4184153f

drivers/md/dm-log.c

+11 −7
Original line number Diff line number Diff line
@@ -208,7 +208,8 @@ struct log_header { 


struct log_c {

	struct dm_target *ti;

	int touched;

	int touched_dirtied;

	int touched_cleaned;

	uint32_t region_size;

	unsigned int region_count;

	region_t sync_count;
@@ -253,14 +254,14 @@ static inline void log_set_bit(struct log_c *l, 
			       uint32_t *bs, unsigned bit)

{

	ext2_set_bit(bit, (unsigned long *) bs);

	l->touched = 1;

	l->touched_cleaned = 1;

}



static inline void log_clear_bit(struct log_c *l,

				 uint32_t *bs, unsigned bit)

{

	ext2_clear_bit(bit, (unsigned long *) bs);

	l->touched = 1;

	l->touched_dirtied = 1;

}



/*----------------------------------------------------------------
@@ -378,7 +379,8 @@ static int create_log_context(struct dm_dirty_log *log, struct dm_target *ti, 
	}



	lc->ti = ti;

	lc->touched = 0;

	lc->touched_dirtied = 0;

	lc->touched_cleaned = 0;

	lc->region_size = region_size;

	lc->region_count = region_count;

	lc->sync = sync;
@@ -660,14 +662,16 @@ static int disk_flush(struct dm_dirty_log *log) 
	struct log_c *lc = (struct log_c *) log->context;



	/* only write if the log has changed */

	if (!lc->touched)

	if (!lc->touched_cleaned && !lc->touched_dirtied)

		return 0;



	r = rw_header(lc, WRITE);

	if (r)

		fail_log_device(lc);

	else

		lc->touched = 0;

	else {

		lc->touched_dirtied = 0;

		lc->touched_cleaned = 0;

	}



	return r;

}