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: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm-log.c b/drivers/md/dm-log.c
index 9443896..31dc33d 100644
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -208,7 +208,8 @@
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 @@
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 @@
}
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 @@
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;
}