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dm raid1: split touched state into two

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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>
This commit is contained in:
Mikulas Patocka 2009-12-10 23:51:59 +00:00 committed by Alasdair G Kergon
parent 4184153f9e
commit b09acf1aa7
1 changed files with 11 additions and 7 deletions
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18
drivers/md/dm-log.c
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@ -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;
}