dm log: add flush_header function
Introduce flush_header and use it to flush the log device.
Note that we don't have to flush if all the regions transition
from "dirty" to "clean" state.
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 31dc33d..6b23631 100644
--- a/drivers/md/dm-log.c
+++ b/drivers/md/dm-log.c
@@ -288,6 +288,19 @@
return dm_io(&lc->io_req, 1, &lc->header_location, NULL);
}
+static int flush_header(struct log_c *lc)
+{
+ struct dm_io_region null_location = {
+ .bdev = lc->header_location.bdev,
+ .sector = 0,
+ .count = 0,
+ };
+
+ lc->io_req.bi_rw = WRITE_BARRIER;
+
+ return dm_io(&lc->io_req, 1, &null_location, NULL);
+}
+
static int read_header(struct log_c *log)
{
int r;
@@ -616,6 +629,8 @@
/* write the new header */
r = rw_header(lc, WRITE);
+ if (!r)
+ r = flush_header(lc);
if (r) {
DMWARN("%s: Failed to write header on dirty region log device",
lc->log_dev->name);
@@ -669,7 +684,13 @@
if (r)
fail_log_device(lc);
else {
- lc->touched_dirtied = 0;
+ if (lc->touched_dirtied) {
+ r = flush_header(lc);
+ if (r)
+ fail_log_device(lc);
+ else
+ lc->touched_dirtied = 0;
+ }
lc->touched_cleaned = 0;
}