dm writecache: return the exact table values that were set

BugLink: https://bugs.launchpad.net/bugs/1939442

commit 054bee1 upstream.

LVM doesn't like it when the target returns different values from what
was set in the constructor. Fix dm-writecache so that the returned
table values are exactly the same as requested values.

Signed-off-by: Mikulas Patocka <[email protected]>
Cc: [email protected] # v4.18+
Signed-off-by: Mike Snitzer <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Kamal Mostafa <[email protected]>
Signed-off-by: Kelsey Skunberg <[email protected]>

Author: Mikulas Patocka

drivers/md/dm-writecache.c

@@ -154,6 +154,7 @@ struct dm_writecache {
 	bool overwrote_committed:1;
 	bool memory_vmapped:1;
 
+	bool start_sector_set:1;
 	bool high_wm_percent_set:1;
 	bool low_wm_percent_set:1;
 	bool max_writeback_jobs_set:1;
@@ -162,6 +163,10 @@ struct dm_writecache {
 	bool writeback_fua_set:1;
 	bool flush_on_suspend:1;
 
+	unsigned high_wm_percent_value;
+	unsigned low_wm_percent_value;
+	unsigned autocommit_time_value;
+
 	unsigned writeback_all;
 	struct workqueue_struct *writeback_wq;
 	struct work_struct writeback_work;
@@ -2069,6 +2074,7 @@ static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv)
 			if (sscanf(string, "%llu%c", &start_sector, &dummy) != 1)
 				goto invalid_optional;
 			wc->start_sector = start_sector;
+			wc->start_sector_set = true;
 			if (wc->start_sector != start_sector ||
 			    wc->start_sector >= wc->memory_map_size >> SECTOR_SHIFT)
 				goto invalid_optional;
@@ -2078,13 +2084,15 @@ static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv)
 				goto invalid_optional;
 			if (high_wm_percent < 0 || high_wm_percent > 100)
 				goto invalid_optional;
+			wc->high_wm_percent_value = high_wm_percent;
 			wc->high_wm_percent_set = true;
 		} else if (!strcasecmp(string, "low_watermark") && opt_params >= 1) {
 			string = dm_shift_arg(&as), opt_params--;
 			if (sscanf(string, "%d%c", &low_wm_percent, &dummy) != 1)
 				goto invalid_optional;
 			if (low_wm_percent < 0 || low_wm_percent > 100)
 				goto invalid_optional;
+			wc->low_wm_percent_value = low_wm_percent;
 			wc->low_wm_percent_set = true;
 		} else if (!strcasecmp(string, "writeback_jobs") && opt_params >= 1) {
 			string = dm_shift_arg(&as), opt_params--;
@@ -2104,6 +2112,7 @@ static int writecache_ctr(struct dm_target *ti, unsigned argc, char **argv)
 			if (autocommit_msecs > 3600000)
 				goto invalid_optional;
 			wc->autocommit_jiffies = msecs_to_jiffies(autocommit_msecs);
+			wc->autocommit_time_value = autocommit_msecs;
 			wc->autocommit_time_set = true;
 		} else if (!strcasecmp(string, "fua")) {
 			if (WC_MODE_PMEM(wc)) {
@@ -2305,7 +2314,6 @@ static void writecache_status(struct dm_target *ti, status_type_t type,
 	struct dm_writecache *wc = ti->private;
 	unsigned extra_args;
 	unsigned sz = 0;
-	uint64_t x;
 
 	switch (type) {
 	case STATUSTYPE_INFO:
@@ -2317,7 +2325,7 @@ static void writecache_status(struct dm_target *ti, status_type_t type,
 		DMEMIT("%c %s %s %u ", WC_MODE_PMEM(wc) ? 'p' : 's',
 				wc->dev->name, wc->ssd_dev->name, wc->block_size);
 		extra_args = 0;
-		if (wc->start_sector)
+		if (wc->start_sector_set)
 			extra_args += 2;
 		if (wc->high_wm_percent_set)
 			extra_args += 2;
@@ -2333,26 +2341,18 @@ static void writecache_status(struct dm_target *ti, status_type_t type,
 			extra_args++;
 
 		DMEMIT("%u", extra_args);
-		if (wc->start_sector)
+		if (wc->start_sector_set)
 			DMEMIT(" start_sector %llu", (unsigned long long)wc->start_sector);
-		if (wc->high_wm_percent_set) {
-			x = (uint64_t)wc->freelist_high_watermark * 100;
-			x += wc->n_blocks / 2;
-			do_div(x, (size_t)wc->n_blocks);
-			DMEMIT(" high_watermark %u", 100 - (unsigned)x);
-		}
-		if (wc->low_wm_percent_set) {
-			x = (uint64_t)wc->freelist_low_watermark * 100;
-			x += wc->n_blocks / 2;
-			do_div(x, (size_t)wc->n_blocks);
-			DMEMIT(" low_watermark %u", 100 - (unsigned)x);
-		}
+		if (wc->high_wm_percent_set)
+			DMEMIT(" high_watermark %u", wc->high_wm_percent_value);
+		if (wc->low_wm_percent_set)
+			DMEMIT(" low_watermark %u", wc->low_wm_percent_value);
 		if (wc->max_writeback_jobs_set)
 			DMEMIT(" writeback_jobs %u", wc->max_writeback_jobs);
 		if (wc->autocommit_blocks_set)
 			DMEMIT(" autocommit_blocks %u", wc->autocommit_blocks);
 		if (wc->autocommit_time_set)
-			DMEMIT(" autocommit_time %u", jiffies_to_msecs(wc->autocommit_jiffies));
+			DMEMIT(" autocommit_time %u", wc->autocommit_time_value);
 		if (wc->writeback_fua_set)
 			DMEMIT(" %sfua", wc->writeback_fua ? "" : "no");
 		break;