dm dust: report some message results directly back to user

Some messages (queryblock, countbadblocks, removebadblock) are best
reported directly to user directly. Do so with DMEMIT.

[Bryan: maintain __func__ output in DMEMIT messages]
Signed-off-by: yangerkun <yangerkun@huawei.com>
Signed-off-by: Bryan Gurney <bgurney@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Documentation/admin-guide/device-mapper/dm-dust.rst

@@ -69,10 +69,11 @@ Create the dm-dust device:
         $ sudo dmsetup create dust1 --table '0 33552384 dust /dev/vdb1 0 4096'
 
 Check the status of the read behavior ("bypass" indicates that all I/O
-will be passed through to the underlying device)::
+will be passed through to the underlying device; "verbose" indicates that
+bad block additions, removals, and remaps will be verbosely logged)::
 
         $ sudo dmsetup status dust1
-        0 33552384 dust 252:17 bypass
+        0 33552384 dust 252:17 bypass verbose
 
         $ sudo dd if=/dev/mapper/dust1 of=/dev/null bs=512 count=128 iflag=direct
         128+0 records in
@@ -164,7 +165,7 @@ following message command::
 A message will print with the number of bad blocks currently
 configured on the device::
 
-        kernel: device-mapper: dust: countbadblocks: 895 badblock(s) found
+        countbadblocks: 895 badblock(s) found
 
 Querying for specific bad blocks
 --------------------------------
@@ -176,11 +177,11 @@ following message command::
 
 The following message will print if the block is in the list::
 
-        device-mapper: dust: queryblock: block 72 found in badblocklist
+        dust_query_block: block 72 found in badblocklist
 
 The following message will print if the block is not in the list::
 
-        device-mapper: dust: queryblock: block 72 not found in badblocklist
+        dust_query_block: block 72 not found in badblocklist
 
 The "queryblock" message command will work in both the "enabled"
 and "disabled" modes, allowing the verification of whether a block
@@ -198,12 +199,12 @@ following message command::
 
 After clearing the bad block list, the following message will appear::
 
-        kernel: device-mapper: dust: clearbadblocks: badblocks cleared
+        dust_clear_badblocks: badblocks cleared
 
 If there were no bad blocks to clear, the following message will
 appear::
 
-        kernel: device-mapper: dust: clearbadblocks: no badblocks found
+        dust_clear_badblocks: no badblocks found
 
 Message commands list
 ---------------------

drivers/md/dm-dust.c

@@ -138,20 +138,22 @@ static int dust_add_block(struct dust_device *dd, unsigned long long block,
 	return 0;
 }
 
-static int dust_query_block(struct dust_device *dd, unsigned long long block)
+static int dust_query_block(struct dust_device *dd, unsigned long long block, char *result,
+			    unsigned int maxlen, unsigned int *sz_ptr)
 {
 	struct badblock *bblock;
 	unsigned long flags;
+	unsigned int sz = *sz_ptr;
 
 	spin_lock_irqsave(&dd->dust_lock, flags);
 	bblock = dust_rb_search(&dd->badblocklist, block);
 	if (bblock != NULL)
-		DMINFO("%s: block %llu found in badblocklist", __func__, block);
+		DMEMIT("%s: block %llu found in badblocklist", __func__, block);
 	else
-		DMINFO("%s: block %llu not found in badblocklist", __func__, block);
+		DMEMIT("%s: block %llu not found in badblocklist", __func__, block);
 	spin_unlock_irqrestore(&dd->dust_lock, flags);
 
-	return 0;
+	return 1;
 }
 
 static int __dust_map_read(struct dust_device *dd, sector_t thisblock)
@@ -259,11 +261,13 @@ static bool __dust_clear_badblocks(struct rb_root *tree,
 	return true;
 }
 
-static int dust_clear_badblocks(struct dust_device *dd)
+static int dust_clear_badblocks(struct dust_device *dd, char *result, unsigned int maxlen,
+				unsigned int *sz_ptr)
 {
 	unsigned long flags;
 	struct rb_root badblocklist;
 	unsigned long long badblock_count;
+	unsigned int sz = *sz_ptr;
 
 	spin_lock_irqsave(&dd->dust_lock, flags);
 	badblocklist = dd->badblocklist;
@@ -273,11 +277,11 @@ static int dust_clear_badblocks(struct dust_device *dd)
 	spin_unlock_irqrestore(&dd->dust_lock, flags);
 
 	if (!__dust_clear_badblocks(&badblocklist, badblock_count))
-		DMINFO("%s: no badblocks found", __func__);
+		DMEMIT("%s: no badblocks found", __func__);
 	else
-		DMINFO("%s: badblocks cleared", __func__);
+		DMEMIT("%s: badblocks cleared", __func__);
 
-	return 0;
+	return 1;
 }
 
 /*
@@ -383,7 +387,7 @@ static void dust_dtr(struct dm_target *ti)
 }
 
 static int dust_message(struct dm_target *ti, unsigned int argc, char **argv,
-			char *result_buf, unsigned int maxlen)
+			char *result, unsigned int maxlen)
 {
 	struct dust_device *dd = ti->private;
 	sector_t size = i_size_read(dd->dev->bdev->bd_inode) >> SECTOR_SHIFT;
@@ -393,6 +397,7 @@ static int dust_message(struct dm_target *ti, unsigned int argc, char **argv,
 	unsigned char wr_fail_cnt;
 	unsigned int tmp_ui;
 	unsigned long flags;
+	unsigned int sz = 0;
 	char dummy;
 
 	if (argc == 1) {
@@ -410,12 +415,12 @@ static int dust_message(struct dm_target *ti, unsigned int argc, char **argv,
 			r = 0;
 		} else if (!strcasecmp(argv[0], "countbadblocks")) {
 			spin_lock_irqsave(&dd->dust_lock, flags);
-			DMINFO("countbadblocks: %llu badblock(s) found",
+			DMEMIT("countbadblocks: %llu badblock(s) found",
 			       dd->badblock_count);
 			spin_unlock_irqrestore(&dd->dust_lock, flags);
-			r = 0;
+			r = 1;
 		} else if (!strcasecmp(argv[0], "clearbadblocks")) {
-			r = dust_clear_badblocks(dd);
+			r = dust_clear_badblocks(dd, result, maxlen, &sz);
 		} else if (!strcasecmp(argv[0], "quiet")) {
 			if (!dd->quiet_mode)
 				dd->quiet_mode = true;
@@ -441,7 +446,7 @@ static int dust_message(struct dm_target *ti, unsigned int argc, char **argv,
 		else if (!strcasecmp(argv[0], "removebadblock"))
 			r = dust_remove_block(dd, block);
 		else if (!strcasecmp(argv[0], "queryblock"))
-			r = dust_query_block(dd, block);
+			r = dust_query_block(dd, block, result, maxlen, &sz);
 		else
 			invalid_msg = true;