[dm-devel] [PATCH] dm table: improve terse warning messages with more context

[Mike Snitzer]

NOTE: this patch depends on the pending device_area_is_invalid() patch:
http://patchwork.kernel.org/patch/37759/

---

The lack of context in two dm-table warnings has already proven
unfortunate when analyzing the root-cause of these warnings.  Two recent
fixes went in to address issues that triggered these terse warnings:
5dea271b6d87bd1d79a59c1d5baac2596a841c37
ea9df47cc92573b159ef3b4fda516c32cba9c4fd

If the warnings contained the additional info that this patch provides
it would have made life easier on both the developers and end-users.

Having specific information up-front will improve the dialog with users
that hit these warnings in the future.

Signed-off-by: Mike Snitzer <snitzer at redhat.com>

---

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index aa60526..50981b0 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -360,8 +360,12 @@ static int device_area_is_invalid(struct dm_target *ti, struct dm_dev *dev,
 		return 0;
 
 	if ((start >= dev_size) || (start + len > dev_size)) {
-		DMWARN("%s: %s too small for target",
-		       dm_device_name(ti->table->md), bdevname(bdev, b));
+		DMWARN("%s: %s too small for target: "
+		       "start=%llu, len=%llu, dev_size=%llu",
+		       dm_device_name(ti->table->md), bdevname(bdev, b),
+		       (unsigned long long)start,
+		       (unsigned long long)len,
+		       (unsigned long long)dev_size);
 		return 1;
 	}
 
@@ -496,8 +500,13 @@ int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev,
 	}
 
 	if (blk_stack_limits(limits, &q->limits, start << 9) < 0)
-		DMWARN("%s: target device %s is misaligned",
-		       dm_device_name(ti->table->md), bdevname(bdev, b));
+		DMWARN("%s: target device %s is misaligned: "
+		       "physical_block_size=%hu, alignment_offset=%hu, "
+		       "start=%llu",
+		       dm_device_name(ti->table->md), bdevname(bdev, b),
+		       q->limits.physical_block_size,
+		       q->limits.alignment_offset,
+		       (unsigned long long) start << 9);
 
 	/*
 	 * Check if merge fn is supported.