Right now we use DMWARN to output a message on console if thin/snap device
creation fails. It has two problems.
- First of all this is not a warning and an error. In case of error, just
returning code to user space should be good enough. If we need some debug
info out, then a better choice will be pr_debug() which can be enabled
when the need be.
- dm-thin expects users to keep track of already used device id. If an
application tries to reuse the id, then -EEXIST is returned but this
message is also displayed on console.
[17991.140135] device-mapper: thin: Creation of new snapshot 33 of device 3 failed
Docker does not keep track of already used device ids. Instead it starts from
0 and keeps on incrementing this id and retrying till it succeeds. And that
leads to flooding console with above messages.
I think it is better to just return error code to user space and not give
any warning. Instead convert this into pr_debug() so that if need be one
can enable it dynamically using debugfs and get some debug data out on a
running system.
One can enable all pr_debug() in dm-thin.c file using following.
echo 'file dm-thin.c +p' > /sys/kernel/debug/dynamic_debug/control
Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
drivers/md/dm-thin.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
Index: linux-2.6/drivers/md/dm-thin.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-thin.c 2014-11-04 10:05:43.504600136 -0500
+++ linux-2.6/drivers/md/dm-thin.c 2014-11-04 10:15:48.984908908 -0500
@@ -4,6 +4,8 @@
* This file is released under the GPL.
*/
+#define pr_fmt(fmt) "device-mapper: thin: " fmt
+
#include "dm-thin-metadata.h"
#include "dm-bio-prison.h"
#include "dm.h"
@@ -2819,7 +2821,7 @@ static int process_create_thin_mesg(unsi
r = dm_pool_create_thin(pool->pmd, dev_id);
if (r) {
- DMWARN("Creation of new thinly-provisioned device with id %s failed.",
+ pr_debug("Creation of new thinly-provisioned device with id %s failed.",
argv[1]);
return r;
}
@@ -2847,7 +2849,7 @@ static int process_create_snap_mesg(unsi
r = dm_pool_create_snap(pool->pmd, dev_id, origin_dev_id);
if (r) {
- DMWARN("Creation of new snapshot %s of device %s failed.",
+ pr_debug("Creation of new snapshot %s of device %s failed.",
argv[1], argv[2]);
return r;
}
--
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