[3.11.y.z extended stable] Patch "dm thin: switch to read only mode if a mapping insert fails" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    dm thin: switch to read only mode if a mapping insert fails

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 76a4f4efe9c8662ff0c392543a3c45ddb1c5a009 Mon Sep 17 00:00:00 2001
From: Joe Thornber <ejt at redhat.com>
Date: Mon, 2 Dec 2013 17:57:42 -0500
Subject: dm thin: switch to read only mode if a mapping insert fails

commit fafc7a815e40255d24e80a1cb7365892362fa398 upstream.

Switch the thin pool to read-only mode when dm_thin_insert_block() fails
since there is little reason to expect the cause of the failure to be
resolved without further action by user space.

This issue was noticed with the device-mapper-test-suite using:
dmtest run --suite thin-provisioning -n /exhausting_metadata_space_causes_fail_mode/

The quantity of errors logged in this case must be reduced.

before patch:

device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: dm_thin_insert_block() failed
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map metadata: unable to allocate new metadata block
<snip ... these repeat for a long while ... >
device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: space map common: dm_tm_shadow_block() failed
device-mapper: thin: 253:4: no free metadata space available.
device-mapper: thin: 253:4: switching pool to read-only mode

after patch:

device-mapper: space map metadata: unable to allocate new metadata block
device-mapper: thin: 253:4: dm_thin_insert_block() failed: error = -28
device-mapper: thin: 253:4: switching pool to read-only mode

Signed-off-by: Joe Thornber <ejt at redhat.com>
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/md/dm-thin.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 88f2f80..e36f81e 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -640,7 +640,9 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)
 	 */
 	r = dm_thin_insert_block(tc->td, m->virt_block, m->data_block);
 	if (r) {
-		DMERR_LIMIT("dm_thin_insert_block() failed");
+		DMERR_LIMIT("%s: dm_thin_insert_block() failed: error = %d",
+			    dm_device_name(pool->pool_md), r);
+		set_pool_mode(pool, PM_READ_ONLY);
 		cell_error(pool, m->cell);
 		goto out;
 	}
--
1.8.3.2