[3.8.y.z extended stable] Patch "dm thin: always fallback the pool mode if commit fails" has been added to staging queue

[Kamal Mostafa]

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

    dm thin: always fallback the pool mode if commit fails

to the linux-3.8.y-queue branch of the 3.8.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-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.16.

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

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 7c98552d2a45bf36d9ed63c7ef05dafb9b918db6 Mon Sep 17 00:00:00 2001
From: Joe Thornber <ejt at redhat.com>
Date: Wed, 4 Dec 2013 15:05:36 -0500
Subject: dm thin: always fallback the pool mode if commit fails

commit 020cc3b5e28c2e24f59f53a9154faf08564f308e upstream.

Rename commit_or_fallback() to commit().  Now all previous calls to
commit() will trigger the pool mode to fallback if the commit fails.

Also, check the error returned from commit() in alloc_data_block().

Signed-off-by: Joe Thornber <ejt at redhat.com>
Signed-off-by: Mike Snitzer <snitzer at redhat.com>
[ kamal: backport to 3.8 (context) ]
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/md/dm-thin.c | 36 +++++++++++++++---------------------
 1 file changed, 15 insertions(+), 21 deletions(-)

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index c29e967..7ac3dd4 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -810,31 +810,23 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
 	}
 }

-static int commit(struct pool *pool)
-{
-	int r;
-
-	r = dm_pool_commit_metadata(pool->pmd);
-	if (r)
-		DMERR_LIMIT("commit failed: error = %d", r);
-
-	return r;
-}
-
 /*
  * A non-zero return indicates read_only or fail_io mode.
  * Many callers don't care about the return value.
  */
-static int commit_or_fallback(struct pool *pool)
+static int commit(struct pool *pool)
 {
 	int r;

 	if (get_pool_mode(pool) != PM_WRITE)
 		return -EINVAL;

-	r = commit(pool);
-	if (r)
+	r = dm_pool_commit_metadata(pool->pmd);
+	if (r) {
+		DMERR_LIMIT("%s: dm_pool_commit_metadata failed: error = %d",
+			    dm_device_name(pool->pool_md), r);
 		set_pool_mode(pool, PM_READ_ONLY);
+	}

 	return r;
 }
@@ -867,7 +859,9 @@ static int alloc_data_block(struct thin_c *tc, dm_block_t *result)
 			 * Try to commit to see if that will free up some
 			 * more space.
 			 */
-			(void) commit_or_fallback(pool);
+			r = commit(pool);
+			if (r)
+				return r;

 			r = dm_pool_get_free_block_count(pool->pmd, &free_blocks);
 			if (r)
@@ -1271,7 +1265,7 @@ static void process_deferred_bios(struct pool *pool)
 	if (bio_list_empty(&bios) && !need_commit_due_to_time(pool))
 		return;

-	if (commit_or_fallback(pool)) {
+	if (commit(pool)) {
 		while ((bio = bio_list_pop(&bios)))
 			bio_io_error(bio);
 		return;
@@ -2056,7 +2050,7 @@ static int pool_preresume(struct dm_target *ti)
 			return r;
 		}

-		(void) commit_or_fallback(pool);
+		(void) commit(pool);
 	}

 	return 0;
@@ -2084,7 +2078,7 @@ static void pool_postsuspend(struct dm_target *ti)

 	cancel_delayed_work(&pool->waker);
 	flush_workqueue(pool->wq);
-	(void) commit_or_fallback(pool);
+	(void) commit(pool);
 }

 static int check_arg_count(unsigned argc, unsigned args_required)
@@ -2218,7 +2212,7 @@ static int process_reserve_metadata_snap_mesg(unsigned argc, char **argv, struct
 	if (r)
 		return r;

-	(void) commit_or_fallback(pool);
+	(void) commit(pool);

 	r = dm_pool_reserve_metadata_snap(pool->pmd);
 	if (r)
@@ -2280,7 +2274,7 @@ static int pool_message(struct dm_target *ti, unsigned argc, char **argv)
 		DMWARN("Unrecognised thin pool target message received: %s", argv[0]);

 	if (!r)
-		(void) commit_or_fallback(pool);
+		(void) commit(pool);

 	return r;
 }
@@ -2335,7 +2329,7 @@ static void pool_status(struct dm_target *ti, status_type_t type,

 		/* Commit to ensure statistics aren't out-of-date */
 		if (!(status_flags & DM_STATUS_NOFLUSH_FLAG) && !dm_suspended(ti))
-			(void) commit_or_fallback(pool);
+			(void) commit(pool);

 		r = dm_pool_get_metadata_transaction_id(pool->pmd, &transaction_id);
 		if (r) {
--
1.8.3.2