linux-kernel - [PATCH 3.14 016/130] dm thin: restore requested error_if_no_space setting on OODS to WRITE transition

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Message-Id: <20160301234500.333312024@linuxfoundation.org>
Date:	Tue, 01 Mar 2016 23:51:04 +0000
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	<linux-kernel@...r.kernel.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<stable@...r.kernel.org>, Vivek Goyal <vgoyal@...hat.com>,
	Mike Snitzer <snitzer@...hat.com>,
	Joe Thornber <ejt@...hat.com>
Subject: [PATCH 3.14 016/130] dm thin: restore requested error_if_no_space setting on OODS to WRITE transition

3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mike Snitzer <snitzer@...hat.com>

commit 172c238612ebf81cabccc86b788c9209af591f61 upstream.

A thin-pool that is in out-of-data-space (OODS) mode may transition back
to write mode -- without the admin adding more space to the thin-pool --
if/when blocks are released (either by deleting thin devices or
discarding provisioned blocks).

But as part of the thin-pool's earlier transition to out-of-data-space
mode the thin-pool may have set the 'error_if_no_space' flag to true if
the no_space_timeout expires without more space having been made
available.  That implementation detail, of changing the pool's
error_if_no_space setting, needs to be reset back to the default that
the user specified when the thin-pool's table was loaded.

Otherwise we'll drop the user requested behaviour on the floor when this
out-of-data-space to write mode transition occurs.

Reported-by: Vivek Goyal <vgoyal@...hat.com>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
Acked-by: Joe Thornber <ejt@...hat.com>
Fixes: 2c43fd26e4 ("dm thin: fix missing out-of-data-space to write mode transition if blocks are released")
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/md/dm-thin.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -1619,6 +1619,7 @@ static void set_pool_mode(struct pool *p
 	case PM_WRITE:
 		if (old_mode != new_mode)
 			notify_of_pool_mode_change(pool, "write");
+		pool->pf.error_if_no_space = pt->requested_pf.error_if_no_space;
 		dm_pool_metadata_read_write(pool->pmd);
 		pool->process_bio = process_bio;
 		pool->process_discard = process_discard;