dm thin: restore requested 'error_if_no_space' setting on OODS to WRITE transition

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@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Joe Thornber <ejt@redhat.com>
Fixes: 2c43fd26e4 ("dm thin: fix missing out-of-data-space to write mode transition if blocks are released")
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 6d8895422f31a23e3b83ab1090bf85930d8c0d53..e298762d29a66c9ba668634359e9883f3291ca7b 100644 (file)
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -1786,6 +1786,7 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
        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;