[PATCH 3.16.y-ckt 183/216] dm thin: fix missing out-of-data-space to write mode transition if blocks are released

Luis Henriques
2015-01-12T18:41:28Z

From: Joe Thornber <ejt@redhat.com>

commit 2c43fd26e46734430122b8d2ad3024bb532df3ef upstream.

Discard bios and thin device deletion have the potential to release data
blocks. If the thin-pool is in out-of-data-space mode, and blocks were
released, transition the thin-pool back to full write mode.

The correct time to do this is just after the thin-pool metadata commit.
It cannot be done before the commit because the space maps will not
allow immediate reuse of the data blocks in case there's a rollback
following power failure.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
drivers/md/dm-thin.c | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index c13efb1020d9..408ffba7ec63 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -936,6 +936,24 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
}
}

+static void set_pool_mode(struct pool *pool, enum pool_mode new_mode);
+
+static void check_for_space(struct pool *pool)
+{
+ int r;
+ dm_block_t nr_free;
+
+ if (get_pool_mode(pool) != PM_OUT_OF_DATA_SPACE)
+ return;
+
+ r = dm_pool_get_free_block_count(pool->pmd, &nr_free);
+ if (r)
+ return;
+
+ if (nr_free)
+ set_pool_mode(pool, PM_WRITE);
+}
+
/*
* A non-zero return indicates read_only or fail_io mode.
* Many callers don't care about the return value.
@@ -950,6 +968,8 @@ static int commit(struct pool *pool)
r = dm_pool_commit_metadata(pool->pmd);
if (r)
metadata_operation_failed(pool, "dm_pool_commit_metadata", r);
+ else
+ check_for_space(pool);

return r;
}
@@ -968,8 +988,6 @@ static void check_low_water_mark(struct pool *pool, dm_block_t free_blocks)
}
}

-static void set_pool_mode(struct pool *pool, enum pool_mode new_mode);
-
static int alloc_data_block(struct thin_c *tc, dm_block_t *result)
{
int r;
--
2.1.4