dm thin: fix missing out-of-data-space to write mode transition if blocks are released

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index eb6aac8e30610fc8e082019950993acf183922ed..f7e052c7ab5f31e8a99c10c664f1f531523f3cba 100644 (file)
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -916,6 +916,24 @@ 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.
@@ -930,6 +948,8 @@ 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;
 }
@@ -948,8 +968,6 @@ 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;