dm thin: stay in out-of-data-space mode once no_space_timeout expires
This fixes an issue where running out of data space would cause the
thin-pool's metadata to become read-only. There was no reason to make
metadata read-only -- calling set_pool_mode() with PM_READ_ONLY was a
misguided way to error all queued and future write IOs. We can
accomplish the same by degrading from PM_OUT_OF_DATA_SPACE to
PM_OUT_OF_DATA_SPACE with error_if_no_space enabled.
Otherwise, the use of PM_READ_ONLY could cause a race where commit() was
started before the PM_READ_ONLY transition but dm_pool_commit_metadata()
would go on to fail because the block manager had transitioned to
read-only. The return of -EPERM from dm_pool_commit_metadata(), due to
attempting to commit while in read-only mode, caused the thin-pool to
set 'needs_check' because a metadata_operation_failed(). This needless
cascade of failures makes life for users more difficult than needed.
Reported-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 8f015d9..34e7953 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -2282,18 +2282,23 @@
queue_delayed_work(pool->wq, &pool->waker, COMMIT_PERIOD);
}
+static void notify_of_pool_mode_change_to_oods(struct pool *pool);
+
/*
* We're holding onto IO to allow userland time to react. After the
* timeout either the pool will have been resized (and thus back in
- * PM_WRITE mode), or we degrade to PM_READ_ONLY and start erroring IO.
+ * PM_WRITE mode), or we degrade to PM_OUT_OF_DATA_SPACE w/ error_if_no_space.
*/
static void do_no_space_timeout(struct work_struct *ws)
{
struct pool *pool = container_of(to_delayed_work(ws), struct pool,
no_space_timeout);
- if (get_pool_mode(pool) == PM_OUT_OF_DATA_SPACE && !pool->pf.error_if_no_space)
- set_pool_mode(pool, PM_READ_ONLY);
+ if (get_pool_mode(pool) == PM_OUT_OF_DATA_SPACE && !pool->pf.error_if_no_space) {
+ pool->pf.error_if_no_space = true;
+ notify_of_pool_mode_change_to_oods(pool);
+ error_retry_list(pool);
+ }
}
/*----------------------------------------------------------------*/
@@ -2371,6 +2376,14 @@
dm_device_name(pool->pool_md), new_mode);
}
+static void notify_of_pool_mode_change_to_oods(struct pool *pool)
+{
+ if (!pool->pf.error_if_no_space)
+ notify_of_pool_mode_change(pool, "out-of-data-space (queue IO)");
+ else
+ notify_of_pool_mode_change(pool, "out-of-data-space (error IO)");
+}
+
static bool passdown_enabled(struct pool_c *pt)
{
return pt->adjusted_pf.discard_passdown;
@@ -2455,7 +2468,7 @@
* frequently seeing this mode.
*/
if (old_mode != new_mode)
- notify_of_pool_mode_change(pool, "out-of-data-space");
+ notify_of_pool_mode_change_to_oods(pool);
pool->process_bio = process_bio_read_only;
pool->process_discard = process_discard_bio;
pool->process_cell = process_cell_read_only;