1 files changed, 49 insertions, 0 deletions

diff --git a/storage/innobase/fsp/fsp0fsp.c b/storage/innobase/fsp/fsp0fsp.c
index 1ec1c262a52..1f033c4b140 100644
--- a/storage/innobase/fsp/fsp0fsp.c
+++ b/storage/innobase/fsp/fsp0fsp.c
@@ -2842,12 +2842,61 @@ fsp_get_available_space_in_free_extents(
 
 	ut_ad(!mutex_own(&kernel_mutex));
 
+	/* The convoluted mutex acquire is to overcome latching order
+	issues: The problem is that the fil_mutex is at a lower level
+	than the tablespace latch and the buffer pool mutex. We have to
+	first prevent any operations on the file system by acquiring the
+	dictionary mutex. Then acquire the tablespace latch to obey the
+	latching order and then release the dictionary mutex. That way we
+	ensure that the tablespace instance can't be freed while we are
+	examining its contents (see fil_space_free()).
+
+	However, there is one further complication, we release the fil_mutex
+	when we need to invalidate the the pages in the buffer pool and we
+	reacquire the fil_mutex when deleting and freeing the tablespace
+	instance in fil0fil.c. Here we need to account for that situation
+	too. */
+
+	dict_mutex_enter_for_mysql();
+
+	/* At this stage there is no guarantee that the tablespace even
+	exists in the cache. */
+
+	if (fil_tablespace_deleted_or_being_deleted_in_mem(space, -1)) {
+
+		dict_mutex_exit_for_mysql();
+
+		return(ULLINT_UNDEFINED);
+	}
+
 	mtr_start(&mtr);
 
 	latch = fil_space_get_latch(space);
 
+	/* This should ensure that the tablespace instance can't be freed
+	by another thread. However, the tablespace pages can still be freed
+	from the buffer pool. We need to check for that again. */
+
 	mtr_x_lock(latch, &mtr);
 
+	dict_mutex_exit_for_mysql();
+
+	/* At this point it is possible for the tablespace to be deleted and
+	its pages removed from the buffer pool. We need to check for that
+	situation. However, the tablespace instance can't be deleted because
+	our latching above should ensure that. */
+
+	if (fil_tablespace_is_being_deleted(space)) {
+
+		mtr_commit(&mtr);
+
+		return(ULLINT_UNDEFINED);
+	}
+
+	/* From here on even if the user has dropped the tablespace, the
+	pages _must_ still exist in the buffer pool and the tablespace
+	instance _must be in the file system hash table. */
+
 	space_header = fsp_get_space_header(space, &mtr);
 
 	size = mtr_read_ulint(space_header + FSP_SIZE, MLOG_4BYTES, &mtr);