dm cache: avoid calls to prealloc_free_structs() if possible

If no work was performed then prealloc_data_structs() wasn't ever called
so there isn't any need to call prealloc_free_structs().

Signed-off-by: Mike Snitzer <snitzer@redhat.com>

1 files changed, 12 insertions, 3 deletions

diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c
index 408dd276d6c9..b680da5d7b93 100644
--- a/drivers/md/dm-cache-target.c
+++ b/drivers/md/dm-cache-target.c
@@ -1946,6 +1946,7 @@ static int commit_if_needed(struct cache *cache)
 
 static void process_deferred_bios(struct cache *cache)
 {
+        bool prealloc_used = false;
         unsigned long flags;
         struct bio_list bios;
         struct bio *bio;
@@ -1980,13 +1981,16 @@ static void process_deferred_bios(struct cache *cache)
                         process_discard_bio(cache, &structs, bio);
                 else
                         process_bio(cache, &structs, bio);
+                prealloc_used = true;
         }
 
-        prealloc_free_structs(cache, &structs);
+        if (prealloc_used)
+                prealloc_free_structs(cache, &structs);
 }
 
 static void process_deferred_cells(struct cache *cache)
 {
+        bool prealloc_used = false;
         unsigned long flags;
         struct dm_bio_prison_cell *cell, *tmp;
         struct list_head cells;
@@ -2014,9 +2018,11 @@ static void process_deferred_cells(struct cache *cache)
                 }
 
                 process_cell(cache, &structs, cell);
+                prealloc_used = true;
         }
 
-        prealloc_free_structs(cache, &structs);
+        if (prealloc_used)
+                prealloc_free_structs(cache, &structs);
 }
 
 static void process_deferred_flush_bios(struct cache *cache, bool submit_bios)
@@ -2061,6 +2067,7 @@ static void process_deferred_writethrough_bios(struct cache *cache)
 
 static void writeback_some_dirty_blocks(struct cache *cache)
 {
+        bool prealloc_used = false;
         dm_oblock_t oblock;
         dm_cblock_t cblock;
         struct prealloc structs;
@@ -2080,9 +2087,11 @@ static void writeback_some_dirty_blocks(struct cache *cache)
                 }
 
                 writeback(cache, &structs, oblock, cblock, old_ocell);
+                prealloc_used = true;
         }
 
-        prealloc_free_structs(cache, &structs);
+        if (prealloc_used)
+                prealloc_free_structs(cache, &structs);
 }
 
 /*----------------------------------------------------------------