Btrfs: allocate prelim_ref with a slab allocater

struct __prelim_ref is allocated and freed frequently when
walking backref tree, using slab allocater can not only
speed up allocating but also detect memory leaks.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Reviewed-by: Miao Xie <miaox@cn.fujitsu.com>
Reviewed-by: Jan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

3 files changed, 37 insertions, 6 deletions

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index f3cb19114c95..0552a599b28f 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -119,6 +119,26 @@ struct __prelim_ref {
         u64 wanted_disk_byte;
 };
 
+static struct kmem_cache *btrfs_prelim_ref_cache;
+
+int __init btrfs_prelim_ref_init(void)
+{
+        btrfs_prelim_ref_cache = kmem_cache_create("btrfs_prelim_ref",
+                                        sizeof(struct __prelim_ref),
+                                        0,
+                                        SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
+                                        NULL);
+        if (!btrfs_prelim_ref_cache)
+                return -ENOMEM;
+        return 0;
+}
+
+void btrfs_prelim_ref_exit(void)
+{
+        if (btrfs_prelim_ref_cache)
+                kmem_cache_destroy(btrfs_prelim_ref_cache);
+}
+
 /*
  * the rules for all callers of this function are:
  * - obtaining the parent is the goal
@@ -165,7 +185,7 @@ static int __add_prelim_ref(struct list_head *head, u64 root_id,
 {
         struct __prelim_ref *ref;
 
-        ref = kmalloc(sizeof(*ref), gfp_mask);
+        ref = kmem_cache_alloc(btrfs_prelim_ref_cache, gfp_mask);
         if (!ref)
                 return -ENOMEM;
 
@@ -368,7 +388,8 @@ static int __resolve_indirect_refs(struct btrfs_fs_info *fs_info,
 
                 /* additional parents require new refs being added here */
                 while ((node = ulist_next(parents, &uiter))) {
-                        new_ref = kmalloc(sizeof(*new_ref), GFP_NOFS);
+                        new_ref = kmem_cache_alloc(btrfs_prelim_ref_cache,
+                                                   GFP_NOFS);
                         if (!new_ref) {
                                 ret = -ENOMEM;
                                 goto out;
@@ -492,7 +513,7 @@ static void __merge_refs(struct list_head *head, int mode)
                         ref1->count += ref2->count;
 
                         list_del(&ref2->list);
-                        kfree(ref2);
+                        kmem_cache_free(btrfs_prelim_ref_cache, ref2);
                 }
 
         }
@@ -955,7 +976,7 @@ again:
                         }
                 }
                 list_del(&ref->list);
-                kfree(ref);
+                kmem_cache_free(btrfs_prelim_ref_cache, ref);
         }
 
 out:
@@ -963,13 +984,13 @@ out:
         while (!list_empty(&prefs)) {
                 ref = list_first_entry(&prefs, struct __prelim_ref, list);
                 list_del(&ref->list);
-                kfree(ref);
+                kmem_cache_free(btrfs_prelim_ref_cache, ref);
         }
         while (!list_empty(&prefs_delayed)) {
                 ref = list_first_entry(&prefs_delayed, struct __prelim_ref,
                                        list);
                 list_del(&ref->list);
-                kfree(ref);
+                kmem_cache_free(btrfs_prelim_ref_cache, ref);
         }
 
         return ret;
diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
index 8f2e76702932..a910b27a8ad9 100644
--- a/fs/btrfs/backref.h
+++ b/fs/btrfs/backref.h
@@ -72,4 +72,6 @@ int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
                           struct btrfs_inode_extref **ret_extref,
                           u64 *found_off);
 
+int __init btrfs_prelim_ref_init(void);
+void btrfs_prelim_ref_exit(void);
 #endif
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 4d5d0f3eb0d8..3aab10ce63e8 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -56,6 +56,7 @@
 #include "rcu-string.h"
 #include "dev-replace.h"
 #include "free-space-cache.h"
+#include "backref.h"
 #include "tests/btrfs-tests.h"
 
 #define CREATE_TRACE_POINTS
@@ -1810,6 +1811,10 @@ static int __init init_btrfs_fs(void)
         if (err)
                 goto free_auto_defrag;
 
+        err = btrfs_prelim_ref_init();
+        if (err)
+                goto free_prelim_ref;
+
         err = btrfs_interface_init();
         if (err)
                 goto free_delayed_ref;
@@ -1830,6 +1835,8 @@ static int __init init_btrfs_fs(void)
 
 unregister_ioctl:
         btrfs_interface_exit();
+free_prelim_ref:
+        btrfs_prelim_ref_exit();
 free_delayed_ref:
         btrfs_delayed_ref_exit();
 free_auto_defrag:
@@ -1856,6 +1863,7 @@ static void __exit exit_btrfs_fs(void)
         btrfs_delayed_ref_exit();
         btrfs_auto_defrag_exit();
         btrfs_delayed_inode_exit();
+        btrfs_prelim_ref_exit();
         ordered_data_exit();
         extent_map_exit();
         extent_io_exit();