UBI: add slab cache for ubi_scan_leb objects

During scanning UBI allocates one struct ubi_scan_leb object for each PEB,
so it can end up allocating thousands of them. Use slab cache to reduce
memory consumption for these 48-byte objects, because currently used
'kmalloc()' ends up allocating 64 bytes per object, instead of 48.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

3 files changed, 25 insertions, 11 deletions

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index ef296350aa8f..ec0ad19c691a 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -923,6 +923,8 @@ int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num, int vid_hdr_offset)
         spin_lock_init(&ubi->volumes_lock);
 
         ubi_msg("attaching mtd%d to ubi%d", mtd->index, ubi_num);
+        dbg_msg("sizeof(struct ubi_scan_leb) %zu", sizeof(struct ubi_scan_leb));
+        dbg_msg("sizeof(struct ubi_wl_entry) %zu", sizeof(struct ubi_wl_entry));
 
         err = io_init(ubi);
         if (err)
diff --git a/drivers/mtd/ubi/scan.c b/drivers/mtd/ubi/scan.c
index 79ca304fc4db..0028bf283930 100644
--- a/drivers/mtd/ubi/scan.c
+++ b/drivers/mtd/ubi/scan.c
@@ -115,7 +115,7 @@ static int add_to_list(struct ubi_scan_info *si, int pnum, int ec, int to_head,
         } else
                 BUG();
 
-        seb = kmalloc(sizeof(struct ubi_scan_leb), GFP_KERNEL);
+        seb = kmem_cache_alloc(si->scan_leb_slab, GFP_KERNEL);
         if (!seb)
                 return -ENOMEM;
 
@@ -144,7 +144,7 @@ static int add_corrupted(struct ubi_scan_info *si, int pnum, int ec)
 
         dbg_bld("add to corrupted: PEB %d, EC %d", pnum, ec);
 
-        seb = kmalloc(sizeof(struct ubi_scan_leb), GFP_KERNEL);
+        seb = kmem_cache_alloc(si->scan_leb_slab, GFP_KERNEL);
         if (!seb)
                 return -ENOMEM;
 
@@ -553,7 +553,7 @@ int ubi_scan_add_used(struct ubi_device *ubi, struct ubi_scan_info *si,
         if (err)
                 return err;
 
-        seb = kmalloc(sizeof(struct ubi_scan_leb), GFP_KERNEL);
+        seb = kmem_cache_alloc(si->scan_leb_slab, GFP_KERNEL);
         if (!seb)
                 return -ENOMEM;
 
@@ -1152,9 +1152,15 @@ struct ubi_scan_info *ubi_scan(struct ubi_device *ubi)
         si->volumes = RB_ROOT;
 
         err = -ENOMEM;
+        si->scan_leb_slab = kmem_cache_create("ubi_scan_leb_slab",
+                                              sizeof(struct ubi_scan_leb),
+                                              0, 0, NULL);
+        if (!si->scan_leb_slab)
+                goto out_si;
+
         ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
         if (!ech)
-                goto out_si;
+                goto out_slab;
 
         vidh = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
         if (!vidh)
@@ -1215,6 +1221,8 @@ out_vidh:
         ubi_free_vid_hdr(ubi, vidh);
 out_ech:
         kfree(ech);
+out_slab:
+        kmem_cache_destroy(si->scan_leb_slab);
 out_si:
         ubi_scan_destroy_si(si);
         return ERR_PTR(err);
@@ -1223,11 +1231,12 @@ out_si:
 /**
  * destroy_sv - free the scanning volume information
  * @sv: scanning volume information
+ * @si: scanning information
  *
  * This function destroys the volume RB-tree (@sv->root) and the scanning
  * volume information.
  */
-static void destroy_sv(struct ubi_scan_volume *sv)
+static void destroy_sv(struct ubi_scan_info *si, struct ubi_scan_volume *sv)
 {
         struct ubi_scan_leb *seb;
         struct rb_node *this = sv->root.rb_node;
@@ -1247,7 +1256,7 @@ static void destroy_sv(struct ubi_scan_volume *sv)
                                         this->rb_right = NULL;
                         }
 
-                        kfree(seb);
+                        kmem_cache_free(si->scan_leb_slab, seb);
                 }
         }
         kfree(sv);
@@ -1265,19 +1274,19 @@ void ubi_scan_destroy_si(struct ubi_scan_info *si)
 
         list_for_each_entry_safe(seb, seb_tmp, &si->alien, u.list) {
                 list_del(&seb->u.list);
-                kfree(seb);
+                kmem_cache_free(si->scan_leb_slab, seb);
         }
         list_for_each_entry_safe(seb, seb_tmp, &si->erase, u.list) {
                 list_del(&seb->u.list);
-                kfree(seb);
+                kmem_cache_free(si->scan_leb_slab, seb);
         }
         list_for_each_entry_safe(seb, seb_tmp, &si->corr, u.list) {
                 list_del(&seb->u.list);
-                kfree(seb);
+                kmem_cache_free(si->scan_leb_slab, seb);
         }
         list_for_each_entry_safe(seb, seb_tmp, &si->free, u.list) {
                 list_del(&seb->u.list);
-                kfree(seb);
+                kmem_cache_free(si->scan_leb_slab, seb);
         }
 
         /* Destroy the volume RB-tree */
@@ -1298,10 +1307,11 @@ void ubi_scan_destroy_si(struct ubi_scan_info *si)
                                         rb->rb_right = NULL;
                         }
 
-                        destroy_sv(sv);
+                        destroy_sv(si, sv);
                 }
         }
 
+        kmem_cache_destroy(si->scan_leb_slab);
         kfree(si);
 }
 
diff --git a/drivers/mtd/ubi/scan.h b/drivers/mtd/ubi/scan.h
index a3264f0bef2b..d48aef15ab5d 100644
--- a/drivers/mtd/ubi/scan.h
+++ b/drivers/mtd/ubi/scan.h
@@ -109,6 +109,7 @@ struct ubi_scan_volume {
  * @mean_ec: mean erase counter value
  * @ec_sum: a temporary variable used when calculating @mean_ec
  * @ec_count: a temporary variable used when calculating @mean_ec
+ * @scan_leb_slab: slab cache for &struct ubi_scan_leb objects
  *
  * This data structure contains the result of scanning and may be used by other
  * UBI sub-systems to build final UBI data structures, further error-recovery
@@ -134,6 +135,7 @@ struct ubi_scan_info {
         int mean_ec;
         uint64_t ec_sum;
         int ec_count;
+        struct kmem_cache *scan_leb_slab;
 };
 
 struct ubi_device;