UBIFS: allocate scanning buffer on demand

Instead of using pre-allocated 'c->dbg->buf' buffer in
'scan_check_cb()', dynamically allocate it when needed. The intend
is to get rid of the pre-allocated 'c->dbg->buf' buffer and save
128KiB of RAM (or more if PEB size is larger). Indeed, currently we
allocate this memory even if the user never enables any self-check,
which is wasteful.

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

1 files changed, 20 insertions, 6 deletions

diff --git a/fs/ubifs/lprops.c b/fs/ubifs/lprops.c
index 4d4ca388889b..c7b25e2f7764 100644
--- a/fs/ubifs/lprops.c
+++ b/fs/ubifs/lprops.c
@@ -1035,7 +1035,8 @@ static int scan_check_cb(struct ubifs_info *c,
         struct ubifs_scan_leb *sleb;
         struct ubifs_scan_node *snod;
         struct ubifs_lp_stats *lst = &data->lst;
-        int cat, lnum = lp->lnum, is_idx = 0, used = 0, free, dirty;
+        int cat, lnum = lp->lnum, is_idx = 0, used = 0, free, dirty, ret;
+        void *buf = NULL;
 
         cat = lp->flags & LPROPS_CAT_MASK;
         if (cat != LPROPS_UNCAT) {
@@ -1093,7 +1094,13 @@ static int scan_check_cb(struct ubifs_info *c,
                 }
         }
 
-        sleb = ubifs_scan(c, lnum, 0, c->dbg->buf, 0);
+        buf = __vmalloc(c->leb_size, GFP_KERNEL | GFP_NOFS, PAGE_KERNEL);
+        if (!buf) {
+                ubifs_err("cannot allocate memory to scan LEB %d", lnum);
+                goto out;
+        }
+
+        sleb = ubifs_scan(c, lnum, 0, buf, 0);
         if (IS_ERR(sleb)) {
                 /*
                  * After an unclean unmount, empty and freeable LEBs
@@ -1105,7 +1112,8 @@ static int scan_check_cb(struct ubifs_info *c,
                         lst->empty_lebs += 1;
                         lst->total_free += c->leb_size;
                         lst->total_dark += ubifs_calc_dark(c, c->leb_size);
-                        return LPT_SCAN_CONTINUE;
+                        ret = LPT_SCAN_CONTINUE;
+                        goto exit;
                 }
 
                 if (lp->free + lp->dirty == c->leb_size &&
@@ -1115,10 +1123,12 @@ static int scan_check_cb(struct ubifs_info *c,
                         lst->total_free  += lp->free;
                         lst->total_dirty += lp->dirty;
                         lst->total_dark  +=  ubifs_calc_dark(c, c->leb_size);
-                        return LPT_SCAN_CONTINUE;
+                        ret = LPT_SCAN_CONTINUE;
+                        goto exit;
                 }
                 data->err = PTR_ERR(sleb);
-                return LPT_SCAN_STOP;
+                ret = LPT_SCAN_STOP;
+                goto exit;
         }
 
         is_idx = -1;
@@ -1236,7 +1246,10 @@ static int scan_check_cb(struct ubifs_info *c,
         }
 
         ubifs_scan_destroy(sleb);
-        return LPT_SCAN_CONTINUE;
+        ret = LPT_SCAN_CONTINUE;
+exit:
+        vfree(buf);
+        return ret;
 
 out_print:
         ubifs_err("bad accounting of LEB %d: free %d, dirty %d flags %#x, "
@@ -1246,6 +1259,7 @@ out_print:
 out_destroy:
         ubifs_scan_destroy(sleb);
 out:
+        vfree(buf);
         data->err = -EINVAL;
         return LPT_SCAN_STOP;
 }