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>

diff --git a/fs/ubifs/lprops.c b/fs/ubifs/lprops.c
index 4d4ca38..c7b25e2 100644 (file)
--- 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;
 }