UBIFS: allocate dump buffer on demand

Instead of using pre-allocated 'c->dbg->buf' buffer in
'dbg_dump_leb()', 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, 13 insertions, 2 deletions

diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index 02c10dccdd60..c2e5c08a9d30 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -810,16 +810,24 @@ void dbg_dump_leb(const struct ubifs_info *c, int lnum)
 {
         struct ubifs_scan_leb *sleb;
         struct ubifs_scan_node *snod;
+        void *buf;
 
         if (dbg_failure_mode)
                 return;
 
         printk(KERN_DEBUG "(pid %d) start dumping LEB %d\n",
                current->pid, lnum);
-        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 for dumping LEB %d", lnum);
+                return;
+        }
+
+        sleb = ubifs_scan(c, lnum, 0, buf, 0);
         if (IS_ERR(sleb)) {
                 ubifs_err("scan error %d", (int)PTR_ERR(sleb));
-                return;
+                goto out;
         }
 
         printk(KERN_DEBUG "LEB %d has %d nodes ending at %d\n", lnum,
@@ -835,6 +843,9 @@ void dbg_dump_leb(const struct ubifs_info *c, int lnum)
         printk(KERN_DEBUG "(pid %d) finish dumping LEB %d\n",
                current->pid, lnum);
         ubifs_scan_destroy(sleb);
+
+out:
+        vfree(buf);
         return;
 }