UBIFS: allocate lpt dump buffer on demand

Instead of using pre-allocated 'c->dbg->buf' buffer in
'dump_lpt_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, 18 insertions, 9 deletions

diff --git a/fs/ubifs/lpt_commit.c b/fs/ubifs/lpt_commit.c
index 62a38d9c55e9..0a3c2c3f5c4a 100644
--- a/fs/ubifs/lpt_commit.c
+++ b/fs/ubifs/lpt_commit.c
@@ -1881,25 +1881,31 @@ int dbg_chk_lpt_sz(struct ubifs_info *c, int action, int len)
 static void dump_lpt_leb(const struct ubifs_info *c, int lnum)
 {
         int err, len = c->leb_size, node_type, node_num, node_len, offs;
-        void *buf = c->dbg->buf;
+        void *buf, *p;
 
         printk(KERN_DEBUG "(pid %d) start dumping LEB %d\n",
                current->pid, lnum);
+        buf = p = __vmalloc(c->leb_size, GFP_KERNEL | GFP_NOFS, PAGE_KERNEL);
+        if (!buf) {
+                ubifs_err("cannot allocate memory to dump LPT");
+                return;
+        }
+
         err = ubi_read(c->ubi, lnum, buf, 0, c->leb_size);
         if (err) {
                 ubifs_err("cannot read LEB %d, error %d", lnum, err);
-                return;
+                goto out;
         }
         while (1) {
                 offs = c->leb_size - len;
-                if (!is_a_node(c, buf, len)) {
+                if (!is_a_node(c, p, len)) {
                         int pad_len;
 
-                        pad_len = get_pad_len(c, buf, len);
+                        pad_len = get_pad_len(c, p, len);
                         if (pad_len) {
                                 printk(KERN_DEBUG "LEB %d:%d, pad %d bytes\n",
                                        lnum, offs, pad_len);
-                                buf += pad_len;
+                                p += pad_len;
                                 len -= pad_len;
                                 continue;
                         }
@@ -1909,7 +1915,7 @@ static void dump_lpt_leb(const struct ubifs_info *c, int lnum)
                         break;
                 }
 
-                node_type = get_lpt_node_type(c, buf, &node_num);
+                node_type = get_lpt_node_type(c, p, &node_num);
                 switch (node_type) {
                 case UBIFS_LPT_PNODE:
                 {
@@ -1934,7 +1940,7 @@ static void dump_lpt_leb(const struct ubifs_info *c, int lnum)
                         else
                                 printk(KERN_DEBUG "LEB %d:%d, nnode, ",
                                        lnum, offs);
-                        err = ubifs_unpack_nnode(c, buf, &nnode);
+                        err = ubifs_unpack_nnode(c, p, &nnode);
                         for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
                                 printk(KERN_CONT "%d:%d", nnode.nbranch[i].lnum,
                                        nnode.nbranch[i].offs);
@@ -1955,15 +1961,18 @@ static void dump_lpt_leb(const struct ubifs_info *c, int lnum)
                         break;
                 default:
                         ubifs_err("LPT node type %d not recognized", node_type);
-                        return;
+                        goto out;
                 }
 
-                buf += node_len;
+                p += node_len;
                 len -= node_len;
         }
 
         printk(KERN_DEBUG "(pid %d) finish dumping LEB %d\n",
                current->pid, lnum);
+out:
+        vfree(buf);
+        return;
 }
 
 /**