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>

diff --git a/fs/ubifs/lpt_commit.c b/fs/ubifs/lpt_commit.c
index 62a38d9c55e9140adc90291bc5dd6c65c72b052d..0a3c2c3f5c4a305675d94f2a191d4b362879c869 100644 (file)
--- 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;
 }
 
 /**