ubifs: Implement UBIFS_FLG_DOUBLE_HASH

This feature flag indicates that all directory entry nodes have a 32bit
cookie set and therefore UBIFS is allowed to perform lookups by hash.

Signed-off-by: Richard Weinberger <richard@nod.at>

1 files changed, 11 insertions, 3 deletions

diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
index 88d33775f18b..a459211a1c21 100644
--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -501,6 +501,14 @@ static void mark_inode_clean(struct ubifs_info *c, struct ubifs_inode *ui)
 	ui->dirty = 0;
 }
 
+static void set_dent_cookie(struct ubifs_info *c, struct ubifs_dent_node *dent)
+{
+	if (c->double_hash)
+		dent->cookie = prandom_u32();
+	else
+		dent->cookie = 0;
+}
+
 /**
  * ubifs_jnl_update - update inode.
  * @c: UBIFS file-system description object
@@ -589,7 +597,7 @@ int ubifs_jnl_update(struct ubifs_info *c, const struct inode *dir,
 	dent->nlen = cpu_to_le16(fname_len(nm));
 	memcpy(dent->name, fname_name(nm), fname_len(nm));
 	dent->name[fname_len(nm)] = '\0';
-	dent->cookie = prandom_u32();
+	set_dent_cookie(c, dent);
 
 	zero_dent_node_unused(dent);
 	ubifs_prep_grp_node(c, dent, dlen, 0);
@@ -1125,7 +1133,7 @@ int ubifs_jnl_rename(struct ubifs_info *c, const struct inode *old_dir,
 	dent->nlen = cpu_to_le16(fname_len(new_nm));
 	memcpy(dent->name, fname_name(new_nm), fname_len(new_nm));
 	dent->name[fname_len(new_nm)] = '\0';
-	dent->cookie = prandom_u32();
+	set_dent_cookie(c, dent);
 	zero_dent_node_unused(dent);
 	ubifs_prep_grp_node(c, dent, dlen1, 0);
 
@@ -1144,7 +1152,7 @@ int ubifs_jnl_rename(struct ubifs_info *c, const struct inode *old_dir,
 	dent2->nlen = cpu_to_le16(fname_len(old_nm));
 	memcpy(dent2->name, fname_name(old_nm), fname_len(old_nm));
 	dent2->name[fname_len(old_nm)] = '\0';
-	dent2->cookie = prandom_u32();
+	set_dent_cookie(c, dent2);
 	zero_dent_node_unused(dent2);
 	ubifs_prep_grp_node(c, dent2, dlen2, 0);