ext4: Add support for non-native signed/unsigned htree hash algorithms

The original ext3 hash algorithms assumed that variables of type char
were signed, as God and K&R intended.  Unfortunately, this assumption
is not true on some architectures.  Userspace support for marking
filesystems with non-native signed/unsigned chars was added two years
ago, but the kernel-side support was never added (until now).

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 12 insertions, 0 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 04158ad74dbb..08fc86a358d3 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2118,6 +2118,18 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
         for (i = 0; i < 4; i++)
                 sbi->s_hash_seed[i] = le32_to_cpu(es->s_hash_seed[i]);
         sbi->s_def_hash_version = es->s_def_hash_version;
+        i = le32_to_cpu(es->s_flags);
+        if (i & EXT2_FLAGS_UNSIGNED_HASH)
+                sbi->s_hash_unsigned = 3;
+        else if ((i & EXT2_FLAGS_SIGNED_HASH) == 0) {
+#ifdef __CHAR_UNSIGNED__
+                es->s_flags |= cpu_to_le32(EXT2_FLAGS_UNSIGNED_HASH);
+                sbi->s_hash_unsigned = 3;
+#else
+                es->s_flags |= cpu_to_le32(EXT2_FLAGS_SIGNED_HASH);
+#endif
+                sb->s_dirt = 1;
+        }
 
         if (sbi->s_blocks_per_group > blocksize * 8) {
                 printk(KERN_ERR