2 files changed, 105 insertions, 1 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 2a2e6ed9aab4..c1504c471fef 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1313,7 +1313,9 @@ struct ext4_super_block {
         __u8    s_first_error_time_hi;
         __u8    s_last_error_time_hi;
         __u8    s_pad[2];
-        __le32  s_reserved[96];         /* Padding to the end of the block */
+        __le16  s_encoding;             /* Filename charset encoding */
+        __le16  s_encoding_flags;       /* Filename charset encoding flags */
+        __le32  s_reserved[95];         /* Padding to the end of the block */
         __le32  s_checksum;             /* crc32c(superblock) */
 };
 
@@ -1338,6 +1340,16 @@ struct ext4_super_block {
 /* Number of quota types we support */
 #define EXT4_MAXQUOTAS 3
 
+#define EXT4_ENC_UTF8_12_1      1
+
+/*
+ * Flags for ext4_sb_info.s_encoding_flags.
+ */
+#define EXT4_ENC_STRICT_MODE_FL (1 << 0)
+
+#define ext4_has_strict_mode(sbi) \
+        (sbi->s_encoding_flags & EXT4_ENC_STRICT_MODE_FL)
+
 /*
  * fourth extended-fs super-block data in memory
  */
@@ -1387,6 +1399,10 @@ struct ext4_sb_info {
         struct kobject s_kobj;
         struct completion s_kobj_unregister;
         struct super_block *s_sb;
+#ifdef CONFIG_UNICODE
+        struct unicode_map *s_encoding;
+        __u16 s_encoding_flags;
+#endif
 
         /* Journaling */
         struct journal_s *s_journal;
@@ -1660,6 +1676,7 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
 #define EXT4_FEATURE_INCOMPAT_LARGEDIR          0x4000 /* >2GB or 3-lvl htree */
 #define EXT4_FEATURE_INCOMPAT_INLINE_DATA       0x8000 /* data in inode */
 #define EXT4_FEATURE_INCOMPAT_ENCRYPT           0x10000
+#define EXT4_FEATURE_INCOMPAT_CASEFOLD          0x20000
 
 extern void ext4_update_dynamic_rev(struct super_block *sb);
 
@@ -1753,6 +1770,7 @@ EXT4_FEATURE_INCOMPAT_FUNCS(csum_seed,		CSUM_SEED)
 EXT4_FEATURE_INCOMPAT_FUNCS(largedir,           LARGEDIR)
 EXT4_FEATURE_INCOMPAT_FUNCS(inline_data,        INLINE_DATA)
 EXT4_FEATURE_INCOMPAT_FUNCS(encrypt,            ENCRYPT)
+EXT4_FEATURE_INCOMPAT_FUNCS(casefold,           CASEFOLD)
 
 #define EXT2_FEATURE_COMPAT_SUPP        EXT4_FEATURE_COMPAT_EXT_ATTR
 #define EXT2_FEATURE_INCOMPAT_SUPP      (EXT4_FEATURE_INCOMPAT_FILETYPE| \
@@ -1780,6 +1798,7 @@ EXT4_FEATURE_INCOMPAT_FUNCS(encrypt,		ENCRYPT)
                                          EXT4_FEATURE_INCOMPAT_MMP | \
                                          EXT4_FEATURE_INCOMPAT_INLINE_DATA | \
                                          EXT4_FEATURE_INCOMPAT_ENCRYPT | \
+                                         EXT4_FEATURE_INCOMPAT_CASEFOLD | \
                                          EXT4_FEATURE_INCOMPAT_CSUM_SEED | \
                                          EXT4_FEATURE_INCOMPAT_LARGEDIR)
 #define EXT4_FEATURE_RO_COMPAT_SUPP     (EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER| \
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 184944d4d8d1..c1b02c3a5a68 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -42,6 +42,7 @@
 #include <linux/cleancache.h>
 #include <linux/uaccess.h>
 #include <linux/iversion.h>
+#include <linux/unicode.h>
 
 #include <linux/kthread.h>
 #include <linux/freezer.h>
@@ -1054,6 +1055,9 @@ static void ext4_put_super(struct super_block *sb)
                 crypto_free_shash(sbi->s_chksum_driver);
         kfree(sbi->s_blockgroup_lock);
         fs_put_dax(sbi->s_daxdev);
+#ifdef CONFIG_UNICODE
+        utf8_unload(sbi->s_encoding);
+#endif
         kfree(sbi);
 }
 
@@ -1750,6 +1754,36 @@ static const struct mount_opts {
         {Opt_err, 0, 0}
 };
 
+#ifdef CONFIG_UNICODE
+static const struct ext4_sb_encodings {
+        __u16 magic;
+        char *name;
+        char *version;
+} ext4_sb_encoding_map[] = {
+        {EXT4_ENC_UTF8_12_1, "utf8", "12.1.0"},
+};
+
+static int ext4_sb_read_encoding(const struct ext4_super_block *es,
+                                 const struct ext4_sb_encodings **encoding,
+                                 __u16 *flags)
+{
+        __u16 magic = le16_to_cpu(es->s_encoding);
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(ext4_sb_encoding_map); i++)
+                if (magic == ext4_sb_encoding_map[i].magic)
+                        break;
+
+        if (i >= ARRAY_SIZE(ext4_sb_encoding_map))
+                return -EINVAL;
+
+        *encoding = &ext4_sb_encoding_map[i];
+        *flags = le16_to_cpu(es->s_encoding_flags);
+
+        return 0;
+}
+#endif
+
 static int handle_mount_opt(struct super_block *sb, char *opt, int token,
                             substring_t *args, unsigned long *journal_devnum,
                             unsigned int *journal_ioprio, int is_remount)
@@ -2880,6 +2914,15 @@ static int ext4_feature_set_ok(struct super_block *sb, int readonly)
                 return 0;
         }
 
+#ifndef CONFIG_UNICODE
+        if (ext4_has_feature_casefold(sb)) {
+                ext4_msg(sb, KERN_ERR,
+                         "Filesystem with casefold feature cannot be "
+                         "mounted without CONFIG_UNICODE");
+                return 0;
+        }
+#endif
+
         if (readonly)
                 return 1;
 
@@ -3770,6 +3813,43 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
                            &journal_ioprio, 0))
                 goto failed_mount;
 
+#ifdef CONFIG_UNICODE
+        if (ext4_has_feature_casefold(sb) && !sbi->s_encoding) {
+                const struct ext4_sb_encodings *encoding_info;
+                struct unicode_map *encoding;
+                __u16 encoding_flags;
+
+                if (ext4_has_feature_encrypt(sb)) {
+                        ext4_msg(sb, KERN_ERR,
+                                 "Can't mount with encoding and encryption");
+                        goto failed_mount;
+                }
+
+                if (ext4_sb_read_encoding(es, &encoding_info,
+                                          &encoding_flags)) {
+                        ext4_msg(sb, KERN_ERR,
+                                 "Encoding requested by superblock is unknown");
+                        goto failed_mount;
+                }
+
+                encoding = utf8_load(encoding_info->version);
+                if (IS_ERR(encoding)) {
+                        ext4_msg(sb, KERN_ERR,
+                                 "can't mount with superblock charset: %s-%s "
+                                 "not supported by the kernel. flags: 0x%x.",
+                                 encoding_info->name, encoding_info->version,
+                                 encoding_flags);
+                        goto failed_mount;
+                }
+                ext4_msg(sb, KERN_INFO,"Using encoding defined by superblock: "
+                         "%s-%s with flags 0x%hx", encoding_info->name,
+                         encoding_info->version?:"\b", encoding_flags);
+
+                sbi->s_encoding = encoding;
+                sbi->s_encoding_flags = encoding_flags;
+        }
+#endif
+
         if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA) {
                 printk_once(KERN_WARNING "EXT4-fs: Warning: mounting "
                             "with data=journal disables delayed "
@@ -4586,6 +4666,11 @@ failed_mount2:
 failed_mount:
         if (sbi->s_chksum_driver)
                 crypto_free_shash(sbi->s_chksum_driver);
+
+#ifdef CONFIG_UNICODE
+        utf8_unload(sbi->s_encoding);
+#endif
+
 #ifdef CONFIG_QUOTA
         for (i = 0; i < EXT4_MAXQUOTAS; i++)
                 kfree(sbi->s_qf_names[i]);