[PATCH NOMERGE 09/13] ext4: Include encoding information on the superblock

[Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxxxx>]

Signed-off-by: Gabriel Krisman Bertazi <krisman@xxxxxxxxxxxxxxx>
---
 fs/ext4/ext4.h  |  1 +
 fs/ext4/super.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 3241475a1733..22f49d7d3efc 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1366,6 +1366,7 @@ struct ext4_sb_info {
 	struct kobject s_kobj;
 	struct completion s_kobj_unregister;
 	struct super_block *s_sb;
+	struct nls_table *encoding;
 
 	/* Journaling */
 	struct journal_s *s_journal;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 39bf464c35f1..bbf0a5c4104b 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/nls.h>
 
 #include <linux/kthread.h>
 #include <linux/freezer.h>
@@ -1352,6 +1353,7 @@ enum {
 	Opt_dioread_nolock, Opt_dioread_lock,
 	Opt_discard, Opt_nodiscard, Opt_init_itable, Opt_noinit_itable,
 	Opt_max_dir_size_kb, Opt_nojournal_checksum, Opt_nombcache,
+	Opt_encoding,
 };
 
 static const match_table_t tokens = {
@@ -1434,6 +1436,7 @@ static const match_table_t tokens = {
 	{Opt_noinit_itable, "noinit_itable"},
 	{Opt_max_dir_size_kb, "max_dir_size_kb=%u"},
 	{Opt_test_dummy_encryption, "test_dummy_encryption"},
+	{Opt_encoding, "encoding=%s"},
 	{Opt_nombcache, "nombcache"},
 	{Opt_nombcache, "no_mbcache"},	/* for backward compatibility */
 	{Opt_removed, "check=none"},	/* mount option from ext2/3 */
@@ -1644,9 +1647,24 @@ static const struct mount_opts {
 	{Opt_max_dir_size_kb, 0, MOPT_GTE0},
 	{Opt_test_dummy_encryption, 0, MOPT_GTE0},
 	{Opt_nombcache, EXT4_MOUNT_NO_MBCACHE, MOPT_SET},
+	{Opt_encoding, 0, MOPT_EXT4_ONLY | MOPT_STRING},
 	{Opt_err, 0, 0}
 };
 
+static void split_charset_version(char *encoding_arg, char **charset,
+				  char **version)
+{
+	char *separator;
+	*version = NULL;
+	*charset = encoding_arg;
+
+	separator = strchr(encoding_arg, '-');
+	if (separator && *separator && *(separator+1) != '\0') {
+		*separator = '\0';
+		*version = separator + 1;
+	}
+}
+
 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)
@@ -1879,6 +1897,21 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
 		sbi->s_mount_opt |= m->mount_opt;
 	} else if (token == Opt_data_err_ignore) {
 		sbi->s_mount_opt &= ~m->mount_opt;
+	} else if (token == Opt_encoding) {
+		char *encoding_arg = match_strdup(&args[0]);
+		char *charset = NULL;
+		char *version = NULL;
+
+		split_charset_version(encoding_arg, &charset, &version);
+
+		sbi->encoding = load_nls_version(charset, version);
+		if (IS_ERR(sbi->encoding)) {
+			ext4_msg(sb, KERN_ERR, "Encoding %s-%s not supported",
+				 charset,version);
+			kfree(encoding_arg);
+			return -1;
+		}
+		kfree(encoding_arg);
 	} else {
 		if (!args->from)
 			arg = 1;
@@ -1965,6 +1998,12 @@ static int parse_options(char *options, struct super_block *sb,
 			return 0;
 		}
 	}
+
+	if (!sbi->encoding) {
+		ext4_msg(sb, KERN_WARNING, "Encoding not explicitly specified "
+			 "or identified on the superblock.  ASCII is assumed.");
+	}
+
 	return 1;
 }
 
@@ -3595,6 +3634,12 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 			   &journal_ioprio, 0))
 		goto failed_mount;
 
+	if (!sbi->encoding) {
+		sbi->encoding = load_nls("ascii");
+		if (!sbi->encoding)
+			goto failed_mount;
+	}
+
 	if (test_opt(sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA) {
 		printk_once(KERN_WARNING "EXT4-fs: Warning: mounting "
 			    "with data=journal disables delayed "
-- 
2.17.0