[RFC PATCH 1/4] fs/ntfs3: Use new api for mounting

[Kari Argillander]

We have now new mount api as described in Documentation/filesystems. We
should use it as it gives us some benefits which are desribed here
https://lore.kernel.org/linux-fsdevel/159646178122.1784947.11705396571718464082.stgit@xxxxxxxxxxxxxxxxxxxxxx/

Nls loading is changed a little bit because new api not have default
optioni for mount parameters. So we need to load nls table before and
change that if user specifie someting else.

Also try to use fsparam_flag_no as much as possible. This is just nice
little touch and is not mandatory but it should not make any harm. It
is just convenient that we can use example acl/noacl mount options.

Signed-off-by: Kari Argillander <kari.argillander@xxxxxxxxx>
---
 fs/ntfs3/super.c | 382 ++++++++++++++++++++++++-----------------------
 1 file changed, 193 insertions(+), 189 deletions(-)

diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c
index 6be13e256c1a..d805e0b31404 100644
--- a/fs/ntfs3/super.c
+++ b/fs/ntfs3/super.c
@@ -28,10 +28,11 @@
 #include <linux/buffer_head.h>
 #include <linux/exportfs.h>
 #include <linux/fs.h>
+#include <linux/fs_context.h>
+#include <linux/fs_parser.h>
 #include <linux/iversion.h>
 #include <linux/module.h>
 #include <linux/nls.h>
-#include <linux/parser.h>
 #include <linux/seq_file.h>
 #include <linux/statfs.h>
 
@@ -197,6 +198,30 @@ void *ntfs_put_shared(void *ptr)
 	return ret;
 }
 
+/*
+ * ntfs_load_nls
+ *
+ * Load nls table or if @nls is utf8 then return NULL because
+ * nls=utf8 is totally broken.
+ */
+static struct nls_table *ntfs_load_nls(char *nls)
+{
+	struct nls_table *ret;
+
+	if (!nls)
+		return ERR_PTR(-EINVAL);
+	if (strcmp(nls, "utf8"))
+		return NULL;
+	if (strcmp(nls, CONFIG_NLS_DEFAULT))
+		return load_nls_default();
+
+	ret = load_nls(nls);
+	if (!ret)
+		return ERR_PTR(-EINVAL);
+
+	return ret;
+}
+
 static inline void clear_mount_options(struct ntfs_mount_options *options)
 {
 	unload_nls(options->nls);
@@ -222,208 +247,164 @@ enum Opt {
 	Opt_err,
 };
 
-static const match_table_t ntfs_tokens = {
-	{ Opt_uid, "uid=%u" },
-	{ Opt_gid, "gid=%u" },
-	{ Opt_umask, "umask=%o" },
-	{ Opt_dmask, "dmask=%o" },
-	{ Opt_fmask, "fmask=%o" },
-	{ Opt_immutable, "sys_immutable" },
-	{ Opt_discard, "discard" },
-	{ Opt_force, "force" },
-	{ Opt_sparse, "sparse" },
-	{ Opt_nohidden, "nohidden" },
-	{ Opt_acl, "acl" },
-	{ Opt_noatime, "noatime" },
-	{ Opt_showmeta, "showmeta" },
-	{ Opt_nls, "nls=%s" },
-	{ Opt_prealloc, "prealloc" },
-	{ Opt_no_acs_rules, "no_acs_rules" },
-	{ Opt_err, NULL },
+// clang-format off
+static const struct fs_parameter_spec ntfs_fs_parameters[] = {
+	fsparam_u32("uid",			Opt_uid),
+	fsparam_u32("gid",			Opt_gid),
+	fsparam_u32oct("umask",			Opt_umask),
+	fsparam_u32oct("dmask",			Opt_dmask),
+	fsparam_u32oct("fmask",			Opt_fmask),
+	fsparam_flag_no("sys_immutable",	Opt_immutable),
+	fsparam_flag_no("discard",		Opt_discard),
+	fsparam_flag_no("force",		Opt_force),
+	fsparam_flag_no("sparse",		Opt_sparse),
+	fsparam_flag("nohidden",		Opt_nohidden),
+	fsparam_flag_no("acl",			Opt_acl),
+	fsparam_flag("noatime",			Opt_noatime),
+	fsparam_flag_no("showmeta",		Opt_showmeta),
+	fsparam_string("nls",			Opt_nls),
+	fsparam_flag_no("prealloc",		Opt_prealloc),
+	fsparam_flag("no_acs_rules",		Opt_no_acs_rules),
+	{}
 };
+// clang-format on
 
-static noinline int ntfs_parse_options(struct super_block *sb, char *options,
-				       int silent,
-				       struct ntfs_mount_options *opts)
+static void ntfs_default_options(struct ntfs_mount_options *opts)
 {
-	char *p;
-	substring_t args[MAX_OPT_ARGS];
-	int option;
-	char nls_name[30];
-	struct nls_table *nls;
-
 	opts->fs_uid = current_uid();
 	opts->fs_gid = current_gid();
-	opts->fs_fmask_inv = opts->fs_dmask_inv = ~current_umask();
-	nls_name[0] = 0;
-
-	if (!options)
-		goto out;
+	opts->fs_fmask_inv = ~current_umask();
+	opts->fs_dmask_inv = ~current_umask();
+	opts->nls = ntfs_load_nls(CONFIG_NLS_DEFAULT);
+}
 
-	while ((p = strsep(&options, ","))) {
-		int token;
+static int ntfs_fs_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+	struct ntfs_sb_info *sbi = fc->s_fs_info;
+	struct ntfs_mount_options *opts = &sbi->options;
+	struct fs_parse_result result;
+	int opt;
 
-		if (!*p)
-			continue;
+	opt = fs_parse(fc, ntfs_fs_parameters, param, &result);
+	if (opt < 0)
+		return opt;
 
-		token = match_token(p, ntfs_tokens, args);
-		switch (token) {
-		case Opt_immutable:
-			opts->sys_immutable = 1;
-			break;
-		case Opt_uid:
-			if (match_int(&args[0], &option))
-				return -EINVAL;
-			opts->fs_uid = make_kuid(current_user_ns(), option);
-			if (!uid_valid(opts->fs_uid))
-				return -EINVAL;
-			opts->uid = 1;
-			break;
-		case Opt_gid:
-			if (match_int(&args[0], &option))
-				return -EINVAL;
-			opts->fs_gid = make_kgid(current_user_ns(), option);
-			if (!gid_valid(opts->fs_gid))
-				return -EINVAL;
-			opts->gid = 1;
-			break;
-		case Opt_umask:
-			if (match_octal(&args[0], &option))
-				return -EINVAL;
-			opts->fs_fmask_inv = opts->fs_dmask_inv = ~option;
-			opts->fmask = opts->dmask = 1;
-			break;
-		case Opt_dmask:
-			if (match_octal(&args[0], &option))
-				return -EINVAL;
-			opts->fs_dmask_inv = ~option;
-			opts->dmask = 1;
-			break;
-		case Opt_fmask:
-			if (match_octal(&args[0], &option))
-				return -EINVAL;
-			opts->fs_fmask_inv = ~option;
-			opts->fmask = 1;
-			break;
-		case Opt_discard:
-			opts->discard = 1;
-			break;
-		case Opt_force:
-			opts->force = 1;
-			break;
-		case Opt_sparse:
-			opts->sparse = 1;
-			break;
-		case Opt_nohidden:
-			opts->nohidden = 1;
-			break;
-		case Opt_acl:
+	switch (opt) {
+	case Opt_uid:
+		opts->fs_uid = make_kuid(current_user_ns(), result.uint_32);
+		if (!uid_valid(opts->fs_uid))
+			return -EINVAL;
+		opts->uid = 1;
+		break;
+	case Opt_gid:
+		opts->fs_gid = make_kgid(current_user_ns(), result.uint_32);
+		if (!gid_valid(opts->fs_gid))
+			return -EINVAL;
+		opts->gid = 1;
+		break;
+	case Opt_umask:
+		opts->fs_fmask_inv = ~result.uint_32;
+		opts->fs_dmask_inv = ~result.uint_32;
+		opts->fmask = 1;
+		opts->dmask = 1;
+		break;
+	case Opt_dmask:
+		opts->fs_dmask_inv = ~result.uint_32;
+		opts->dmask = 1;
+		break;
+	case Opt_fmask:
+		opts->fs_fmask_inv = ~result.uint_32;
+		opts->fmask = 1;
+		break;
+	case Opt_immutable:
+		opts->sys_immutable = result.negated ? 0 : 1;
+		break;
+	case Opt_discard:
+		opts->discard = result.negated ? 0 : 1;
+		break;
+	case Opt_force:
+		opts->force = result.negated ? 0 : 1;
+		break;
+	case Opt_sparse:
+		opts->sparse = result.negated ? 0 : 1;
+		break;
+	case Opt_nohidden:
+		opts->nohidden = 1;
+		break;
+	case Opt_acl:
+		if (!result.negated)
 #ifdef CONFIG_NTFS3_FS_POSIX_ACL
-			sb->s_flags |= SB_POSIXACL;
-			break;
+			fc->sb_flags |= SB_POSIXACL;
 #else
-			ntfs_err(sb, "support for ACL not compiled in!");
-			return -EINVAL;
+			return invalf(fc, "ntfs3: Support for ACL not compiled in!");
 #endif
-		case Opt_noatime:
-			sb->s_flags |= SB_NOATIME;
-			break;
-		case Opt_showmeta:
-			opts->showmeta = 1;
-			break;
-		case Opt_nls:
-			match_strlcpy(nls_name, &args[0], sizeof(nls_name));
-			break;
-		case Opt_prealloc:
-			opts->prealloc = 1;
-			break;
-		case Opt_no_acs_rules:
-			opts->no_acs_rules = 1;
-			break;
-		default:
-			if (!silent)
-				ntfs_err(
-					sb,
-					"Unrecognized mount option \"%s\" or missing value",
-					p);
-			//return -EINVAL;
+		else
+			fc->sb_flags &= ~SB_POSIXACL;
+		break;
+	case Opt_noatime:
+		fc->sb_flags |= SB_NOATIME;
+		break;
+	case Opt_showmeta:
+		opts->showmeta = result.negated ? 0 : 1;
+		break;
+	case Opt_nls:
+		unload_nls(opts->nls);
+
+		opts->nls = ntfs_load_nls(param->string);
+		if (IS_ERR(opts->nls)) {
+			return invalf(fc, "ntfs3: Cannot load nls %s",
+				      param->string);
 		}
-	}
 
-out:
-	if (!strcmp(nls_name[0] ? nls_name : CONFIG_NLS_DEFAULT, "utf8")) {
-		/* For UTF-8 use utf16s_to_utf8s/utf8s_to_utf16s instead of nls */
-		nls = NULL;
-	} else if (nls_name[0]) {
-		nls = load_nls(nls_name);
-		if (!nls) {
-			ntfs_err(sb, "failed to load \"%s\"", nls_name);
-			return -EINVAL;
-		}
-	} else {
-		nls = load_nls_default();
-		if (!nls) {
-			ntfs_err(sb, "failed to load default nls");
-			return -EINVAL;
-		}
+		param->string = NULL;
+		break;
+	case Opt_prealloc:
+		opts->prealloc = result.negated ? 0 : 1;
+		break;
+	case Opt_no_acs_rules:
+		opts->no_acs_rules = 1;
+		break;
+	default:
+		/* Should not be here unless we forget add case. */
+		return -EINVAL;
 	}
-	opts->nls = nls;
-
 	return 0;
 }
 
-static int ntfs_remount(struct super_block *sb, int *flags, char *data)
+static int ntfs_fs_reconfigure(struct fs_context *fc)
 {
-	int err, ro_rw;
+	int ro_rw;
+	struct super_block *sb = fc->root->d_sb;
 	struct ntfs_sb_info *sbi = sb->s_fs_info;
-	struct ntfs_mount_options old_opts;
-	char *orig_data = kstrdup(data, GFP_KERNEL);
-
-	if (data && !orig_data)
-		return -ENOMEM;
-
-	/* Store  original options */
-	memcpy(&old_opts, &sbi->options, sizeof(old_opts));
-	clear_mount_options(&sbi->options);
-	memset(&sbi->options, 0, sizeof(sbi->options));
-
-	err = ntfs_parse_options(sb, data, 0, &sbi->options);
-	if (err)
-		goto restore_opts;
+	struct ntfs_mount_options *new_opts = fc->s_fs_info;
+	int *flags = &fc->sb_flags;
 
 	ro_rw = sb_rdonly(sb) && !(*flags & SB_RDONLY);
 	if (ro_rw && (sbi->flags & NTFS_FLAGS_NEED_REPLAY)) {
-		ntfs_warn(
-			sb,
+		ntfs_warn(sb,
 			"Couldn't remount rw because journal is not replayed. Please umount/remount instead\n");
-		err = -EINVAL;
-		goto restore_opts;
+		goto clear_new_mount;
 	}
 
 	sync_filesystem(sb);
 
 	if (ro_rw && (sbi->volume.flags & VOLUME_FLAG_DIRTY) &&
-	    !sbi->options.force) {
+	    !new_opts->force) {
 		ntfs_warn(sb, "volume is dirty and \"force\" flag is not set!");
-		err = -EINVAL;
-		goto restore_opts;
+		goto clear_new_mount;
 	}
 
-	clear_mount_options(&old_opts);
+	*flags |= (*flags & ~SB_LAZYTIME) | (sb->s_flags & SB_LAZYTIME) |
+		  SB_NODIRATIME | SB_NOATIME;
 
-	*flags = (*flags & ~SB_LAZYTIME) | (sb->s_flags & SB_LAZYTIME) |
-		 SB_NODIRATIME | SB_NOATIME;
-	ntfs_info(sb, "re-mounted. Opts: %s", orig_data);
-	err = 0;
-	goto out;
-
-restore_opts:
 	clear_mount_options(&sbi->options);
-	memcpy(&sbi->options, &old_opts, sizeof(old_opts));
+	sbi->options = *new_opts;
 
-out:
-	kfree(orig_data);
-	return err;
+	return 0;
+
+clear_new_mount:
+	clear_mount_options(new_opts);
+	return -EINVAL;
 }
 
 static struct kmem_cache *ntfs_inode_cachep;
@@ -628,7 +609,6 @@ static const struct super_operations ntfs_sops = {
 	.statfs = ntfs_statfs,
 	.show_options = ntfs_show_options,
 	.sync_fs = ntfs_sync_fs,
-	.remount_fs = ntfs_remount,
 	.write_inode = ntfs3_write_inode,
 };
 
@@ -892,10 +872,10 @@ static int ntfs_init_from_boot(struct super_block *sb, u32 sector_size,
 }
 
 /* try to mount*/
-static int ntfs_fill_super(struct super_block *sb, void *data, int silent)
+static int ntfs_fill_super(struct super_block *sb, struct fs_context *fc)
 {
 	int err;
-	struct ntfs_sb_info *sbi;
+	struct ntfs_sb_info *sbi = sb->s_fs_info;
 	struct block_device *bdev = sb->s_bdev;
 	struct inode *bd_inode = bdev->bd_inode;
 	struct request_queue *rq = bdev_get_queue(bdev);
@@ -914,11 +894,6 @@ static int ntfs_fill_super(struct super_block *sb, void *data, int silent)
 
 	ref.high = 0;
 
-	sbi = ntfs_zalloc(sizeof(struct ntfs_sb_info));
-	if (!sbi)
-		return -ENOMEM;
-
-	sb->s_fs_info = sbi;
 	sbi->sb = sb;
 	sb->s_flags |= SB_NODIRATIME;
 	sb->s_magic = 0x7366746e; // "ntfs"
@@ -930,10 +905,6 @@ static int ntfs_fill_super(struct super_block *sb, void *data, int silent)
 	ratelimit_state_init(&sbi->msg_ratelimit, DEFAULT_RATELIMIT_INTERVAL,
 			     DEFAULT_RATELIMIT_BURST);
 
-	err = ntfs_parse_options(sb, data, silent, &sbi->options);
-	if (err)
-		goto out;
-
 	if (!rq || !blk_queue_discard(rq) || !rq->limits.discard_granularity) {
 		;
 	} else {
@@ -1409,19 +1380,52 @@ int ntfs_discard(struct ntfs_sb_info *sbi, CLST lcn, CLST len)
 	return err;
 }
 
-static struct dentry *ntfs_mount(struct file_system_type *fs_type, int flags,
-				 const char *dev_name, void *data)
+static int ntfs_fs_get_tree(struct fs_context *fc)
+{
+	return get_tree_bdev(fc, ntfs_fill_super);
+}
+
+static void ntfs_fs_free(struct fs_context *fc)
 {
-	return mount_bdev(fs_type, flags, dev_name, data, ntfs_fill_super);
+	struct ntfs_sb_info *sbi = fc->s_fs_info;
+
+	if (sbi)
+		put_ntfs(sbi);
+}
+
+static const struct fs_context_operations ntfs_context_ops = {
+	.parse_param	= ntfs_fs_parse_param,
+	.get_tree	= ntfs_fs_get_tree,
+	.reconfigure	= ntfs_fs_reconfigure,
+	.free		= ntfs_fs_free,
+};
+
+/*
+ * Set up the filesystem mount context.
+ */
+static int ntfs_init_fs_context(struct fs_context *fc)
+{
+	struct ntfs_sb_info *sbi;
+
+	sbi = ntfs_zalloc(sizeof(struct ntfs_sb_info));
+	if (!sbi)
+		return -ENOMEM;
+
+	ntfs_default_options(&sbi->options);
+
+	fc->s_fs_info = sbi;
+	fc->ops = &ntfs_context_ops;
+	return 0;
 }
 
 // clang-format off
 static struct file_system_type ntfs_fs_type = {
-	.owner		= THIS_MODULE,
-	.name		= "ntfs3",
-	.mount		= ntfs_mount,
-	.kill_sb	= kill_block_super,
-	.fs_flags	= FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
+	.owner			= THIS_MODULE,
+	.name			= "ntfs3",
+	.init_fs_context	= ntfs_init_fs_context,
+	.parameters		= ntfs_fs_parameters,
+	.kill_sb		= kill_block_super,
+	.fs_flags		= FS_REQUIRES_DEV | FS_ALLOW_IDMAP,
 };
 // clang-format on
 
-- 
2.25.1