From: David Howells <dhowells@redhat.com>
Date: Mon, 25 Mar 2019 16:38:31 +0000
Subject: vfs: subtype handling moved to fuse
Git-commit: c7eb6869632a5d33b41d0a00d683b8395392b7ee
Patch-mainline: v5.4-rc1
References: jsc#SLE-13782

The unused vfs code can be removed.  Don't pass empty subtype (same as if
->parse callback isn't called).

The bits that are left involve determining whether it's permitted to split the
filesystem type string passed in to mount(2).  Consequently, this means that we
cannot get rid of the FS_HAS_SUBTYPE flag unless we define that a type string
with a dot in it always indicates a subtype specification.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Acked-by: Luis Henriques <lhenriques@suse.com>
---
 fs/fs_context.c            | 14 --------------
 fs/fuse/inode.c            |  3 +--
 fs/namespace.c             |  2 --
 fs/proc_namespace.c        |  2 +-
 fs/super.c                 |  5 -----
 include/linux/fs_context.h |  1 -
 6 files changed, 2 insertions(+), 25 deletions(-)

diff --git a/fs/fs_context.c b/fs/fs_context.c
index 87c2c9687d90..138b5b4d621d 100644
--- a/fs/fs_context.c
+++ b/fs/fs_context.c
@@ -504,7 +504,6 @@ void put_fs_context(struct fs_context *fc)
 	put_net(fc->net_ns);
 	put_user_ns(fc->user_ns);
 	put_cred(fc->cred);
-	kfree(fc->subtype);
 	put_fc_log(fc);
 	put_filesystem(fc->fs_type);
 	kfree(fc->source);
@@ -571,17 +570,6 @@ static int legacy_parse_param(struct fs_context *fc, struct fs_parameter *param)
 		return 0;
 	}
 
-	if ((fc->fs_type->fs_flags & FS_HAS_SUBTYPE) &&
-	    strcmp(param->key, "subtype") == 0) {
-		if (param->type != fs_value_is_string)
-			return invalf(fc, "VFS: Legacy: Non-string subtype");
-		if (fc->subtype)
-			return invalf(fc, "VFS: Legacy: Multiple subtype");
-		fc->subtype = param->string;
-		param->string = NULL;
-		return 0;
-	}
-
 	if (ctx->param_type == LEGACY_FS_MONOLITHIC_PARAMS)
 		return invalf(fc, "VFS: Legacy: Can't mix monolithic and individual options");
 
@@ -738,8 +726,6 @@ void vfs_clean_context(struct fs_context *fc)
 	fc->s_fs_info = NULL;
 	fc->sb_flags = 0;
 	security_free_mnt_opts(&fc->security);
-	kfree(fc->subtype);
-	fc->subtype = NULL;
 	kfree(fc->source);
 	fc->source = NULL;
 
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index c334f95e799a..2183967261a4 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -473,8 +473,7 @@ static const struct fs_parameter_spec fuse_param_specs[] = {
 	fsparam_flag	("allow_other",		OPT_ALLOW_OTHER),
 	fsparam_u32	("max_read",		OPT_MAX_READ),
 	fsparam_u32	("blksize",		OPT_BLKSIZE),
-	__fsparam(fs_param_is_string, "subtype", OPT_SUBTYPE,
-		  fs_param_v_optional),
+	fsparam_string	("subtype",		OPT_SUBTYPE),
 	{}
 };
 
diff --git a/fs/namespace.c b/fs/namespace.c
index d28d30b13043..105f995543f6 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2768,8 +2768,6 @@ static int do_new_mount(struct path *path, const char *fstype, int sb_flags,
 				put_filesystem(type);
 				return -EINVAL;
 			}
-		} else {
-			subtype = "";
 		}
 	}
 
diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c
index e16fb8f2049e..273ee82d8aa9 100644
--- a/fs/proc_namespace.c
+++ b/fs/proc_namespace.c
@@ -88,7 +88,7 @@ static inline void mangle(struct seq_file *m, const char *s)
 static void show_type(struct seq_file *m, struct super_block *sb)
 {
 	mangle(m, sb->s_type->name);
-	if (sb->s_subtype && sb->s_subtype[0]) {
+	if (sb->s_subtype) {
 		seq_putc(m, '.');
 		mangle(m, sb->s_subtype);
 	}
diff --git a/fs/super.c b/fs/super.c
index da223b4cfbca..a6ceed7bcd89 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -1530,11 +1530,6 @@ int vfs_get_tree(struct fs_context *fc)
 	sb = fc->root->d_sb;
 	WARN_ON(!sb->s_bdi);
 
-	if (fc->subtype && !sb->s_subtype) {
-		sb->s_subtype = fc->subtype;
-		fc->subtype = NULL;
-	}
-
 	/*
 	 * Write barrier is for super_cache_count(). We place it before setting
 	 * SB_BORN as the data dependency between the two functions is the
diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h
index 84a5eaa09f19..f6c86d58ea91 100644
--- a/include/linux/fs_context.h
+++ b/include/linux/fs_context.h
@@ -95,7 +95,6 @@ struct fs_context {
 	const struct cred	*cred;		/* The mounter's credentials */
 	struct fc_log		*log;		/* Logging buffer */
 	const char		*source;	/* The source name (eg. dev path) */
-	const char		*subtype;	/* The subtype to set on the superblock */
 	void			*security;	/* Linux S&M options */
 	void			*s_fs_info;	/* Proposed s_fs_info */
 	unsigned int		sb_flags;	/* Proposed superblock flags (SB_*) */