[PATCH V2] Fix mounting with MS_I_VERSION

[Matthew Garrett <mjg59@google.com>]

commit e462ec50cb5fa ("VFS: Differentiate mount flags (MS_*) from
internal superblock flags") reworked the flags that are passed through
do mount, and in the process dropped MS_I_VERSION. Confusingly, things
continue working if the i_version mount option is used because that's
directly passed to ext4 which interprets it, while iversion is turned
into MS_I_VERSION and dropped on the floor. This breaks IMA and EVM and
my heart. Pass SB_I_VERSION through, and update the consumers to use it
instead of MS_I_VERSION.

Signed-off-by: Matthew Garrett <mjg59@google.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org
---
 fs/btrfs/super.c   | 2 +-
 fs/ext4/super.c    | 4 ++--
 fs/fuse/inode.c    | 2 +-
 fs/namespace.c     | 3 ++-
 fs/xfs/xfs_super.c | 2 +-
 5 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 35a128acfbd1..161694b66038 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1135,7 +1135,7 @@ static int btrfs_fill_super(struct super_block *sb,
 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
 	sb->s_flags |= MS_POSIXACL;
 #endif
-	sb->s_flags |= MS_I_VERSION;
+	sb->s_flags |= SB_I_VERSION;
 	sb->s_iflags |= SB_I_CGROUPWB;
 
 	err = super_setup_bdi(sb);
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index b104096fce9e..b0915b734a38 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1677,7 +1677,7 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
 		sbi->s_mount_flags |= EXT4_MF_FS_ABORTED;
 		return 1;
 	case Opt_i_version:
-		sb->s_flags |= MS_I_VERSION;
+		sb->s_flags |= SB_I_VERSION;
 		return 1;
 	case Opt_lazytime:
 		sb->s_flags |= MS_LAZYTIME;
@@ -2060,7 +2060,7 @@ static int _ext4_show_options(struct seq_file *seq, struct super_block *sb,
 		SEQ_OPTS_PRINT("min_batch_time=%u", sbi->s_min_batch_time);
 	if (nodefs || sbi->s_max_batch_time != EXT4_DEF_MAX_BATCH_TIME)
 		SEQ_OPTS_PRINT("max_batch_time=%u", sbi->s_max_batch_time);
-	if (sb->s_flags & MS_I_VERSION)
+	if (sb->s_flags & SB_I_VERSION)
 		SEQ_OPTS_PUTS("i_version");
 	if (nodefs || sbi->s_stripe)
 		SEQ_OPTS_PRINT("stripe=%lu", sbi->s_stripe);
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 65c88379a3a1..94a745acaef8 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -1059,7 +1059,7 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
 	if (sb->s_flags & MS_MANDLOCK)
 		goto err;
 
-	sb->s_flags &= ~(MS_NOSEC | MS_I_VERSION);
+	sb->s_flags &= ~(MS_NOSEC | SB_I_VERSION);
 
 	if (!parse_fuse_opt(data, &d, is_bdev))
 		goto err;
diff --git a/fs/namespace.c b/fs/namespace.c
index 3b601f115b6c..d18deb4c410b 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -2825,7 +2825,8 @@ long do_mount(const char *dev_name, const char __user *dir_name,
 			    SB_MANDLOCK |
 			    SB_DIRSYNC |
 			    SB_SILENT |
-			    SB_POSIXACL);
+			    SB_POSIXACL |
+			    SB_I_VERSION);
 
 	if (flags & MS_REMOUNT)
 		retval = do_remount(&path, flags, sb_flags, mnt_flags,
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 584cf2d573ba..f663022353c0 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1637,7 +1637,7 @@ xfs_fs_fill_super(
 
 	/* version 5 superblocks support inode version counters. */
 	if (XFS_SB_VERSION_NUM(&mp->m_sb) == XFS_SB_VERSION_5)
-		sb->s_flags |= MS_I_VERSION;
+		sb->s_flags |= SB_I_VERSION;
 
 	if (mp->m_flags & XFS_MOUNT_DAX) {
 		xfs_warn(mp,
-- 
2.15.0.rc1.287.g2b38de12cc-goog