I think I need to include something like the attached change in this patch. Changes also need to be made to proc and cgroup.
David --- commit 1a336480a0f664b3e1988a581bccd4fa10d98764 Author: David Howells <[email protected]> Date: Tue Sep 18 17:25:23 2018 +0100 fix remount diff --git a/fs/fs_context.c b/fs/fs_context.c index a82679441031..1f36b72e3ee9 100644 --- a/fs/fs_context.c +++ b/fs/fs_context.c @@ -42,8 +42,6 @@ struct legacy_fs_context { enum legacy_fs_param param_type; }; -static int legacy_init_fs_context(struct fs_context *fc, struct dentry *dentry); - static const struct constant_table common_set_sb_flag[] = { { "dirsync", SB_DIRSYNC }, { "lazytime", SB_LAZYTIME }, @@ -293,7 +291,6 @@ struct fs_context *vfs_new_fs_context(struct file_system_type *fs_type, break; } - /* TODO: Make all filesystems support this unconditionally */ init_fs_context = fc->fs_type->init_fs_context; if (!init_fs_context) @@ -662,12 +659,20 @@ const struct fs_context_operations legacy_fs_context_ops = { * Initialise a legacy context for a filesystem that doesn't support * fs_context. */ -static int legacy_init_fs_context(struct fs_context *fc, struct dentry *dentry) +int legacy_init_fs_context(struct fs_context *fc, struct dentry *dentry) { + switch (fc->purpose) { + default: + fc->fs_private = kzalloc(sizeof(struct legacy_fs_context), + GFP_KERNEL); + if (!fc->fs_private) + return -ENOMEM; + break; - fc->fs_private = kzalloc(sizeof(struct legacy_fs_context), GFP_KERNEL); - if (!fc->fs_private) - return -ENOMEM; + case FS_CONTEXT_FOR_UMOUNT: + case FS_CONTEXT_FOR_EMERGENCY_RO: + break; + } fc->ops = &legacy_fs_context_ops; return 0; diff --git a/fs/internal.h b/fs/internal.h index d25cb82af69d..fc2da60abbcd 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -55,6 +55,7 @@ extern void __init chrdev_init(void); * fs_context.c */ extern const struct fs_context_operations legacy_fs_context_ops; +extern int legacy_init_fs_context(struct fs_context *fc, struct dentry *dentry); /* * fsopen.c diff --git a/fs/namespace.c b/fs/namespace.c index ddb2c3b88cd6..86b60566fcdf 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1429,9 +1429,19 @@ static int do_umount_root(struct super_block *sb) }; down_write(&sb->s_umount); - if (!sb_rdonly(sb)) - /* Might want to call ->init_fs_context(). */ - ret = reconfigure_super(&fc); + if (!sb_rdonly(sb)) { + int ret; + + if (fc.fs_type->init_fs_context) + ret = fc.fs_type->init_fs_context(&fc, NULL); + else + ret = legacy_init_fs_context(&fc, NULL); + + if (ret == 0) { + ret = reconfigure_super(&fc); + fc.ops->free(&fc); + } + } up_write(&sb->s_umount); return ret; } @@ -2396,7 +2406,7 @@ static int do_remount(struct path *path, int ms_flags, int sb_flags, err = security_fs_context_validate(fc); if (err) - return err; + goto err_fc; down_write(&sb->s_umount); err = -EPERM; diff --git a/fs/super.c b/fs/super.c index e00b03249bfa..df8c4cebd000 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1026,12 +1026,20 @@ static void do_emergency_remount_callback(struct super_block *sb) down_write(&sb->s_umount); if (sb->s_root && sb->s_bdev && (sb->s_flags & SB_BORN) && - !sb_rdonly(sb)) - /* Might want to call ->init_fs_context(). */ + !sb_rdonly(sb)) { + int ret; + + if (fc.fs_type->init_fs_context) + ret = fc.fs_type->init_fs_context(&fc, NULL); + else + ret = legacy_init_fs_context(&fc, NULL); + /* * What lock protects sb->s_flags?? */ - reconfigure_super(&fc); + if (ret == 0) + reconfigure_super(&fc); + } up_write(&sb->s_umount); }
