vfs: create a generic checking and prep function for FS_IOC_SETFLAGS

Create a generic function to check incoming FS_IOC_SETFLAGS flag values
and later prepare the inode for updates so that we can standardize the
implementations that follow ext4's flag values.

Note that the efivarfs implementation no longer fails a no-op SETFLAGS
without CAP_LINUX_IMMUTABLE since that's the behavior in ext*.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: David Sterba <dsterba@suse.com>
Reviewed-by: Bob Peterson <rpeterso@redhat.com>

1 files changed, 17 insertions, 9 deletions

diff --git a/fs/efivarfs/file.c b/fs/efivarfs/file.c
index 8e568428c88b..a3cc10b1bfe1 100644
--- a/fs/efivarfs/file.c
+++ b/fs/efivarfs/file.c
@@ -110,16 +110,22 @@ out_free:
 	return size;
 }
 
-static int
-efivarfs_ioc_getxflags(struct file *file, void __user *arg)
+static inline unsigned int efivarfs_getflags(struct inode *inode)
 {
-	struct inode *inode = file->f_mapping->host;
 	unsigned int i_flags;
 	unsigned int flags = 0;
 
 	i_flags = inode->i_flags;
 	if (i_flags & S_IMMUTABLE)
 		flags |= FS_IMMUTABLE_FL;
+	return flags;
+}
+
+static int
+efivarfs_ioc_getxflags(struct file *file, void __user *arg)
+{
+	struct inode *inode = file->f_mapping->host;
+	unsigned int flags = efivarfs_getflags(inode);
 
 	if (copy_to_user(arg, &flags, sizeof(flags)))
 		return -EFAULT;
@@ -132,6 +138,7 @@ efivarfs_ioc_setxflags(struct file *file, void __user *arg)
 	struct inode *inode = file->f_mapping->host;
 	unsigned int flags;
 	unsigned int i_flags = 0;
+	unsigned int oldflags = efivarfs_getflags(inode);
 	int error;
 
 	if (!inode_owner_or_capable(inode))
@@ -143,9 +150,6 @@ efivarfs_ioc_setxflags(struct file *file, void __user *arg)
 	if (flags & ~FS_IMMUTABLE_FL)
 		return -EOPNOTSUPP;
 
-	if (!capable(CAP_LINUX_IMMUTABLE))
-		return -EPERM;
-
 	if (flags & FS_IMMUTABLE_FL)
 		i_flags |= S_IMMUTABLE;
 
@@ -155,12 +159,16 @@ efivarfs_ioc_setxflags(struct file *file, void __user *arg)
 		return error;
 
 	inode_lock(inode);
+
+	error = vfs_ioc_setflags_prepare(inode, oldflags, flags);
+	if (error)
+		goto out;
+
 	inode_set_flags(inode, i_flags, S_IMMUTABLE);
+out:
 	inode_unlock(inode);
-
 	mnt_drop_write_file(file);
-
-	return 0;
+	return error;
 }
 
 static long