[RFC PATCH 1/3] fat: add a vfat_rename2() and make existing .rename callback a helper

[Javier Martinez Canillas <javierm@redhat.com>]

Currently vfat only supports the RENAME_NOREPLACE flag which is handled by
the virtual file system layer but doesn't support the RENAME_EXCHANGE flag.

Add a vfat_rename2() function to be used as the .rename callback and move
the current vfat_rename() handler to a helper. This is in preparation for
implementing the RENAME_NOREPLACE flag using a different helper function.

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
---

 fs/fat/namei_vfat.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c
index c573314806cf..88ccb2ee3537 100644
--- a/fs/fat/namei_vfat.c
+++ b/fs/fat/namei_vfat.c
@@ -889,9 +889,8 @@ static int vfat_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
 	return err;
 }
 
-static int vfat_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
-		       struct dentry *old_dentry, struct inode *new_dir,
-		       struct dentry *new_dentry, unsigned int flags)
+static int vfat_rename(struct inode *old_dir, struct dentry *old_dentry,
+		       struct inode *new_dir, struct dentry *new_dentry)
 {
 	struct buffer_head *dotdot_bh;
 	struct msdos_dir_entry *dotdot_de;
@@ -902,9 +901,6 @@ static int vfat_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 	int err, is_dir, update_dotdot, corrupt = 0;
 	struct super_block *sb = old_dir->i_sb;
 
-	if (flags & ~RENAME_NOREPLACE)
-		return -EINVAL;
-
 	old_sinfo.bh = sinfo.bh = dotdot_bh = NULL;
 	old_inode = d_inode(old_dentry);
 	new_inode = d_inode(new_dentry);
@@ -1021,13 +1017,24 @@ static int vfat_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
 	goto out;
 }
 
+static int vfat_rename2(struct user_namespace *mnt_userns, struct inode *old_dir,
+			struct dentry *old_dentry, struct inode *new_dir,
+			struct dentry *new_dentry, unsigned int flags)
+{
+	if (flags & ~RENAME_NOREPLACE)
+		return -EINVAL;
+
+	/* VFS already handled RENAME_NOREPLACE, handle it as a normal rename */
+	return vfat_rename(old_dir, old_dentry, new_dir, new_dentry);
+}
+
 static const struct inode_operations vfat_dir_inode_operations = {
 	.create		= vfat_create,
 	.lookup		= vfat_lookup,
 	.unlink		= vfat_unlink,
 	.mkdir		= vfat_mkdir,
 	.rmdir		= vfat_rmdir,
-	.rename		= vfat_rename,
+	.rename		= vfat_rename2,
 	.setattr	= fat_setattr,
 	.getattr	= fat_getattr,
 	.update_time	= fat_update_time,
-- 
2.35.1