libfs: support RENAME_NOREPLACE in simple_rename()

This is trivial to do:

 - add flags argument to simple_rename()
 - check if flags doesn't have any other than RENAME_NOREPLACE
 - assign simple_rename() to .rename2 instead of .rename

Filesystems converted:

hugetlbfs, ramfs, bpf.

Debugfs uses simple_rename() to implement debugfs_rename(), which is for
debugfs instances to rename files internally, not for userspace filesystem
access.  For this case pass zero flags to simple_rename().

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Alexei Starovoitov <ast@kernel.org>

6 files changed, 11 insertions, 6 deletions

diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 72361baf9da7..5ac27c9de669 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -748,7 +748,7 @@ struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry,
         old_name = fsnotify_oldname_init(old_dentry->d_name.name);
 
         error = simple_rename(d_inode(old_dir), old_dentry, d_inode(new_dir),
-                dentry);
+                              dentry, 0);
         if (error) {
                 fsnotify_oldname_free(old_name);
                 goto exit;
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 4ea71eba40a5..50cd7475a942 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -988,7 +988,7 @@ static const struct inode_operations hugetlbfs_dir_inode_operations = {
         .mkdir          = hugetlbfs_mkdir,
         .rmdir          = simple_rmdir,
         .mknod          = hugetlbfs_mknod,
-        .rename         = simple_rename,
+        .rename2        = simple_rename,
         .setattr        = hugetlbfs_setattr,
 };
 
diff --git a/fs/libfs.c b/fs/libfs.c
index 74dc8b9e7f53..4758353b2d41 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -349,11 +349,15 @@ int simple_rmdir(struct inode *dir, struct dentry *dentry)
 EXPORT_SYMBOL(simple_rmdir);
 
 int simple_rename(struct inode *old_dir, struct dentry *old_dentry,
-                struct inode *new_dir, struct dentry *new_dentry)
+                  struct inode *new_dir, struct dentry *new_dentry,
+                  unsigned int flags)
 {
         struct inode *inode = d_inode(old_dentry);
         int they_are_dirs = d_is_dir(old_dentry);
 
+        if (flags & ~RENAME_NOREPLACE)
+                return -EINVAL;
+
         if (!simple_empty(new_dentry))
                 return -ENOTEMPTY;
 
diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
index 1ab6e6c2e60e..c2aa068ff974 100644
--- a/fs/ramfs/inode.c
+++ b/fs/ramfs/inode.c
@@ -146,7 +146,7 @@ static const struct inode_operations ramfs_dir_inode_operations = {
         .mkdir          = ramfs_mkdir,
         .rmdir          = simple_rmdir,
         .mknod          = ramfs_mknod,
-        .rename         = simple_rename,
+        .rename2        = simple_rename,
 };
 
 static const struct super_operations ramfs_ops = {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 901e25d495cc..2bd67545fdf8 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2950,7 +2950,8 @@ extern int simple_open(struct inode *inode, struct file *file);
 extern int simple_link(struct dentry *, struct inode *, struct dentry *);
 extern int simple_unlink(struct inode *, struct dentry *);
 extern int simple_rmdir(struct inode *, struct dentry *);
-extern int simple_rename(struct inode *, struct dentry *, struct inode *, struct dentry *);
+extern int simple_rename(struct inode *, struct dentry *,
+                         struct inode *, struct dentry *, unsigned int);
 extern int noop_fsync(struct file *, loff_t, loff_t, int);
 extern int simple_empty(struct dentry *);
 extern int simple_readpage(struct file *file, struct page *page);
diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index 5967b870a895..c92fd8936d33 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -189,7 +189,7 @@ static const struct inode_operations bpf_dir_iops = {
         .mknod          = bpf_mkobj,
         .mkdir          = bpf_mkdir,
         .rmdir          = simple_rmdir,
-        .rename         = simple_rename,
+        .rename2        = simple_rename,
         .link           = simple_link,
         .unlink         = simple_unlink,
 };