linux-kernel - [PATCH 3/7] libfs: support RENAME_NOREPLACE in simple

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Date:   Tue, 23 Aug 2016 16:05:28 +0200
From:   Miklos Szeredi <mszeredi@...hat.com>
To:     linux-fsdevel@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
        Alexei Starovoitov <ast@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH 3/7] 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@...hat.com>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/debugfs/inode.c   | 2 +-
 fs/hugetlbfs/inode.c | 2 +-
 fs/libfs.c           | 6 +++++-
 fs/ramfs/inode.c     | 2 +-
 include/linux/fs.h   | 3 ++-
 kernel/bpf/inode.c   | 2 +-
 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 3523bf62f328..8aebcfc42f26 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2949,7 +2949,8 @@ 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,
 };
-- 
2.5.5