fuse: add renameat2 support

Support RENAME_EXCHANGE and RENAME_NOREPLACE flags on the userspace ABI.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

fs/fuse/dir.c

@@ -752,23 +752,26 @@ static int fuse_rmdir(struct inode *dir, struct dentry *entry)
 	return err;
 }
 
-static int fuse_rename(struct inode *olddir, struct dentry *oldent,
-		       struct inode *newdir, struct dentry *newent)
+static int fuse_rename_common(struct inode *olddir, struct dentry *oldent,
+			      struct inode *newdir, struct dentry *newent,
+			      unsigned int flags, int opcode, size_t argsize)
 {
 	int err;
-	struct fuse_rename_in inarg;
+	struct fuse_rename2_in inarg;
 	struct fuse_conn *fc = get_fuse_conn(olddir);
-	struct fuse_req *req = fuse_get_req_nopages(fc);
+	struct fuse_req *req;
 
+	req = fuse_get_req_nopages(fc);
 	if (IS_ERR(req))
 		return PTR_ERR(req);
 
-	memset(&inarg, 0, sizeof(inarg));
+	memset(&inarg, 0, argsize);
 	inarg.newdir = get_node_id(newdir);
-	req->in.h.opcode = FUSE_RENAME;
+	inarg.flags = flags;
+	req->in.h.opcode = opcode;
 	req->in.h.nodeid = get_node_id(olddir);
 	req->in.numargs = 3;
-	req->in.args[0].size = sizeof(inarg);
+	req->in.args[0].size = argsize;
 	req->in.args[0].value = &inarg;
 	req->in.args[1].size = oldent->d_name.len + 1;
 	req->in.args[1].value = oldent->d_name.name;
@@ -782,12 +785,17 @@ static int fuse_rename(struct inode *olddir, struct dentry *oldent,
 		fuse_invalidate_attr(oldent->d_inode);
 		fuse_update_ctime(oldent->d_inode);
 
+		if (flags & RENAME_EXCHANGE) {
+			fuse_invalidate_attr(newent->d_inode);
+			fuse_update_ctime(newent->d_inode);
+		}
+
 		fuse_invalidate_attr(olddir);
 		if (olddir != newdir)
 			fuse_invalidate_attr(newdir);
 
 		/* newent will end up negative */
-		if (newent->d_inode) {
+		if (!(flags & RENAME_EXCHANGE) && newent->d_inode) {
 			fuse_invalidate_attr(newent->d_inode);
 			fuse_invalidate_entry_cache(newent);
 			fuse_update_ctime(newent->d_inode);
@@ -806,6 +814,36 @@ static int fuse_rename(struct inode *olddir, struct dentry *oldent,
 	return err;
 }
 
+static int fuse_rename(struct inode *olddir, struct dentry *oldent,
+		       struct inode *newdir, struct dentry *newent)
+{
+	return fuse_rename_common(olddir, oldent, newdir, newent, 0,
+				  FUSE_RENAME, sizeof(struct fuse_rename_in));
+}
+
+static int fuse_rename2(struct inode *olddir, struct dentry *oldent,
+			struct inode *newdir, struct dentry *newent,
+			unsigned int flags)
+{
+	struct fuse_conn *fc = get_fuse_conn(olddir);
+	int err;
+
+	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))
+		return -EINVAL;
+
+	if (fc->no_rename2 || fc->minor < 23)
+		return -EINVAL;
+
+	err = fuse_rename_common(olddir, oldent, newdir, newent, flags,
+				 FUSE_RENAME2, sizeof(struct fuse_rename2_in));
+	if (err == -ENOSYS) {
+		fc->no_rename2 = 1;
+		err = -EINVAL;
+	}
+	return err;
+
+}
+
 static int fuse_link(struct dentry *entry, struct inode *newdir,
 		     struct dentry *newent)
 {
@@ -1980,6 +2018,7 @@ static const struct inode_operations fuse_dir_inode_operations = {
 	.unlink		= fuse_unlink,
 	.rmdir		= fuse_rmdir,
 	.rename		= fuse_rename,
+	.rename2	= fuse_rename2,
 	.link		= fuse_link,
 	.setattr	= fuse_setattr,
 	.create		= fuse_create,

fs/fuse/fuse_i.h

@@ -542,6 +542,9 @@ struct fuse_conn {
 	/** Is fallocate not implemented by fs? */
 	unsigned no_fallocate:1;
 
+	/** Is rename with flags implemented by fs? */
+	unsigned no_rename2:1;
+
 	/** Use enhanced/automatic page cache invalidation. */
 	unsigned auto_inval_data:1;
 

include/uapi/linux/fuse.h

@@ -100,6 +100,7 @@
  *  - add reserved space to fuse_init_out
  *  - add FATTR_CTIME
  *  - add ctime and ctimensec to fuse_setattr_in
+ *  - add FUSE_RENAME2 request
  */
 
 #ifndef _LINUX_FUSE_H
@@ -353,6 +354,7 @@ enum fuse_opcode {
 	FUSE_BATCH_FORGET  = 42,
 	FUSE_FALLOCATE     = 43,
 	FUSE_READDIRPLUS   = 44,
+	FUSE_RENAME2       = 45,
 
 	/* CUSE specific operations */
 	CUSE_INIT          = 4096,
@@ -431,6 +433,12 @@ struct fuse_rename_in {
 	uint64_t	newdir;
 };
 
+struct fuse_rename2_in {
+	uint64_t	newdir;
+	uint32_t	flags;
+	uint32_t	padding;
+};
+
 struct fuse_link_in {
 	uint64_t	oldnodeid;
 };