[O_TMPFILE] it's still short a few helpers, but infrastructure should be OK now...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

5 files changed, 122 insertions, 5 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index f09b908..b7f049c 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2968,6 +2968,22 @@ rename_retry:
 	goto again;
 }
 
+void d_tmpfile(struct dentry *dentry, struct inode *inode)
+{
+	inode_dec_link_count(inode);
+	BUG_ON(dentry->d_name.name != dentry->d_iname ||
+		!hlist_unhashed(&dentry->d_alias) ||
+		!d_unlinked(dentry));
+	spin_lock(&dentry->d_parent->d_lock);
+	spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
+	dentry->d_name.len = sprintf(dentry->d_iname, "#%llu",
+				(unsigned long long)inode->i_ino);
+	spin_unlock(&dentry->d_lock);
+	spin_unlock(&dentry->d_parent->d_lock);
+	d_instantiate(dentry, inode);
+}
+EXPORT_SYMBOL(d_tmpfile);
+
 /**
  * find_inode_number - check for dentry with name
  * @dir: directory to check
diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
index 73b0d95..256dd5f 100644
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -119,6 +119,29 @@ static int ext2_create (struct inode * dir, struct dentry * dentry, umode_t mode
 	return ext2_add_nondir(dentry, inode);
 }
 
+static int ext2_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+	struct inode *inode = ext2_new_inode(dir, mode, NULL);
+	if (IS_ERR(inode))
+		return PTR_ERR(inode);
+
+	inode->i_op = &ext2_file_inode_operations;
+	if (ext2_use_xip(inode->i_sb)) {
+		inode->i_mapping->a_ops = &ext2_aops_xip;
+		inode->i_fop = &ext2_xip_file_operations;
+	} else if (test_opt(inode->i_sb, NOBH)) {
+		inode->i_mapping->a_ops = &ext2_nobh_aops;
+		inode->i_fop = &ext2_file_operations;
+	} else {
+		inode->i_mapping->a_ops = &ext2_aops;
+		inode->i_fop = &ext2_file_operations;
+	}
+	mark_inode_dirty(inode);
+	d_tmpfile(dentry, inode);
+	unlock_new_inode(inode);
+	return 0;
+}
+
 static int ext2_mknod (struct inode * dir, struct dentry *dentry, umode_t mode, dev_t rdev)
 {
 	struct inode * inode;
@@ -398,6 +421,7 @@ const struct inode_operations ext2_dir_inode_operations = {
 #endif
 	.setattr	= ext2_setattr,
 	.get_acl	= ext2_get_acl,
+	.tmpfile	= ext2_tmpfile,
 };
 
 const struct inode_operations ext2_special_inode_operations = {
diff --git a/fs/minix/namei.c b/fs/minix/namei.c
index 0db73d9..cd950e2 100644
--- a/fs/minix/namei.c
+++ b/fs/minix/namei.c
@@ -54,6 +54,18 @@ static int minix_mknod(struct inode * dir, struct dentry *dentry, umode_t mode,
 	return error;
 }
 
+static int minix_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+	int error;
+	struct inode *inode = minix_new_inode(dir, mode, &error);
+	if (inode) {
+		minix_set_inode(inode, 0);
+		mark_inode_dirty(inode);
+		d_tmpfile(dentry, inode);
+	}
+	return error;
+}
+
 static int minix_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 		bool excl)
 {
@@ -254,4 +266,5 @@ const struct inode_operations minix_dir_inode_operations = {
 	.mknod		= minix_mknod,
 	.rename		= minix_rename,
 	.getattr	= minix_getattr,
+	.tmpfile	= minix_tmpfile,
 };
diff --git a/fs/namei.c b/fs/namei.c
index 402eda3..778e253 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2902,6 +2902,61 @@ stale_open:
 	goto retry_lookup;
 }
 
+static int do_tmpfile(int dfd, struct filename *pathname,
+		struct nameidata *nd, int flags,
+		const struct open_flags *op,
+		struct file *file, int *opened)
+{
+	static const struct qstr name = QSTR_INIT("/", 1);
+	struct dentry *dentry, *child;
+	struct inode *dir;
+	int error = path_lookupat(dfd, pathname->name,
+				  flags | LOOKUP_DIRECTORY, nd);
+	if (unlikely(error))
+		return error;
+	error = mnt_want_write(nd->path.mnt);
+	if (unlikely(error))
+		goto out;
+	/* we want directory to be writable */
+	error = inode_permission(nd->inode, MAY_WRITE | MAY_EXEC);
+	if (error)
+		goto out2;
+	dentry = nd->path.dentry;
+	dir = dentry->d_inode;
+	if (!dir->i_op->tmpfile) {
+		error = -EOPNOTSUPP;
+		goto out2;
+	}
+	child = d_alloc(dentry, &name);
+	if (unlikely(!child)) {
+		error = -ENOMEM;
+		goto out2;
+	}
+	nd->flags &= ~LOOKUP_DIRECTORY;
+	nd->flags |= op->intent;
+	dput(nd->path.dentry);
+	nd->path.dentry = child;
+	error = dir->i_op->tmpfile(dir, nd->path.dentry, op->mode);
+	if (error)
+		goto out2;
+	audit_inode(pathname, nd->path.dentry, 0);
+	error = may_open(&nd->path, op->acc_mode, op->open_flag);
+	if (error)
+		goto out2;
+	file->f_path.mnt = nd->path.mnt;
+	error = finish_open(file, nd->path.dentry, NULL, opened);
+	if (error)
+		goto out2;
+	error = open_check_o_direct(file);
+	if (error)
+		fput(file);
+out2:
+	mnt_drop_write(nd->path.mnt);
+out:
+	path_put(&nd->path);
+	return error;
+}
+
 static struct file *path_openat(int dfd, struct filename *pathname,
 		struct nameidata *nd, const struct open_flags *op, int flags)
 {
@@ -2917,6 +2972,11 @@ static struct file *path_openat(int dfd, struct filename *pathname,
 
 	file->f_flags = op->open_flag;
 
+	if (unlikely(file->f_flags & O_TMPFILE)) {
+		error = do_tmpfile(dfd, pathname, nd, flags, op, file, &opened);
+		goto out;
+	}
+
 	error = path_init(dfd, pathname->name, flags | LOOKUP_PARENT, nd, &base);
 	if (unlikely(error))
 		goto out;
diff --git a/fs/open.c b/fs/open.c
index 5a40a4a..fca72c4 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -840,11 +840,15 @@ static inline int build_open_flags(int flags, umode_t mode, struct open_flags *o
 	if (flags & __O_SYNC)
 		flags |= O_DSYNC;
 
-	/*
-	 * If we have O_PATH in the open flag. Then we
-	 * cannot have anything other than the below set of flags
-	 */
-	if (flags & O_PATH) {
+	if (flags & O_TMPFILE) {
+		if (!(flags & O_CREAT))
+			return -EINVAL;
+		acc_mode = MAY_OPEN | ACC_MODE(flags);
+	} else if (flags & O_PATH) {
+		/*
+		 * If we have O_PATH in the open flag. Then we
+		 * cannot have anything other than the below set of flags
+		 */
 		flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH;
 		acc_mode = 0;
 	} else {