vfs: open inside ->tmpfile()

This is in preparation for adding tmpfile support to fuse, which requires
that the tmpfile creation and opening are done as a single operation.

Replace the 'struct dentry *' argument of i_op->tmpfile with
'struct file *'.

Call finish_open_simple() as the last thing in ->tmpfile() instances (may
be omitted in the error case).

Change d_tmpfile() argument to 'struct file *' as well to make callers more
readable.

Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

Documentation/filesystems/locking.rst

@@ -79,7 +79,8 @@ prototypes::
 	int (*atomic_open)(struct inode *, struct dentry *,
 				struct file *, unsigned open_flag,
 				umode_t create_mode);
-	int (*tmpfile) (struct inode *, struct dentry *, umode_t);
+	int (*tmpfile) (struct user_namespace *, struct inode *,
+			struct file *, umode_t);
 	int (*fileattr_set)(struct user_namespace *mnt_userns,
 			    struct dentry *dentry, struct fileattr *fa);
 	int (*fileattr_get)(struct dentry *dentry, struct fileattr *fa);

Documentation/filesystems/porting.rst

@@ -922,3 +922,13 @@ is provided - file_open_root_mnt().  In-tree users adjusted.
 no_llseek is gone; don't set .llseek to that - just leave it NULL instead.
 Checks for "does that file have llseek(2), or should it fail with ESPIPE"
 should be done by looking at FMODE_LSEEK in file->f_mode.
+
+---
+
+**mandatory**
+
+Calling conventions for ->tmpfile() have changed.  It now takes a struct
+file pointer instead of struct dentry pointer.  d_tmpfile() is similarly
+changed to simplify callers.  The passed file is in a non-open state and on
+success must be opened before returning (e.g. by calling
+finish_open_simple()).

Documentation/filesystems/vfs.rst

@@ -439,7 +439,7 @@ As of kernel 2.6.22, the following members are defined:
 		void (*update_time)(struct inode *, struct timespec *, int);
 		int (*atomic_open)(struct inode *, struct dentry *, struct file *,
 				   unsigned open_flag, umode_t create_mode);
-		int (*tmpfile) (struct user_namespace *, struct inode *, struct dentry *, umode_t);
+		int (*tmpfile) (struct user_namespace *, struct inode *, struct file *, umode_t);
 	        int (*set_acl)(struct user_namespace *, struct inode *, struct posix_acl *, int);
 		int (*fileattr_set)(struct user_namespace *mnt_userns,
 				    struct dentry *dentry, struct fileattr *fa);
@@ -589,7 +589,9 @@ otherwise noted.
 ``tmpfile``
 	called in the end of O_TMPFILE open().  Optional, equivalent to
 	atomically creating, opening and unlinking a file in given
-	directory.
+	directory.  On success needs to return with the file already
+	open; this can be done by calling finish_open_simple() right at
+	the end.
 
 ``fileattr_get``
 	called on ioctl(FS_IOC_GETFLAGS) and ioctl(FS_IOC_FSGETXATTR) to

fs/bad_inode.c

@@ -147,7 +147,7 @@ static int bad_inode_atomic_open(struct inode *inode, struct dentry *dentry,
 }
 
 static int bad_inode_tmpfile(struct user_namespace *mnt_userns,
-			     struct inode *inode, struct dentry *dentry,
+			     struct inode *inode, struct file *file,
 			     umode_t mode)
 {
 	return -EIO;

fs/btrfs/inode.c

@@ -10168,15 +10168,15 @@ static int btrfs_permission(struct user_namespace *mnt_userns,
 }
 
 static int btrfs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
-			 struct dentry *dentry, umode_t mode)
+			 struct file *file, umode_t mode)
 {
 	struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
 	struct btrfs_trans_handle *trans;
 	struct btrfs_root *root = BTRFS_I(dir)->root;
 	struct inode *inode;
 	struct btrfs_new_inode_args new_inode_args = {
 		.dir = dir,
-		.dentry = dentry,
+		.dentry = file->f_path.dentry,
 		.orphan = true,
 	};
 	unsigned int trans_num_items;
@@ -10213,7 +10213,7 @@ static int btrfs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 	set_nlink(inode, 1);
 
 	if (!ret) {
-		d_tmpfile(dentry, inode);
+		d_tmpfile(file, inode);
 		unlock_new_inode(inode);
 		mark_inode_dirty(inode);
 	}
@@ -10225,7 +10225,7 @@ static int btrfs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 out_inode:
 	if (ret)
 		iput(inode);
-	return ret;
+	return finish_open_simple(file, ret);
 }
 
 void btrfs_set_range_writeback(struct btrfs_inode *inode, u64 start, u64 end)

fs/dcache.c

@@ -3258,8 +3258,10 @@ void d_genocide(struct dentry *parent)
 
 EXPORT_SYMBOL(d_genocide);
 
-void d_tmpfile(struct dentry *dentry, struct inode *inode)
+void d_tmpfile(struct file *file, struct inode *inode)
 {
+	struct dentry *dentry = file->f_path.dentry;
+
 	inode_dec_link_count(inode);
 	BUG_ON(dentry->d_name.name != dentry->d_iname ||
 		!hlist_unhashed(&dentry->d_u.d_alias) ||

fs/ext2/namei.c

@@ -120,17 +120,17 @@ static int ext2_create (struct user_namespace * mnt_userns,
 }
 
 static int ext2_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
-			struct dentry *dentry, umode_t mode)
+			struct file *file, umode_t mode)
 {
 	struct inode *inode = ext2_new_inode(dir, mode, NULL);
 	if (IS_ERR(inode))
 		return PTR_ERR(inode);
 
 	ext2_set_file_ops(inode);
 	mark_inode_dirty(inode);
-	d_tmpfile(dentry, inode);
+	d_tmpfile(file, inode);
 	unlock_new_inode(inode);
-	return 0;
+	return finish_open_simple(file, 0);
 }
 
 static int ext2_mknod (struct user_namespace * mnt_userns, struct inode * dir,

fs/ext4/namei.c

@@ -2849,7 +2849,7 @@ static int ext4_mknod(struct user_namespace *mnt_userns, struct inode *dir,
 }
 
 static int ext4_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
-			struct dentry *dentry, umode_t mode)
+			struct file *file, umode_t mode)
 {
 	handle_t *handle;
 	struct inode *inode;
@@ -2871,7 +2871,7 @@ static int ext4_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 		inode->i_op = &ext4_file_inode_operations;
 		inode->i_fop = &ext4_file_operations;
 		ext4_set_aops(inode);
-		d_tmpfile(dentry, inode);
+		d_tmpfile(file, inode);
 		err = ext4_orphan_add(handle, inode);
 		if (err)
 			goto err_unlock_inode;
@@ -2882,7 +2882,7 @@ static int ext4_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 		ext4_journal_stop(handle);
 	if (err == -ENOSPC && ext4_should_retry_alloc(dir->i_sb, &retries))
 		goto retry;
-	return err;
+	return finish_open_simple(file, err);
 err_unlock_inode:
 	ext4_journal_stop(handle);
 	unlock_new_inode(inode);

fs/f2fs/namei.c

@@ -845,7 +845,7 @@ static int f2fs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
 }
 
 static int __f2fs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
-			  struct dentry *dentry, umode_t mode, bool is_whiteout,
+			  struct file *file, umode_t mode, bool is_whiteout,
 			  struct inode **new_inode)
 {
 	struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
@@ -892,8 +892,8 @@ static int __f2fs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 		inode->i_state |= I_LINKABLE;
 		spin_unlock(&inode->i_lock);
 	} else {
-		if (dentry)
-			d_tmpfile(dentry, inode);
+		if (file)
+			d_tmpfile(file, inode);
 		else
 			f2fs_i_links_write(inode, false);
 	}
@@ -915,16 +915,19 @@ static int __f2fs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 }
 
 static int f2fs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
-			struct dentry *dentry, umode_t mode)
+			struct file *file, umode_t mode)
 {
 	struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
+	int err;
 
 	if (unlikely(f2fs_cp_error(sbi)))
 		return -EIO;
 	if (!f2fs_is_checkpoint_ready(sbi))
 		return -ENOSPC;
 
-	return __f2fs_tmpfile(mnt_userns, dir, dentry, mode, false, NULL);
+	err = __f2fs_tmpfile(mnt_userns, dir, file, mode, false, NULL);
+
+	return finish_open_simple(file, err);
 }
 
 static int f2fs_create_whiteout(struct user_namespace *mnt_userns,

fs/hugetlbfs/inode.c

@@ -917,7 +917,7 @@ static int hugetlbfs_create(struct user_namespace *mnt_userns,
 }
 
 static int hugetlbfs_tmpfile(struct user_namespace *mnt_userns,
-			     struct inode *dir, struct dentry *dentry,
+			     struct inode *dir, struct file *file,
 			     umode_t mode)
 {
 	struct inode *inode;
@@ -926,8 +926,8 @@ static int hugetlbfs_tmpfile(struct user_namespace *mnt_userns,
 	if (!inode)
 		return -ENOSPC;
 	dir->i_ctime = dir->i_mtime = current_time(dir);
-	d_tmpfile(dentry, inode);
-	return 0;
+	d_tmpfile(file, inode);
+	return finish_open_simple(file, 0);
 }
 
 static int hugetlbfs_symlink(struct user_namespace *mnt_userns,

fs/minix/namei.c

@@ -53,16 +53,16 @@ static int minix_mknod(struct user_namespace *mnt_userns, struct inode *dir,
 }
 
 static int minix_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
-			 struct dentry *dentry, umode_t mode)
+			 struct file *file, 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);
+		d_tmpfile(file, inode);
 	}
-	return error;
+	return finish_open_simple(file, error);
 }
 
 static int minix_create(struct user_namespace *mnt_userns, struct inode *dir,

fs/namei.c

@@ -3604,8 +3604,7 @@ static int vfs_tmpfile(struct user_namespace *mnt_userns,
 	file->f_path.mnt = parentpath->mnt;
 	file->f_path.dentry = child;
 	mode = vfs_prepare_mode(mnt_userns, dir, mode, mode, mode);
-	error = dir->i_op->tmpfile(mnt_userns, dir, child, mode);
-	error = finish_open_simple(file, error);
+	error = dir->i_op->tmpfile(mnt_userns, dir, file, mode);
 	dput(child);
 	if (error)
 		return error;

fs/ramfs/inode.c

@@ -146,15 +146,15 @@ static int ramfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
 }
 
 static int ramfs_tmpfile(struct user_namespace *mnt_userns,
-			 struct inode *dir, struct dentry *dentry, umode_t mode)
+			 struct inode *dir, struct file *file, umode_t mode)
 {
 	struct inode *inode;
 
 	inode = ramfs_get_inode(dir->i_sb, dir, mode, 0);
 	if (!inode)
 		return -ENOSPC;
-	d_tmpfile(dentry, inode);
-	return 0;
+	d_tmpfile(file, inode);
+	return finish_open_simple(file, 0);
 }
 
 static const struct inode_operations ramfs_dir_inode_operations = {

fs/ubifs/dir.c

@@ -424,8 +424,9 @@ static void unlock_2_inodes(struct inode *inode1, struct inode *inode2)
 }
 
 static int ubifs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
-			 struct dentry *dentry, umode_t mode)
+			 struct file *file, umode_t mode)
 {
+	struct dentry *dentry = file->f_path.dentry;
 	struct inode *inode;
 	struct ubifs_info *c = dir->i_sb->s_fs_info;
 	struct ubifs_budget_req req = { .new_ino = 1, .new_dent = 1,
@@ -475,7 +476,7 @@ static int ubifs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 
 	mutex_lock(&ui->ui_mutex);
 	insert_inode_hash(inode);
-	d_tmpfile(dentry, inode);
+	d_tmpfile(file, inode);
 	ubifs_assert(c, ui->dirty);
 
 	instantiated = 1;
@@ -489,7 +490,7 @@ static int ubifs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 
 	ubifs_release_budget(c, &req);
 
-	return 0;
+	return finish_open_simple(file, 0);
 
 out_cancel:
 	unlock_2_inodes(dir, inode);

fs/udf/namei.c

@@ -626,7 +626,7 @@ static int udf_create(struct user_namespace *mnt_userns, struct inode *dir,
 }
 
 static int udf_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
-		       struct dentry *dentry, umode_t mode)
+		       struct file *file, umode_t mode)
 {
 	struct inode *inode = udf_new_inode(dir, mode);
 
@@ -640,9 +640,9 @@ static int udf_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 	inode->i_op = &udf_file_inode_operations;
 	inode->i_fop = &udf_file_operations;
 	mark_inode_dirty(inode);
-	d_tmpfile(dentry, inode);
+	d_tmpfile(file, inode);
 	unlock_new_inode(inode);
-	return 0;
+	return finish_open_simple(file, 0);
 }
 
 static int udf_mknod(struct user_namespace *mnt_userns, struct inode *dir,

fs/xfs/xfs_iops.c

@@ -167,7 +167,7 @@ xfs_generic_create(
 	struct dentry	*dentry,
 	umode_t		mode,
 	dev_t		rdev,
-	bool		tmpfile)	/* unnamed file */
+	struct file	*tmpfile)	/* unnamed file */
 {
 	struct inode	*inode;
 	struct xfs_inode *ip = NULL;
@@ -234,7 +234,7 @@ xfs_generic_create(
 		 * d_tmpfile can immediately set it back to zero.
 		 */
 		set_nlink(inode, 1);
-		d_tmpfile(dentry, inode);
+		d_tmpfile(tmpfile, inode);
 	} else
 		d_instantiate(dentry, inode);
 
@@ -261,7 +261,7 @@ xfs_vn_mknod(
 	umode_t			mode,
 	dev_t			rdev)
 {
-	return xfs_generic_create(mnt_userns, dir, dentry, mode, rdev, false);
+	return xfs_generic_create(mnt_userns, dir, dentry, mode, rdev, NULL);
 }
 
 STATIC int
@@ -272,7 +272,7 @@ xfs_vn_create(
 	umode_t			mode,
 	bool			flags)
 {
-	return xfs_generic_create(mnt_userns, dir, dentry, mode, 0, false);
+	return xfs_generic_create(mnt_userns, dir, dentry, mode, 0, NULL);
 }
 
 STATIC int
@@ -283,7 +283,7 @@ xfs_vn_mkdir(
 	umode_t			mode)
 {
 	return xfs_generic_create(mnt_userns, dir, dentry, mode | S_IFDIR, 0,
-				  false);
+				  NULL);
 }
 
 STATIC struct dentry *
@@ -1080,10 +1080,12 @@ STATIC int
 xfs_vn_tmpfile(
 	struct user_namespace	*mnt_userns,
 	struct inode		*dir,
-	struct dentry		*dentry,
+	struct file		*file,
 	umode_t			mode)
 {
-	return xfs_generic_create(mnt_userns, dir, dentry, mode, 0, true);
+	int err = xfs_generic_create(mnt_userns, dir, file->f_path.dentry, mode, 0, file);
+
+	return finish_open_simple(file, err);
 }
 
 static const struct inode_operations xfs_inode_operations = {

include/linux/dcache.h

@@ -16,6 +16,7 @@
 #include <linux/wait.h>
 
 struct path;
+struct file;
 struct vfsmount;
 
 /*
@@ -250,7 +251,7 @@ extern struct dentry * d_make_root(struct inode *);
 /* <clickety>-<click> the ramfs-type tree */
 extern void d_genocide(struct dentry *);
 
-extern void d_tmpfile(struct dentry *, struct inode *);
+extern void d_tmpfile(struct file *, struct inode *);
 
 extern struct dentry *d_find_alias(struct inode *);
 extern void d_prune_aliases(struct inode *);

include/linux/fs.h

@@ -2168,7 +2168,7 @@ struct inode_operations {
 			   struct file *, unsigned open_flag,
 			   umode_t create_mode);
 	int (*tmpfile) (struct user_namespace *, struct inode *,
-			struct dentry *, umode_t);
+			struct file *, umode_t);
 	int (*set_acl)(struct user_namespace *, struct inode *,
 		       struct posix_acl *, int);
 	int (*fileattr_set)(struct user_namespace *mnt_userns,