On Tue, Sep 20, 2022 at 09:36:32PM +0200, Miklos Szeredi wrote:
> This is basically equivalent to the FUSE_CREATE operation which creates and
> opens a regular file.
>
> Add a new FUSE_TMPFILE operation, otherwise just reuse the protocol and the
> code for FUSE_CREATE.
>
> Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
> ---
> fs/fuse/dir.c | 25 ++++++++++++++++++++++---
> fs/fuse/fuse_i.h | 3 +++
> include/uapi/linux/fuse.h | 6 +++++-
> 3 files changed, 30 insertions(+), 4 deletions(-)
>
> diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
> index b585b04e815e..01b2d5c5a64a 100644
> --- a/fs/fuse/dir.c
> +++ b/fs/fuse/dir.c
> @@ -529,7 +529,7 @@ static int get_security_context(struct dentry *entry, umode_t mode,
> */
> static int fuse_create_open(struct inode *dir, struct dentry *entry,
> struct file *file, unsigned int flags,
> - umode_t mode)
> + umode_t mode, u32 opcode)
> {
> int err;
> struct inode *inode;
> @@ -573,7 +573,7 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry,
> inarg.open_flags |= FUSE_OPEN_KILL_SUIDGID;
> }
>
> - args.opcode = FUSE_CREATE;
> + args.opcode = opcode;
> args.nodeid = get_node_id(dir);
> args.in_numargs = 2;
> args.in_args[0].size = sizeof(inarg);
> @@ -676,7 +676,7 @@ static int fuse_atomic_open(struct inode *dir, struct dentry *entry,
> if (fc->no_create)
> goto mknod;
>
> - err = fuse_create_open(dir, entry, file, flags, mode);
> + err = fuse_create_open(dir, entry, file, flags, mode, FUSE_CREATE);
> if (err == -ENOSYS) {
> fc->no_create = 1;
> goto mknod;
> @@ -802,6 +802,24 @@ static int fuse_create(struct user_namespace *mnt_userns, struct inode *dir,
> return fuse_mknod(&init_user_ns, dir, entry, mode, 0);
> }
>
> +static int fuse_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
> + struct file *file, umode_t mode)
> +{
> + struct fuse_conn *fc = get_fuse_conn(dir);
> + int err;
> +
> + if (fc->no_tmpfile)
> + goto no_tmpfile;
> +
> + err = fuse_create_open(dir, file->f_path.dentry, file, file->f_flags, mode, FUSE_TMPFILE);
> + if (err == -ENOSYS) {
> + fc->no_tmpfile = 1;
> +no_tmpfile:
> + err = -EOPNOTSUPP;
> + }
> + return err;
> +}
Hm, seems like this could avoid the goto into an if-block:
static int fuse_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
struct file *file, umode_t mode)
{
struct fuse_conn *fc = get_fuse_conn(dir);
int err;
if (fc->no_tmpfile)
return -EOPNOTSUPP;
err = fuse_create_open(dir, file->f_path.dentry, file, file->f_flags, mode, FUSE_TMPFILE);
if (err == -ENOSYS) {
fc->no_tmpfile = 1;
err = -EOPNOTSUPP;
}
return err;
}
> +
> static int fuse_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
> struct dentry *entry, umode_t mode)
> {
> @@ -1913,6 +1931,7 @@ static const struct inode_operations fuse_dir_inode_operations = {
> .setattr = fuse_setattr,
> .create = fuse_create,
> .atomic_open = fuse_atomic_open,
> + .tmpfile = fuse_tmpfile,
> .mknod = fuse_mknod,
> .permission = fuse_permission,
> .getattr = fuse_getattr,
> diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
> index 488b460e046f..98a9cf531873 100644
> --- a/fs/fuse/fuse_i.h
> +++ b/fs/fuse/fuse_i.h
> @@ -784,6 +784,9 @@ struct fuse_conn {
> /* Does the filesystem support per inode DAX? */
> unsigned int inode_dax:1;
>
> + /* Is tmpfile not implemented by fs? */
> + unsigned int no_tmpfile:1;
Just a nit, it might be nicer to turn this into a positive, i.e.,
unsigned int has_tmpfile:1. Easier to understand as people usually
aren't great at processing negations.
> +
> /** The number of requests waiting for completion */
> atomic_t num_waiting;
>
> diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
> index d6ccee961891..76ee8f9e024a 100644
> --- a/include/uapi/linux/fuse.h
> +++ b/include/uapi/linux/fuse.h
> @@ -194,6 +194,9 @@
> * - add FUSE_SECURITY_CTX init flag
> * - add security context to create, mkdir, symlink, and mknod requests
> * - add FUSE_HAS_INODE_DAX, FUSE_ATTR_DAX
> + *
> + * 7.37
> + * - add FUSE_TMPFILE
> */
>
> #ifndef _LINUX_FUSE_H
> @@ -229,7 +232,7 @@
> #define FUSE_KERNEL_VERSION 7
>
> /** Minor version number of this interface */
> -#define FUSE_KERNEL_MINOR_VERSION 36
> +#define FUSE_KERNEL_MINOR_VERSION 37
>
> /** The node ID of the root inode */
> #define FUSE_ROOT_ID 1
> @@ -537,6 +540,7 @@ enum fuse_opcode {
> FUSE_SETUPMAPPING = 48,
> FUSE_REMOVEMAPPING = 49,
> FUSE_SYNCFS = 50,
> + FUSE_TMPFILE = 51,
>
> /* CUSE specific operations */
> CUSE_INIT = 4096,
> --
> 2.37.3
>
