diff mbox series

[v3,9/9] fuse: implement ->tmpfile()

Message ID 20220920193632.2215598-10-mszeredi@redhat.com (mailing list archive)
State New, archived
Headers show
Series fuse tmpfile | expand

Commit Message

Miklos Szeredi Sept. 20, 2022, 7:36 p.m. UTC 
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@redhat.com>
---
 fs/fuse/dir.c             | 25 ++++++++++++++++++++++---
 fs/fuse/fuse_i.h          |  3 +++
 include/uapi/linux/fuse.h |  6 +++++-
 3 files changed, 30 insertions(+), 4 deletions(-)

Comments

Christian Brauner Sept. 21, 2022, 9:15 a.m. UTC | #1 
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@redhat.com>
> ---
>  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
>
Miklos Szeredi Sept. 21, 2022, 3 p.m. UTC | #2 
On Wed, 21 Sept 2022 at 11:17, Christian Brauner <brauner@kernel.org> wrote:

>
> 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;
> }

Okay.

> > +
> >  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.

Fuse has zillions of these no_foobar flags.  Turning this single one
into a positive would be much more confusing IMO.

Thanks,
Miklos
diff mbox series

Patch

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;
+}
+
 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;
+
 	/** 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,