[PATCH v2 0/8] fuse tmpfile

[PATCH v2 0/8] fuse tmpfile

[Miklos Szeredi]

Al,

Would you mind taking this?

git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse.git#fuse-tmpfile

Thanks,
Miklos

V2:
 - rename finish_tmpfile() to finish_open_simple()
 - fix warning reported by kernel test robot
 - patch description improvements

---
Miklos Szeredi (8):
  cachefiles: tmpfile error handling cleanup
  vfs: add tmpfile_open() helper
  cachefiles: use tmpfile_open() helper
  ovl: use tmpfile_open() helper
  vfs: make vfs_tmpfile() static
  vfs: move open right after ->tmpfile()
  vfs: open inside ->tmpfile()
  fuse: implement ->tmpfile()

 fs/bad_inode.c            |  2 +-
 fs/btrfs/inode.c          |  8 ++---
 fs/cachefiles/namei.c     | 67 ++++++++++++++++--------------------
 fs/dcache.c               |  4 ++-
 fs/ext2/namei.c           |  6 ++--
 fs/ext4/namei.c           |  6 ++--
 fs/f2fs/namei.c           | 13 ++++---
 fs/fuse/dir.c             | 25 ++++++++++++--
 fs/fuse/fuse_i.h          |  3 ++
 fs/hugetlbfs/inode.c      | 12 ++++---
 fs/minix/namei.c          |  6 ++--
 fs/namei.c                | 72 +++++++++++++++++++++++++++------------
 fs/overlayfs/copy_up.c    | 49 ++++++++++++++------------
 fs/overlayfs/overlayfs.h  | 12 ++++---
 fs/overlayfs/super.c      | 10 +++---
 fs/ramfs/inode.c          |  6 ++--
 fs/ubifs/dir.c            |  7 ++--
 fs/udf/namei.c            |  6 ++--
 fs/xfs/xfs_iops.c         | 16 +++++----
 include/linux/dcache.h    |  3 +-
 include/linux/fs.h        | 16 +++++++--
 include/uapi/linux/fuse.h |  6 +++-
 mm/shmem.c                |  6 ++--
 23 files changed, 219 insertions(+), 142 deletions(-)

-- 
2.37.3

[PATCH v2 1/8] cachefiles: tmpfile error handling cleanup

[Miklos Szeredi]

Separate the error labels from the success path and use 'ret' to store the
error value before jumping to the error label.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
 fs/cachefiles/namei.c | 55 ++++++++++++++++++++-----------------------
 1 file changed, 26 insertions(+), 29 deletions(-)

diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index facf2ebe464b..d3a5884fe5c9 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -460,31 +460,27 @@ struct file *cachefiles_create_tmpfile(struct cachefiles_object *object)
 
 	path.mnt = cache->mnt;
 	ret = cachefiles_inject_write_error();
-	if (ret == 0)
+	if (ret == 0) {
 		path.dentry = vfs_tmpfile(&init_user_ns, fan, S_IFREG, O_RDWR);
-	else
-		path.dentry = ERR_PTR(ret);
-	if (IS_ERR(path.dentry)) {
-		trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(path.dentry),
+		ret = PTR_ERR_OR_ZERO(path.dentry);
+	}
+	if (ret) {
+		trace_cachefiles_vfs_error(object, d_inode(fan), ret,
 					   cachefiles_trace_tmpfile_error);
-		if (PTR_ERR(path.dentry) == -EIO)
+		if (ret == -EIO)
 			cachefiles_io_error_obj(object, "Failed to create tmpfile");
-		file = ERR_CAST(path.dentry);
-		goto out;
+		goto err;
 	}
 
 	trace_cachefiles_tmpfile(object, d_backing_inode(path.dentry));
 
-	if (!cachefiles_mark_inode_in_use(object, path.dentry)) {
-		file = ERR_PTR(-EBUSY);
-		goto out_dput;
-	}
+	ret = -EBUSY;
+	if (!cachefiles_mark_inode_in_use(object, path.dentry))
+		goto err_dput;
 
 	ret = cachefiles_ondemand_init_object(object);
-	if (ret < 0) {
-		file = ERR_PTR(ret);
-		goto out_unuse;
-	}
+	if (ret < 0)
+		goto err_unuse;
 
 	ni_size = object->cookie->object_size;
 	ni_size = round_up(ni_size, CACHEFILES_DIO_BLOCK_SIZE);
@@ -499,36 +495,37 @@ struct file *cachefiles_create_tmpfile(struct cachefiles_object *object)
 			trace_cachefiles_vfs_error(
 				object, d_backing_inode(path.dentry), ret,
 				cachefiles_trace_trunc_error);
-			file = ERR_PTR(ret);
-			goto out_unuse;
+			goto err_unuse;
 		}
 	}
 
 	file = open_with_fake_path(&path, O_RDWR | O_LARGEFILE | O_DIRECT,
 				   d_backing_inode(path.dentry), cache->cache_cred);
+	ret = PTR_ERR(file);
 	if (IS_ERR(file)) {
 		trace_cachefiles_vfs_error(object, d_backing_inode(path.dentry),
-					   PTR_ERR(file),
-					   cachefiles_trace_open_error);
-		goto out_unuse;
+					   ret, cachefiles_trace_open_error);
+		goto err_unuse;
 	}
+	ret = -EINVAL;
 	if (unlikely(!file->f_op->read_iter) ||
 	    unlikely(!file->f_op->write_iter)) {
 		fput(file);
 		pr_notice("Cache does not support read_iter and write_iter\n");
-		file = ERR_PTR(-EINVAL);
-		goto out_unuse;
+		goto err_unuse;
 	}
-
-	goto out_dput;
-
-out_unuse:
-	cachefiles_do_unmark_inode_in_use(object, path.dentry);
-out_dput:
 	dput(path.dentry);
 out:
 	cachefiles_end_secure(cache, saved_cred);
 	return file;
+
+err_unuse:
+	cachefiles_do_unmark_inode_in_use(object, path.dentry);
+err_dput:
+	dput(path.dentry);
+err:
+	file = ERR_PTR(ret);
+	goto out;
 }
 
 /*
-- 
2.37.3

[PATCH v2 2/8] vfs: add tmpfile_open() helper

[Miklos Szeredi]

This helper unifies tmpfile creation with opening.

Existing vfs_tmpfile() callers outside of fs/namei.c will be converted to
using this helper.  There are two such callers: cachefile and overlayfs.

The cachefiles code currently uses the open_with_fake_path() helper to open
the tmpfile, presumably to disable accounting of the open file.  Overlayfs
uses tmpfile for copy_up, which means these struct file instances will be
short lived, hence it doesn't really matter if they are accounted or not.
Disable accounting in this helper to, which should be okay for both caller.

Add MAY_OPEN permission checking for consistency.  Like for create(2)
read/write permissions are not checked.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
 fs/namei.c         | 41 +++++++++++++++++++++++++++++++++++++++++
 include/linux/fs.h |  4 ++++
 2 files changed, 45 insertions(+)

diff --git a/fs/namei.c b/fs/namei.c
index 53b4bc094db2..5e4a0c59eef6 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3624,6 +3624,47 @@ struct dentry *vfs_tmpfile(struct user_namespace *mnt_userns,
 }
 EXPORT_SYMBOL(vfs_tmpfile);
 
+/**
+ * tmpfile_open - open a tmpfile for kernel internal use
+ * @mnt_userns:	user namespace of the mount the inode was found from
+ * @parentpath:	path of the base directory
+ * @mode:	mode of the new tmpfile
+ * @open_flag:	flags
+ * @cred:	credentials for open
+ *
+ * Create and open a temporary file.  The file is not accounted in nr_files,
+ * hence this is only for kernel internal use, and must not be installed into
+ * file tables or such.
+ */
+struct file *tmpfile_open(struct user_namespace *mnt_userns,
+			  const struct path *parentpath,
+			  umode_t mode, int open_flag, const struct cred *cred)
+{
+	struct file *file;
+	int error;
+	struct path path = { .mnt = parentpath->mnt };
+
+	path.dentry = vfs_tmpfile(mnt_userns, parentpath->dentry, mode, open_flag);
+	if (IS_ERR(path.dentry))
+		return ERR_CAST(path.dentry);
+
+	error = may_open(mnt_userns, &path, 0, open_flag);
+	file = ERR_PTR(error);
+	if (error)
+		goto out_dput;
+
+	/*
+	 * This relies on the "noaccount" property of fake open, otherwise
+	 * equivalent to dentry_open().
+	 */
+	file = open_with_fake_path(&path, open_flag, d_inode(path.dentry), cred);
+out_dput:
+	dput(path.dentry);
+
+	return file;
+}
+EXPORT_SYMBOL(tmpfile_open);
+
 static int do_tmpfile(struct nameidata *nd, unsigned flags,
 		const struct open_flags *op,
 		struct file *file)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9eced4cc286e..34e7a189565b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2007,6 +2007,10 @@ static inline int vfs_whiteout(struct user_namespace *mnt_userns,
 struct dentry *vfs_tmpfile(struct user_namespace *mnt_userns,
 			   struct dentry *dentry, umode_t mode, int open_flag);
 
+struct file *tmpfile_open(struct user_namespace *mnt_userns,
+			  const struct path *parentpath,
+			  umode_t mode, int open_flag, const struct cred *cred);
+
 int vfs_mkobj(struct dentry *, umode_t,
 		int (*f)(struct dentry *, umode_t, void *),
 		void *);
-- 
2.37.3

[PATCH v2 3/8] cachefiles: use tmpfile_open() helper

[Miklos Szeredi]

Use the tmpfile_open() helper instead of doing tmpfile creation and opening
separately.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
 fs/cachefiles/namei.c | 26 ++++++++++----------------
 1 file changed, 10 insertions(+), 16 deletions(-)

diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index d3a5884fe5c9..44f575328af4 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -451,18 +451,19 @@ struct file *cachefiles_create_tmpfile(struct cachefiles_object *object)
 	const struct cred *saved_cred;
 	struct dentry *fan = volume->fanout[(u8)object->cookie->key_hash];
 	struct file *file;
-	struct path path;
+	struct path path = { .mnt = cache->mnt, .dentry = fan };
 	uint64_t ni_size;
 	long ret;
 
 
 	cachefiles_begin_secure(cache, &saved_cred);
 
-	path.mnt = cache->mnt;
 	ret = cachefiles_inject_write_error();
 	if (ret == 0) {
-		path.dentry = vfs_tmpfile(&init_user_ns, fan, S_IFREG, O_RDWR);
-		ret = PTR_ERR_OR_ZERO(path.dentry);
+		file = tmpfile_open(&init_user_ns, &path, S_IFREG,
+				    O_RDWR | O_LARGEFILE | O_DIRECT,
+				    cache->cache_cred);
+		ret = PTR_ERR_OR_ZERO(file);
 	}
 	if (ret) {
 		trace_cachefiles_vfs_error(object, d_inode(fan), ret,
@@ -471,12 +472,14 @@ struct file *cachefiles_create_tmpfile(struct cachefiles_object *object)
 			cachefiles_io_error_obj(object, "Failed to create tmpfile");
 		goto err;
 	}
+	/* From now path refers to the tmpfile */
+	path.dentry = file->f_path.dentry;
 
 	trace_cachefiles_tmpfile(object, d_backing_inode(path.dentry));
 
 	ret = -EBUSY;
 	if (!cachefiles_mark_inode_in_use(object, path.dentry))
-		goto err_dput;
+		goto err_fput;
 
 	ret = cachefiles_ondemand_init_object(object);
 	if (ret < 0)
@@ -499,14 +502,6 @@ struct file *cachefiles_create_tmpfile(struct cachefiles_object *object)
 		}
 	}
 
-	file = open_with_fake_path(&path, O_RDWR | O_LARGEFILE | O_DIRECT,
-				   d_backing_inode(path.dentry), cache->cache_cred);
-	ret = PTR_ERR(file);
-	if (IS_ERR(file)) {
-		trace_cachefiles_vfs_error(object, d_backing_inode(path.dentry),
-					   ret, cachefiles_trace_open_error);
-		goto err_unuse;
-	}
 	ret = -EINVAL;
 	if (unlikely(!file->f_op->read_iter) ||
 	    unlikely(!file->f_op->write_iter)) {
@@ -514,15 +509,14 @@ struct file *cachefiles_create_tmpfile(struct cachefiles_object *object)
 		pr_notice("Cache does not support read_iter and write_iter\n");
 		goto err_unuse;
 	}
-	dput(path.dentry);
 out:
 	cachefiles_end_secure(cache, saved_cred);
 	return file;
 
 err_unuse:
 	cachefiles_do_unmark_inode_in_use(object, path.dentry);
-err_dput:
-	dput(path.dentry);
+err_fput:
+	fput(file);
 err:
 	file = ERR_PTR(ret);
 	goto out;
-- 
2.37.3

[PATCH v2 4/8] ovl: use tmpfile_open() helper

[Miklos Szeredi]

If tmpfile is used for copy up, then use this helper to create the tmpfile
and open it at the same time.  This will later allow filesystems such as
fuse to do this operation atomically.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
 fs/overlayfs/copy_up.c   | 49 ++++++++++++++++++++++------------------
 fs/overlayfs/overlayfs.h | 12 ++++++----
 fs/overlayfs/super.c     | 10 ++++----
 3 files changed, 40 insertions(+), 31 deletions(-)

diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index fdde6c56cc3d..ac087b48b5da 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -194,16 +194,16 @@ static int ovl_copy_fileattr(struct inode *inode, struct path *old,
 }
 
 static int ovl_copy_up_data(struct ovl_fs *ofs, struct path *old,
-			    struct path *new, loff_t len)
+			    struct path *new, struct file *new_file, loff_t len)
 {
 	struct file *old_file;
-	struct file *new_file;
 	loff_t old_pos = 0;
 	loff_t new_pos = 0;
 	loff_t cloned;
 	loff_t data_pos = -1;
 	loff_t hole_len;
 	bool skip_hole = false;
+	bool fput_new = false;
 	int error = 0;
 
 	if (len == 0)
@@ -213,10 +213,13 @@ static int ovl_copy_up_data(struct ovl_fs *ofs, struct path *old,
 	if (IS_ERR(old_file))
 		return PTR_ERR(old_file);
 
-	new_file = ovl_path_open(new, O_LARGEFILE | O_WRONLY);
-	if (IS_ERR(new_file)) {
-		error = PTR_ERR(new_file);
-		goto out_fput;
+	if (!new_file) {
+		new_file = ovl_path_open(new, O_LARGEFILE | O_WRONLY);
+		if (IS_ERR(new_file)) {
+			error = PTR_ERR(new_file);
+			goto out_fput;
+		}
+		fput_new = true;
 	}
 
 	/* Try to use clone_file_range to clone up within the same fs */
@@ -285,7 +288,8 @@ static int ovl_copy_up_data(struct ovl_fs *ofs, struct path *old,
 out:
 	if (!error && ovl_should_sync(ofs))
 		error = vfs_fsync(new_file, 0);
-	fput(new_file);
+	if (fput_new)
+		fput(new_file);
 out_fput:
 	fput(old_file);
 	return error;
@@ -556,7 +560,8 @@ static int ovl_link_up(struct ovl_copy_up_ctx *c)
 	return err;
 }
 
-static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
+static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp,
+			     struct file *tmpfile)
 {
 	struct ovl_fs *ofs = OVL_FS(c->dentry->d_sb);
 	struct inode *inode = d_inode(c->dentry);
@@ -575,7 +580,7 @@ static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
 	 */
 	if (S_ISREG(c->stat.mode) && !c->metacopy) {
 		ovl_path_lowerdata(c->dentry, &datapath);
-		err = ovl_copy_up_data(ofs, &datapath, &upperpath,
+		err = ovl_copy_up_data(ofs, &datapath, &upperpath, tmpfile,
 				       c->stat.size);
 		if (err)
 			return err;
@@ -688,7 +693,7 @@ static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
 	if (IS_ERR(temp))
 		goto unlock;
 
-	err = ovl_copy_up_inode(c, temp);
+	err = ovl_copy_up_inode(c, temp, NULL);
 	if (err)
 		goto cleanup;
 
@@ -732,6 +737,7 @@ static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c)
 	struct ovl_fs *ofs = OVL_FS(c->dentry->d_sb);
 	struct inode *udir = d_inode(c->destdir);
 	struct dentry *temp, *upper;
+	struct file *tmpfile;
 	struct ovl_cu_creds cc;
 	int err;
 
@@ -739,15 +745,16 @@ static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c)
 	if (err)
 		return err;
 
-	temp = ovl_do_tmpfile(ofs, c->workdir, c->stat.mode);
+	tmpfile = ovl_do_tmpfile(ofs, c->workdir, c->stat.mode);
 	ovl_revert_cu_creds(&cc);
 
-	if (IS_ERR(temp))
-		return PTR_ERR(temp);
+	if (IS_ERR(tmpfile))
+		return PTR_ERR(tmpfile);
 
-	err = ovl_copy_up_inode(c, temp);
+	temp = tmpfile->f_path.dentry;
+	err = ovl_copy_up_inode(c, temp, tmpfile);
 	if (err)
-		goto out_dput;
+		goto out_fput;
 
 	inode_lock_nested(udir, I_MUTEX_PARENT);
 
@@ -761,16 +768,14 @@ static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c)
 	inode_unlock(udir);
 
 	if (err)
-		goto out_dput;
+		goto out_fput;
 
 	if (!c->metacopy)
 		ovl_set_upperdata(d_inode(c->dentry));
-	ovl_inode_update(d_inode(c->dentry), temp);
+	ovl_inode_update(d_inode(c->dentry), dget(temp));
 
-	return 0;
-
-out_dput:
-	dput(temp);
+out_fput:
+	fput(tmpfile);
 	return err;
 }
 
@@ -919,7 +924,7 @@ static int ovl_copy_up_meta_inode_data(struct ovl_copy_up_ctx *c)
 			goto out;
 	}
 
-	err = ovl_copy_up_data(ofs, &datapath, &upperpath, c->stat.size);
+	err = ovl_copy_up_data(ofs, &datapath, &upperpath, NULL, c->stat.size);
 	if (err)
 		goto out_free;
 
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 87759165d32b..259a6e73d0c4 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -310,14 +310,16 @@ static inline int ovl_do_whiteout(struct ovl_fs *ofs,
 	return err;
 }
 
-static inline struct dentry *ovl_do_tmpfile(struct ovl_fs *ofs,
-					    struct dentry *dentry, umode_t mode)
+static inline struct file *ovl_do_tmpfile(struct ovl_fs *ofs,
+					  struct dentry *dentry, umode_t mode)
 {
-	struct dentry *ret = vfs_tmpfile(ovl_upper_mnt_userns(ofs), dentry, mode, 0);
-	int err = PTR_ERR_OR_ZERO(ret);
+	struct path path = { .mnt = ovl_upper_mnt(ofs), .dentry = dentry };
+	struct file *file = tmpfile_open(ovl_upper_mnt_userns(ofs), &path, mode,
+					O_LARGEFILE | O_WRONLY, current_cred());
+	int err = PTR_ERR_OR_ZERO(file);
 
 	pr_debug("tmpfile(%pd2, 0%o) = %i\n", dentry, mode, err);
-	return ret;
+	return file;
 }
 
 static inline struct dentry *ovl_lookup_upper(struct ovl_fs *ofs,
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index ec746d447f1b..7837223689c1 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -15,6 +15,7 @@
 #include <linux/seq_file.h>
 #include <linux/posix_acl_xattr.h>
 #include <linux/exportfs.h>
+#include <linux/file.h>
 #include "overlayfs.h"
 
 MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
@@ -1356,7 +1357,8 @@ static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs,
 			    struct path *workpath)
 {
 	struct vfsmount *mnt = ovl_upper_mnt(ofs);
-	struct dentry *temp, *workdir;
+	struct dentry *workdir;
+	struct file *tmpfile;
 	bool rename_whiteout;
 	bool d_type;
 	int fh_type;
@@ -1392,10 +1394,10 @@ static int ovl_make_workdir(struct super_block *sb, struct ovl_fs *ofs,
 		pr_warn("upper fs needs to support d_type.\n");
 
 	/* Check if upper/work fs supports O_TMPFILE */
-	temp = ovl_do_tmpfile(ofs, ofs->workdir, S_IFREG | 0);
-	ofs->tmpfile = !IS_ERR(temp);
+	tmpfile = ovl_do_tmpfile(ofs, ofs->workdir, S_IFREG | 0);
+	ofs->tmpfile = !IS_ERR(tmpfile);
 	if (ofs->tmpfile)
-		dput(temp);
+		fput(tmpfile);
 	else
 		pr_warn("upper fs does not support tmpfile.\n");
 
-- 
2.37.3

[PATCH v2 5/8] vfs: make vfs_tmpfile() static

[Miklos Szeredi]

No callers outside of fs/namei.c anymore.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
 fs/namei.c         | 3 +--
 include/linux/fs.h | 3 ---
 2 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 5e4a0c59eef6..652d09ae66fb 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3583,7 +3583,7 @@ static int do_open(struct nameidata *nd,
  * On non-idmapped mounts or if permission checking is to be performed on the
  * raw inode simply passs init_user_ns.
  */
-struct dentry *vfs_tmpfile(struct user_namespace *mnt_userns,
+static struct dentry *vfs_tmpfile(struct user_namespace *mnt_userns,
 			   struct dentry *dentry, umode_t mode, int open_flag)
 {
 	struct dentry *child = NULL;
@@ -3622,7 +3622,6 @@ struct dentry *vfs_tmpfile(struct user_namespace *mnt_userns,
 	dput(child);
 	return ERR_PTR(error);
 }
-EXPORT_SYMBOL(vfs_tmpfile);
 
 /**
  * tmpfile_open - open a tmpfile for kernel internal use
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 34e7a189565b..a445da4842e0 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2004,9 +2004,6 @@ static inline int vfs_whiteout(struct user_namespace *mnt_userns,
 			 WHITEOUT_DEV);
 }
 
-struct dentry *vfs_tmpfile(struct user_namespace *mnt_userns,
-			   struct dentry *dentry, umode_t mode, int open_flag);
-
 struct file *tmpfile_open(struct user_namespace *mnt_userns,
 			  const struct path *parentpath,
 			  umode_t mode, int open_flag, const struct cred *cred);
-- 
2.37.3

[PATCH v2 6/8] vfs: move open right after ->tmpfile()

[Miklos Szeredi]

Create a helper finish_open_simple() that opens the file with the original
dentry.  Handle the error case here as well to simplify callers.

Call this helper right after ->tmpfile() is called.

Next patch will change the tmpfile API and move this call into tmpfile
instances.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
 fs/namei.c         | 65 ++++++++++++++++++++--------------------------
 include/linux/fs.h |  9 +++++++
 2 files changed, 37 insertions(+), 37 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 652d09ae66fb..eb1e1956450f 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3583,11 +3583,12 @@ static int do_open(struct nameidata *nd,
  * On non-idmapped mounts or if permission checking is to be performed on the
  * raw inode simply passs init_user_ns.
  */
-static struct dentry *vfs_tmpfile(struct user_namespace *mnt_userns,
-			   struct dentry *dentry, umode_t mode, int open_flag)
+static int vfs_tmpfile(struct user_namespace *mnt_userns,
+		       const struct path *parentpath,
+		       struct file *file, umode_t mode)
 {
-	struct dentry *child = NULL;
-	struct inode *dir = dentry->d_inode;
+	struct dentry *child;
+	struct inode *dir = d_inode(parentpath->dentry);
 	struct inode *inode;
 	int error;
 
@@ -3599,28 +3600,34 @@ static struct dentry *vfs_tmpfile(struct user_namespace *mnt_userns,
 	if (!dir->i_op->tmpfile)
 		goto out_err;
 	error = -ENOMEM;
-	child = d_alloc(dentry, &slash_name);
+	child = d_alloc(parentpath->dentry, &slash_name);
 	if (unlikely(!child))
 		goto out_err;
+	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);
+	dput(child);
+	if (error)
+		goto out_err;
+	error = may_open(mnt_userns, &file->f_path, 0, file->f_flags);
 	if (error)
 		goto out_err;
 	error = -ENOENT;
 	inode = child->d_inode;
 	if (unlikely(!inode))
 		goto out_err;
-	if (!(open_flag & O_EXCL)) {
+	if (!(file->f_flags & O_EXCL)) {
 		spin_lock(&inode->i_lock);
 		inode->i_state |= I_LINKABLE;
 		spin_unlock(&inode->i_lock);
 	}
 	ima_post_create_tmpfile(mnt_userns, inode);
-	return child;
+	return 0;
 
 out_err:
-	dput(child);
-	return ERR_PTR(error);
+	return error;
 }
 
 /**
@@ -3641,25 +3648,15 @@ struct file *tmpfile_open(struct user_namespace *mnt_userns,
 {
 	struct file *file;
 	int error;
-	struct path path = { .mnt = parentpath->mnt };
-
-	path.dentry = vfs_tmpfile(mnt_userns, parentpath->dentry, mode, open_flag);
-	if (IS_ERR(path.dentry))
-		return ERR_CAST(path.dentry);
-
-	error = may_open(mnt_userns, &path, 0, open_flag);
-	file = ERR_PTR(error);
-	if (error)
-		goto out_dput;
-
-	/*
-	 * This relies on the "noaccount" property of fake open, otherwise
-	 * equivalent to dentry_open().
-	 */
-	file = open_with_fake_path(&path, open_flag, d_inode(path.dentry), cred);
-out_dput:
-	dput(path.dentry);
 
+	file = alloc_empty_file_noaccount(open_flag, cred);
+	if (!IS_ERR(file)) {
+		error = vfs_tmpfile(mnt_userns, parentpath, file, mode);
+		if (error) {
+			fput(file);
+			file = ERR_PTR(error);
+		}
+	}
 	return file;
 }
 EXPORT_SYMBOL(tmpfile_open);
@@ -3669,26 +3666,20 @@ static int do_tmpfile(struct nameidata *nd, unsigned flags,
 		struct file *file)
 {
 	struct user_namespace *mnt_userns;
-	struct dentry *child;
 	struct path path;
 	int error = path_lookupat(nd, flags | LOOKUP_DIRECTORY, &path);
+
 	if (unlikely(error))
 		return error;
 	error = mnt_want_write(path.mnt);
 	if (unlikely(error))
 		goto out;
 	mnt_userns = mnt_user_ns(path.mnt);
-	child = vfs_tmpfile(mnt_userns, path.dentry, op->mode, op->open_flag);
-	error = PTR_ERR(child);
-	if (IS_ERR(child))
+	error = vfs_tmpfile(mnt_userns, &path, file, op->mode);
+	if (error)
 		goto out2;
-	dput(path.dentry);
-	path.dentry = child;
-	audit_inode(nd->name, child, 0);
+	audit_inode(nd->name, file->f_path.dentry, 0);
 	/* Don't check for other permissions, the inode was just created */
-	error = may_open(mnt_userns, &path, 0, op->open_flag);
-	if (!error)
-		error = vfs_open(&path, file);
 out2:
 	mnt_drop_write(path.mnt);
 out:
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a445da4842e0..f0d17eefb966 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2780,6 +2780,15 @@ extern int finish_open(struct file *file, struct dentry *dentry,
 			int (*open)(struct inode *, struct file *));
 extern int finish_no_open(struct file *file, struct dentry *dentry);
 
+/* Helper for the simple case when original dentry is used */
+static inline int finish_open_simple(struct file *file, int error)
+{
+	if (error)
+		return error;
+
+	return finish_open(file, file->f_path.dentry, NULL);
+}
+
 /* fs/dcache.c */
 extern void __init vfs_caches_init_early(void);
 extern void __init vfs_caches_init(void);
-- 
2.37.3

[PATCH v2 7/8] vfs: open inside ->tmpfile()

[Miklos Szeredi]

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.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
---
 fs/bad_inode.c         |  2 +-
 fs/btrfs/inode.c       |  8 ++++----
 fs/dcache.c            |  4 +++-
 fs/ext2/namei.c        |  6 +++---
 fs/ext4/namei.c        |  6 +++---
 fs/f2fs/namei.c        | 13 ++++++++-----
 fs/hugetlbfs/inode.c   | 12 +++++++-----
 fs/minix/namei.c       |  6 +++---
 fs/namei.c             |  3 +--
 fs/ramfs/inode.c       |  6 +++---
 fs/ubifs/dir.c         |  7 ++++---
 fs/udf/namei.c         |  6 +++---
 fs/xfs/xfs_iops.c      | 16 +++++++++-------
 include/linux/dcache.h |  3 ++-
 include/linux/fs.h     |  2 +-
 mm/shmem.c             |  6 +++---
 16 files changed, 58 insertions(+), 48 deletions(-)

diff --git a/fs/bad_inode.c b/fs/bad_inode.c
index 12b8fdcc445b..9d1cde8066cf 100644
--- a/fs/bad_inode.c
+++ b/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;
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 1372210869b1..416373721085 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -10168,7 +10168,7 @@ 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;
@@ -10176,7 +10176,7 @@ static int btrfs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 	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)
diff --git a/fs/dcache.c b/fs/dcache.c
index bb0c4d0038db..89dc61389102 100644
--- a/fs/dcache.c
+++ b/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) ||
diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
index 5fd9a22d2b70..9125eab85146 100644
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -120,7 +120,7 @@ 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))
@@ -128,9 +128,9 @@ static int ext2_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 
 	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,
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 3a31b662f661..9c3fde633a6e 100644
--- a/fs/ext4/namei.c
+++ b/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);
diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index bf00d5057abb..d5065a5af1f8 100644
--- a/fs/f2fs/namei.c
+++ b/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,
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index f7a5b5124d8a..eb8689c83369 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -889,7 +889,7 @@ static int do_hugetlbfs_mknod(struct inode *dir,
 			struct dentry *dentry,
 			umode_t mode,
 			dev_t dev,
-			bool tmpfile)
+			struct file *tmpfile)
 {
 	struct inode *inode;
 	int error = -ENOSPC;
@@ -898,7 +898,7 @@ static int do_hugetlbfs_mknod(struct inode *dir,
 	if (inode) {
 		dir->i_ctime = dir->i_mtime = current_time(dir);
 		if (tmpfile) {
-			d_tmpfile(dentry, inode);
+			d_tmpfile(tmpfile, inode);
 		} else {
 			d_instantiate(dentry, inode);
 			dget(dentry);/* Extra count - pin the dentry in core */
@@ -911,7 +911,7 @@ static int do_hugetlbfs_mknod(struct inode *dir,
 static int hugetlbfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
 			   struct dentry *dentry, umode_t mode, dev_t dev)
 {
-	return do_hugetlbfs_mknod(dir, dentry, mode, dev, false);
+	return do_hugetlbfs_mknod(dir, dentry, mode, dev, NULL);
 }
 
 static int hugetlbfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
@@ -932,10 +932,12 @@ 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)
 {
-	return do_hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0, true);
+	int err = do_hugetlbfs_mknod(dir, file->f_path.dentry, mode | S_IFREG, 0, file);
+
+	return finish_open_simple(file, err);
 }
 
 static int hugetlbfs_symlink(struct user_namespace *mnt_userns,
diff --git a/fs/minix/namei.c b/fs/minix/namei.c
index 937fa5fae2b8..8afdc408ca4f 100644
--- a/fs/minix/namei.c
+++ b/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,
diff --git a/fs/namei.c b/fs/namei.c
index eb1e1956450f..1548161b563c 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3606,8 +3606,7 @@ 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)
 		goto out_err;
diff --git a/fs/ramfs/inode.c b/fs/ramfs/inode.c
index bc66d0173e33..b3257e852820 100644
--- a/fs/ramfs/inode.c
+++ b/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 = {
diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
index 86151889548e..f59acd6a3615 100644
--- a/fs/ubifs/dir.c
+++ b/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);
diff --git a/fs/udf/namei.c b/fs/udf/namei.c
index b3d5f97f16cd..fb4c30e05245 100644
--- a/fs/udf/namei.c
+++ b/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,
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 45518b8c613c..764409c466fd 100644
--- a/fs/xfs/xfs_iops.c
+++ b/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 = {
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 92c78ed02b54..bde9f8ff8869 100644
--- a/include/linux/dcache.h
+++ b/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 *);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index f0d17eefb966..e08efecd2644 100644
--- a/include/linux/fs.h
+++ b/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,
diff --git a/mm/shmem.c b/mm/shmem.c
index 42e5888bf84d..f63c51bc373e 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2912,7 +2912,7 @@ shmem_mknod(struct user_namespace *mnt_userns, struct inode *dir,
 
 static int
 shmem_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
-	      struct dentry *dentry, umode_t mode)
+	      struct file *file, umode_t mode)
 {
 	struct inode *inode;
 	int error = -ENOSPC;
@@ -2927,9 +2927,9 @@ shmem_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
 		error = simple_acl_create(dir, inode);
 		if (error)
 			goto out_iput;
-		d_tmpfile(dentry, inode);
+		d_tmpfile(file, inode);
 	}
-	return error;
+	return finish_open_simple(file, error);
 out_iput:
 	iput(inode);
 	return error;
-- 
2.37.3

[PATCH v2 8/8] fuse: implement ->tmpfile()

[Miklos Szeredi]

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;
+}
+
 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,
-- 
2.37.3

Re: [PATCH v2 4/8] ovl: use tmpfile_open() helper

[Al Viro]

On Mon, Sep 19, 2022 at 04:10:27PM +0200, Miklos Szeredi wrote:
> If tmpfile is used for copy up, then use this helper to create the tmpfile
> and open it at the same time.  This will later allow filesystems such as
> fuse to do this operation atomically.
> 
> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
> ---
>  fs/overlayfs/copy_up.c   | 49 ++++++++++++++++++++++------------------
>  fs/overlayfs/overlayfs.h | 12 ++++++----
>  fs/overlayfs/super.c     | 10 ++++----
>  3 files changed, 40 insertions(+), 31 deletions(-)
> 
> diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
> index fdde6c56cc3d..ac087b48b5da 100644
> --- a/fs/overlayfs/copy_up.c
> +++ b/fs/overlayfs/copy_up.c
> @@ -194,16 +194,16 @@ static int ovl_copy_fileattr(struct inode *inode, struct path *old,
>  }
>  
>  static int ovl_copy_up_data(struct ovl_fs *ofs, struct path *old,
> -			    struct path *new, loff_t len)
> +			    struct path *new, struct file *new_file, loff_t len)
>  {

Ugh...  Lift opening into both callers and get rid of struct path *new,
please.  Would be much easier to follow that way...

> -	err = ovl_copy_up_inode(c, temp);
> +	err = ovl_copy_up_inode(c, temp, NULL);

FWIW, I would consider passing a struct file * in all cases, with O_PATH
for non-regular ones...

> -	temp = ovl_do_tmpfile(ofs, ofs->workdir, S_IFREG | 0);
> -	ofs->tmpfile = !IS_ERR(temp);
> +	tmpfile = ovl_do_tmpfile(ofs, ofs->workdir, S_IFREG | 0);
> +	ofs->tmpfile = !IS_ERR(tmpfile);
>  	if (ofs->tmpfile)
> -		dput(temp);
> +		fput(tmpfile);

	Careful - that part essentially checks if we have a working
->tmpfile(), but we rely upon more than just having it - we want
dentry-based setxattr() and friends to work after O_TMPFILE.
Are we making that a requirement for ->tmpfile()?  I.e. that
after O_TMPFILE open notify_change() et.al. on its dentry
will work *without* corresponding struct file.  In particular,
fuse seems to check for ATTR_FILE...

Re: [PATCH v2 6/8] vfs: move open right after ->tmpfile()

[Al Viro]

On Mon, Sep 19, 2022 at 04:10:29PM +0200, Miklos Szeredi wrote:

> -	child = d_alloc(dentry, &slash_name);
> +	child = d_alloc(parentpath->dentry, &slash_name);
>  	if (unlikely(!child))
>  		goto out_err;
> +	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);
> +	dput(child);
> +	if (error)
> +		goto out_err;
> +	error = may_open(mnt_userns, &file->f_path, 0, file->f_flags);
>  	if (error)
>  		goto out_err;
>  	error = -ENOENT;
>  	inode = child->d_inode;
>  	if (unlikely(!inode))
>  		goto out_err;

Ugh...  First of all, goto out_err leading to immediate return error;
is obfuscation for no good reason.  What's more, how the hell can
we get a negative dentry here?  The only thing that makes this check
valid is that after successful open child is pinned as file->f_path.dentry -
otherwise dput() above might have very well freed it.  And if we ever
end up with a negative dentry in file->f_path.dentry of an opened
file, we are really screwed...

Re: [PATCH v2 7/8] vfs: open inside ->tmpfile()

[Al Viro]

On Mon, Sep 19, 2022 at 04:10:30PM +0200, Miklos Szeredi wrote:
> 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.

It really needs to add to Documentation/filesystems/porting.

> --- a/fs/hugetlbfs/inode.c
> +++ b/fs/hugetlbfs/inode.c
> @@ -889,7 +889,7 @@ static int do_hugetlbfs_mknod(struct inode *dir,
>  			struct dentry *dentry,
>  			umode_t mode,
>  			dev_t dev,
> -			bool tmpfile)
> +			struct file *tmpfile)
>  {
>  	struct inode *inode;
>  	int error = -ENOSPC;
> @@ -898,7 +898,7 @@ static int do_hugetlbfs_mknod(struct inode *dir,
>  	if (inode) {
>  		dir->i_ctime = dir->i_mtime = current_time(dir);
>  		if (tmpfile) {
> -			d_tmpfile(dentry, inode);
> +			d_tmpfile(tmpfile, inode);
>  		} else {
>  			d_instantiate(dentry, inode);
>  			dget(dentry);/* Extra count - pin the dentry in core */
> @@ -911,7 +911,7 @@ static int do_hugetlbfs_mknod(struct inode *dir,
>  static int hugetlbfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
>  			   struct dentry *dentry, umode_t mode, dev_t dev)
>  {
> -	return do_hugetlbfs_mknod(dir, dentry, mode, dev, false);
> +	return do_hugetlbfs_mknod(dir, dentry, mode, dev, NULL);
>  }
>  
>  static int hugetlbfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
> @@ -932,10 +932,12 @@ 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)
>  {
> -	return do_hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0, true);
> +	int err = do_hugetlbfs_mknod(dir, file->f_path.dentry, mode | S_IFREG, 0, file);
> +
> +	return finish_open_simple(file, err);
>  }
>  
>  static int hugetlbfs_symlink(struct user_namespace *mnt_userns,

I would prefer to separate tmpfile from mknod in that one.  And to hell
with the last argument in do_hugetlbfs_mknod().  Something like (completely
untested) patch below as prereq:

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index f7a5b5124d8a..0b458beb318c 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -885,33 +885,18 @@ static struct inode *hugetlbfs_get_inode(struct super_block *sb,
 /*
  * File creation. Allocate an inode, and we're done..
  */
-static int do_hugetlbfs_mknod(struct inode *dir,
-			struct dentry *dentry,
-			umode_t mode,
-			dev_t dev,
-			bool tmpfile)
+static int hugetlbfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
+			   struct dentry *dentry, umode_t mode, dev_t dev)
 {
 	struct inode *inode;
-	int error = -ENOSPC;
 
 	inode = hugetlbfs_get_inode(dir->i_sb, dir, mode, dev);
-	if (inode) {
-		dir->i_ctime = dir->i_mtime = current_time(dir);
-		if (tmpfile) {
-			d_tmpfile(dentry, inode);
-		} else {
-			d_instantiate(dentry, inode);
-			dget(dentry);/* Extra count - pin the dentry in core */
-		}
-		error = 0;
-	}
-	return error;
-}
-
-static int hugetlbfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
-			   struct dentry *dentry, umode_t mode, dev_t dev)
-{
-	return do_hugetlbfs_mknod(dir, dentry, mode, dev, false);
+	if (!inode)
+		return -ENOSPC;
+	dir->i_ctime = dir->i_mtime = current_time(dir);
+	d_instantiate(dentry, inode);
+	dget(dentry);/* Extra count - pin the dentry in core */
+	return 0;
 }
 
 static int hugetlbfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
@@ -935,7 +920,14 @@ static int hugetlbfs_tmpfile(struct user_namespace *mnt_userns,
 			     struct inode *dir, struct dentry *dentry,
 			     umode_t mode)
 {
-	return do_hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0, true);
+	struct inode *inode;
+
+	inode = hugetlbfs_get_inode(dir->i_sb, dir, mode | S_IFREG, 0);
+	if (!inode)
+		return -ENOSPC;
+	dir->i_ctime = dir->i_mtime = current_time(dir);
+	d_tmpfile(dentry, inode);
+	return 0;
 }
 
 static int hugetlbfs_symlink(struct user_namespace *mnt_userns,

Re: [PATCH v2 4/8] ovl: use tmpfile_open() helper

[Miklos Szeredi]

On Tue, 20 Sept 2022 at 03:33, Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> On Mon, Sep 19, 2022 at 04:10:27PM +0200, Miklos Szeredi wrote:
> > If tmpfile is used for copy up, then use this helper to create the tmpfile
> > and open it at the same time.  This will later allow filesystems such as
> > fuse to do this operation atomically.
> >
> > Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
> > ---
> >  fs/overlayfs/copy_up.c   | 49 ++++++++++++++++++++++------------------
> >  fs/overlayfs/overlayfs.h | 12 ++++++----
> >  fs/overlayfs/super.c     | 10 ++++----
> >  3 files changed, 40 insertions(+), 31 deletions(-)
> >
> > diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
> > index fdde6c56cc3d..ac087b48b5da 100644
> > --- a/fs/overlayfs/copy_up.c
> > +++ b/fs/overlayfs/copy_up.c
> > @@ -194,16 +194,16 @@ static int ovl_copy_fileattr(struct inode *inode, struct path *old,
> >  }
> >
> >  static int ovl_copy_up_data(struct ovl_fs *ofs, struct path *old,
> > -                         struct path *new, loff_t len)
> > +                         struct path *new, struct file *new_file, loff_t len)
> >  {
>
> Ugh...  Lift opening into both callers and get rid of struct path *new,
> please.  Would be much easier to follow that way...
>
> > -     err = ovl_copy_up_inode(c, temp);
> > +     err = ovl_copy_up_inode(c, temp, NULL);
>
> FWIW, I would consider passing a struct file * in all cases, with O_PATH
> for non-regular ones...

OK.

>
> > -     temp = ovl_do_tmpfile(ofs, ofs->workdir, S_IFREG | 0);
> > -     ofs->tmpfile = !IS_ERR(temp);
> > +     tmpfile = ovl_do_tmpfile(ofs, ofs->workdir, S_IFREG | 0);
> > +     ofs->tmpfile = !IS_ERR(tmpfile);
> >       if (ofs->tmpfile)
> > -             dput(temp);
> > +             fput(tmpfile);
>
>         Careful - that part essentially checks if we have a working
> ->tmpfile(), but we rely upon more than just having it - we want
> dentry-based setxattr() and friends to work after O_TMPFILE.
> Are we making that a requirement for ->tmpfile()?

Yes, I think that should be expected of all sane filesystems.   Adding
tmpfile support to a fuse filesystem will require explicit code, so no
regression risk there.

Thanks,
Miklos

Re: [PATCH v2 6/8] vfs: move open right after ->tmpfile()

[Miklos Szeredi]

On Tue, 20 Sept 2022 at 03:41, Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> On Mon, Sep 19, 2022 at 04:10:29PM +0200, Miklos Szeredi wrote:
>
> > -     child = d_alloc(dentry, &slash_name);
> > +     child = d_alloc(parentpath->dentry, &slash_name);
> >       if (unlikely(!child))
> >               goto out_err;
> > +     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);
> > +     dput(child);
> > +     if (error)
> > +             goto out_err;
> > +     error = may_open(mnt_userns, &file->f_path, 0, file->f_flags);
> >       if (error)
> >               goto out_err;
> >       error = -ENOENT;
> >       inode = child->d_inode;
> >       if (unlikely(!inode))
> >               goto out_err;
>
> Ugh...  First of all, goto out_err leading to immediate return error;
> is obfuscation for no good reason.  What's more, how the hell can
> we get a negative dentry here?  The only thing that makes this check
> valid is that after successful open child is pinned as file->f_path.dentry -
> otherwise dput() above might have very well freed it.  And if we ever
> end up with a negative dentry in file->f_path.dentry of an opened
> file, we are really screwed...

OK.

Thanks,
Miklos

Re: [PATCH v2 7/8] vfs: open inside ->tmpfile()

[Miklos Szeredi]

On Tue, 20 Sept 2022 at 03:51, Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> On Mon, Sep 19, 2022 at 04:10:30PM +0200, Miklos Szeredi wrote:
> > 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.
>
> It really needs to add to Documentation/filesystems/porting.

OK.  Also updated signature and description in locking.rst and vfs.rst.

> I would prefer to separate tmpfile from mknod in that one.  And to hell
> with the last argument in do_hugetlbfs_mknod().  Something like (completely
> untested) patch below as prereq:
>
> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
> index f7a5b5124d8a..0b458beb318c 100644
> --- a/fs/hugetlbfs/inode.c
> +++ b/fs/hugetlbfs/inode.c
> @@ -885,33 +885,18 @@ static struct inode *hugetlbfs_get_inode(struct super_block *sb,
>  /*
>   * File creation. Allocate an inode, and we're done..
>   */
> -static int do_hugetlbfs_mknod(struct inode *dir,
> -                       struct dentry *dentry,
> -                       umode_t mode,
> -                       dev_t dev,
> -                       bool tmpfile)
> +static int hugetlbfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
> +                          struct dentry *dentry, umode_t mode, dev_t dev)
>  {
>         struct inode *inode;
> -       int error = -ENOSPC;
>
>         inode = hugetlbfs_get_inode(dir->i_sb, dir, mode, dev);
> -       if (inode) {
> -               dir->i_ctime = dir->i_mtime = current_time(dir);
> -               if (tmpfile) {
> -                       d_tmpfile(dentry, inode);
> -               } else {
> -                       d_instantiate(dentry, inode);
> -                       dget(dentry);/* Extra count - pin the dentry in core */
> -               }
> -               error = 0;
> -       }
> -       return error;
> -}
> -
> -static int hugetlbfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
> -                          struct dentry *dentry, umode_t mode, dev_t dev)
> -{
> -       return do_hugetlbfs_mknod(dir, dentry, mode, dev, false);
> +       if (!inode)
> +               return -ENOSPC;
> +       dir->i_ctime = dir->i_mtime = current_time(dir);
> +       d_instantiate(dentry, inode);
> +       dget(dentry);/* Extra count - pin the dentry in core */
> +       return 0;
>  }
>
>  static int hugetlbfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
> @@ -935,7 +920,14 @@ static int hugetlbfs_tmpfile(struct user_namespace *mnt_userns,
>                              struct inode *dir, struct dentry *dentry,
>                              umode_t mode)
>  {
> -       return do_hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0, true);
> +       struct inode *inode;
> +
> +       inode = hugetlbfs_get_inode(dir->i_sb, dir, mode | S_IFREG, 0);
> +       if (!inode)
> +               return -ENOSPC;
> +       dir->i_ctime = dir->i_mtime = current_time(dir);
> +       d_tmpfile(dentry, inode);
> +       return 0;
>  }
>
>  static int hugetlbfs_symlink(struct user_namespace *mnt_userns,

Added with your authorship and signoff.

Thanks,
Miklos