VFS/knfsd: Teach dentry_create() to use atomic_open()

While knfsd offers combined exclusive create and open results to clients,
on some filesystems those results may not be atomic.  This behavior can be
observed.  For example, an open O_CREAT with mode 0 will succeed in creating
the file but unexpectedly return -EACCES from vfs_open().

Additionally reducing the number of remote RPC calls required for O_CREAT
on network filesystem provides a performance benefit in the open path.

Teach knfsd's helper dentry_create() to use atomic_open() for filesystems
that support it.  The previously const @path is passed up to atomic_open()
and may be modified depending on whether an existing entry was found or if
the atomic_open() returned an error and consumed the passed-in dentry.

Signed-off-by: Benjamin Coddington <bcodding@hammerspace.com>
Link: https://patch.msgid.link/8e449bfb64ab055abb9fd82641a171531415a88c.1764259052.git.bcodding@hammerspace.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 04ceeca12a0d..1cb3385ee852 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2457,7 +2457,7 @@ struct file *dentry_open(const struct path *path, int flags,
 			 const struct cred *creds);
 struct file *dentry_open_nonotify(const struct path *path, int flags,
 				  const struct cred *cred);
-struct file *dentry_create(const struct path *path, int flags, umode_t mode,
+struct file *dentry_create(struct path *path, int flags, umode_t mode,
 			   const struct cred *cred);
 const struct path *backing_file_user_path(const struct file *f);