[PATCH v2 13/14] nfsd: separate out VFS-specific from from nfsd4_create_file()

From: NeilBrown <neil-+NVA1uvv1dVBDLzU/[email protected]>

All the code in nfsd4_create_file() that is VFS manipulation, with now
NFS-specific knowledge, has been localised.  Now we split that out into
a separate function: do_lookup_open().

It is planned to provide a vfs_lookup_open() in vfs code which provides
this functionality.  This will share more code with the syscall open
path, and make it easier to modify locking at the VFS level.

Signed-off-by: NeilBrown <neil-+NVA1uvv1dVBDLzU/[email protected]>
---
 fs/nfsd/nfs4proc.c | 108 ++++++++++++++++++++++++---------------------
 1 file changed, 58 insertions(+), 50 deletions(-)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 10323c620b71..643cf4302db5 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -201,6 +201,47 @@ static inline bool nfsd4_create_is_exclusive(int createmode)
 		createmode == NFS4_CREATE_EXCLUSIVE4_1;
 }
 
+static struct file *do_lookup_open(struct path *parent,
+				   struct qstr *name,
+				   unsigned int oflags,
+				   umode_t mode)
+{
+	struct file *filp = NULL;
+	struct path path;
+	struct dentry *child;
+	int error = 0;
+
+	error = mnt_want_write(parent->mnt);
+
+	if (error)
+		return ERR_PTR(error);
+
+	child = start_creating(&nop_mnt_idmap, parent->dentry, name);
+	if (IS_ERR(child)) {
+		filp = ERR_CAST(child);
+		goto out;
+	}
+	path.mnt = parent->mnt;
+	path.dentry = child;
+
+	if (d_really_is_positive(child)) {
+		/*
+		 * open the file so that, unless it is O_RDONLY, we
+		 * have write-access to the fs for setattr below.
+		 */
+		filp = dentry_open(&path, oflags, current_cred());
+	} else if (!(oflags & O_CREAT)) {
+		filp = ERR_PTR(-ENOENT);
+	} else {
+		filp = dentry_create(&path, oflags, mode, current_cred());
+		child = path.dentry;
+	}
+	end_creating(child);
+out:
+	mnt_drop_write(parent->mnt);
+	return filp;
+}
+
 /*
  * Implement NFSv4's unchecked, guarded, and exclusive create
  * semantics for regular files. Open state for this new file is
@@ -218,14 +259,13 @@ nfsd4_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
 		.na_seclabel	= &open->op_label,
 	};
 	int oflags = O_CREAT | O_LARGEFILE;
-	struct dentry *parent, *child = ERR_PTR(-EINVAL);
-	struct path path = {
+	struct dentry *child = ERR_PTR(-EINVAL);
+	struct path parent = {
 		.mnt = fhp->fh_export->ex_path.mnt,
+		.dentry = fhp->fh_dentry,
 	};
 	__u32 v_mtime, v_atime;
-	struct inode *inode;
 	__be32 status, create_status;
-	int host_err;
 
 	if (name_is_dot_dotdot(open->op_fname, open->op_fnamelen))
 		return nfserr_exist;
@@ -235,10 +275,8 @@ nfsd4_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	status = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_EXEC);
 	if (status != nfs_ok)
 		return status;
-	parent = fhp->fh_dentry;
-	inode = d_inode(parent);
 
-	if (!IS_POSIXACL(inode))
+	if (!IS_POSIXACL(d_inode(parent.dentry)))
 		iap->ia_mode &= ~current_umask();
 
 	/*
@@ -303,53 +341,23 @@ nfsd4_create_file(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	}
 
 	create_status = fh_verify(rqstp, fhp, S_IFDIR, NFSD_MAY_CREATE);
-
-	host_err = fh_want_write(fhp);
-	if (host_err) {
-		status = nfserrno(host_err);
-		goto out;
-	}
-
-	child = start_creating(&nop_mnt_idmap, parent,
-			       &QSTR_LEN(open->op_fname, open->op_fnamelen));
-	if (IS_ERR(child)) {
-		status = nfserrno(PTR_ERR(child));
-		fh_drop_write(fhp);
+	if (create_status)
+		oflags &= ~O_CREAT;
+	open->op_filp = do_lookup_open(&parent,
+				       &QSTR_LEN(open->op_fname,
+						 open->op_fnamelen),
+				       oflags,
+				       open->op_iattr.ia_mode);
+	if (IS_ERR(open->op_filp)) {
+		status = nfserrno(PTR_ERR(open->op_filp));
+		open->op_filp = NULL;
+		if (status == NFSERR_NOENT && create_status)
+			status = create_status;
 		goto out;
 	}
-	path.dentry = child;
-
-	if (d_really_is_positive(child)) {
-		/*
-		 * open the file so that, unless it is O_RDONLY, we
-		 * have write-access to the fs for setattr below.
-		 * Also we can be sure that op_filp->f_path.dentry is valid.
-		 */
-		open->op_filp = dentry_open(&path, oflags, current_cred());
-		if (IS_ERR(open->op_filp)) {
-			status = nfserrno(PTR_ERR(open->op_filp));
-			open->op_filp = NULL;
-		}
-	} else if (create_status) {
-		status = create_status;
-	} else {
-		open->op_filp = dentry_create(&path, oflags, open->op_iattr.ia_mode,
-					      current_cred());
-		child = path.dentry;
-
-		if (IS_ERR(open->op_filp)) {
-			status = nfserrno(PTR_ERR(open->op_filp));
-			open->op_filp = NULL;
-		} else {
-			open->op_created = open->op_filp->f_mode & FMODE_CREATED;
-		}
-	}
-	end_creating(child);
-	fh_drop_write(fhp);
-	if (status != nfs_ok)
-		goto out;
 
 	child = open->op_filp->f_path.dentry;
+	open->op_created = open->op_filp->f_mode & FMODE_CREATED;
 
 	status = fh_compose(resfhp, fhp->fh_export, child, fhp);
 	if (status != nfs_ok)
-- 
2.50.0.107.gf914562f5916.dirty