ceph: implement i_op->atomic_open()

Add an ->atomic_open implementation which replaces the atomic lookup+open+create
operation implemented via ->lookup and ->create operations.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: Sage Weil <sage@newdream.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/ceph/dir.c

@@ -594,14 +594,6 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry,
 	if (err < 0)
 		return ERR_PTR(err);
 
-	/* open (but not create!) intent? */
-	if (nd &&
-	    (nd->flags & LOOKUP_OPEN) &&
-	    !(nd->intent.open.flags & O_CREAT)) {
-		int mode = nd->intent.open.create_mode & ~current->fs->umask;
-		return ceph_lookup_open(dir, dentry, nd, mode);
-	}
-
 	/* can we conclude ENOENT locally? */
 	if (dentry->d_inode == NULL) {
 		struct ceph_inode_info *ci = ceph_inode(dir);
@@ -642,6 +634,47 @@ static struct dentry *ceph_lookup(struct inode *dir, struct dentry *dentry,
 	return dentry;
 }
 
+struct file *ceph_atomic_open(struct inode *dir, struct dentry *dentry,
+			      struct opendata *od, unsigned flags, umode_t mode,
+			      bool *created)
+{
+	int err;
+	struct dentry *res = NULL;
+	struct file *filp;
+
+	if (!(flags & O_CREAT)) {
+		if (dentry->d_name.len > NAME_MAX)
+			return ERR_PTR(-ENAMETOOLONG);
+
+		err = ceph_init_dentry(dentry);
+		if (err < 0)
+			return ERR_PTR(err);
+
+		return ceph_lookup_open(dir, dentry, od, flags, mode);
+	}
+
+	if (d_unhashed(dentry)) {
+		res = ceph_lookup(dir, dentry, NULL);
+		if (IS_ERR(res))
+			return ERR_CAST(res);
+
+		if (res)
+			dentry = res;
+	}
+
+	/* We don't deal with positive dentries here */
+	if (dentry->d_inode) {
+		finish_no_open(od, res);
+		return NULL;
+	}
+
+	*created = true;
+	filp = ceph_lookup_open(dir, dentry, od, flags, mode);
+	dput(res);
+
+	return filp;
+}
+
 /*
  * If we do a create but get no trace back from the MDS, follow up with
  * a lookup (the VFS expects us to link up the provided dentry).
@@ -702,23 +735,7 @@ static int ceph_mknod(struct inode *dir, struct dentry *dentry,
 static int ceph_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 		       struct nameidata *nd)
 {
-	dout("create in dir %p dentry %p name '%.*s'\n",
-	     dir, dentry, dentry->d_name.len, dentry->d_name.name);
-
-	if (ceph_snap(dir) != CEPH_NOSNAP)
-		return -EROFS;
-
-	if (nd) {
-		BUG_ON((nd->flags & LOOKUP_OPEN) == 0);
-		dentry = ceph_lookup_open(dir, dentry, nd, mode);
-		/* hrm, what should i do here if we get aliased? */
-		if (IS_ERR(dentry))
-			return PTR_ERR(dentry);
-		return 0;
-	}
-
-	/* fall back to mknod */
-	return ceph_mknod(dir, dentry, (mode & ~S_IFMT) | S_IFREG, 0);
+	return ceph_mknod(dir, dentry, mode, 0);
 }
 
 static int ceph_symlink(struct inode *dir, struct dentry *dentry,
@@ -1357,6 +1374,7 @@ const struct inode_operations ceph_dir_iops = {
 	.rmdir = ceph_unlink,
 	.rename = ceph_rename,
 	.create = ceph_create,
+	.atomic_open = ceph_atomic_open,
 };
 
 const struct dentry_operations ceph_dentry_ops = {

fs/ceph/file.c

@@ -213,21 +213,15 @@ int ceph_open(struct inode *inode, struct file *file)
  * may_open() fails, the struct *file gets cleaned up (i.e.
  * ceph_release gets called).  So fear not!
  */
-/*
- * flags
- *  path_lookup_open   -> LOOKUP_OPEN
- *  path_lookup_create -> LOOKUP_OPEN|LOOKUP_CREATE
- */
-struct dentry *ceph_lookup_open(struct inode *dir, struct dentry *dentry,
-				struct nameidata *nd, int mode)
+struct file *ceph_lookup_open(struct inode *dir, struct dentry *dentry,
+			      struct opendata *od, unsigned flags, umode_t mode)
 {
 	struct ceph_fs_client *fsc = ceph_sb_to_client(dir->i_sb);
 	struct ceph_mds_client *mdsc = fsc->mdsc;
-	struct file *file;
+	struct file *file = NULL;
 	struct ceph_mds_request *req;
 	struct dentry *ret;
 	int err;
-	int flags = nd->intent.open.flags;
 
 	dout("ceph_lookup_open dentry %p '%.*s' flags %d mode 0%o\n",
 	     dentry, dentry->d_name.len, dentry->d_name.name, flags, mode);
@@ -253,14 +247,19 @@ struct dentry *ceph_lookup_open(struct inode *dir, struct dentry *dentry,
 		err = ceph_handle_notrace_create(dir, dentry);
 	if (err)
 		goto out;
-	file = lookup_instantiate_filp(nd, req->r_dentry, ceph_open);
+	file = finish_open(od, req->r_dentry, ceph_open);
 	if (IS_ERR(file))
 		err = PTR_ERR(file);
 out:
 	ret = ceph_finish_lookup(req, dentry, err);
 	ceph_mdsc_put_request(req);
 	dout("ceph_lookup_open result=%p\n", ret);
-	return ret;
+
+	if (IS_ERR(ret))
+		return ERR_CAST(ret);
+
+	dput(ret);
+	return err ? ERR_PTR(err) : file;
 }
 
 int ceph_release(struct inode *inode, struct file *file)

fs/ceph/super.h

@@ -806,8 +806,9 @@ extern int ceph_copy_from_page_vector(struct page **pages,
 				    loff_t off, size_t len);
 extern struct page **ceph_alloc_page_vector(int num_pages, gfp_t flags);
 extern int ceph_open(struct inode *inode, struct file *file);
-extern struct dentry *ceph_lookup_open(struct inode *dir, struct dentry *dentry,
-				       struct nameidata *nd, int mode);
+extern struct file *ceph_lookup_open(struct inode *dir, struct dentry *dentry,
+				     struct opendata *od, unsigned flags,
+				     umode_t mode);
 extern int ceph_release(struct inode *inode, struct file *filp);
 
 /* dir.c */