NFS: Reduce the stack usage in NFSv3 create operations

Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs3proc.c

@@ -248,6 +248,53 @@ static int nfs3_proc_readlink(struct inode *inode, struct page *page,
 	return status;
 }
 
+struct nfs3_createdata {
+	struct rpc_message msg;
+	union {
+		struct nfs3_createargs create;
+		struct nfs3_mkdirargs mkdir;
+		struct nfs3_symlinkargs symlink;
+		struct nfs3_mknodargs mknod;
+	} arg;
+	struct nfs3_diropres res;
+	struct nfs_fh fh;
+	struct nfs_fattr fattr;
+	struct nfs_fattr dir_attr;
+};
+
+static struct nfs3_createdata *nfs3_alloc_createdata(void)
+{
+	struct nfs3_createdata *data;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (data != NULL) {
+		data->msg.rpc_argp = &data->arg;
+		data->msg.rpc_resp = &data->res;
+		data->res.fh = &data->fh;
+		data->res.fattr = &data->fattr;
+		data->res.dir_attr = &data->dir_attr;
+		nfs_fattr_init(data->res.fattr);
+		nfs_fattr_init(data->res.dir_attr);
+	}
+	return data;
+}
+
+static int nfs3_do_create(struct inode *dir, struct dentry *dentry, struct nfs3_createdata *data)
+{
+	int status;
+
+	status = rpc_call_sync(NFS_CLIENT(dir), &data->msg, 0);
+	nfs_post_op_update_inode(dir, data->res.dir_attr);
+	if (status == 0)
+		status = nfs_instantiate(dentry, data->res.fh, data->res.fattr);
+	return status;
+}
+
+static void nfs3_free_createdata(struct nfs3_createdata *data)
+{
+	kfree(data);
+}
+
 /*
  * Create a regular file.
  * For now, we don't implement O_EXCL.
@@ -256,70 +303,60 @@ static int
 nfs3_proc_create(struct inode *dir, struct dentry *dentry, struct iattr *sattr,
 		 int flags, struct nameidata *nd)
 {
-	struct nfs_fh		fhandle;
-	struct nfs_fattr	fattr;
-	struct nfs_fattr	dir_attr;
-	struct nfs3_createargs	arg = {
-		.fh		= NFS_FH(dir),
-		.name		= dentry->d_name.name,
-		.len		= dentry->d_name.len,
-		.sattr		= sattr,
-	};
-	struct nfs3_diropres	res = {
-		.dir_attr	= &dir_attr,
-		.fh		= &fhandle,
-		.fattr		= &fattr
-	};
-	struct rpc_message msg = {
-		.rpc_proc	= &nfs3_procedures[NFS3PROC_CREATE],
-		.rpc_argp	= &arg,
-		.rpc_resp	= &res,
-	};
+	struct nfs3_createdata *data;
 	mode_t mode = sattr->ia_mode;
-	int status;
+	int status = -ENOMEM;
 
 	dprintk("NFS call  create %s\n", dentry->d_name.name);
-	arg.createmode = NFS3_CREATE_UNCHECKED;
+
+	data = nfs3_alloc_createdata();
+	if (data == NULL)
+		goto out;
+
+	data->msg.rpc_proc = &nfs3_procedures[NFS3PROC_CREATE];
+	data->arg.create.fh = NFS_FH(dir);
+	data->arg.create.name = dentry->d_name.name;
+	data->arg.create.len = dentry->d_name.len;
+	data->arg.create.sattr = sattr;
+
+	data->arg.create.createmode = NFS3_CREATE_UNCHECKED;
 	if (flags & O_EXCL) {
-		arg.createmode  = NFS3_CREATE_EXCLUSIVE;
-		arg.verifier[0] = jiffies;
-		arg.verifier[1] = current->pid;
+		data->arg.create.createmode  = NFS3_CREATE_EXCLUSIVE;
+		data->arg.create.verifier[0] = jiffies;
+		data->arg.create.verifier[1] = current->pid;
 	}
 
 	sattr->ia_mode &= ~current->fs->umask;
 
-again:
-	nfs_fattr_init(&dir_attr);
-	nfs_fattr_init(&fattr);
-	status = rpc_call_sync(NFS_CLIENT(dir), &msg, 0);
-	nfs_refresh_inode(dir, &dir_attr);
+	for (;;) {
+		status = nfs3_do_create(dir, dentry, data);
 
-	/* If the server doesn't support the exclusive creation semantics,
-	 * try again with simple 'guarded' mode. */
-	if (status == -ENOTSUPP) {
-		switch (arg.createmode) {
+		if (status != -ENOTSUPP)
+			break;
+		/* If the server doesn't support the exclusive creation
+		 * semantics, try again with simple 'guarded' mode. */
+		switch (data->arg.create.createmode) {
 			case NFS3_CREATE_EXCLUSIVE:
-				arg.createmode = NFS3_CREATE_GUARDED;
+				data->arg.create.createmode = NFS3_CREATE_GUARDED;
 				break;
 
 			case NFS3_CREATE_GUARDED:
-				arg.createmode = NFS3_CREATE_UNCHECKED;
+				data->arg.create.createmode = NFS3_CREATE_UNCHECKED;
 				break;
 
 			case NFS3_CREATE_UNCHECKED:
 				goto out;
 		}
-		goto again;
+		nfs_fattr_init(data->res.dir_attr);
+		nfs_fattr_init(data->res.fattr);
 	}
 
-	if (status == 0)
-		status = nfs_instantiate(dentry, &fhandle, &fattr);
 	if (status != 0)
 		goto out;
 
 	/* When we created the file with exclusive semantics, make
 	 * sure we set the attributes afterwards. */
-	if (arg.createmode == NFS3_CREATE_EXCLUSIVE) {
+	if (data->arg.create.createmode == NFS3_CREATE_EXCLUSIVE) {
 		dprintk("NFS call  setattr (post-create)\n");
 
 		if (!(sattr->ia_valid & ATTR_ATIME_SET))
@@ -330,14 +367,15 @@ nfs3_proc_create(struct inode *dir, struct dentry *dentry, struct iattr *sattr,
 		/* Note: we could use a guarded setattr here, but I'm
 		 * not sure this buys us anything (and I'd have
 		 * to revamp the NFSv3 XDR code) */
-		status = nfs3_proc_setattr(dentry, &fattr, sattr);
-		nfs_post_op_update_inode(dentry->d_inode, &fattr);
+		status = nfs3_proc_setattr(dentry, data->res.fattr, sattr);
+		nfs_post_op_update_inode(dentry->d_inode, data->res.fattr);
 		dprintk("NFS reply setattr (post-create): %d\n", status);
-	}
 		if (status != 0)
 			goto out;
+	}
 	status = nfs3_proc_set_default_acl(dir, dentry->d_inode, mode);
 out:
+	nfs3_free_createdata(data);
 	dprintk("NFS reply create: %d\n", status);
 	return status;
 }
@@ -452,40 +490,28 @@ static int
 nfs3_proc_symlink(struct inode *dir, struct dentry *dentry, struct page *page,
 		  unsigned int len, struct iattr *sattr)
 {
-	struct nfs_fh fhandle;
-	struct nfs_fattr fattr, dir_attr;
-	struct nfs3_symlinkargs	arg = {
-		.fromfh		= NFS_FH(dir),
-		.fromname	= dentry->d_name.name,
-		.fromlen	= dentry->d_name.len,
-		.pages		= &page,
-		.pathlen	= len,
-		.sattr		= sattr
-	};
-	struct nfs3_diropres	res = {
-		.dir_attr	= &dir_attr,
-		.fh		= &fhandle,
-		.fattr		= &fattr
-	};
-	struct rpc_message msg = {
-		.rpc_proc	= &nfs3_procedures[NFS3PROC_SYMLINK],
-		.rpc_argp	= &arg,
-		.rpc_resp	= &res,
-	};
-	int			status;
+	struct nfs3_createdata *data;
+	int status = -ENOMEM;
 
 	if (len > NFS3_MAXPATHLEN)
 		return -ENAMETOOLONG;
 
 	dprintk("NFS call  symlink %s\n", dentry->d_name.name);
 
-	nfs_fattr_init(&dir_attr);
-	nfs_fattr_init(&fattr);
-	status = rpc_call_sync(NFS_CLIENT(dir), &msg, 0);
-	nfs_post_op_update_inode(dir, &dir_attr);
-	if (status != 0)
+	data = nfs3_alloc_createdata();
+	if (data == NULL)
 		goto out;
-	status = nfs_instantiate(dentry, &fhandle, &fattr);
+	data->msg.rpc_proc = &nfs3_procedures[NFS3PROC_SYMLINK];
+	data->arg.symlink.fromfh = NFS_FH(dir);
+	data->arg.symlink.fromname = dentry->d_name.name;
+	data->arg.symlink.fromlen = dentry->d_name.len;
+	data->arg.symlink.pages = &page;
+	data->arg.symlink.pathlen = len;
+	data->arg.symlink.sattr = sattr;
+
+	status = nfs3_do_create(dir, dentry, data);
+
+	nfs3_free_createdata(data);
 out:
 	dprintk("NFS reply symlink: %d\n", status);
 	return status;
@@ -494,42 +520,31 @@ nfs3_proc_symlink(struct inode *dir, struct dentry *dentry, struct page *page,
 static int
 nfs3_proc_mkdir(struct inode *dir, struct dentry *dentry, struct iattr *sattr)
 {
-	struct nfs_fh fhandle;
-	struct nfs_fattr fattr, dir_attr;
-	struct nfs3_mkdirargs	arg = {
-		.fh		= NFS_FH(dir),
-		.name		= dentry->d_name.name,
-		.len		= dentry->d_name.len,
-		.sattr		= sattr
-	};
-	struct nfs3_diropres	res = {
-		.dir_attr	= &dir_attr,
-		.fh		= &fhandle,
-		.fattr		= &fattr
-	};
-	struct rpc_message msg = {
-		.rpc_proc	= &nfs3_procedures[NFS3PROC_MKDIR],
-		.rpc_argp	= &arg,
-		.rpc_resp	= &res,
-	};
+	struct nfs3_createdata *data;
 	int mode = sattr->ia_mode;
-	int status;
+	int status = -ENOMEM;
 
 	dprintk("NFS call  mkdir %s\n", dentry->d_name.name);
 
 	sattr->ia_mode &= ~current->fs->umask;
 
-	nfs_fattr_init(&dir_attr);
-	nfs_fattr_init(&fattr);
-	status = rpc_call_sync(NFS_CLIENT(dir), &msg, 0);
-	nfs_post_op_update_inode(dir, &dir_attr);
-	if (status != 0)
+	data = nfs3_alloc_createdata();
+	if (data == NULL)
 		goto out;
-	status = nfs_instantiate(dentry, &fhandle, &fattr);
+
+	data->msg.rpc_proc = &nfs3_procedures[NFS3PROC_MKDIR];
+	data->arg.mkdir.fh = NFS_FH(dir);
+	data->arg.mkdir.name = dentry->d_name.name;
+	data->arg.mkdir.len = dentry->d_name.len;
+	data->arg.mkdir.sattr = sattr;
+
+	status = nfs3_do_create(dir, dentry, data);
 	if (status != 0)
 		goto out;
+
 	status = nfs3_proc_set_default_acl(dir, dentry->d_inode, mode);
 out:
+	nfs3_free_createdata(data);
 	dprintk("NFS reply mkdir: %d\n", status);
 	return status;
 }
@@ -615,52 +630,50 @@ static int
 nfs3_proc_mknod(struct inode *dir, struct dentry *dentry, struct iattr *sattr,
 		dev_t rdev)
 {
-	struct nfs_fh fh;
-	struct nfs_fattr fattr, dir_attr;
-	struct nfs3_mknodargs	arg = {
-		.fh		= NFS_FH(dir),
-		.name		= dentry->d_name.name,
-		.len		= dentry->d_name.len,
-		.sattr		= sattr,
-		.rdev		= rdev
-	};
-	struct nfs3_diropres	res = {
-		.dir_attr	= &dir_attr,
-		.fh		= &fh,
-		.fattr		= &fattr
-	};
-	struct rpc_message msg = {
-		.rpc_proc	= &nfs3_procedures[NFS3PROC_MKNOD],
-		.rpc_argp	= &arg,
-		.rpc_resp	= &res,
-	};
+	struct nfs3_createdata *data;
 	mode_t mode = sattr->ia_mode;
-	int status;
-
-	switch (sattr->ia_mode & S_IFMT) {
-	case S_IFBLK:	arg.type = NF3BLK;  break;
-	case S_IFCHR:	arg.type = NF3CHR;  break;
-	case S_IFIFO:	arg.type = NF3FIFO; break;
-	case S_IFSOCK:	arg.type = NF3SOCK; break;
-	default:	return -EINVAL;
-	}
+	int status = -ENOMEM;
 
 	dprintk("NFS call  mknod %s %u:%u\n", dentry->d_name.name,
 			MAJOR(rdev), MINOR(rdev));
 
 	sattr->ia_mode &= ~current->fs->umask;
 
-	nfs_fattr_init(&dir_attr);
-	nfs_fattr_init(&fattr);
-	status = rpc_call_sync(NFS_CLIENT(dir), &msg, 0);
-	nfs_post_op_update_inode(dir, &dir_attr);
-	if (status != 0)
+	data = nfs3_alloc_createdata();
+	if (data == NULL)
+		goto out;
+
+	data->msg.rpc_proc = &nfs3_procedures[NFS3PROC_MKNOD];
+	data->arg.mknod.fh = NFS_FH(dir);
+	data->arg.mknod.name = dentry->d_name.name;
+	data->arg.mknod.len = dentry->d_name.len;
+	data->arg.mknod.sattr = sattr;
+	data->arg.mknod.rdev = rdev;
+
+	switch (sattr->ia_mode & S_IFMT) {
+	case S_IFBLK:
+		data->arg.mknod.type = NF3BLK;
+		break;
+	case S_IFCHR:
+		data->arg.mknod.type = NF3CHR;
+		break;
+	case S_IFIFO:
+		data->arg.mknod.type = NF3FIFO;
+		break;
+	case S_IFSOCK:
+		data->arg.mknod.type = NF3SOCK;
+		break;
+	default:
+		status = -EINVAL;
 		goto out;
-	status = nfs_instantiate(dentry, &fh, &fattr);
+	}
+
+	status = nfs3_do_create(dir, dentry, data);
 	if (status != 0)
 		goto out;
 	status = nfs3_proc_set_default_acl(dir, dentry->d_inode, mode);
 out:
+	nfs3_free_createdata(data);
 	dprintk("NFS reply mknod: %d\n", status);
 	return status;
 }