7068 need a way to change the tmpfs size on a mounted fs

Reviewed by: Robert Mustacchi <rm@joyent.com>
Reviewed by: Garrett D'Amore <garrett@damore.org>
Approved by: Dan McDonald <danmcd@omniti.com>

2 files changed, 31 insertions, 8 deletions

diff --git a/usr/src/man/man1m/mount_tmpfs.1m b/usr/src/man/man1m/mount_tmpfs.1m
index a4f38d3b1f..ef7a2a6a35 100644
--- a/usr/src/man/man1m/mount_tmpfs.1m
+++ b/usr/src/man/man1m/mount_tmpfs.1m
@@ -1,9 +1,10 @@
 '\" te
 .\"  Copyright (c) 2003, Sun Microsystems, Inc.  All Rights Reserved
+.\"  Copyright (c) 2011, Joyent, Inc.  All Rights Reserved
 .\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
 .\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.  See the License for the specific language governing permissions and limitations under the License.
 .\" When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE.  If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
-.TH MOUNT_TMPFS 1M "Nov 24, 2003"
+.TH MOUNT_TMPFS 1M "Dec 2, 2011"
 .SH NAME
 mount_tmpfs \- mount tmpfs file systems
 .SH SYNOPSIS
@@ -13,7 +14,6 @@ mount_tmpfs \- mount tmpfs file systems
 .fi
 
 .SH DESCRIPTION
-.sp
 .LP
 \fBtmpfs\fR is a memory based file system which uses kernel resources relating
 to the \fBVM\fR system and page cache as a file system.
@@ -32,7 +32,6 @@ values.
 The \fIspecial\fR argument is usually specified as \fBswap\fR but is in fact
 disregarded and assumed to be the virtual memory resources within the system.
 .SH OPTIONS
-.sp
 .ne 2
 .na
 \fB\fB-o\fR \fIspecific_options\fR\fR
@@ -45,6 +44,17 @@ available:
 .sp
 .ne 2
 .na
+\fB\fBremount\fR\fR
+.ad
+.sp .6
+.RS 19n
+Remounts a file system with a new size. A size not explicitly
+set with \fBremount\fR reverts to no limit.
+.RE
+
+.sp
+.ne 2
+.na
 \fBsize=\fIsz\fR\fR
 .ad
 .RS 19n
@@ -82,7 +92,6 @@ producing the error\f(CWdevice busy\fR.
 .RE
 
 .SH FILES
-.sp
 .ne 2
 .na
 \fB\fB/etc/mnttab\fR\fR
@@ -92,13 +101,11 @@ Table of mounted file systems
 .RE
 
 .SH SEE ALSO
-.sp
 .LP
 \fBmount\fR(1M), \fBmkdir\fR(2), \fBmount\fR(2), \fBopen\fR(2),
 \fBumount\fR(2), \fBmnttab\fR(4), \fBattributes\fR(5), \fBfsattr\fR(5),
 \fBtmpfs\fR(7FS)
 .SH NOTES
-.sp
 .LP
 If the directory on which a file system is to be mounted is a symbolic link,
 the file system is mounted on the directory to which the symbolic link refers,
diff --git a/usr/src/uts/common/fs/tmpfs/tmp_vfsops.c b/usr/src/uts/common/fs/tmpfs/tmp_vfsops.c
index f8a36a528f..f22cc3ecf0 100644
--- a/usr/src/uts/common/fs/tmpfs/tmp_vfsops.c
+++ b/usr/src/uts/common/fs/tmpfs/tmp_vfsops.c
@@ -20,6 +20,7 @@
  */
 /*
  * Copyright (c) 1990, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, Joyent, Inc. All rights reserved.
  */
 
 #include <sys/types.h>
@@ -76,7 +77,7 @@ static vfsdef_t vfw = {
 	VFSDEF_VERSION,
 	"tmpfs",
 	tmpfsinit,
-	VSW_HASPROTO|VSW_STATS|VSW_ZMOUNT,
+	VSW_HASPROTO|VSW_CANREMOUNT|VSW_STATS|VSW_ZMOUNT,
 	&tmpfs_proto_opttbl
 };
 
@@ -249,7 +250,7 @@ tmp_mount(
 		return (ENOTDIR);
 
 	mutex_enter(&mvp->v_lock);
-	if ((uap->flags & MS_OVERLAY) == 0 &&
+	if ((uap->flags & MS_REMOUNT) == 0 && (uap->flags & MS_OVERLAY) == 0 &&
 	    (mvp->v_count != 1 || (mvp->v_flag & VROOT))) {
 		mutex_exit(&mvp->v_lock);
 		return (EBUSY);
@@ -286,6 +287,21 @@ tmp_mount(
 	    (uap->flags & MS_SYSSPACE) ? UIO_SYSSPACE : UIO_USERSPACE, &dpn))
 		goto out;
 
+	if (uap->flags & MS_REMOUNT) {
+		tm = (struct tmount *)VFSTOTM(vfsp);
+
+		/*
+		 * If we change the size so its less than what is currently
+		 * being used, we allow that. The file system will simply be
+		 * full until enough files have been removed to get below the
+		 * new max.
+		 */
+		mutex_enter(&tm->tm_contents);
+		tm->tm_anonmax = anonmax;
+		mutex_exit(&tm->tm_contents);
+		goto out;
+	}
+
 	if ((tm = tmp_memalloc(sizeof (struct tmount), 0)) == NULL) {
 		pn_free(&dpn);
 		error = ENOMEM;