xfs: more reserved blocks fixups

This mangles the reserved blocks counts a little more.

1) add a helper function for the default reserved count
2) add helper functions to save/restore counts on ro/rw
3) save/restore reserved blocks on freeze/thaw
4) disallow changing reserved count while readonly

V2: changed field name to match Dave's changes

Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Signed-off-by: Alex Elder <aelder@sgi.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/xfs/linux-2.6/xfs_ioctl.c b/fs/xfs/linux-2.6/xfs_ioctl.c
index 3906e85abfdc..4ea1ee18aded 100644
--- a/fs/xfs/linux-2.6/xfs_ioctl.c
+++ b/fs/xfs/linux-2.6/xfs_ioctl.c
@@ -1431,6 +1431,9 @@ xfs_file_ioctl(
                 if (!capable(CAP_SYS_ADMIN))
                         return -EPERM;
 
+                if (mp->m_flags & XFS_MOUNT_RDONLY)
+                        return -XFS_ERROR(EROFS);
+
                 if (copy_from_user(&inout, arg, sizeof(inout)))
                         return -XFS_ERROR(EFAULT);