[PATCH] ext2 reservations: fix for r/o bind mounts: take-writer-count (v2)

[Dave Hansen <haveblue@us.ibm.com>]

Please throw away what I send a moment ago, it was the wrong
patch.

This is on top of the ext2-reservations.patch in -mm.

The original r/o bind mount set didn't address the new
ext2 ioctl: EXT2_IOC_SETRSVSZ, because it doesn't exist
in mainline.  This fixes that up for -mm.  

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
---

 lxc-dave/fs/ext2/ioctl.c |   24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff -puN fs/ext2/ioctl.c~ext2-reservations-take-writer-count fs/ext2/ioctl.c
--- lxc/fs/ext2/ioctl.c~ext2-reservations-take-writer-count	2007-09-24 13:08:29.000000000 -0700
+++ lxc-dave/fs/ext2/ioctl.c	2007-09-24 13:12:09.000000000 -0700
@@ -111,14 +111,18 @@ setflags_out:
 		if (!test_opt(inode->i_sb, RESERVATION) ||!S_ISREG(inode->i_mode))
 			return -ENOTTY;
 
-		if (IS_RDONLY(inode))
-			return -EROFS;
-
-		if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
-			return -EACCES;
-
-		if (get_user(rsv_window_size, (int __user *)arg))
-			return -EFAULT;
+		ret = mnt_want_write(filp->f_vfsmnt);
+		if (ret)
+			return ret;
+
+		if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER)) {
+			ret = -EACCES;
+			goto setrsvsz_out;
+		}
+		if (get_user(rsv_window_size, (int __user *)arg)) {
+			ret = -EFAULT;
+			goto setrsvsz_out;
+		}
 
 		if (rsv_window_size > EXT2_MAX_RESERVE_BLOCKS)
 			rsv_window_size = EXT2_MAX_RESERVE_BLOCKS;
@@ -140,7 +144,9 @@ setflags_out:
 			rsv->rsv_goal_size = rsv_window_size;
 		}
 		mutex_unlock(&ei->truncate_mutex);
-		return 0;
+	setrsvsz_out:
+		mnt_drop_write(filp->f_vfsmnt);
+		return ret;
 	}
 	default:
 		return -ENOTTY;
diff -puN fs/namespace.c~ext2-reservations-take-writer-count fs/namespace.c
_