Re: [PATCH] use proper mnt_want_write calls for handle ioctls

Christoph Hellwig
2008-09-12T08:43:29Z

ping? Without this patch the CVS tree won't properly work with
read-only bind mounts.

On Thu, Aug 14, 2008 at 10:39:52PM +0200, Christoph Hellwig wrote:
> Since 2.6.26 all writes to filesystems need to be enclosed by a
> mnt_want_write / mnt_drop_write pair instead of checking for IS_RDONLY.
>
> XFs was updated for this in mainline but the changes to xfs_ioctl.c
> were never megred back into the CVS tree.
>
> The original commit introducing this was:
>
> commit 42a74f206b914db13ee1f5ae932dcd91a77c8579
> Author: Dave Hansen <haveblue@us.ibm.com>
> Date: Fri Feb 15 14:37:46 2008 -0800
>
> [PATCH] r/o bind mounts: elevate write count for ioctls()
>
> Index: linux-2.6-xfs/fs/xfs/linux-2.6/xfs_ioctl.c
> ===================================================================
> --- linux-2.6-xfs.orig/fs/xfs/linux-2.6/xfs_ioctl.c 2008-08-14 14:54:53.000000000 -0300
> +++ linux-2.6-xfs/fs/xfs/linux-2.6/xfs_ioctl.c 2008-08-14 15:15:49.000000000 -0300
> @@ -543,8 +543,6 @@ xfs_attrmulti_attr_set(
> char *kbuf;
> int error = EFAULT;
>
> - if (IS_RDONLY(inode))
> - return -EROFS;
> if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
> return EPERM;
> if (len > XATTR_SIZE_MAX)
> @@ -570,8 +568,6 @@ xfs_attrmulti_attr_remove(
> char *name,
> __uint32_t flags)
> {
> - if (IS_RDONLY(inode))
> - return -EROFS;
> if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
> return EPERM;
> return xfs_attr_remove(XFS_I(inode), name, flags);
> @@ -581,6 +577,7 @@ STATIC int
> xfs_attrmulti_by_handle(
> xfs_mount_t *mp,
> void __user *arg,
> + struct file *parfilp,
> struct inode *parinode)
> {
> int error;
> @@ -634,13 +631,21 @@ xfs_attrmulti_by_handle(
> &ops[i].am_length, ops[i].am_flags);
> break;
> case ATTR_OP_SET:
> + ops[i].am_error = mnt_want_write(parfilp->f_path.mnt);
> + if (ops[i].am_error)
> + break;
> ops[i].am_error = xfs_attrmulti_attr_set(inode,
> attr_name, ops[i].am_attrvalue,
> ops[i].am_length, ops[i].am_flags);
> + mnt_drop_write(parfilp->f_path.mnt);
> break;
> case ATTR_OP_REMOVE:
> + ops[i].am_error = mnt_want_write(parfilp->f_path.mnt);
> + if (ops[i].am_error)
> + break;
> ops[i].am_error = xfs_attrmulti_attr_remove(inode,
> attr_name, ops[i].am_flags);
> + mnt_drop_write(parfilp->f_path.mnt);
> break;
> default:
> ops[i].am_error = EINVAL;
> @@ -1431,7 +1436,7 @@ xfs_ioctl(
> return xfs_attrlist_by_handle(mp, arg, inode);
>
> case XFS_IOC_ATTRMULTI_BY_HANDLE:
> - return xfs_attrmulti_by_handle(mp, arg, inode);
> + return xfs_attrmulti_by_handle(mp, arg, filp, inode);
>
> case XFS_IOC_SWAPEXT: {
> error = xfs_swapext((struct xfs_swapext __user *)arg);