On Thu, Mar 28, 2019 at 10:50:47AM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> The chattr manpage has this to say about immutable files:
>
> "A file with the 'i' attribute cannot be modified: it cannot be deleted
> or renamed, no link can be created to this file, most of the file's
> metadata can not be modified, and the file can not be opened in write
> mode."
>
> This means that we need to flush the page cache when setting the
nit: flush and invalidate the page cache.
> immutable flag so that programs cannot continue to write to writable
> mappings.
Do we even need to invalidate the page cache for this? i.e. we've
cleaned the pages so that any new write to them will fault,
that will see the immutable flag via ->page_mkwrite and then the
app should segv, right?
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> fs/xfs/xfs_ioctl.c | 63 +++++++++++++++++++++++++++++++++++-----------------
> 1 file changed, 43 insertions(+), 20 deletions(-)
>
>
> diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> index 6ecdbb3af7de..2bd1c5ab5008 100644
> --- a/fs/xfs/xfs_ioctl.c
> +++ b/fs/xfs/xfs_ioctl.c
> @@ -998,6 +998,37 @@ xfs_diflags_to_linux(
> #endif
> }
>
> +static int
> +xfs_ioctl_setattr_flush(
> + struct xfs_inode *ip,
> + int *join_flags)
> +{
> + struct inode *inode = VFS_I(ip);
> + int error;
> +
> + if (S_ISDIR(inode->i_mode))
> + return 0;
> + if ((*join_flags) & (XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL))
> + return 0;
> +
> + /* lock, flush and invalidate mapping in preparation for flag change */
> + xfs_ilock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL);
> + error = filemap_write_and_wait(inode->i_mapping);
> + if (error)
> + goto out_unlock;
> + error = invalidate_inode_pages2(inode->i_mapping);
> + if (error)
> + goto out_unlock;
> +
> + *join_flags = XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL;
> + return 0;
> +
> +out_unlock:
> + xfs_iunlock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL);
> + return error;
> +
> +}
Doesn't wait for direct IO to drain. Wouldn't it be better to do
this?
lock()
xfs_flush_unmap_range(ip, 0, XFS_SIZE(ip));
unlock()
Otherwise looks ok.
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
