On Thu, Dec 18, 2014 at 10:29:18PM -0800, Omar Sandoval wrote:
> Most filesystems prevent truncation of an active swapfile by way of
> inode_newsize_ok, called from inode_change_ok. NFS doesn't call either
> from nfs_setattr, presumably because most of these checks are expected
> to be done server-side. However, the IS_SWAPFILE check can only be done
> client-side, and not doing so is dangerous.
>
> Signed-off-by: Omar Sandoval <osandov@xxxxxxxxxxx>
> ---
> fs/nfs/inode.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
> index 4bffe63..9205513 100644
> --- a/fs/nfs/inode.c
> +++ b/fs/nfs/inode.c
> @@ -506,10 +506,15 @@ nfs_setattr(struct dentry *dentry, struct iattr *attr)
> attr->ia_valid &= ~ATTR_MODE;
>
> if (attr->ia_valid & ATTR_SIZE) {
> + loff_t i_size;
> +
> BUG_ON(!S_ISREG(inode->i_mode));
>
> - if (attr->ia_size == i_size_read(inode))
> + i_size = i_size_read(inode);
> + if (attr->ia_size == i_size)
> attr->ia_valid &= ~ATTR_SIZE;
> + else if (attr->ia_size < i_size && IS_SWAPFILE(inode))
> + return -ETXTBSY;
> }
>
> /* Optimization: if the end result is no change, don't RPC */
> --
> 2.2.0
>
Sorry, forgot to mention that this applies to Linus' tree as of today.
--
Omar
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