On Tue, Mar 03, 2020 at 11:10:23AM -0800, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> In commit dc617f29dbe5 we tried to prevent userspace programs from
> writing to active swap devices. However, it turns out that userspace
> hibernation requires the ability to write the hibernation image to a
> swap device, so revert the write path checks.
>
> Fixes: dc617f29dbe5 ("vfs: don't allow writes to swap files")
> Reported-by: Domenico Andreoli <domenico.andreoli@xxxxxxxxx>
> Reported-by: Marian Klein <mkleinsoft@xxxxxxxxx>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
self-NAK, Domenico Andreoli has taken this on. Andrew, could you please
drop this patch from your queue?
--D
> ---
> fs/block_dev.c | 3 ---
> mm/filemap.c | 3 ---
> mm/memory.c | 4 ----
> mm/mmap.c | 8 ++------
> 4 files changed, 2 insertions(+), 16 deletions(-)
>
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index 69bf2fb6f7cd..08b088dac1f0 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -2001,9 +2001,6 @@ ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
> if (bdev_read_only(I_BDEV(bd_inode)))
> return -EPERM;
>
> - if (IS_SWAPFILE(bd_inode))
> - return -ETXTBSY;
> -
> if (!iov_iter_count(from))
> return 0;
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 1784478270e1..d1b8cd15b2bf 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -2920,9 +2920,6 @@ inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)
> loff_t count;
> int ret;
>
> - if (IS_SWAPFILE(inode))
> - return -ETXTBSY;
> -
> if (!iov_iter_count(from))
> return 0;
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 0bccc622e482..e908490f7034 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2357,10 +2357,6 @@ static vm_fault_t do_page_mkwrite(struct vm_fault *vmf)
>
> vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
>
> - if (vmf->vma->vm_file &&
> - IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host))
> - return VM_FAULT_SIGBUS;
> -
> ret = vmf->vma->vm_ops->page_mkwrite(vmf);
> /* Restore original flags so that caller is not surprised */
> vmf->flags = old_flags;
> diff --git a/mm/mmap.c b/mm/mmap.c
> index d681a20eb4ea..77d086139e13 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1461,12 +1461,8 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
> case MAP_SHARED_VALIDATE:
> if (flags & ~flags_mask)
> return -EOPNOTSUPP;
> - if (prot & PROT_WRITE) {
> - if (!(file->f_mode & FMODE_WRITE))
> - return -EACCES;
> - if (IS_SWAPFILE(file->f_mapping->host))
> - return -ETXTBSY;
> - }
> + if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE))
> + return -EACCES;
>
> /*
> * Make sure we don't allow writing to an append-only
