On Thu, Sep 24, 2020 at 01:56:08PM +0100, Matthew Wilcox (Oracle) wrote:
> For filesystems with block size < page size, we need to set all the
> per-block uptodate bits if the page was already uptodate at the time
> we create the per-block metadata. This can happen if the page is
> invalidated (eg by a write to drop_caches) but ultimately not removed
> from the page cache.
>
> This is a data corruption issue as page writeback skips blocks which
> are marked !uptodate.
>
> Fixes: 9dc55f1389f9 ("iomap: add support for sub-pagesize buffered I/O without buffer heads")
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> Reported-by: Qian Cai <cai@xxxxxxxxxx>
> Cc: Brian Foster <bfoster@xxxxxxxxxx>
Makes sense to me,
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
--D
> ---
> fs/iomap/buffered-io.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index 8b6cca7e34e4..8180061b9e16 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -60,6 +60,8 @@ iomap_page_create(struct inode *inode, struct page *page)
> iop = kzalloc(struct_size(iop, uptodate, BITS_TO_LONGS(nr_blocks)),
> GFP_NOFS | __GFP_NOFAIL);
> spin_lock_init(&iop->uptodate_lock);
> + if (PageUptodate(page))
> + bitmap_fill(iop->uptodate, nr_blocks);
> attach_page_private(page, iop);
> return iop;
> }
> --
> 2.28.0
>
