[PATCH 4.19.y] iomap: Set all uptodate bits for an Uptodate page

[PATCH 4.19.y] iomap: Set all uptodate bits for an Uptodate page

[zhangshida]

From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

commit 4595a298d5563cf76c1d852970f162051fd1a7a6 upstream.

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@infradead.org>
Reported-by: Qian Cai <cai@redhat.com>
Cc: Brian Foster <bfoster@redhat.com>
Reviewed-by: Gao Xiang <hsiangkao@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Shida Zhang <zhangshida@kylinos.cn>
---
 fs/iomap.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/iomap.c b/fs/iomap.c
index ac7b2152c3ad..04e82b6bd9bf 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -109,6 +109,7 @@ static struct iomap_page *
 iomap_page_create(struct inode *inode, struct page *page)
 {
 	struct iomap_page *iop = to_iomap_page(page);
+	unsigned int nr_blocks = PAGE_SIZE / i_blocksize(inode);
 
 	if (iop || i_blocksize(inode) == PAGE_SIZE)
 		return iop;
@@ -118,6 +119,8 @@ iomap_page_create(struct inode *inode, struct page *page)
 	atomic_set(&iop->write_count, 0);
 	spin_lock_init(&iop->uptodate_lock);
 	bitmap_zero(iop->uptodate, PAGE_SIZE / SECTOR_SIZE);
+	if (PageUptodate(page))
+		bitmap_fill(iop->uptodate, nr_blocks);
 
 	/*
 	 * migrate_page_move_mapping() assumes that pages with private data have
-- 
2.27.0

Re: [PATCH 4.19.y] iomap: Set all uptodate bits for an Uptodate page

[Greg KH]

On Thu, Nov 16, 2023 at 02:40:10PM +0800, zhangshida wrote:
> From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
> 
> commit 4595a298d5563cf76c1d852970f162051fd1a7a6 upstream.
> 
> 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@infradead.org>
> Reported-by: Qian Cai <cai@redhat.com>
> Cc: Brian Foster <bfoster@redhat.com>
> Reviewed-by: Gao Xiang <hsiangkao@redhat.com>
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Shida Zhang <zhangshida@kylinos.cn>
> ---
>  fs/iomap.c | 3 +++
>  1 file changed, 3 insertions(+)

Now queued up, thanks.

greg k-h