nfs_update_folio has code to extend a write to the entire page under
certain conditions. With the support for large folios this now
suddenly extents to the variable sized and potentially much larger folio.
Add code to limit the extension to the page boundaries of the start and
end of the write, which matches the historic expecation and the code
comments.
Fixes: b73fe2dd6cd5 ("nfs: add support for large folios")
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/nfs/write.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index f3b556ff35f9d2..4e81325f95d740 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1294,8 +1294,12 @@ int nfs_update_folio(struct file *file, struct folio *folio,
goto out;
if (nfs_can_extend_write(file, folio, pagelen)) {
- count = max(count + offset, pagelen);
- offset = 0;
+ unsigned int end = count + offset;
+
+ offset = round_down(offset, PAGE_SIZE);
+ if (end < pagelen)
+ end = min(round_up(end, PAGE_SIZE), pagelen);
+ count = end - offset;
}
status = nfs_writepage_setup(ctx, folio, offset, count);
--
2.43.0
