From 39c910a430370fd25d5b5e4b2f4b24581a705499 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Fri, 5 Jul 2024 07:42:51 +0200 Subject: [PATCH] nfs: do not extend writes to the entire folio 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 Reviewed-by: Sagi Grimberg Reviewed-by: Benjamin Coddington Signed-off-by: Anna Schumaker --- 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 f0a124b45291..acf2d942d78f 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -1351,8 +1351,12 @@ 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);