[PATCH 3/4] netfs: Fix netfs_release_folio() to say no if folio dirty

David Howells
2024-08-20T23:21:41Z

Fix netfs_release_folio() to say no (ie. return false) if the folio is
dirty (analogous with iomap's behaviour). Without this, it will say yes to
the release of a dirty page by split_huge_page_to_list_to_order(), which
will result in the loss of untruncated data in the folio.

Without this, the generic/075 and generic/112 xfstests (both fsx-based
tests) fail with minimum folio size patches applied[1].

Fixes: c1ec4d7c2e13 ("netfs: Provide invalidate_folio and release_folio calls")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Matthew Wilcox (Oracle) <willy@infradead.org>
cc: Pankaj Raghav <p.raghav@samsung.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
cc: netfs@lists.linux.dev
cc: linux-mm@kvack.org
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20240815090849.972355-1-kernel@pankajraghav.com/ [1]
---
fs/netfs/misc.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/fs/netfs/misc.c b/fs/netfs/misc.c
index 554a1a4615ad..69324761fcf7 100644
--- a/fs/netfs/misc.c
+++ b/fs/netfs/misc.c
@@ -161,6 +161,9 @@ bool netfs_release_folio(struct folio *folio, gfp_t gfp)
struct netfs_inode *ctx = netfs_inode(folio_inode(folio));
unsigned long long end;

+ if (folio_test_dirty(folio))
+ return false;
+
end = folio_pos(folio) + folio_size(folio);
if (end > ctx->zero_point)
ctx->zero_point = end;