[PATCH 01/15] ubifs: Set page uptodate in the correct place

Matthew Wilcox (Oracle)
2024-01-20T23:08:48Z

Page cache reads are lockless, so setting the freshly allocated page
uptodate before we've overwritten it with the data it's supposed to have
in it will allow a simultaneous reader to see old data. Move the call
to SetPageUptodate into ubifs_write_end(), which is after we copied the
new data into the page.

Fixes: 1e51764a3c2a ("UBIFS: add new flash file system")
Cc: stable@vger.kernel.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
fs/ubifs/file.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index 5029eb3390a5..40a9b03ef821 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -463,9 +463,6 @@ static int ubifs_write_begin(struct file *file, struct address_space *mapping,
return err;
}
}
-
- SetPageUptodate(page);
- ClearPageError(page);
}

err = allocate_budget(c, page, ui, appending);
@@ -569,6 +566,9 @@ static int ubifs_write_end(struct file *file, struct address_space *mapping,
goto out;
}

+ if (len == PAGE_SIZE)
+ SetPageUptodate(page);
+
if (!PagePrivate(page)) {
attach_page_private(page, (void *)1);
atomic_long_inc(&c->dirty_pg_cnt);
--
2.43.0