[PATCH 6.6 047/396] ubifs: Set page uptodate in the correct place

Greg Kroah-Hartman
2024-04-01T16:37:16Z

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

[ Upstream commit 723012cab779eee8228376754e22c6594229bf8f ]

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>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ubifs/file.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index e5382f0b25878..781206d0ec845 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -261,9 +261,6 @@ static int write_begin_slow(struct address_space *mapping,
return err;
}
}
-
- SetPageUptodate(page);
- ClearPageError(page);
}

if (PagePrivate(page))
@@ -462,9 +459,6 @@ 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);
@@ -474,10 +468,8 @@ static int ubifs_write_begin(struct file *file, struct address_space *mapping,
* If we skipped reading the page because we were going to
* write all of it, then it is not up to date.
*/
- if (skipped_read) {
+ if (skipped_read)
ClearPageChecked(page);
- ClearPageUptodate(page);
- }
/*
* Budgeting failed which means it would have to force
* write-back but didn't, because we set the @fast flag in the
@@ -568,6 +560,9 @@ 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