5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
[ 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@xxxxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reviewed-by: Zhihao Cheng <chengzhihao1@xxxxxxxxxx>
Signed-off-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 4d3a5cb6e9b03..ebad140f8d056 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -262,9 +262,6 @@ static int write_begin_slow(struct address_space *mapping,
return err;
}
}
-
- SetPageUptodate(page);
- ClearPageError(page);
}
if (PagePrivate(page))
@@ -463,9 +460,6 @@ 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);
@@ -475,10 +469,8 @@ 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
@@ -569,6 +561,9 @@ static int ubifs_write_end(struct file *file, struct address_space *mapping,
goto out;
}
+ if (len == PAGE_SIZE)
+ SetPageUptodate(page);
+
if (!PagePrivate(page)) {
SetPagePrivate(page);
atomic_long_inc(&c->dirty_pg_cnt);
--
2.43.0
