On Wed, Jun 30, 2021 at 04:33:10PM +0900, 권오훈 wrote:

Current cleancache api implementation has potential race as follows,
which might lead to corruption in filesystems using cleancache.

thread 0                thread 1                        thread 2

                        in put_page
                        get pool_id K for fs1
invalidate_fs on fs1
frees pool_id K
                                                        init_fs for fs2
                                                        allocates pool_id K
                        put_page puts page
                        which belongs to fs1
                        into cleancache pool for fs2

At this point, a file cache which originally belongs to fs1 might be
copied back to cleancache pool of fs2, which might be later used as if
it were normal cleancache of fs2, and could eventually corrupt fs2 when
flushed back.

Add rwlock in order to synchronize invalidate_fs with other cleancache
operations.

In normal situations where filesystems are not frequently mounted or
unmounted, there will be little performance impact since
read_lock/read_unlock apis are used.

Signed-off-by: Ohhoon Kwon <redacted>

What commit does this fix?  Should it go to stable kernels?

thanks,

greg k-h