We need to check i_count again with i_lock held, because iput might re-add i_count when lazytime is on. Without this check, we could end up with double-free or use-after-free.
Cc: Alexander Viro <v...@zeniv.linux.org.uk> Cc: linux-fsde...@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: sta...@vger.kernel.org Signed-off-by: Chunwei Chen <david.c...@osnexus.com> --- fs/inode.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/fs/inode.c b/fs/inode.c index 4ccbc21..10bb020 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -607,7 +607,12 @@ again: continue; spin_lock(&inode->i_lock); - if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { + /* + * check i_count again with lock, because iput might re-add + * it when lazytime is on. + */ + if (atomic_read(&inode->i_count) || + (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE))) { spin_unlock(&inode->i_lock); continue; } -- 2.7.4