From 03b6abee9ba67c20c4e5253e1a347d8c26edc511 Mon Sep 17 00:00:00 2001 From: Christian Brauner <brauner@kernel.org> Date: Thu, 3 Feb 2022 14:14:09 +0100 Subject: [PATCH] fs: simplify check in mount_setattr_commit() In order to determine whether we need to call mnt_unhold_writers() in mount_setattr_commit() we currently do not just check whether MNT_WRITE_HOLD is set but also if a read-only mount was requested. However, checking whether MNT_WRITE_HOLD is set is enough. Setting MNT_WRITE_HOLD requires lock_mount_hash() to be held and it must be unset before calling unlock_mount_hash(). This guarantees that if we see MNT_WRITE_HOLD we know that we were the ones who set it earlier. We don't need to care about why we set it. Plus, leaving this additional read-only check in makes the code more confusing because it implies that MNT_WRITE_HOLD could've been set by another thread when it really can't. Remove it and update the associated comment. Link: https://lore.kernel.org/r/20220203131411.3093040-6-brauner@kernel.org Cc: Seth Forshee <seth.forshee@digitalocean.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christian Brauner <brauner@kernel.org> --- fs/namespace.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index 7e5535ed155d9..ddae5c08ea8c8 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -4096,13 +4096,8 @@ static void mount_setattr_commit(struct mount_kattr *kattr, WRITE_ONCE(m->mnt.mnt_flags, flags); } - /* - * We either set MNT_READONLY above so make it visible - * before ~MNT_WRITE_HOLD or we failed to recursively - * apply mount options. - */ - if ((kattr->attr_set & MNT_READONLY) && - (m->mnt.mnt_flags & MNT_WRITE_HOLD)) + /* If we had to hold writers unblock them. */ + if (m->mnt.mnt_flags & MNT_WRITE_HOLD) mnt_unhold_writers(m); if (!err && kattr->propagation) -- GitLab