From: Al Viro Date: Sat, 22 Mar 2008 20:19:49 +0000 (-0400) Subject: [PATCH] lock exclusively in collect_mounts() and drop_collected_mounts() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=1a60a280778ff90270fc7390d9ec102f713a5a29;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git [PATCH] lock exclusively in collect_mounts() and drop_collected_mounts() Taking namespace_sem shared there isn't worth the trouble, especially with vfsmount ID allocation about to be added. That way we know that umount_tree(), copy_tree() and clone_mnt() are _always_ serialized by namespace_sem. umount_tree() still needs vfsmount_lock (it manipulates hash chains, among other things), but that's a separate story. Signed-off-by: Al Viro --- diff --git a/fs/namespace.c b/fs/namespace.c index 678f7ce060f2..af2fb3707d0a 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -1091,20 +1091,20 @@ Enomem: struct vfsmount *collect_mounts(struct vfsmount *mnt, struct dentry *dentry) { struct vfsmount *tree; - down_read(&namespace_sem); + down_write(&namespace_sem); tree = copy_tree(mnt, dentry, CL_COPY_ALL | CL_PRIVATE); - up_read(&namespace_sem); + up_write(&namespace_sem); return tree; } void drop_collected_mounts(struct vfsmount *mnt) { LIST_HEAD(umount_list); - down_read(&namespace_sem); + down_write(&namespace_sem); spin_lock(&vfsmount_lock); umount_tree(mnt, 0, &umount_list); spin_unlock(&vfsmount_lock); - up_read(&namespace_sem); + up_write(&namespace_sem); release_mounts(&umount_list); }