From aa1d058d48f292aa138e33ad12b7b4d18b5407cd Mon Sep 17 00:00:00 2001 From: Ian Kent <raven@themaw.net> Date: Tue, 18 Oct 2022 10:32:42 +0800 Subject: kernfs: dont take i_lock on inode attr read The kernfs write lock is held when the kernfs node inode attributes are updated. Therefore, when either kernfs_iop_getattr() or kernfs_iop_permission() are called the kernfs node inode attributes won't change. Consequently concurrent kernfs_refresh_inode() calls always copy the same values from the kernfs node. So there's no need to take the inode i_lock to get consistent values for generic_fillattr() and generic_permission(), the kernfs read lock is sufficient. Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Ian Kent <raven@themaw.net> Link: https://lore.kernel.org/r/166606036215.13363.1288735296954908554.stgit@donald.themaw.net Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- fs/kernfs/inode.c | 4 ---- 1 file changed, 4 deletions(-) (limited to 'fs/kernfs/inode.c') diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c index 3d783d80f5da..74f3453f4639 100644 --- a/fs/kernfs/inode.c +++ b/fs/kernfs/inode.c @@ -190,10 +190,8 @@ int kernfs_iop_getattr(struct user_namespace *mnt_userns, struct kernfs_root *root = kernfs_root(kn); down_read(&root->kernfs_rwsem); - spin_lock(&inode->i_lock); kernfs_refresh_inode(kn, inode); generic_fillattr(&init_user_ns, inode, stat); - spin_unlock(&inode->i_lock); up_read(&root->kernfs_rwsem); return 0; @@ -288,10 +286,8 @@ int kernfs_iop_permission(struct user_namespace *mnt_userns, root = kernfs_root(kn); down_read(&root->kernfs_rwsem); - spin_lock(&inode->i_lock); kernfs_refresh_inode(kn, inode); ret = generic_permission(&init_user_ns, inode, mask); - spin_unlock(&inode->i_lock); up_read(&root->kernfs_rwsem); return ret; -- cgit v1.2.3