From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena Schedulers on the default cid mapping treat [0, nr_online_cids) as the online set and restart on hotplug. Schedulers that install their own mapping with scx_bpf_cid_override() have no way to learn which cids are online: the count no longer identifies members and the CPU-form cpumask is unusable from cid programs. This is an obvious hole in the cid API. Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's arena, allocated alongside the per-CPU scratch masks and populated after the cid mapping is finalized and before ops.init(), for child schedulers too. The pointer stays valid through ops.exit() with no reference to take. It is the arena offset as a void pointer, the same form struct_ops arena arguments arrive in. The verifier types the void return as a scalar for the program's arena cast. The mask follows the SCX hotplug notifications: seeded from cpu_active_mask and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask only inside a hotplug transition. Updates walk the scheduler list under the lock that also serializes unlinking. Reads are live, not atomic snapshots. Root initialization excludes hotplug. v2: Reworded the getter kerneldoc (Andrea Righi). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- fs/ecryptfs/dentry.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 76 insertions(+) create mode 100644 fs/ecryptfs/dentry.c (limited to 'fs/ecryptfs/dentry.c') diff --git a/fs/ecryptfs/dentry.c b/fs/ecryptfs/dentry.c new file mode 100644 index 000000000..6648a924e --- /dev/null +++ b/fs/ecryptfs/dentry.c @@ -0,0 +1,76 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * eCryptfs: Linux filesystem encryption layer + * + * Copyright (C) 1997-2003 Erez Zadok + * Copyright (C) 2001-2003 Stony Brook University + * Copyright (C) 2004-2006 International Business Machines Corp. + * Author(s): Michael A. Halcrow + */ + +#include +#include +#include +#include +#include +#include "ecryptfs_kernel.h" + +/** + * ecryptfs_d_revalidate - revalidate an ecryptfs dentry + * @dir: inode of expected parent + * @name: expected name + * @dentry: dentry to revalidate + * @flags: lookup flags + * + * Called when the VFS needs to revalidate a dentry. This + * is called whenever a name lookup finds a dentry in the + * dcache. Most filesystems leave this as NULL, because all their + * dentries in the dcache are valid. + * + * Returns 1 if valid, 0 otherwise. + * + */ +static int ecryptfs_d_revalidate(struct inode *dir, const struct qstr *name, + struct dentry *dentry, unsigned int flags) +{ + struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry); + int rc = 1; + + if (flags & LOOKUP_RCU) + return -ECHILD; + + if (lower_dentry->d_flags & DCACHE_OP_REVALIDATE) { + struct inode *lower_dir = ecryptfs_inode_to_lower(dir); + struct name_snapshot n; + + take_dentry_name_snapshot(&n, lower_dentry); + rc = lower_dentry->d_op->d_revalidate(lower_dir, &n.name, + lower_dentry, flags); + release_dentry_name_snapshot(&n); + } + + if (d_really_is_positive(dentry)) { + struct inode *inode = d_inode(dentry); + + fsstack_copy_attr_all(inode, ecryptfs_inode_to_lower(inode)); + if (!inode->i_nlink) + return 0; + } + return rc; +} + +/** + * ecryptfs_d_release + * @dentry: The ecryptfs dentry + * + * Called when a dentry is really deallocated. + */ +static void ecryptfs_d_release(struct dentry *dentry) +{ + dput(dentry->d_fsdata); +} + +const struct dentry_operations ecryptfs_dops = { + .d_revalidate = ecryptfs_d_revalidate, + .d_release = ecryptfs_d_release, +}; -- cgit v1.3.1