Merge tag 'vfs-6.11-rc6.fixes' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:
 "VFS:

   - Ensure that backing files uses file->f_ops->splice_write() for
     splice

  netfs:

   - Revert the removal of PG_private_2 from netfs_release_folio() as
     cephfs still relies on this

   - When AS_RELEASE_ALWAYS is set on a mapping the folio needs to
     always be invalidated during truncation

   - Fix losing untruncated data in a folio by making letting
     netfs_release_folio() return false if the folio is dirty

   - Fix trimming of streaming-write folios in netfs_inval_folio()

   - Reset iterator before retrying a short read

   - Fix interaction of streaming writes with zero-point tracker

  afs:

   - During truncation afs currently calls truncate_setsize() which sets
     i_size, expands the pagecache and truncates it. The first two
     operations aren't needed because they will have already been done.
     So call truncate_pagecache() instead and skip the redundant parts

  overlayfs:

   - Fix checking of the number of allowed lower layers so 500 layers
     can actually be used instead of just 499

   - Add missing '\n' to pr_err() output

   - Pass string to ovl_parse_layer() and thus allow it to be used for
     Opt_lowerdir as well

  pidfd:

   - Revert blocking the creation of pidfds for kthread as apparently
     userspace relies on this. Specifically, it breaks systemd during
     shutdown

  romfs:

   - Fix romfs_read_folio() to use the correct offset with
     folio_zero_tail()"

* tag 'vfs-6.11-rc6.fixes' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs:
  netfs: Fix interaction of streaming writes with zero-point tracker
  netfs: Fix missing iterator reset on retry of short read
  netfs: Fix trimming of streaming-write folios in netfs_inval_folio()
  netfs: Fix netfs_release_folio() to say no if folio dirty
  afs: Fix post-setattr file edit to do truncation correctly
  mm: Fix missing folio invalidation calls during truncation
  ovl: ovl_parse_param_lowerdir: Add missed '\n' for pr_err
  ovl: fix wrong lowerdir number check for parameter Opt_lowerdir
  ovl: pass string to ovl_parse_layer()
  backing-file: convert to using fops->splice_write
  Revert "pidfd: prevent creation of pidfds for kthreads"
  romfs: fix romfs_read_folio()
  netfs, ceph: Partially revert "netfs: Replace PG_fscache by setting folio->private and marking dirty"

1 files changed, 3 insertions, 22 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 18bdc87209d0..cc760491f201 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2053,23 +2053,10 @@ static int __pidfd_prepare(struct pid *pid, unsigned int flags, struct file **re
  */
 int pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret)
 {
-	if (!pid)
-		return -EINVAL;
-
-	scoped_guard(rcu) {
-		struct task_struct *tsk;
-
-		if (flags & PIDFD_THREAD)
-			tsk = pid_task(pid, PIDTYPE_PID);
-		else
-			tsk = pid_task(pid, PIDTYPE_TGID);
-		if (!tsk)
-			return -EINVAL;
+	bool thread = flags & PIDFD_THREAD;
 
-		/* Don't create pidfds for kernel threads for now. */
-		if (tsk->flags & PF_KTHREAD)
-			return -EINVAL;
-	}
+	if (!pid || !pid_has_task(pid, thread ? PIDTYPE_PID : PIDTYPE_TGID))
+		return -EINVAL;
 
 	return __pidfd_prepare(pid, flags, ret);
 }
@@ -2416,12 +2403,6 @@ __latent_entropy struct task_struct *copy_process(
 	if (clone_flags & CLONE_PIDFD) {
 		int flags = (clone_flags & CLONE_THREAD) ? PIDFD_THREAD : 0;
 
-		/* Don't create pidfds for kernel threads for now. */
-		if (args->kthread) {
-			retval = -EINVAL;
-			goto bad_fork_free_pid;
-		}
-
 		/* Note that no task has been attached to @pid yet. */
 		retval = __pidfd_prepare(pid, flags, &pidfile);
 		if (retval < 0)