Merge branch 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull the big VFS changes from Al Viro:
 "This one is *big* and changes quite a few things around VFS.  What's in there:

   - the first of two really major architecture changes - death to open
     intents.

     The former is finally there; it was very long in making, but with
     Miklos getting through really hard and messy final push in
     fs/namei.c, we finally have it.  Unlike his variant, this one
     doesn't introduce struct opendata; what we have instead is
     ->atomic_open() taking preallocated struct file * and passing
     everything via its fields.

     Instead of returning struct file *, it returns -E...  on error, 0
     on success and 1 in "deal with it yourself" case (e.g.  symlink
     found on server, etc.).

     See comments before fs/namei.c:atomic_open().  That made a lot of
     goodies finally possible and quite a few are in that pile:
     ->lookup(), ->d_revalidate() and ->create() do not get struct
     nameidata * anymore; ->lookup() and ->d_revalidate() get lookup
     flags instead, ->create() gets "do we want it exclusive" flag.

     With the introduction of new helper (kern_path_locked()) we are rid
     of all struct nameidata instances outside of fs/namei.c; it's still
     visible in namei.h, but not for long.  Come the next cycle,
     declaration will move either to fs/internal.h or to fs/namei.c
     itself.  [me, miklos, hch]

   - The second major change: behaviour of final fput().  Now we have
     __fput() done without any locks held by caller *and* not from deep
     in call stack.

     That obviously lifts a lot of constraints on the locking in there.
     Moreover, it's legal now to call fput() from atomic contexts (which
     has immediately simplified life for aio.c).  We also don't need
     anti-recursion logics in __scm_destroy() anymore.

     There is a price, though - the damn thing has become partially
     asynchronous.  For fput() from normal process we are guaranteed
     that pending __fput() will be done before the caller returns to
     userland, exits or gets stopped for ptrace.

     For kernel threads and atomic contexts it's done via
     schedule_work(), so theoretically we might need a way to make sure
     it's finished; so far only one such place had been found, but there
     might be more.

     There's flush_delayed_fput() (do all pending __fput()) and there's
     __fput_sync() (fput() analog doing __fput() immediately).  I hope
     we won't need them often; see warnings in fs/file_table.c for
     details.  [me, based on task_work series from Oleg merged last
     cycle]

   - sync series from Jan

   - large part of "death to sync_supers()" work from Artem; the only
     bits missing here are exofs and ext4 ones.  As far as I understand,
     those are going via the exofs and ext4 trees resp.; once they are
     in, we can put ->write_super() to the rest, along with the thread
     calling it.

   - preparatory bits from unionmount series (from dhowells).

   - assorted cleanups and fixes all over the place, as usual.

  This is not the last pile for this cycle; there's at least jlayton's
  ESTALE work and fsfreeze series (the latter - in dire need of fixes,
  so I'm not sure it'll make the cut this cycle).  I'll probably throw
  symlink/hardlink restrictions stuff from Kees into the next pile, too.
  Plus there's a lot of misc patches I hadn't thrown into that one -
  it's large enough as it is..."

* 'for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (127 commits)
  ext4: switch EXT4_IOC_RESIZE_FS to mnt_want_write_file()
  btrfs: switch btrfs_ioctl_balance() to mnt_want_write_file()
  switch dentry_open() to struct path, make it grab references itself
  spufs: shift dget/mntget towards dentry_open()
  zoran: don't bother with struct file * in zoran_map
  ecryptfs: don't reinvent the wheels, please - use struct completion
  don't expose I_NEW inodes via dentry->d_inode
  tidy up namei.c a bit
  unobfuscate follow_up() a bit
  ext3: pass custom EOF to generic_file_llseek_size()
  ext4: use core vfs llseek code for dir seeks
  vfs: allow custom EOF in generic_file_llseek code
  vfs: Avoid unnecessary WB_SYNC_NONE writeback during sys_sync and reorder sync passes
  vfs: Remove unnecessary flushing of block devices
  vfs: Make sys_sync writeout also block device inodes
  vfs: Create function for iterating over block devices
  vfs: Reorder operations during sys_sync
  quota: Move quota syncing to ->sync_fs method
  quota: Split dquot_quota_sync() to writeback and cache flushing part
  vfs: Move noop_backing_dev_info check from sync into writeback
  ...

6 files changed, 18 insertions, 26 deletions

diff --git a/security/keys/internal.h b/security/keys/internal.h
index 3dcbf86..c246ba5 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -149,7 +149,7 @@ extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
 #define KEY_LOOKUP_FOR_UNLINK	0x04
 
 extern long join_session_keyring(const char *name);
-extern void key_change_session_keyring(struct task_work *twork);
+extern void key_change_session_keyring(struct callback_head *twork);
 
 extern struct work_struct key_gc_work;
 extern unsigned key_gc_delay;
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 0f5b3f0..f1b59ae 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -1456,7 +1456,7 @@ long keyctl_session_to_parent(void)
 {
 	struct task_struct *me, *parent;
 	const struct cred *mycred, *pcred;
-	struct task_work *newwork, *oldwork;
+	struct callback_head *newwork, *oldwork;
 	key_ref_t keyring_r;
 	struct cred *cred;
 	int ret;
@@ -1466,19 +1466,17 @@ long keyctl_session_to_parent(void)
 		return PTR_ERR(keyring_r);
 
 	ret = -ENOMEM;
-	newwork = kmalloc(sizeof(struct task_work), GFP_KERNEL);
-	if (!newwork)
-		goto error_keyring;
 
 	/* our parent is going to need a new cred struct, a new tgcred struct
 	 * and new security data, so we allocate them here to prevent ENOMEM in
 	 * our parent */
 	cred = cred_alloc_blank();
 	if (!cred)
-		goto error_newwork;
+		goto error_keyring;
+	newwork = &cred->rcu;
 
 	cred->tgcred->session_keyring = key_ref_to_ptr(keyring_r);
-	init_task_work(newwork, key_change_session_keyring, cred);
+	init_task_work(newwork, key_change_session_keyring);
 
 	me = current;
 	rcu_read_lock();
@@ -1488,6 +1486,7 @@ long keyctl_session_to_parent(void)
 	oldwork = NULL;
 	parent = me->real_parent;
 
+	task_lock(parent);
 	/* the parent mustn't be init and mustn't be a kernel thread */
 	if (parent->pid <= 1 || !parent->mm)
 		goto unlock;
@@ -1531,20 +1530,15 @@ long keyctl_session_to_parent(void)
 	if (!ret)
 		newwork = NULL;
 unlock:
+	task_unlock(parent);
 	write_unlock_irq(&tasklist_lock);
 	rcu_read_unlock();
-	if (oldwork) {
-		put_cred(oldwork->data);
-		kfree(oldwork);
-	}
-	if (newwork) {
-		put_cred(newwork->data);
-		kfree(newwork);
-	}
+	if (oldwork)
+		put_cred(container_of(oldwork, struct cred, rcu));
+	if (newwork)
+		put_cred(cred);
 	return ret;
 
-error_newwork:
-	kfree(newwork);
 error_keyring:
 	key_ref_put(keyring_r);
 	return ret;
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 4ad54ee..54339cf 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -834,12 +834,11 @@ error:
  * Replace a process's session keyring on behalf of one of its children when
  * the target  process is about to resume userspace execution.
  */
-void key_change_session_keyring(struct task_work *twork)
+void key_change_session_keyring(struct callback_head *twork)
 {
 	const struct cred *old = current_cred();
-	struct cred *new = twork->data;
+	struct cred *new = container_of(twork, struct cred, rcu);
 
-	kfree(twork);
 	if (unlikely(current->flags & PF_EXITING)) {
 		put_cred(new);
 		return;
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index ffd8900..9292a89 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2157,8 +2157,7 @@ static inline void flush_unauthorized_files(const struct cred *cred,
 						get_file(devnull);
 					} else {
 						devnull = dentry_open(
-							dget(selinux_null),
-							mntget(selinuxfs_mount),
+							&selinux_null,
 							O_RDWR, cred);
 						if (IS_ERR(devnull)) {
 							devnull = NULL;
diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h
index dde2005..6d38851 100644
--- a/security/selinux/include/security.h
+++ b/security/selinux/include/security.h
@@ -221,7 +221,7 @@ extern void selinux_status_update_policyload(int seqno);
 extern void selinux_complete_init(void);
 extern int selinux_disable(void);
 extern void exit_sel_fs(void);
-extern struct dentry *selinux_null;
+extern struct path selinux_null;
 extern struct vfsmount *selinuxfs_mount;
 extern void selnl_notify_setenforce(int val);
 extern void selnl_notify_policyload(u32 seqno);
diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index 3ad2902..298e695 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -1297,7 +1297,7 @@ out:
 
 #define NULL_FILE_NAME "null"
 
-struct dentry *selinux_null;
+struct path selinux_null;
 
 static ssize_t sel_read_avc_cache_threshold(struct file *filp, char __user *buf,
 					    size_t count, loff_t *ppos)
@@ -1838,7 +1838,7 @@ static int sel_fill_super(struct super_block *sb, void *data, int silent)
 
 	init_special_inode(inode, S_IFCHR | S_IRUGO | S_IWUGO, MKDEV(MEM_MAJOR, 3));
 	d_add(dentry, inode);
-	selinux_null = dentry;
+	selinux_null.dentry = dentry;
 
 	dentry = sel_make_dir(sb->s_root, "avc", &sel_last_ino);
 	if (IS_ERR(dentry)) {
@@ -1912,7 +1912,7 @@ static int __init init_sel_fs(void)
 		return err;
 	}
 
-	selinuxfs_mount = kern_mount(&sel_fs_type);
+	selinux_null.mnt = selinuxfs_mount = kern_mount(&sel_fs_type);
 	if (IS_ERR(selinuxfs_mount)) {
 		printk(KERN_ERR "selinuxfs:  could not mount!\n");
 		err = PTR_ERR(selinuxfs_mount);