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

…/git/viro/vfs

Pull misc VFS updates from Al Viro:
 "This cycle a lot of stuff sits on topical branches, so I'll be sending
  more or less one pull request per branch.

  This is the first pile; more to follow in a few.  In this one are
  several misc commits from early in the cycle (before I went for
  separate branches), plus the rework of mntput/dput ordering on umount,
  switching to use of fs_pin instead of convoluted games in
  namespace_unlock()"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  switch the IO-triggering parts of umount to fs_pin
  new fs_pin killing logics
  allow attaching fs_pin to a group not associated with some superblock
  get rid of the second argument of acct_kill()
  take count and rcu_head out of fs_pin
  dcache: let the dentry count go down to zero without taking d_lock
  pull bumping refcount into ->kill()
  kill pin_put()
  mode_t whack-a-mole: chelsio
  file->f_path.dentry is pinned down for as long as the file is open...
  get rid of lustre_dump_dentry()
  gut proc_register() a bit
  kill d_validate()
  ncpfs: get rid of d_validate() nonsense
  selinuxfs: don't open-code d_genocide()

drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.h

@@ -55,7 +55,7 @@ static const struct file_operations name##_debugfs_fops = { \
 struct t4_debugfs_entry {
 	const char *name;
 	const struct file_operations *ops;
-	mode_t mode;
+	umode_t mode;
 	unsigned char data;
 };
 

drivers/staging/lustre/lustre/llite/dcache.c

@@ -263,14 +263,6 @@ void ll_invalidate_aliases(struct inode *inode)
 		       dentry, dentry, dentry->d_parent,
 		       dentry->d_inode, dentry->d_flags);
 
-		if (unlikely(dentry == dentry->d_sb->s_root)) {
-			CERROR("%s: called on root dentry=%p, fid="DFID"\n",
-			       ll_get_fsname(dentry->d_sb, NULL, 0),
-			       dentry, PFID(ll_inode2fid(inode)));
-			lustre_dump_dentry(dentry, 1);
-			dump_stack();
-		}
-
 		d_lustre_invalidate(dentry, 0);
 	}
 	ll_unlock_dcache(inode);

drivers/staging/lustre/lustre/llite/llite_internal.h

@@ -816,7 +816,6 @@ int ll_show_options(struct seq_file *seq, struct dentry *dentry);
 void ll_dirty_page_discard_warn(struct page *page, int ioret);
 int ll_prep_inode(struct inode **inode, struct ptlrpc_request *req,
 		  struct super_block *, struct lookup_intent *);
-void lustre_dump_dentry(struct dentry *, int recur);
 int ll_obd_statfs(struct inode *inode, void *arg);
 int ll_get_max_mdsize(struct ll_sb_info *sbi, int *max_mdsize);
 int ll_get_default_mdsize(struct ll_sb_info *sbi, int *default_mdsize);

drivers/staging/lustre/lustre/llite/llite_lib.c

@@ -665,48 +665,6 @@ int ll_get_default_cookiesize(struct ll_sb_info *sbi, int *lmmsize)
 	return rc;
 }
 
-static void ll_dump_inode(struct inode *inode)
-{
-	struct ll_d_hlist_node *tmp;
-	int dentry_count = 0;
-
-	LASSERT(inode != NULL);
-
-	ll_d_hlist_for_each(tmp, &inode->i_dentry)
-		dentry_count++;
-
-	CERROR("inode %p dump: dev=%s ino=%lu mode=%o count=%u, %d dentries\n",
-	       inode, ll_i2mdexp(inode)->exp_obd->obd_name, inode->i_ino,
-	       inode->i_mode, atomic_read(&inode->i_count), dentry_count);
-}
-
-void lustre_dump_dentry(struct dentry *dentry, int recur)
-{
-	struct list_head *tmp;
-	int subdirs = 0;
-
-	LASSERT(dentry != NULL);
-
-	list_for_each(tmp, &dentry->d_subdirs)
-		subdirs++;
-
-	CERROR("dentry %p dump: name=%pd parent=%pd (%p), inode=%p, count=%u, flags=0x%x, fsdata=%p, %d subdirs\n",
-	       dentry, dentry, dentry->d_parent, dentry->d_parent,
-	       dentry->d_inode, d_count(dentry),
-	       dentry->d_flags, dentry->d_fsdata, subdirs);
-	if (dentry->d_inode != NULL)
-		ll_dump_inode(dentry->d_inode);
-
-	if (recur == 0)
-		return;
-
-	list_for_each(tmp, &dentry->d_subdirs) {
-		struct dentry *d = list_entry(tmp, struct dentry, d_child);
-
-		lustre_dump_dentry(d, recur - 1);
-	}
-}
-
 static void client_common_put_super(struct super_block *sb)
 {
 	struct ll_sb_info *sbi = ll_s2sbi(sb);

fs/dcache.c

@@ -511,7 +511,7 @@ static void __dentry_kill(struct dentry *dentry)
 	 * dentry_iput drops the locks, at which point nobody (except
 	 * transient RCU lookups) can reach this dentry.
 	 */
-	BUG_ON((int)dentry->d_lockref.count > 0);
+	BUG_ON(dentry->d_lockref.count > 0);
 	this_cpu_dec(nr_dentry);
 	if (dentry->d_op && dentry->d_op->d_release)
 		dentry->d_op->d_release(dentry);
@@ -564,7 +564,7 @@ static inline struct dentry *lock_parent(struct dentry *dentry)
 	struct dentry *parent = dentry->d_parent;
 	if (IS_ROOT(dentry))
 		return NULL;
-	if (unlikely((int)dentry->d_lockref.count < 0))
+	if (unlikely(dentry->d_lockref.count < 0))
 		return NULL;
 	if (likely(spin_trylock(&parent->d_lock)))
 		return parent;
@@ -593,6 +593,110 @@ static inline struct dentry *lock_parent(struct dentry *dentry)
 	return parent;
 }
 
+/*
+ * Try to do a lockless dput(), and return whether that was successful.
+ *
+ * If unsuccessful, we return false, having already taken the dentry lock.
+ *
+ * The caller needs to hold the RCU read lock, so that the dentry is
+ * guaranteed to stay around even if the refcount goes down to zero!
+ */
+static inline bool fast_dput(struct dentry *dentry)
+{
+	int ret;
+	unsigned int d_flags;
+
+	/*
+	 * If we have a d_op->d_delete() operation, we sould not
+	 * let the dentry count go to zero, so use "put__or_lock".
+	 */
+	if (unlikely(dentry->d_flags & DCACHE_OP_DELETE))
+		return lockref_put_or_lock(&dentry->d_lockref);
+
+	/*
+	 * .. otherwise, we can try to just decrement the
+	 * lockref optimistically.
+	 */
+	ret = lockref_put_return(&dentry->d_lockref);
+
+	/*
+	 * If the lockref_put_return() failed due to the lock being held
+	 * by somebody else, the fast path has failed. We will need to
+	 * get the lock, and then check the count again.
+	 */
+	if (unlikely(ret < 0)) {
+		spin_lock(&dentry->d_lock);
+		if (dentry->d_lockref.count > 1) {
+			dentry->d_lockref.count--;
+			spin_unlock(&dentry->d_lock);
+			return 1;
+		}
+		return 0;
+	}
+
+	/*
+	 * If we weren't the last ref, we're done.
+	 */
+	if (ret)
+		return 1;
+
+	/*
+	 * Careful, careful. The reference count went down
+	 * to zero, but we don't hold the dentry lock, so
+	 * somebody else could get it again, and do another
+	 * dput(), and we need to not race with that.
+	 *
+	 * However, there is a very special and common case
+	 * where we don't care, because there is nothing to
+	 * do: the dentry is still hashed, it does not have
+	 * a 'delete' op, and it's referenced and already on
+	 * the LRU list.
+	 *
+	 * NOTE! Since we aren't locked, these values are
+	 * not "stable". However, it is sufficient that at
+	 * some point after we dropped the reference the
+	 * dentry was hashed and the flags had the proper
+	 * value. Other dentry users may have re-gotten
+	 * a reference to the dentry and change that, but
+	 * our work is done - we can leave the dentry
+	 * around with a zero refcount.
+	 */
+	smp_rmb();
+	d_flags = ACCESS_ONCE(dentry->d_flags);
+	d_flags &= DCACHE_REFERENCED | DCACHE_LRU_LIST;
+
+	/* Nothing to do? Dropping the reference was all we needed? */
+	if (d_flags == (DCACHE_REFERENCED | DCACHE_LRU_LIST) && !d_unhashed(dentry))
+		return 1;
+
+	/*
+	 * Not the fast normal case? Get the lock. We've already decremented
+	 * the refcount, but we'll need to re-check the situation after
+	 * getting the lock.
+	 */
+	spin_lock(&dentry->d_lock);
+
+	/*
+	 * Did somebody else grab a reference to it in the meantime, and
+	 * we're no longer the last user after all? Alternatively, somebody
+	 * else could have killed it and marked it dead. Either way, we
+	 * don't need to do anything else.
+	 */
+	if (dentry->d_lockref.count) {
+		spin_unlock(&dentry->d_lock);
+		return 1;
+	}
+
+	/*
+	 * Re-get the reference we optimistically dropped. We hold the
+	 * lock, and we just tested that it was zero, so we can just
+	 * set it to 1.
+	 */
+	dentry->d_lockref.count = 1;
+	return 0;
+}
+
+
 /* 
  * This is dput
  *
@@ -625,8 +729,14 @@ void dput(struct dentry *dentry)
 		return;
 
 repeat:
-	if (lockref_put_or_lock(&dentry->d_lockref))
+	rcu_read_lock();
+	if (likely(fast_dput(dentry))) {
+		rcu_read_unlock();
 		return;
+	}
+
+	/* Slow case: now with the dentry lock held */
+	rcu_read_unlock();
 
 	/* Unreachable? Get rid of it */
 	if (unlikely(d_unhashed(dentry)))
@@ -813,7 +923,7 @@ static void shrink_dentry_list(struct list_head *list)
 		 * We found an inuse dentry which was not removed from
 		 * the LRU because of laziness during lookup. Do not free it.
 		 */
-		if ((int)dentry->d_lockref.count > 0) {
+		if (dentry->d_lockref.count > 0) {
 			spin_unlock(&dentry->d_lock);
 			if (parent)
 				spin_unlock(&parent->d_lock);
@@ -2191,37 +2301,6 @@ struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
 }
 EXPORT_SYMBOL(d_hash_and_lookup);
 
-/**
- * d_validate - verify dentry provided from insecure source (deprecated)
- * @dentry: The dentry alleged to be valid child of @dparent
- * @dparent: The parent dentry (known to be valid)
- *
- * An insecure source has sent us a dentry, here we verify it and dget() it.
- * This is used by ncpfs in its readdir implementation.
- * Zero is returned in the dentry is invalid.
- *
- * This function is slow for big directories, and deprecated, do not use it.
- */
-int d_validate(struct dentry *dentry, struct dentry *dparent)
-{
-	struct dentry *child;
-
-	spin_lock(&dparent->d_lock);
-	list_for_each_entry(child, &dparent->d_subdirs, d_child) {
-		if (dentry == child) {
-			spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
-			__dget_dlock(dentry);
-			spin_unlock(&dentry->d_lock);
-			spin_unlock(&dparent->d_lock);
-			return 1;
-		}
-	}
-	spin_unlock(&dparent->d_lock);
-
-	return 0;
-}
-EXPORT_SYMBOL(d_validate);
-
 /*
  * When a file is deleted, we have two options:
  * - turn this dentry into a negative dentry