Merge branch 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull misc dcache updates from Al Viro:
"Most of this pile is putting name length into struct name_snapshot and
making use of it.

The beginning of this series ("ovl_lookup_real_one(): don't bother
with strlen()") ought to have been split in two (separate switch of
name_snapshot to struct qstr from overlayfs reaping the trivial
benefits of that), but I wanted to avoid a rebase - by the time I'd
spotted that it was (a) in -next and (b) close to 5.1-final ;-/"

* 'work.dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
audit_compare_dname_path(): switch to const struct qstr *
audit_update_watch(): switch to const struct qstr *
inotify_handle_event(): don't bother with strlen()
fsnotify: switch send_to_group() and ->handle_event to const struct qstr *
fsnotify(): switch to passing const struct qstr * for file_name
switch fsnotify_move() to passing const struct qstr * for old_name
ovl_lookup_real_one(): don't bother with strlen()
sysv: bury the broken "quietly truncate the long filenames" logics
nsfs: unobfuscate
unexport d_alloc_pseudo()

Documentation/filesystems/porting

···
 	DCACHE_RCUACCESS is gone; having an RCU delay on dentry freeing is the
 	default.  DCACHE_NORCU opts out, and only d_alloc_pseudo() has any
 	business doing so.
+--
+[mandatory]
+	d_alloc_pseudo() is internal-only; uses outside of alloc_file_pseudo() are
+	very suspect (and won't work in modules).  Such uses are very likely to
+	be misspelled d_alloc_anon().

fs/dcache.c

···
 void take_dentry_name_snapshot(struct name_snapshot *name, struct dentry *dentry)
 {
 	spin_lock(&dentry->d_lock);
+	name->name = dentry->d_name;
 	if (unlikely(dname_external(dentry))) {
-		struct external_name *p = external_name(dentry);
-		atomic_inc(&p->u.count);
-		spin_unlock(&dentry->d_lock);
-		name->name = p->name;
+		atomic_inc(&external_name(dentry)->u.count);
 	} else {
 		memcpy(name->inline_name, dentry->d_iname,
 		       dentry->d_name.len + 1);
-		spin_unlock(&dentry->d_lock);
-		name->name = name->inline_name;
+		name->name.name = name->inline_name;
 	}
+	spin_unlock(&dentry->d_lock);
 }
 EXPORT_SYMBOL(take_dentry_name_snapshot);
 
 void release_dentry_name_snapshot(struct name_snapshot *name)
 {
-	if (unlikely(name->name != name->inline_name)) {
+	if (unlikely(name->name.name != name->inline_name)) {
 		struct external_name *p;
-		p = container_of(name->name, struct external_name, name[0]);
+		p = container_of(name->name.name, struct external_name, name[0]);
 		if (unlikely(atomic_dec_and_test(&p->u.count)))
 			kfree_rcu(p, u.head);
 	}
···
  * never be anyone's children or parents.  Unlike all other
  * dentries, these will not have RCU delay between dropping the
  * last reference and freeing them.
+ *
+ * The only user is alloc_file_pseudo() and that's what should
+ * be considered a public interface.  Don't use directly.
  */
 struct dentry *d_alloc_pseudo(struct super_block *sb, const struct qstr *name)
 {
···
 		dentry->d_flags |= DCACHE_NORCU;
 	return dentry;
 }
-EXPORT_SYMBOL(d_alloc_pseudo);
 
 struct dentry *d_alloc_name(struct dentry *parent, const char *name)
 {

fs/debugfs/inode.c

···
 		goto exit;
 	}
 	d_move(old_dentry, dentry);
-	fsnotify_move(d_inode(old_dir), d_inode(new_dir), old_name.name,
+	fsnotify_move(d_inode(old_dir), d_inode(new_dir), &old_name.name,
 		d_is_dir(old_dentry),
 		NULL, old_dentry);
 	release_dentry_name_snapshot(&old_name);

fs/internal.h

···
 extern int d_set_mounted(struct dentry *dentry);
 extern long prune_dcache_sb(struct super_block *sb, struct shrink_control *sc);
 extern struct dentry *d_alloc_cursor(struct dentry *);
+extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
 
 /*
  * read_write.c

fs/kernfs/file.c

···
 	list_for_each_entry(info, &kernfs_root(kn)->supers, node) {
 		struct kernfs_node *parent;
 		struct inode *inode;
+		struct qstr name;
 
 		/*
 		 * We want fsnotify_modify() on @kn but as the
···
 		if (!inode)
 			continue;
 
+		name = (struct qstr)QSTR_INIT(kn->name, strlen(kn->name));
 		parent = kernfs_get_parent(kn);
 		if (parent) {
 			struct inode *p_inode;
···
 			p_inode = ilookup(info->sb, parent->id.ino);
 			if (p_inode) {
 				fsnotify(p_inode, FS_MODIFY | FS_EVENT_ON_CHILD,
-					 inode, FSNOTIFY_EVENT_INODE, kn->name, 0);
+					 inode, FSNOTIFY_EVENT_INODE, &name, 0);
 				iput(p_inode);
 			}
 
···
 		}
 
 		fsnotify(inode, FS_MODIFY, inode, FSNOTIFY_EVENT_INODE,
-			 kn->name, 0);
+			 &name, 0);
 		iput(inode);
 	}
 

fs/namei.c

···
 		inode_unlock(target);
 	dput(new_dentry);
 	if (!error) {
-		fsnotify_move(old_dir, new_dir, old_name.name, is_dir,
+		fsnotify_move(old_dir, new_dir, &old_name.name, is_dir,
 			      !(flags & RENAME_EXCHANGE) ? target : NULL, old_dentry);
 		if (flags & RENAME_EXCHANGE) {
-			fsnotify_move(new_dir, old_dir, old_dentry->d_name.name,
+			fsnotify_move(new_dir, old_dir, &old_dentry->d_name,
 				      new_is_dir, NULL, new_dentry);
 		}
 	}

fs/notify/dnotify/dnotify.c

···
 static int dnotify_handle_event(struct fsnotify_group *group,
 				struct inode *inode,
 				u32 mask, const void *data, int data_type,
-				const unsigned char *file_name, u32 cookie,
+				const struct qstr *file_name, u32 cookie,
 				struct fsnotify_iter_info *iter_info)
 {
 	struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);

fs/notify/fanotify/fanotify.c

···
 static int fanotify_handle_event(struct fsnotify_group *group,
 				 struct inode *inode,
 				 u32 mask, const void *data, int data_type,
-				 const unsigned char *file_name, u32 cookie,
+				 const struct qstr *file_name, u32 cookie,
 				 struct fsnotify_iter_info *iter_info)
 {
 	int ret = 0;

fs/notify/fsnotify.c

···
 		take_dentry_name_snapshot(&name, dentry);
 		if (path)
 			ret = fsnotify(p_inode, mask, path, FSNOTIFY_EVENT_PATH,
-				       name.name, 0);
+				       &name.name, 0);
 		else
 			ret = fsnotify(p_inode, mask, dentry->d_inode, FSNOTIFY_EVENT_INODE,
-				       name.name, 0);
+				       &name.name, 0);
 		release_dentry_name_snapshot(&name);
 	}
 
···
 static int send_to_group(struct inode *to_tell,
 			 __u32 mask, const void *data,
 			 int data_is, u32 cookie,
-			 const unsigned char *file_name,
+			 const struct qstr *file_name,
 			 struct fsnotify_iter_info *iter_info)
 {
 	struct fsnotify_group *group = NULL;
···
  * notification event in whatever means they feel necessary.
  */
 int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
-	     const unsigned char *file_name, u32 cookie)
+	     const struct qstr *file_name, u32 cookie)
 {
 	struct fsnotify_iter_info iter_info = {};
 	struct super_block *sb = to_tell->i_sb;

fs/notify/inotify/inotify.h

···
 extern int inotify_handle_event(struct fsnotify_group *group,
 				struct inode *inode,
 				u32 mask, const void *data, int data_type,
-				const unsigned char *file_name, u32 cookie,
+				const struct qstr *file_name, u32 cookie,
 				struct fsnotify_iter_info *iter_info);
 
 extern const struct fsnotify_ops inotify_fsnotify_ops;

fs/notify/inotify/inotify_fsnotify.c

···
 int inotify_handle_event(struct fsnotify_group *group,
 			 struct inode *inode,
 			 u32 mask, const void *data, int data_type,
-			 const unsigned char *file_name, u32 cookie,
+			 const struct qstr *file_name, u32 cookie,
 			 struct fsnotify_iter_info *iter_info)
 {
 	struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);
···
 			return 0;
 	}
 	if (file_name) {
-		len = strlen(file_name);
+		len = file_name->len;
 		alloc_len += len + 1;
 	}
 
···
 	event->sync_cookie = cookie;
 	event->name_len = len;
 	if (len)
-		strcpy(event->name, file_name);
+		strcpy(event->name, file_name->name);
 
 	ret = fsnotify_add_event(group, fsn_event, inotify_merge);
 	if (ret) {

fs/nsfs.c

···
 void *ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb,
 		     void *private_data)
 {
-	struct ns_common *ns;
 	void *ret;
 
-again:
-	ns = ns_get_cb(private_data);
-	if (!ns)
-		return ERR_PTR(-ENOENT);
+	do {
+		struct ns_common *ns = ns_get_cb(private_data);
+		if (!ns)
+			return ERR_PTR(-ENOENT);
 
-	ret = __ns_get_path(path, ns);
-	if (IS_ERR(ret) && PTR_ERR(ret) == -EAGAIN)
-		goto again;
+		ret = __ns_get_path(path, ns);
+	} while (ret == ERR_PTR(-EAGAIN));
+
 	return ret;
 }
 
···
 	if (fd < 0)
 		return fd;
 
-	while (1) {
+	do {
 		struct ns_common *relative;
 
 		relative = get_ns(ns);
···
 		}
 
 		err = __ns_get_path(&path, relative);
-		if (IS_ERR(err) && PTR_ERR(err) == -EAGAIN)
-			continue;
-		break;
-	}
+	} while (err == ERR_PTR(-EAGAIN));
+
 	if (IS_ERR(err)) {
 		put_unused_fd(fd);
 		return PTR_ERR(err);

fs/overlayfs/export.c

···
 	 * pointer because we hold no lock on the real dentry.
 	 */
 	take_dentry_name_snapshot(&name, real);
-	this = lookup_one_len(name.name, connected, strlen(name.name));
+	this = lookup_one_len(name.name.name, connected, name.name.len);
 	err = PTR_ERR(this);
 	if (IS_ERR(this)) {
 		goto fail;

fs/sysv/namei.c

···
 	return err;
 }
 
-static int sysv_hash(const struct dentry *dentry, struct qstr *qstr)
-{
-	/* Truncate the name in place, avoids having to define a compare
-	   function. */
-	if (qstr->len > SYSV_NAMELEN) {
-		qstr->len = SYSV_NAMELEN;
-		qstr->hash = full_name_hash(dentry, qstr->name, qstr->len);
-	}
-	return 0;
-}
-
-const struct dentry_operations sysv_dentry_operations = {
-	.d_hash		= sysv_hash,
-};
-
 static struct dentry *sysv_lookup(struct inode * dir, struct dentry * dentry, unsigned int flags)
 {
 	struct inode * inode = NULL;

fs/sysv/super.c

···
 
 	flavour_setup[sbi->s_type](sbi, &sb->s_max_links);
 	
-	sbi->s_truncate = 1;
 	sbi->s_ndatazones = sbi->s_nzones - sbi->s_firstdatazone;
 	sbi->s_inodes_per_block = bsize >> 6;
 	sbi->s_inodes_per_block_1 = (bsize >> 6)-1;
···
 	sb->s_op = &sysv_sops;
 	if (sbi->s_forced_ro)
 		sb->s_flags |= SB_RDONLY;
-	if (sbi->s_truncate)
-		sb->s_d_op = &sysv_dentry_operations;
 	root_inode = sysv_iget(sb, SYSV_ROOT_INO);
 	if (IS_ERR(root_inode)) {
 		printk("SysV FS: get root inode failed\n");

fs/sysv/sysv.h

···
 	struct super_block *s_sb;	/* VFS superblock */
 	int	       s_type;		/* file system type: FSTYPE_{XENIX|SYSV|COH} */
 	char	       s_bytesex;	/* bytesex (le/be/pdp) */
-	char	       s_truncate;	/* if 1: names > SYSV_NAMELEN chars are truncated */
-					/* if 0: they are disallowed (ENAMETOOLONG) */
 	unsigned int   s_inodes_per_block;	/* number of inodes per block */
 	unsigned int   s_inodes_per_block_1;	/* inodes_per_block - 1 */
 	unsigned int   s_inodes_per_block_bits;	/* log2(inodes_per_block) */
···
 extern const struct file_operations sysv_dir_operations;
 extern const struct address_space_operations sysv_aops;
 extern const struct super_operations sysv_sops;
-extern const struct dentry_operations sysv_dentry_operations;
 
 
 enum {

include/linux/dcache.h

···
 /* allocate/de-allocate */
 extern struct dentry * d_alloc(struct dentry *, const struct qstr *);
 extern struct dentry * d_alloc_anon(struct super_block *);
-extern struct dentry * d_alloc_pseudo(struct super_block *, const struct qstr *);
 extern struct dentry * d_alloc_parallel(struct dentry *, const struct qstr *,
 					wait_queue_head_t *);
 extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
···
 }
 
 struct name_snapshot {
-	const unsigned char *name;
+	struct qstr name;
 	unsigned char inline_name[DNAME_INLINE_LEN];
 };
 void take_dentry_name_snapshot(struct name_snapshot *, struct dentry *);

include/linux/fsnotify.h

···
 				  __u32 mask)
 {
 	return fsnotify(dir, mask, d_inode(dentry), FSNOTIFY_EVENT_INODE,
-			dentry->d_name.name, 0);
+			&dentry->d_name, 0);
 }
 
 /* Notify this dentry's parent about a child's events. */
···
  * fsnotify_move - file old_name at old_dir was moved to new_name at new_dir
  */
 static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir,
-				 const unsigned char *old_name,
+				 const struct qstr *old_name,
 				 int isdir, struct inode *target,
 				 struct dentry *moved)
 {
···
 	__u32 old_dir_mask = FS_MOVED_FROM;
 	__u32 new_dir_mask = FS_MOVED_TO;
 	__u32 mask = FS_MOVE_SELF;
-	const unsigned char *new_name = moved->d_name.name;
+	const struct qstr *new_name = &moved->d_name;
 
 	if (old_dir == new_dir)
 		old_dir_mask |= FS_DN_RENAME;
···
 	take_dentry_name_snapshot(&name, dentry);
 
 	fsnotify(d_inode(parent), mask, d_inode(dentry), FSNOTIFY_EVENT_INODE,
-		 name.name, 0);
+		 &name.name, 0);
 
 	release_dentry_name_snapshot(&name);
 	dput(parent);
···
 	fsnotify_link_count(inode);
 	audit_inode_child(dir, new_dentry, AUDIT_TYPE_CHILD_CREATE);
 
-	fsnotify(dir, FS_CREATE, inode, FSNOTIFY_EVENT_INODE, new_dentry->d_name.name, 0);
+	fsnotify(dir, FS_CREATE, inode, FSNOTIFY_EVENT_INODE, &new_dentry->d_name, 0);
 }
 
 /*

include/linux/fsnotify_backend.h

···
 	int (*handle_event)(struct fsnotify_group *group,
 			    struct inode *inode,
 			    u32 mask, const void *data, int data_type,
-			    const unsigned char *file_name, u32 cookie,
+			    const struct qstr *file_name, u32 cookie,
 			    struct fsnotify_iter_info *iter_info);
 	void (*free_group_priv)(struct fsnotify_group *group);
 	void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);
···
 
 /* main fsnotify call to send events */
 extern int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
-		    const unsigned char *name, u32 cookie);
+		    const struct qstr *name, u32 cookie);
 extern int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask);
 extern void __fsnotify_inode_delete(struct inode *inode);
 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
···
 #else
 
 static inline int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
-			   const unsigned char *name, u32 cookie)
+			   const struct qstr *name, u32 cookie)
 {
 	return 0;
 }

kernel/audit.h

···
 extern int audit_uid_comparator(kuid_t left, u32 op, kuid_t right);
 extern int audit_gid_comparator(kgid_t left, u32 op, kgid_t right);
 extern int parent_len(const char *path);
-extern int audit_compare_dname_path(const char *dname, const char *path, int plen);
+extern int audit_compare_dname_path(const struct qstr *dname, const char *path, int plen);
 extern struct sk_buff *audit_make_reply(int seq, int type, int done, int multi,
 					const void *payload, int size);
 extern void		    audit_panic(const char *message);

kernel/audit_fsnotify.c

···
 static int audit_mark_handle_event(struct fsnotify_group *group,
 				    struct inode *to_tell,
 				    u32 mask, const void *data, int data_type,
-				    const unsigned char *dname, u32 cookie,
+				    const struct qstr *dname, u32 cookie,
 				    struct fsnotify_iter_info *iter_info)
 {
 	struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);

kernel/audit_tree.c

···
 static int audit_tree_handle_event(struct fsnotify_group *group,
 				   struct inode *to_tell,
 				   u32 mask, const void *data, int data_type,
-				   const unsigned char *file_name, u32 cookie,
+				   const struct qstr *file_name, u32 cookie,
 				   struct fsnotify_iter_info *iter_info)
 {
 	return 0;

kernel/audit_watch.c

···
 
 /* Update inode info in audit rules based on filesystem event. */
 static void audit_update_watch(struct audit_parent *parent,
-			       const char *dname, dev_t dev,
+			       const struct qstr *dname, dev_t dev,
 			       unsigned long ino, unsigned invalidating)
 {
 	struct audit_watch *owatch, *nwatch, *nextw;
···
 static int audit_watch_handle_event(struct fsnotify_group *group,
 				    struct inode *to_tell,
 				    u32 mask, const void *data, int data_type,
-				    const unsigned char *dname, u32 cookie,
+				    const struct qstr *dname, u32 cookie,
 				    struct fsnotify_iter_info *iter_info)
 {
 	struct fsnotify_mark *inode_mark = fsnotify_iter_inode_mark(iter_info);

kernel/auditfilter.c

···
  * @parentlen:	length of the parent if known. Passing in AUDIT_NAME_FULL
  * 		here indicates that we must compute this value.
  */
-int audit_compare_dname_path(const char *dname, const char *path, int parentlen)
+int audit_compare_dname_path(const struct qstr *dname, const char *path, int parentlen)
 {
 	int dlen, pathlen;
 	const char *p;
 
-	dlen = strlen(dname);
+	dlen = dname->len;
 	pathlen = strlen(path);
 	if (pathlen < dlen)
 		return 1;
···
 
 	p = path + parentlen;
 
-	return strncmp(p, dname, dlen);
+	return strncmp(p, dname->name, dlen);
 }
 
 int audit_filter(int msgtype, unsigned int listtype)

kernel/auditsc.c

···
 {
 	struct audit_context *context = audit_context();
 	struct inode *inode = d_backing_inode(dentry);
-	const char *dname = dentry->d_name.name;
+	const struct qstr *dname = &dentry->d_name;
 	struct audit_names *n, *found_parent = NULL, *found_child = NULL;
 	struct audit_entry *e;
 	struct list_head *list = &audit_filter_list[AUDIT_FILTER_FS];
···
 		    (n->type != type && n->type != AUDIT_TYPE_UNKNOWN))
 			continue;
 
-		if (!strcmp(dname, n->name->name) ||
+		if (!strcmp(dname->name, n->name->name) ||
 		    !audit_compare_dname_path(dname, n->name->name,
 						found_parent ?
 						found_parent->name_len :