text: /*	$NetBSD: tmpfs.h,v 1.26 2007/02/22 06:37:00 thorpej Exp $	*/
  
  /*-
   * Copyright (c) 2005, 2006 The NetBSD Foundation, Inc.
   * All rights reserved.
   *
   * This code is derived from software contributed to The NetBSD Foundation
   * by Julio M. Merino Vidal, developed as part of Google's Summer of Code
   * 2005 program.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
   * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
   * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
   * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   *
   * $FreeBSD: src/sys/fs/tmpfs/tmpfs.h,v 1.18 2009/10/11 07:03:56 delphij Exp $
   */
  
  #ifndef _VFS_TMPFS_TMPFS_H_
  #define _VFS_TMPFS_TMPFS_H_
  
  /* ---------------------------------------------------------------------
   * KERNEL-SPECIFIC DEFINITIONS
   * --------------------------------------------------------------------- */
  #include <sys/dirent.h>
  #include <sys/mount.h>
  #include <sys/tree.h>
  #include <sys/vnode.h>
  #include <sys/file.h>
  #include <sys/lock.h>
  #include <sys/lockf.h>
  #include <sys/mutex.h>
  #include <sys/objcache.h>
  
  /* --------------------------------------------------------------------- */
  #include <sys/malloc.h>
  #ifdef _KERNEL
  #include <sys/systm.h>
  #endif
  #include <sys/vmmeter.h>
  #include <vm/swap_pager.h>
  
  MALLOC_DECLARE(M_TMPFSMNT);
  
  /* --------------------------------------------------------------------- */
  
  /*
   * Internal representation of a tmpfs directory entry.
   */
  struct tmpfs_dirent {
  	RB_ENTRY(tmpfs_dirent)	rb_node;
  	RB_ENTRY(tmpfs_dirent)	rb_cookienode;
  
  	/* Length of the name stored in this directory entry.  This avoids
  	 * the need to recalculate it every time the name is used. */
  	uint16_t		td_namelen;
  
  	/* The name of the entry, allocated from a string pool.  This
  	* string is not required to be zero-terminated; therefore, the
  	* td_namelen field must always be used when accessing its value. */
  	char 			*td_name;
  
  	/* Pointer to the node this entry refers to. */
  	struct tmpfs_node 	*td_node;
  };
  
  struct tmpfs_dirtree;
  RB_HEAD(tmpfs_dirtree, tmpfs_dirent);
  RB_PROTOTYPE(tmpfs_dirtree, tmpfs_dirent, rb_node,
  	tmpfs_dirtree_compare);
  
  RB_HEAD(tmpfs_dirtree_cookie, tmpfs_dirent);
  RB_PROTOTYPE(tmpfs_dirtree_cookie, tmpfs_dirent, rb_cookienode,
  	tmpfs_dirtree_cookie_compare);
  
  
  /*
   * A directory in tmpfs holds a set of directory entries, which in
   * turn point to other files (which can be directories themselves).
   *
   * In tmpfs, this set is managed by a red-black tree, whose root is defined
   * by the struct tmpfs_dirtree type.
   *
   * It is important to notice that directories do not have entries for . and
   * .. as other file systems do.  These can be generated when requested
   * based on information available by other means, such as the pointer to
   * the node itself in the former case or the pointer to the parent directory
   * in the latter case.  This is done to simplify tmpfs's code and, more
   * importantly, to remove redundancy.
   *
   * Each entry in a directory has a cookie that identifies it.  Cookies
   * supersede offsets within directories because, given how tmpfs stores
   * directories in memory, there is no such thing as an offset.  (Emulating
   * a real offset could be very difficult.)
   *
   * The '.', '..' and the end of directory markers have fixed cookies which
   * cannot collide with the cookies generated by other entries.  The cookies
   * for the other entries are generated based on the memory address on which
   * stores their information is stored.
   *
   * DragonFly binaries use 64-bit cookies.  We mask-off the signed bit to
   * ensure that cookie 'offsets' are positive.
   */
  #ifdef _KERNEL
  
  #define	TMPFS_DIRCOOKIE_DOT	0
  #define	TMPFS_DIRCOOKIE_DOTDOT	1
  #define	TMPFS_DIRCOOKIE_EOF	2
  
  static __inline
  off_t
  tmpfs_dircookie(struct tmpfs_dirent *de)
  {
  	return (((off_t)(uintptr_t)de >> 1) & 0x7FFFFFFFFFFFFFFFLLU);
  }
  
  #endif
  
  /* --------------------------------------------------------------------- */
  
  /*
   * Internal representation of a tmpfs file system node.
   *
   * This structure is splitted in two parts: one holds attributes common
   * to all file types and the other holds data that is only applicable to
   * a particular type.  The code must be careful to only access those
   * attributes that are actually allowed by the node's type.
   */
  struct tmpfs_node {
  	/* Doubly-linked list entry which links all existing nodes for a
  	 * single file system.  This is provided to ease the removal of
  	 * all nodes during the unmount operation. */
  	LIST_ENTRY(tmpfs_node)	tn_entries;
  
  	/* The node's type.  Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO',
  	 * 'VLNK', 'VREG' and 'VSOCK' is allowed.  The usage of vnode
  	 * types instead of a custom enumeration is to make things simpler
  	 * and faster, as we do not need to convert between two types. */
  	enum vtype		tn_type;
  
  	/* Node identifier. */
  	ino_t			tn_id;
  
  	/* Node's internal status.  This is used by several file system
  	 * operations to do modifications to the node in a delayed
  	 * fashion. */
  	int			tn_status;
  #define	TMPFS_NODE_ACCESSED	(1 << 1)
  #define	TMPFS_NODE_MODIFIED	(1 << 2)
  #define	TMPFS_NODE_CHANGED	(1 << 3)
  
  	/* The node size.  It does not necessarily match the real amount
  	 * of memory consumed by it. */
  	off_t			tn_size;
  
  	/* Generic node attributes. */
  	uid_t			tn_uid;
  	gid_t			tn_gid;
  	mode_t			tn_mode;
  	int			tn_flags;
  	nlink_t			tn_links;
  	int32_t			tn_atime;
  	int32_t			tn_atimensec;
  	int32_t			tn_mtime;
  	int32_t			tn_mtimensec;
  	int32_t			tn_ctime;
  	int32_t			tn_ctimensec;
  	unsigned long		tn_gen;
  	struct lockf		tn_advlock;
  
  	/* As there is a single vnode for each active file within the
  	 * system, care has to be taken to avoid allocating more than one
  	 * vnode per file.  In order to do this, a bidirectional association
  	 * is kept between vnodes and nodes.
  	 *
  	 * Whenever a vnode is allocated, its v_data field is updated to
  	 * point to the node it references.  At the same time, the node's
  	 * tn_vnode field is modified to point to the new vnode representing
  	 * it.  Further attempts to allocate a vnode for this same node will
  	 * result in returning a new reference to the value stored in
  	 * tn_vnode.
  	 *
  	 * May be NULL when the node is unused (that is, no vnode has been
  	 * allocated for it or it has been reclaimed). */
  	struct vnode *		tn_vnode;
  
  	/* interlock to protect tn_vpstate */
  	struct lock		tn_interlock;
  
  	/* Identify if current node has vnode assiocate with
  	 * or allocating vnode.
  	 */
  	int		tn_vpstate;
  
  	/* misc data field for different tn_type node */
  	union {
  		/* Valid when tn_type == VBLK || tn_type == VCHR. */
  		dev_t			tn_rdev; /*int32_t ?*/
  
  		/* Valid when tn_type == VDIR. */
  		struct tn_dir {
  			/*
  			 * Pointer to the parent directory.  The root
  			 * directory has a pointer to itself in this field;
  			 * this property identifies the root node.
  			 */
  			struct tmpfs_node *	tn_parent;
  
  			/*
  			 * Directory entries are indexed by name and also
  			 * indexed by cookie.
  			 */
  			struct tmpfs_dirtree		tn_dirtree;
  			struct tmpfs_dirtree_cookie	tn_cookietree;
  		} tn_dir;
  
  		/* Valid when tn_type == VLNK. */
  		/* The link's target, allocated from a string pool. */
  		char *			tn_link;
  
  		/* Valid when tn_type == VREG. */
  		struct tn_reg {
  			/* The contents of regular files stored in a tmpfs
  			 * file system are represented by a single anonymous
  			 * memory object (aobj, for short).  The aobj provides
  			 * direct access to any position within the file,
  			 * because its contents are always mapped in a
  			 * contiguous region of virtual memory.  It is a task
  			 * of the memory management subsystem (see uvm(9)) to
  			 * issue the required page ins or page outs whenever
  			 * a position within the file is accessed. */
  			vm_object_t		tn_aobj;
  			size_t			tn_aobj_pages;
  
  		} tn_reg;
  
  		/* Valid when tn_type = VFIFO */
  		struct tn_fifo {
  			int (*tn_fo_read)  (struct file *fp, struct uio *uio,
  			        struct ucred *cred, int flags);
  			int (*tn_fo_write) (struct file *fp, struct uio *uio,
  			        struct ucred *cred, int flags);
  		} tn_fifo;
  	} tn_spec;
  };
  
  #define VTOI(vp)	((struct tmpfs_node *)(vp)->v_data)
  
  #ifdef _KERNEL
  LIST_HEAD(tmpfs_node_list, tmpfs_node);
  
  #define tn_rdev tn_spec.tn_rdev
  #define tn_dir tn_spec.tn_dir
  #define tn_link tn_spec.tn_link
  #define tn_reg tn_spec.tn_reg
  #define tn_fifo tn_spec.tn_fifo
  
  #define TMPFS_NODE_LOCK(node) lockmgr(&(node)->tn_interlock, LK_EXCLUSIVE|LK_RETRY)
  #define TMPFS_NODE_LOCK_SH(node) lockmgr(&(node)->tn_interlock, LK_SHARED|LK_RETRY)
  #define TMPFS_NODE_UNLOCK(node) lockmgr(&(node)->tn_interlock, LK_RELEASE)
  #define TMPFS_NODE_MTX(node) (&(node)->tn_interlock)
  
  #ifdef INVARIANTS
  #define TMPFS_ASSERT_LOCKED(node) do {					\
  		KKASSERT(node != NULL);					\
  		KKASSERT(node->tn_vnode != NULL);			\
  		if (!vn_islocked(node->tn_vnode) &&			\
  		    (lockstatus(TMPFS_NODE_MTX(node), curthread) == LK_EXCLUSIVE ))		\
  			panic("tmpfs: node is not locked: %p", node);	\
  	} while (0)
  #define TMPFS_ASSERT_ELOCKED(node) do {					\
  		KKASSERT((node) != NULL);				\
  		KKASSERT(lockstatus(TMPFS_NODE_MTX(node), curthread) == LK_EXCLUSIVE);		\
  	} while (0)
  #else
  #define TMPFS_ASSERT_LOCKED(node) (void)0
  #define TMPFS_ASSERT_ELOCKED(node) (void)0
  #endif
  
  #define TMPFS_VNODE_ALLOCATING	1
  #define TMPFS_VNODE_WANT	2
  #define TMPFS_VNODE_DOOMED	4
  /* --------------------------------------------------------------------- */
  
  /*
   * Internal representation of a tmpfs mount point.
   */
  struct tmpfs_mount {
  	struct mount		*tm_mount;
  
  	/* Maximum number of memory pages available for use by the file
  	 * system, set during mount time.  This variable must never be
  	 * used directly as it may be bigger than the current amount of
  	 * free memory; in the extreme case, it will hold the SIZE_MAX
  	 * value.  Instead, use the TMPFS_PAGES_MAX macro. */
  	vm_pindex_t		tm_pages_max;
  
  	/* Number of pages in use by the file system.  Cannot be bigger
  	 * than the value returned by TMPFS_PAGES_MAX in any case. */
  	vm_pindex_t		tm_pages_used;
  
  	/* Pointer to the node representing the root directory of this
  	 * file system. */
  	struct tmpfs_node *	tm_root;
  
  	/* Maximum number of possible nodes for this file system; set
  	 * during mount time.  We need a hard limit on the maximum number
  	 * of nodes to avoid allocating too much of them; their objects
  	 * cannot be released until the file system is unmounted.
  	 * Otherwise, we could easily run out of memory by creating lots
  	 * of empty files and then simply removing them. */
  	ino_t			tm_nodes_max;
  
  	/* Number of nodes currently that are in use. */
  	ino_t			tm_nodes_inuse;
  
  	/* maximum representable file size */
  	u_int64_t		tm_maxfilesize;
  
  	/* Nodes are organized in two different lists.  The used list
  	 * contains all nodes that are currently used by the file system;
  	 * i.e., they refer to existing files.  The available list contains
  	 * all nodes that are currently available for use by new files.
  	 * Nodes must be kept in this list (instead of deleting them)
  	 * because we need to keep track of their generation number (tn_gen
  	 * field).
  	 *
  	 * Note that nodes are lazily allocated: if the available list is
  	 * empty and we have enough space to create more nodes, they will be
  	 * created and inserted in the used list.  Once these are released,
  	 * they will go into the available list, remaining alive until the
  	 * file system is unmounted. */
  	struct tmpfs_node_list	tm_nodes_used;
  
  	/* Per-mount malloc zones for tmpfs nodes, names, and dirents */
  	struct malloc_type	*tm_node_zone;
  	struct malloc_type	*tm_dirent_zone;
  	struct malloc_type	*tm_name_zone;
  
  	struct objcache_malloc_args tm_node_zone_malloc_args;
  	struct objcache_malloc_args tm_dirent_zone_malloc_args;
  
  	/* Pools used to store file system meta data. */
  	struct objcache		*tm_dirent_pool;
  	struct objcache		*tm_node_pool;
  
  	int			tm_ino;
  	int			tm_flags;
  
  	struct netexport	tm_export;
  
  	struct mount		*tm_mnt;
  };
  
  #define TMPFS_LOCK(tm) lwkt_gettoken(&(tm)->tm_mount->mnt_token)
  #define TMPFS_UNLOCK(tm) lwkt_reltoken(&(tm)->tm_mount->mnt_token)
  
  /* --------------------------------------------------------------------- */
  
  /*
   * This structure maps a file identifier to a tmpfs node.  Used by the
   * NFS code.
   */
  struct tmpfs_fid {
  	uint16_t		tf_len;
  	uint16_t		tf_pad;
  	ino_t			tf_id;
  	unsigned long		tf_gen;
  };
  
  /* --------------------------------------------------------------------- */
  
  #ifdef _KERNEL
  /*
   * Prototypes for tmpfs_subr.c.
   */
  
  int	tmpfs_alloc_node(struct tmpfs_mount *, enum vtype,
  	    uid_t uid, gid_t gid, mode_t mode, char *, int, int,
  	    struct tmpfs_node **);
  void	tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *);
  int	tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *,
  	    const char *, uint16_t, struct tmpfs_dirent **);
  void	tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *);
  int	tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, int,
  	    struct vnode **);
  void	tmpfs_free_vp(struct vnode *);
  int	tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *,
  	    struct namecache *, struct ucred *, char *);
  void	tmpfs_dir_attach(struct tmpfs_node *, struct tmpfs_dirent *);
  void	tmpfs_dir_detach(struct tmpfs_node *, struct tmpfs_dirent *);
  struct tmpfs_dirent *	tmpfs_dir_lookup(struct tmpfs_node *node,
  			    struct tmpfs_node *f,
  			    struct namecache *ncp);
  int	tmpfs_dir_getdotdent(struct tmpfs_node *, struct uio *);
  int	tmpfs_dir_getdotdotdent(struct tmpfs_mount *,
  			    struct tmpfs_node *, struct uio *);
  struct tmpfs_dirent *	tmpfs_dir_lookupbycookie(struct tmpfs_node *, off_t);
  int	tmpfs_dir_getdents(struct tmpfs_node *, struct uio *, off_t *);
  int	tmpfs_reg_resize(struct vnode *, off_t, int);
  int	tmpfs_chflags(struct vnode *, int, struct ucred *);
  int	tmpfs_chmod(struct vnode *, mode_t, struct ucred *);
  int	tmpfs_chown(struct vnode *, uid_t, gid_t, struct ucred *);
  int	tmpfs_chsize(struct vnode *, u_quad_t, struct ucred *);
  int	tmpfs_chtimes(struct vnode *, struct timespec *, struct timespec *,
  	    int, struct ucred *);
  void	tmpfs_itimes(struct vnode *, const struct timespec *,
  	    const struct timespec *);
  
  void	tmpfs_update(struct vnode *);
  int	tmpfs_truncate(struct vnode *, off_t);
  boolean_t tmpfs_node_ctor(void *obj, void *privdata, int flags);
  
  /* --------------------------------------------------------------------- */
  
  /*
   * Convenience macros to simplify some logical expressions.
   */
  #define IMPLIES(a, b) (!(a) || (b))
  #define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a))
  
  /* --------------------------------------------------------------------- */
  
  /*
   * Checks that the directory entry pointed by 'de' matches the name 'name'
   * with a length of 'len'.
   */
  #define TMPFS_DIRENT_MATCHES(de, name, len) \
      (de->td_namelen == (uint16_t)len && \
      bcmp((de)->td_name, (name), (de)->td_namelen) == 0)
  
  /* --------------------------------------------------------------------- */
  
  /*
   * Ensures that the node pointed by 'node' is a directory and that its
   * contents are consistent with respect to directories.
   */
  #define TMPFS_VALIDATE_DIR(node) do {	\
      KKASSERT((node)->tn_type == VDIR);	\
      KKASSERT((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \
  } while(0)
  
  #endif
  
  /* --------------------------------------------------------------------- */
  
  /*
   * Macros/functions to convert from generic data structures to tmpfs
   * specific ones.
   */
  
  static inline
  struct tmpfs_mount *
  VFS_TO_TMPFS(struct mount *mp)
  {
  	struct tmpfs_mount *tmp;
  
  	KKASSERT((mp) != NULL && (mp)->mnt_data != NULL);
  	tmp = (struct tmpfs_mount *)(mp)->mnt_data;
  	return tmp;
  }
  
  static inline
  struct tmpfs_node *
  VP_TO_TMPFS_NODE(struct vnode *vp)
  {
  	struct tmpfs_node *node;
  
  	KKASSERT((vp) != NULL && (vp)->v_data != NULL);
  	node = (struct tmpfs_node *)vp->v_data;
  	return node;
  }
  
  static inline
  struct tmpfs_node *
  VP_TO_TMPFS_DIR(struct vnode *vp)
  {
  	struct tmpfs_node *node;
  
  	node = VP_TO_TMPFS_NODE(vp);
  	TMPFS_VALIDATE_DIR(node);
  	return node;
  }
  
  /* --------------------------------------------------------------------- */
  /*
   * buffer cache size
   */
  #define TMPFS_BLKSIZE	16384			/* buffer cache size*/
  #define TMPFS_BLKMASK	(TMPFS_BLKSIZE - 1)
  #define TMPFS_BLKMASK64	((off_t)(TMPFS_BLKSIZE - 1))
  #endif /* _KERNEL */
  
  #endif /* _VFS_TMPFS_TMPFS_H_ */
  