/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#ifndef _SYS_FS_TMPNODE_H
#define _SYS_FS_TMPNODE_H

#include <sys/t_lock.h>
#include <vm/seg.h>
#include <vm/seg_vn.h>
#include <sys/vfs_opreg.h>

#ifdef  __cplusplus
extern "C" {
#endif

/*
 * tmpnode is the file system dependent node for tmpfs.
 *
 *      tn_rwlock protects access of the directory list at tn_dir
 *      as well as syncronizing read and writes to the tmpnode
 *
 *      tn_contents protects growing, shrinking, reading and writing
 *      the file along with tn_rwlock (see below).
 *
 *      tn_tlock protects updates to tn_mode and tn_nlink
 *
 *      tm_contents in the tmount filesystem data structure protects
 *      tn_forw and tn_back which are used to maintain a linked
 *      list of all tmpfs files associated with that file system
 *
 *      The anon array represents the secondary store for tmpfs.
 *      To grow or shrink the file or fill in holes requires
 *      manipulation of the anon array. These operations are protected
 *      by a combination of tn_rwlock and tn_contents. Growing or shrinking
 *      the array requires the write lock on tn_rwlock and tn_contents.
 *      Filling in a slot in the array requires the write lock on tn_contents.
 *      Reading the array requires the read lock on tn_contents.
 *
 *      The ordering of the locking is:
 *      tn_rwlock -> tn_contents -> page locks on pages in file
 *
 *      tn_tlock doesn't require any tmpnode locks
 */

struct tmpnode {
        struct tmpnode  *tn_back;               /* linked list of tmpnodes */
        struct tmpnode  *tn_forw;               /* linked list of tmpnodes */
        union {
                struct {
                        struct tdirent  *un_dirlist; /* dirent list */
                        uint_t  un_dirents;     /* number of dirents */
                } un_dirstruct;
                char            *un_symlink;    /* pointer to symlink */
                struct {
                        struct anon_hdr *un_anon; /* anon backing for file */
                        pgcnt_t un_size;        /* size repres. by array */
                } un_anonstruct;
        } un_tmpnode;
        struct vnode    *tn_vnode;              /* vnode for this tmpnode */
        int             tn_gen;                 /* pseudo gen number for tfid */
        struct vattr    tn_attr;                /* attributes */
        krwlock_t       tn_contents;            /* vm side -serialize mods */
        krwlock_t       tn_rwlock;              /* rw,trunc size - serialize */
                                                /* mods and directory updates */
        kmutex_t        tn_tlock;               /* time, flag, and nlink lock */
        struct tmpnode *tn_xattrdp;             /* ext. attribute directory */
        uint_t          tn_flags;               /* tmpnode specific flags */
};

#define tn_dir          un_tmpnode.un_dirstruct.un_dirlist
#define tn_dirents      un_tmpnode.un_dirstruct.un_dirents
#define tn_symlink      un_tmpnode.un_symlink
#define tn_anon         un_tmpnode.un_anonstruct.un_anon
#define tn_asize        un_tmpnode.un_anonstruct.un_size

/*
 * tmnode flag values.
 */
#define ISXATTR         0x1

/*
 * Attributes
 */
#define tn_mask         tn_attr.va_mask
#define tn_type         tn_attr.va_type
#define tn_mode         tn_attr.va_mode
#define tn_uid          tn_attr.va_uid
#define tn_gid          tn_attr.va_gid
#define tn_fsid         tn_attr.va_fsid
#define tn_nodeid       tn_attr.va_nodeid
#define tn_nlink        tn_attr.va_nlink
#define tn_size         tn_attr.va_size
#define tn_atime        tn_attr.va_atime
#define tn_mtime        tn_attr.va_mtime
#define tn_ctime        tn_attr.va_ctime
#define tn_rdev         tn_attr.va_rdev
#define tn_blksize      tn_attr.va_blksize
#define tn_nblocks      tn_attr.va_nblocks
#define tn_seq          tn_attr.va_seq

/*
 * tmpfs directories are made up of a linked list of tdirent structures
 * hanging off directory tmpnodes.  File names are not fixed length,
 * but are null terminated.
 */
struct tdirent {
        struct tmpnode  *td_tmpnode;            /* tnode for this file */
        struct tdirent  *td_next;               /* next directory entry */
        struct tdirent  *td_prev;               /* prev directory entry */
        uint_t          td_offset;              /* "offset" of dir entry */
        uint_t          td_hash;                /* a hash of td_name */
        struct tdirent  *td_link;               /* linked via the hash table */
        struct tmpnode  *td_parent;             /* parent, dir we are in */
        char            *td_name;               /* must be null terminated */
                                                /* max length is MAXNAMELEN */
};

/*
 * tfid overlays the fid structure (for VFS_VGET)
 */
struct tfid {
        uint16_t tfid_len;
        ino32_t tfid_ino;
        int32_t tfid_gen;
};

#define ESAME   (-1)            /* trying to rename linked files (special) */

extern struct vnodeops *tmp_vnodeops;
extern const struct fs_operation_def tmp_vnodeops_template[];

#ifdef  __cplusplus
}
#endif

#endif  /* _SYS_FS_TMPNODE_H */