xref: /src/sys/fs/tmpfs/tmpfs.h

/*	$NetBSD: tmpfs.h,v 1.41 2011/05/24 20:17:49 rmind Exp $	*/

/*
 * Copyright (c) 2005, 2006, 2007 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.
 */

#ifndef _FS_TMPFS_TMPFS_H_
#define _FS_TMPFS_TMPFS_H_

#include <sys/dirent.h>
#include <sys/mount.h>
#include <sys/pool.h>
#include <sys/queue.h>
#include <sys/vnode.h>

/*
 * Internal representation of a tmpfs directory entry.
 *
 * All fields are protected by vnode lock.
 */
typedef struct tmpfs_dirent {
	TAILQ_ENTRY(tmpfs_dirent)	td_entries;

	/* Pointer to the inode this entry refers to. */
	struct tmpfs_node *		td_node;

	/* Name and its length. */
	char *				td_name;
	uint16_t			td_namelen;
} tmpfs_dirent_t;

TAILQ_HEAD(tmpfs_dir, tmpfs_dirent);

#if defined(_KERNEL)

/* Validate maximum td_namelen length. */
CTASSERT(MAXNAMLEN < UINT16_MAX);

#define	TMPFS_DIRCOOKIE_DOT	0
#define	TMPFS_DIRCOOKIE_DOTDOT	1
#define	TMPFS_DIRCOOKIE_EOF	2

/*
 * Each entry in a directory has a cookie that identifies it.  Cookies
 * supersede offsets within directories, as tmpfs has no offsets as such.
 *
 * 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 of their representative meta-data structure.
 *
 * XXX: Truncating directory cookies to 31 bits now - workaround for
 * problem with Linux compat, see PR/32034.
 */
static inline off_t
tmpfs_dircookie(tmpfs_dirent_t *de)
{
	off_t cookie;

	cookie = ((off_t)(uintptr_t)de >> 1) & 0x7FFFFFFF;
	KASSERT(cookie != TMPFS_DIRCOOKIE_DOT);
	KASSERT(cookie != TMPFS_DIRCOOKIE_DOTDOT);
	KASSERT(cookie != TMPFS_DIRCOOKIE_EOF);

	return cookie;
}
#endif

/*
 * Internal representation of a tmpfs file system node -- inode.
 *
 * 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.
 *
 * All fields are protected by vnode lock.  The vnode association itself
 * is protected by tmpfs_node_t::tn_vlock.
 */
typedef struct tmpfs_node {
	LIST_ENTRY(tmpfs_node)	tn_entries;

	/* The inode type: VBLK, VCHR, VDIR, VFIFO, VLNK, VREG or VSOCK. */
	enum vtype		tn_type;

	/* Inode identifier. */
	ino_t			tn_id;

	/* Inode status flags (for operations in delayed manner). */
	int			tn_status;

	/* The inode size. */
	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;
	struct timespec		tn_atime;
	struct timespec		tn_mtime;
	struct timespec		tn_ctime;
	struct timespec		tn_birthtime;
	unsigned long		tn_gen;

	/* Head of byte-level lock list (used by tmpfs_advlock). */
	struct lockf *		tn_lockf;

	/*
	 * Each inode has a corresponding vnode.  It is a bi-directional
	 * association.  Whenever vnode is allocated, its v_data field is
	 * set to the inode it reference, and tmpfs_node_t::tn_vnode is
	 * set to point to the said vnode.
	 *
	 * Further attempts to allocate a vnode for this same node will
	 * result in returning a new reference to the value stored in
	 * tn_vnode.  It may be NULL when the node is unused (that is,
	 * no vnode has been allocated or it has been reclaimed).
	 */
	kmutex_t		tn_vlock;
	vnode_t *		tn_vnode;

	union {
		/* Type case: VBLK or VCHR. */
		struct {
			dev_t			tn_rdev;
		} tn_dev;

		/* Type case: VDIR. */
		struct {
			/* Parent directory (root inode points to itself). */
			struct tmpfs_node *	tn_parent;

			/* List of directory entries. */
			struct tmpfs_dir	tn_dir;

			/*
			 * Number and pointer of the last directory entry
			 * returned by the readdir(3) operation.
			 */
			off_t			tn_readdir_lastn;
			struct tmpfs_dirent *	tn_readdir_lastp;
		} tn_dir;

		/* Type case: VLNK. */
		struct tn_lnk {
			/* The link's target. */
			char *			tn_link;
		} tn_lnk;

		/* Type case: VREG. */
		struct tn_reg {
			/* Underlying UVM object to store contents. */
			struct uvm_object *	tn_aobj;
			size_t			tn_aobj_pages;
		} tn_reg;
	} tn_spec;
} tmpfs_node_t;

#if defined(_KERNEL)

LIST_HEAD(tmpfs_node_list, tmpfs_node);

/* Status flags. */
#define	TMPFS_NODE_ACCESSED	0x01
#define	TMPFS_NODE_MODIFIED	0x02
#define	TMPFS_NODE_CHANGED	0x04

#define	TMPFS_NODE_STATUSALL	\
    (TMPFS_NODE_ACCESSED | TMPFS_NODE_MODIFIED | TMPFS_NODE_CHANGED)

/* White-out inode indicator. */
#define	TMPFS_NODE_WHITEOUT	((struct tmpfs_node *)-1)

/*
 * Internal representation of a tmpfs mount point.
 */
typedef struct tmpfs_mount {
	/* Limit and number of bytes in use by the file system. */
	uint64_t		tm_mem_limit;
	uint64_t		tm_bytes_used;
	kmutex_t		tm_acc_lock;

	/* Pointer to the root inode. */
	tmpfs_node_t *		tm_root;

	/* Maximum number of possible nodes for this file system. */
	unsigned int		tm_nodes_max;

	/* Number of nodes currently allocated. */
	unsigned int		tm_nodes_cnt;

	/* List of inodes and the lock protecting it. */
	kmutex_t		tm_lock;
	struct tmpfs_node_list	tm_nodes;
} tmpfs_mount_t;

/*
 * This structure maps a file identifier to a tmpfs node.  Used by the
 * NFS code.
 */
typedef struct tmpfs_fid {
	uint16_t		tf_len;
	uint16_t		tf_pad;
	uint32_t		tf_gen;
	ino_t			tf_id;
} tmpfs_fid_t;

/*
 * Prototypes for tmpfs_subr.c.
 */

int	tmpfs_alloc_node(struct tmpfs_mount *, enum vtype,
	    uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *,
	    char *, dev_t, 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 *,
	    bool);
int	tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, struct vnode **);
void	tmpfs_free_vp(struct vnode *);
int	tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *,
	    struct componentname *, char *);
void	tmpfs_dir_attach(struct vnode *, struct tmpfs_dirent *);
void	tmpfs_dir_detach(struct vnode *, struct tmpfs_dirent *);
struct tmpfs_dirent *	tmpfs_dir_lookup(struct tmpfs_node *node,
			    struct componentname *cnp);
int	tmpfs_dir_getdotdent(struct tmpfs_node *, struct uio *);
int	tmpfs_dir_getdotdotdent(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	tmpfs_chflags(struct vnode *, int, kauth_cred_t, struct lwp *);
int	tmpfs_chmod(struct vnode *, mode_t, kauth_cred_t, struct lwp *);
int	tmpfs_chown(struct vnode *, uid_t, gid_t, kauth_cred_t, struct lwp *);
int	tmpfs_chsize(struct vnode *, u_quad_t, kauth_cred_t, struct lwp *);
int	tmpfs_chtimes(struct vnode *, const struct timespec *,
    const struct timespec *, const struct timespec *, int, kauth_cred_t,
    struct lwp *);
void	tmpfs_update(struct vnode *, const struct timespec *,
	    const struct timespec *, const struct timespec *, int);
int	tmpfs_truncate(struct vnode *, off_t);

/*
 * Prototypes for tmpfs_mem.c.
 */

void		tmpfs_mntmem_init(struct tmpfs_mount *, uint64_t);
void		tmpfs_mntmem_destroy(struct tmpfs_mount *);

size_t		tmpfs_mem_info(bool);
uint64_t	tmpfs_bytes_max(struct tmpfs_mount *);
size_t		tmpfs_pages_avail(struct tmpfs_mount *);
bool		tmpfs_mem_incr(struct tmpfs_mount *, size_t);
void		tmpfs_mem_decr(struct tmpfs_mount *, size_t);

struct tmpfs_dirent *tmpfs_dirent_get(struct tmpfs_mount *);
void		tmpfs_dirent_put(struct tmpfs_mount *, struct tmpfs_dirent *);

struct tmpfs_node *tmpfs_node_get(struct tmpfs_mount *);
void		tmpfs_node_put(struct tmpfs_mount *, struct tmpfs_node *);

char *		tmpfs_strname_alloc(struct tmpfs_mount *, size_t);
void		tmpfs_strname_free(struct tmpfs_mount *, char *, size_t);
bool		tmpfs_strname_neqlen(struct componentname *, struct componentname *);

/*
 * 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) \
    KASSERT((node)->tn_type == VDIR); \
    KASSERT((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \
    KASSERT((node)->tn_spec.tn_dir.tn_readdir_lastp == NULL || \
        tmpfs_dircookie((node)->tn_spec.tn_dir.tn_readdir_lastp) == \
        (node)->tn_spec.tn_dir.tn_readdir_lastn);

/*
 * Memory management stuff.
 */

/* Amount of memory pages to reserve for the system. */
#define	TMPFS_PAGES_RESERVED	(4 * 1024 * 1024 / PAGE_SIZE)

/*
 * Routines to convert VFS structures to tmpfs internal ones.
 */

static inline tmpfs_mount_t *
VFS_TO_TMPFS(struct mount *mp)
{
	tmpfs_mount_t *tmp = mp->mnt_data;

	KASSERT(tmp != NULL);
	return tmp;
}

static inline tmpfs_node_t *
VP_TO_TMPFS_DIR(vnode_t *vp)
{
	tmpfs_node_t *node = vp->v_data;

	KASSERT(node != NULL);
	TMPFS_VALIDATE_DIR(node);
	return node;
}

#endif /* defined(_KERNEL) */

static __inline tmpfs_node_t *
VP_TO_TMPFS_NODE(struct vnode *vp)
{
	tmpfs_node_t *node = vp->v_data;
#ifdef KASSERT
	KASSERT(node != NULL);
#endif
	return node;
}

#endif /* _FS_TMPFS_TMPFS_H_ */