common/sys/fdbuffer.h

	fdbuffer.h revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (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 (c) 1998 by Sun Microsystems, Inc.
 * All rights reserved.
 */

#ifndef _SYS_FDBUFFER_H
#define _SYS_FDBUFFER_H

#pragma ident   "%Z%%M% %I% %E% SMI"

#ifdef __cplusplus
extern "C" {
#endif

#include <vm/page.h>
#include <sys/buf.h>

typedef enum {
    FDB_PAGEIO,     /* fdbuffer is a page buffer */
    FDB_VADDR       /* fdbuffer is a address buffer */
} fdb_type_t;

#define FDB_READ    0x01        /* fdbuffer is readable */
#define FDB_WRITE   0x02        /* fdbuffer is asked for write */
#define FDB_DONE    0x04        /* fdbuffer buffer io done */
#define FDB_ERROR   0x08        /* fdbuffer in error state */
#define FDB_ASYNC   0x10        /* fdbuffer using async i/o requests */
#define FDB_SYNC    0x20        /* fdbuffer using direct i/o requests */
#define FDB_ICALLBACK   0x40        /* fdbuffer immediate call back */
#define FDB_ZEROHOLE    0x80        /* fdbuffer auto-zero holes */

typedef struct fdb_holes {
    struct fdb_holes *next_hole;
    u_offset_t off;     /* start offset for this hole */
    size_t len;     /* length of this hole */
} fdb_holes_t;

struct fdbuffer;

typedef void (*fdb_iodone_t)(struct fdbuffer *fdbuf, void *kargp, buf_t *bp);


/*
 * Implementation notes in the fdbuffer structure members:
 *
 * fd_state: The state variable carries four distinct types of information
 *           it could probably be a bit field as such.
 *
 *  READ/WRITE:
 *      This information is stored in fdbuffer at the time the
 *      The buffer is created and is used for sanity check in
 *      subsequent calls to fdb_iosetup(). This information
 *      persists for the entire life of the buffer.
 *
 *  [A]SYNC:
 *      The buffer can be either in sync or async mode. In
 *      async mode all calls are to be async and the i/o
 *      must take place for the entire range or the fdbuf
 *      i/o must be ended with a call to fdb_ioerrdone()
 *      In the async case the call back is made either
 *      for every i/o completed or only once at the end
 *      of i/o. This depends on how the call back function
 *      is registered. See fdb_set_iofunc(). The fdbuf has
 *      to be freed by the call back function.
 *
 *  ZEROHOLE:
 *      This is the case the holes are to be zeroed. Note
 *      that we do not zero the holes when fdb_add_hole() is
 *      getting called. We leave the zeroing of the holes to
 *      when a list is requested or the buffer is freed. This
 *      so that we can avoid zeroing pages while holding ufs
 *      locks.
 */


typedef struct fdbuffer {
    fdb_type_t fd_type; /* type of buffer */
    int fd_state;   /* state of the fdbfer */
    size_t  fd_len;     /* length of this fdbuffer */
    size_t  fd_iocount; /* total io acked, includes errors and holes */
    int fd_iodispatch;  /* # of io's dispatched */
    int fd_err;     /* last i/o error due from buf_t */
    ssize_t fd_resid;   /* total len in error */

    buf_t *fd_parentbp; /* buf associated with parent buf */

    union {
        page_t *pages;  /* page list for FDPAGE_BUF */
        caddr_t addr;   /* address for FDADDR_BUF */
    } fd_un;

    fdb_holes_t *fd_holes;  /* holes list if this fdbuffer has holes */

    page_t **fd_shadow; /* shadow pages used for direct i/o to uspace */
    struct proc *fd_procp;  /* procp used in bp for direct i/o to uspace */

    /*
     * Call this function when the I/O on the full range of fdbuffer
     * is completed. The call is made only if the i/o requests
     * are asynchronous.
     */

    fdb_iodone_t fd_iofunc;
    void *fd_iargp;     /* iodone function argument to be passed */

    /*
     * The mutex protects iodispatch, iocount, state, and resid
     * flags and variables since they are examined and updated by
     * async call backs. All other structure members are modified
     * in a single threaded fashion and do not require a lock.
     */
    kmutex_t fd_mutex;

} fdbuffer_t;

#define fd_pages    fd_un.pages
#define fd_addr     fd_un.addr

extern fdbuffer_t *fdb_page_create(page_t *pp, size_t len, int flag);
extern fdbuffer_t *fdb_addr_create(caddr_t addr, size_t len, int flag,
    page_t **pplist, struct proc *procp);

extern void fdb_set_iofunc(fdbuffer_t *fdbuf, fdb_iodone_t iofunc, void *ioarg,
    int flags);
extern fdb_holes_t *fdb_get_holes(fdbuffer_t *fdbuf);
extern int fdb_get_error(fdbuffer_t *fdbuf);
extern void fdb_free(fdbuffer_t *fdbuf);
/*
 * Need to add:
 * fdb_get_iolen
 */
extern void fdb_add_hole(fdbuffer_t *fdbuf, u_offset_t off, size_t len);
extern buf_t *fdb_iosetup(fdbuffer_t *fdbuf, u_offset_t off, size_t len,
    struct vnode *vn, int flags);
extern void fdb_iodone(buf_t *bufp);
extern void fdb_ioerrdone(fdbuffer_t *fdbuf, int error);
extern void fdb_init(void);

#ifdef __cplusplus
}
#endif

#endif  /* _SYS_FDBUFFER_H */