/*      $NetBSD: chfs_wbuf.c,v 1.7 2014/10/18 08:33:29 snj Exp $        */

/*-
 * Copyright (c) 2010 Department of Software Engineering,
 *                    University of Szeged, Hungary
 * Copyright (C) 2010 Tamas Toth <ttoth@inf.u-szeged.hu>
 * Copyright (C) 2010 Adam Hoka <ahoka@NetBSD.org>
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by the Department of Software Engineering, University of Szeged, Hungary
 *
 * 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 AUTHOR ``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 AUTHOR 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.
 */

#include <dev/flash/flash.h>
#include <sys/uio.h>
#include "chfs.h"

#define DBG_WBUF 1              /* XXX unused, but should be */

#define PAD(x) (((x)+3)&~3)

#define EB_ADDRESS(x) ( rounddown((x), chmp->chm_ebh->eb_size) )

#define PAGE_DIV(x) ( rounddown((x), chmp->chm_wbuf_pagesize) )
#define PAGE_MOD(x) ( (x) % (chmp->chm_wbuf_pagesize) )

/* writebuffer options */
enum {
        WBUF_NOPAD,
        WBUF_SETPAD
};

/*
 * chfs_flush_wbuf - write wbuf to the flash
 * Returns zero in case of success.
 */
static int
chfs_flush_wbuf(struct chfs_mount *chmp, int pad)
{
        int ret;
        size_t retlen;
        struct chfs_node_ref *nref;
        struct chfs_flash_padding_node* padnode;

        KASSERT(mutex_owned(&chmp->chm_lock_mountfields));
        KASSERT(mutex_owned(&chmp->chm_lock_sizes));
        KASSERT(rw_write_held(&chmp->chm_lock_wbuf));
        KASSERT(pad == WBUF_SETPAD || pad == WBUF_NOPAD);

        /* check padding option */
        if (pad == WBUF_SETPAD) {
                chmp->chm_wbuf_len = PAD(chmp->chm_wbuf_len);
                memset(chmp->chm_wbuf + chmp->chm_wbuf_len, 0,
                    chmp->chm_wbuf_pagesize - chmp->chm_wbuf_len);

                /* add a padding node */
                padnode = (void *)(chmp->chm_wbuf + chmp->chm_wbuf_len);
                padnode->magic = htole16(CHFS_FS_MAGIC_BITMASK);
                padnode->type = htole16(CHFS_NODETYPE_PADDING);
                padnode->length = htole32(chmp->chm_wbuf_pagesize
                    - chmp->chm_wbuf_len);
                padnode->hdr_crc = htole32(crc32(0, (uint8_t *)padnode,
                        sizeof(*padnode)-4));

                nref = chfs_alloc_node_ref(chmp->chm_nextblock);
                nref->nref_offset = chmp->chm_wbuf_ofs + chmp->chm_wbuf_len;
                nref->nref_offset = CHFS_GET_OFS(nref->nref_offset) |
                    CHFS_OBSOLETE_NODE_MASK;
                chmp->chm_wbuf_len = chmp->chm_wbuf_pagesize;

                /* change sizes after padding node */
                chfs_change_size_free(chmp, chmp->chm_nextblock,
                    -padnode->length);
                chfs_change_size_wasted(chmp, chmp->chm_nextblock,
                    padnode->length);
        }

        /* write out the buffer */
        ret = chfs_write_leb(chmp, chmp->chm_nextblock->lnr, chmp->chm_wbuf,
            chmp->chm_wbuf_ofs, chmp->chm_wbuf_len, &retlen);
        if (ret) {
                return ret;
        }

        /* reset the buffer */
        memset(chmp->chm_wbuf, 0xff, chmp->chm_wbuf_pagesize);
        chmp->chm_wbuf_ofs += chmp->chm_wbuf_pagesize;
        chmp->chm_wbuf_len = 0;

        return 0;
}


/*
 * chfs_fill_wbuf - write data to wbuf
 * Return the len of the buf what we didn't write to the wbuf.
 */
static size_t
chfs_fill_wbuf(struct chfs_mount *chmp, const u_char *buf, size_t len)
{
        /* check available space */
        if (len && !chmp->chm_wbuf_len && (len >= chmp->chm_wbuf_pagesize)) {
                return 0;
        }
        /* check buffer's length */
        if (len > (chmp->chm_wbuf_pagesize - chmp->chm_wbuf_len)) {
                len = chmp->chm_wbuf_pagesize - chmp->chm_wbuf_len;
        }
        /* write into the wbuf */
        memcpy(chmp->chm_wbuf + chmp->chm_wbuf_len, buf, len);

        /* update the actual length of writebuffer */
        chmp->chm_wbuf_len += (int) len;
        return len;
}

/*
 * chfs_write_wbuf - write to wbuf and then the flash
 * Returns zero in case of success.
 */
int
chfs_write_wbuf(struct chfs_mount* chmp, const struct iovec *invecs, long count,
    off_t to, size_t *retlen)
{
        int invec, ret = 0;
        size_t wbuf_retlen, donelen = 0;
        int outvec_to = to;

        int lnr = chmp->chm_nextblock->lnr;

        KASSERT(mutex_owned(&chmp->chm_lock_mountfields));
        KASSERT(mutex_owned(&chmp->chm_lock_sizes));
        KASSERT(!rw_write_held(&chmp->chm_lock_wbuf));

        rw_enter(&chmp->chm_lock_wbuf, RW_WRITER);

        if (chmp->chm_wbuf_ofs == 0xffffffff) {
                chmp->chm_wbuf_ofs = PAGE_DIV(to);
                chmp->chm_wbuf_len = PAGE_MOD(to);
                memset(chmp->chm_wbuf, 0xff, chmp->chm_wbuf_pagesize);
        }

        if (EB_ADDRESS(to) != EB_ADDRESS(chmp->chm_wbuf_ofs)) {
                if (chmp->chm_wbuf_len) {
                        ret = chfs_flush_wbuf(chmp, WBUF_SETPAD);
                        if (ret)
                                goto outerr;
                }
                chmp->chm_wbuf_ofs = PAGE_DIV(to);
                chmp->chm_wbuf_len = PAGE_MOD(to);
        }

        if (to != PAD(chmp->chm_wbuf_ofs + chmp->chm_wbuf_len)) {
                dbg("to: %llu != %zu\n", (unsigned long long)to,
                        PAD(chmp->chm_wbuf_ofs + chmp->chm_wbuf_len));
                dbg("Non-contiguous write\n");
                panic("BUG\n");
        }

        /* adjust alignment offset */
        if (chmp->chm_wbuf_len != PAGE_MOD(to)) {
                chmp->chm_wbuf_len = PAGE_MOD(to);
                /* take care of alignment to next page */
                if (!chmp->chm_wbuf_len) {
                        chmp->chm_wbuf_len += chmp->chm_wbuf_pagesize;
                        ret = chfs_flush_wbuf(chmp, WBUF_NOPAD);
                        if (ret)
                                goto outerr;
                }
        }

        for (invec = 0; invec < count; invec++) {
                int vlen = invecs[invec].iov_len;
                u_char* v = invecs[invec].iov_base;

                /* fill the whole wbuf */
                wbuf_retlen = chfs_fill_wbuf(chmp, v, vlen);
                if (chmp->chm_wbuf_len == chmp->chm_wbuf_pagesize) {
                        ret = chfs_flush_wbuf(chmp, WBUF_NOPAD);
                        if (ret) {
                                goto outerr;
                        }
                }

                vlen -= wbuf_retlen;
                outvec_to += wbuf_retlen;
                v += wbuf_retlen;
                donelen += wbuf_retlen;

                /* if there is more residual data than the length of the wbuf
                 * write it out directly until it fits in the wbuf */
                if (vlen >= chmp->chm_wbuf_pagesize) {
                        ret = chfs_write_leb(chmp, lnr, v, outvec_to, PAGE_DIV(vlen), &wbuf_retlen);
                        vlen -= wbuf_retlen;
                        outvec_to += wbuf_retlen;
                        chmp->chm_wbuf_ofs = outvec_to;
                        v += wbuf_retlen;
                        donelen += wbuf_retlen;
                }

                /* write the residual data to the wbuf */
                wbuf_retlen = chfs_fill_wbuf(chmp, v, vlen);
                if (chmp->chm_wbuf_len == chmp->chm_wbuf_pagesize) {
                        ret = chfs_flush_wbuf(chmp, WBUF_NOPAD);
                        if (ret)
                                goto outerr;
                }

                outvec_to += wbuf_retlen;
                donelen += wbuf_retlen;
        }
        *retlen = donelen;
        rw_exit(&chmp->chm_lock_wbuf);
        return ret;

outerr:
        *retlen = 0;
        return ret;
}

/*
 * chfs_flush_peding_wbuf - write wbuf to the flash
 * Used when we must flush wbuf right now.
 * If wbuf has free space, pad it to the size of wbuf and write out.
 */
int chfs_flush_pending_wbuf(struct chfs_mount *chmp)
{
        int err;
        KASSERT(mutex_owned(&chmp->chm_lock_mountfields));
        mutex_enter(&chmp->chm_lock_sizes);
        rw_enter(&chmp->chm_lock_wbuf, RW_WRITER);
        err = chfs_flush_wbuf(chmp, WBUF_SETPAD);
        rw_exit(&chmp->chm_lock_wbuf);
        mutex_exit(&chmp->chm_lock_sizes);
        return err;
}