/* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
 * vim:expandtab:shiftwidth=8:tabstop=8:
 *
 * Lustre Lite I/O page cache for the 2.4 kernel version
 *
 *  Copyright (c) 2001-2003 Cluster File Systems, Inc.
 *
 *   This file is part of Lustre, http://www.lustre.org.
 *
 *   Lustre is free software; you can redistribute it and/or
 *   modify it under the terms of version 2 of the GNU General Public
 *   License as published by the Free Software Foundation.
 *
 *   Lustre is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with Lustre; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/smp_lock.h>
#include <linux/unistd.h>
#include <linux/version.h>
#include <asm/system.h>
#include <asm/uaccess.h>

#include <linux/fs.h>
#include <linux/iobuf.h>
#include <linux/stat.h>
#include <asm/uaccess.h>
#include <asm/segment.h>
#include <linux/mm.h>
#include <linux/pagemap.h>
#include <linux/smp_lock.h>

#define DEBUG_SUBSYSTEM S_LLITE

#include <linux/lustre_mds.h>
#include <linux/lustre_lite.h>
#include "llite_internal.h"
#include <linux/lustre_compat25.h>

static int ll_writepage_24(struct page *page)
{
        struct inode *inode = page->mapping->host;
        struct obd_export *exp;
        struct ll_async_page *llap;
        int rc = 0;
        ENTRY;

        LASSERT(!PageDirty(page));
        LASSERT(PageLocked(page));

        exp = ll_i2obdexp(inode);
        if (exp == NULL)
                GOTO(out, rc = -EINVAL);

        llap = llap_from_page(page);
        if (IS_ERR(llap))
                GOTO(out, rc = PTR_ERR(llap));

        page_cache_get(page);
        if (llap->llap_write_queued) {
                LL_CDEBUG_PAGE(D_PAGE, page, "marking urgent\n");
                rc = obd_set_async_flags(exp, ll_i2info(inode)->lli_smd, NULL,
                                         llap->llap_cookie,
                                         ASYNC_READY | ASYNC_URGENT);
        } else {
                llap->llap_write_queued = 1;
                rc = obd_queue_async_io(exp, ll_i2info(inode)->lli_smd, NULL,
                                        llap->llap_cookie, OBD_BRW_WRITE, 0, 0,
                                        0, ASYNC_READY | ASYNC_URGENT);
                if (rc == 0)
                        LL_CDEBUG_PAGE(D_PAGE, page, "mmap write queued\n");
                else
                        llap->llap_write_queued = 0;
        }
        if (rc)
                page_cache_release(page);
out:
        if (rc)
                unlock_page(page);
        RETURN(rc);
}

static int ll_direct_IO_24(int rw,
#ifdef HAVE_DIO_FILE
                           struct file *file,
#else
                           struct inode *inode,
#endif
                           struct kiobuf *iobuf, unsigned long blocknr,
                           int blocksize)
{
#ifdef HAVE_DIO_FILE
        struct inode *inode = file->f_dentry->d_inode;
#endif
        struct ll_inode_info *lli = ll_i2info(inode);
        struct lov_stripe_md *lsm = lli->lli_smd;
        struct brw_page *pga;
        struct ptlrpc_request_set *set;
        struct obdo oa;
        int length, i, flags, rc = 0;
        loff_t offset;
        ENTRY;

        if (!lsm || !lsm->lsm_object_id)
                RETURN(-EBADF);

        /* FIXME: io smaller than PAGE_SIZE is broken on ia64 */
        if ((iobuf->offset & (PAGE_SIZE - 1)) ||
            (iobuf->length & (PAGE_SIZE - 1)))
                RETURN(-EINVAL);

        set = ptlrpc_prep_set();
        if (set == NULL)
                RETURN(-ENOMEM);

        OBD_ALLOC(pga, sizeof(*pga) * iobuf->nr_pages);
        if (!pga) {
                ptlrpc_set_destroy(set);
                RETURN(-ENOMEM);
        }

        flags = 0 /* | OBD_BRW_DIRECTIO */;
        offset = ((obd_off)blocknr << inode->i_blkbits);
        length = iobuf->length;

        for (i = 0, length = iobuf->length; length > 0;
             length -= pga[i].count, offset += pga[i].count, i++) { /*i last!*/
                pga[i].pg = iobuf->maplist[i];
                pga[i].off = offset;
                /* To the end of the page, or the length, whatever is less */
                pga[i].count = min_t(int, PAGE_SIZE - (offset & ~PAGE_MASK),
                                     length);
                pga[i].flag = flags;
                if (rw == READ)
                        POISON_PAGE(iobuf->maplist[i], 0x0d);
        }

        ll_inode_fill_obdo(inode, rw, &oa);

        if (rw == WRITE)
                lprocfs_counter_add(ll_i2sbi(inode)->ll_stats,
                                    LPROC_LL_DIRECT_WRITE, iobuf->length);
        else
                lprocfs_counter_add(ll_i2sbi(inode)->ll_stats,
                                    LPROC_LL_DIRECT_READ, iobuf->length);
        rc = obd_brw_async(rw == WRITE ? OBD_BRW_WRITE : OBD_BRW_READ,
                           ll_i2obdexp(inode), &oa, lsm, iobuf->nr_pages, pga,
                           set, NULL);
        if (rc) {
                CDEBUG(rc == -ENOSPC ? D_INODE : D_ERROR,
                       "error from obd_brw_async: rc = %d\n", rc);
        } else {
                rc = ptlrpc_set_wait(set);
                if (rc)
                        CERROR("error from callback: rc = %d\n", rc);
        }
        ptlrpc_set_destroy(set);
        if (rc == 0) {
                rc = iobuf->length;
                obdo_to_inode(inode, &oa, OBD_MD_FLBLOCKS);
        }

        OBD_FREE(pga, sizeof(*pga) * iobuf->nr_pages);
        RETURN(rc);
}

struct address_space_operations ll_aops = {
        readpage: ll_readpage,
        direct_IO: ll_direct_IO_24,
        writepage: ll_writepage_24,
        prepare_write: ll_prepare_write,
        commit_write: ll_commit_write,
        removepage: ll_removepage,
        sync_page: NULL,
        bmap: NULL
};