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Annotation of kernel/bsd/ufs/lfs/lfs_bio.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.1 (the "License").  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License.
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: 
        !            25: /*     $NetBSD: lfs_bio.c,v 1.3 1995/01/18 06:19:52 mycroft Exp $      */
        !            26: 
        !            27: /*
        !            28:  * Copyright (c) 1991, 1993
        !            29:  *     The Regents of the University of California.  All rights reserved.
        !            30:  *
        !            31:  * Redistribution and use in source and binary forms, with or without
        !            32:  * modification, are permitted provided that the following conditions
        !            33:  * are met:
        !            34:  * 1. Redistributions of source code must retain the above copyright
        !            35:  *    notice, this list of conditions and the following disclaimer.
        !            36:  * 2. Redistributions in binary form must reproduce the above copyright
        !            37:  *    notice, this list of conditions and the following disclaimer in the
        !            38:  *    documentation and/or other materials provided with the distribution.
        !            39:  * 3. All advertising materials mentioning features or use of this software
        !            40:  *    must display the following acknowledgement:
        !            41:  *     This product includes software developed by the University of
        !            42:  *     California, Berkeley and its contributors.
        !            43:  * 4. Neither the name of the University nor the names of its contributors
        !            44:  *    may be used to endorse or promote products derived from this software
        !            45:  *    without specific prior written permission.
        !            46:  *
        !            47:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            48:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            49:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            50:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            51:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            52:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            53:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            54:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            55:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            56:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            57:  * SUCH DAMAGE.
        !            58:  *
        !            59:  *     @(#)lfs_bio.c   8.4 (Berkeley) 12/30/93
        !            60:  */
        !            61: 
        !            62: #include <sys/param.h>
        !            63: #include <sys/proc.h>
        !            64: #include <sys/buf.h>
        !            65: #include <sys/vnode.h>
        !            66: #include <sys/resourcevar.h>
        !            67: #include <sys/mount.h>
        !            68: #include <sys/kernel.h>
        !            69: 
        !            70: #include <ufs/ufs/quota.h>
        !            71: #include <ufs/ufs/inode.h>
        !            72: #include <ufs/ufs/ufsmount.h>
        !            73: 
        !            74: #include <ufs/lfs/lfs.h>
        !            75: #include <ufs/lfs/lfs_extern.h>
        !            76: 
        !            77: /*
        !            78:  * LFS block write function.
        !            79:  *
        !            80:  * XXX
        !            81:  * No write cost accounting is done.
        !            82:  * This is almost certainly wrong for synchronous operations and NFS.
        !            83:  */
        !            84: int    lfs_allclean_wakeup;            /* Cleaner wakeup address. */
        !            85: int    locked_queue_count;             /* XXX Count of locked-down buffers. */
        !            86: int    lfs_writing;                    /* Set if already kicked off a writer
        !            87:                                           because of buffer space */
        !            88: /*
        !            89: #define WRITE_THRESHHOLD       ((nbuf >> 2) - 10)
        !            90: #define WAIT_THRESHHOLD                ((nbuf >> 1) - 10)
        !            91: */
        !            92: #define WAIT_THRESHHOLD         (nbuf - (nbuf >> 2) - 10)
        !            93: #define WRITE_THRESHHOLD        ((nbuf >> 1) - 10)
        !            94: #define LFS_BUFWAIT    2
        !            95: 
        !            96: int
        !            97: lfs_bwrite(ap)
        !            98:        struct vop_bwrite_args /* {
        !            99:                struct buf *a_bp;
        !           100:        } */ *ap;
        !           101: {
        !           102:        register struct buf *bp = ap->a_bp;
        !           103:        struct lfs *fs;
        !           104:        struct inode *ip;
        !           105:        int error, s;
        !           106: 
        !           107:        /*
        !           108:         * Set the delayed write flag and use reassignbuf to move the buffer
        !           109:         * from the clean list to the dirty one.
        !           110:         *
        !           111:         * Set the B_LOCKED flag and unlock the buffer, causing brelse to move
        !           112:         * the buffer onto the LOCKED free list.  This is necessary, otherwise
        !           113:         * getnewbuf() would try to reclaim the buffers using bawrite, which
        !           114:         * isn't going to work.
        !           115:         *
        !           116:         * XXX we don't let meta-data writes run out of space because they can
        !           117:         * come from the segment writer.  We need to make sure that there is
        !           118:         * enough space reserved so that there's room to write meta-data
        !           119:         * blocks.
        !           120:         */
        !           121:        if (!(bp->b_flags & B_LOCKED)) {
        !           122:                fs = VFSTOUFS(bp->b_vp->v_mount)->um_lfs;
        !           123:                while (!LFS_FITS(fs, fsbtodb(fs, 1)) && !IS_IFILE(bp) &&
        !           124:                    bp->b_lblkno > 0) {
        !           125:                        /* Out of space, need cleaner to run */
        !           126:                        wakeup(&lfs_allclean_wakeup);
        !           127:                        if (error = tsleep(&fs->lfs_avail, PCATCH | PUSER,
        !           128:                            "cleaner", NULL)) {
        !           129:                                brelse(bp);
        !           130:                                return (error);
        !           131:                        }
        !           132:                }
        !           133:                ip = VTOI((bp)->b_vp);
        !           134:                if (!(ip->i_flag & IN_MODIFIED))
        !           135:                        ++fs->lfs_uinodes;
        !           136:                ip->i_flag |= IN_CHANGE | IN_MODIFIED | IN_UPDATE;
        !           137:                fs->lfs_avail -= fsbtodb(fs, 1);
        !           138:                ++locked_queue_count;
        !           139:                bp->b_flags |= B_DELWRI | B_LOCKED;
        !           140:                bp->b_flags &= ~(B_READ | B_ERROR);
        !           141:                s = splbio();
        !           142:                reassignbuf(bp, bp->b_vp);
        !           143:                splx(s);
        !           144:        }
        !           145:        brelse(bp);
        !           146:        return (0);
        !           147: }
        !           148: 
        !           149: /*
        !           150:  * XXX
        !           151:  * This routine flushes buffers out of the B_LOCKED queue when LFS has too
        !           152:  * many locked down.  Eventually the pageout daemon will simply call LFS
        !           153:  * when pages need to be reclaimed.  Note, we have one static count of locked
        !           154:  * buffers, so we can't have more than a single file system.  To make this
        !           155:  * work for multiple file systems, put the count into the mount structure.
        !           156:  */
        !           157: void
        !           158: lfs_flush()
        !           159: {
        !           160:        register struct mount *mp;
        !           161: 
        !           162: #ifdef DOSTATS
        !           163:        ++lfs_stats.write_exceeded;
        !           164: #endif
        !           165:        if (lfs_writing)
        !           166:                return;
        !           167:        lfs_writing = 1;
        !           168:        for (mp = mountlist.cqh_first; mp != (void *)&mountlist;
        !           169:             mp = mp->mnt_list.cqe_next) {
        !           170:                /* The lock check below is to avoid races with unmount. */
        !           171:                if (!strcmp(&mp->mnt_stat.f_fstypename[0], MOUNT_LFS) &&
        !           172:                    (mp->mnt_flag & (MNT_MLOCK|MNT_RDONLY|MNT_UNMOUNT)) == 0 &&
        !           173:                    !((((struct ufsmount *)mp->mnt_data))->ufsmount_u.lfs)->lfs_dirops ) {
        !           174:                        /*
        !           175:                         * We set the queue to 0 here because we are about to
        !           176:                         * write all the dirty buffers we have.  If more come
        !           177:                         * in while we're writing the segment, they may not
        !           178:                         * get written, so we want the count to reflect these
        !           179:                         * new writes after the segwrite completes.
        !           180:                         */
        !           181: #ifdef DOSTATS
        !           182:                        ++lfs_stats.flush_invoked;
        !           183: #endif
        !           184:                        lfs_segwrite(mp, 0);
        !           185:                }
        !           186:        }
        !           187:        lfs_writing = 0;
        !           188: }
        !           189: 
        !           190: int
        !           191: lfs_check(vp, blkno)
        !           192:        struct vnode *vp;
        !           193:        daddr_t blkno;
        !           194: {
        !           195:        extern int lfs_allclean_wakeup;
        !           196:        int error;
        !           197: 
        !           198:        error = 0;
        !           199:        if (incore(vp, blkno))
        !           200:                return (0);
        !           201:        if (locked_queue_count > WRITE_THRESHHOLD)
        !           202:                lfs_flush();
        !           203: 
        !           204:        /* If out of buffers, wait on writer */
        !           205:        while (locked_queue_count > WAIT_THRESHHOLD) {
        !           206: #ifdef DOSTATS
        !           207:            ++lfs_stats.wait_exceeded;
        !           208: #endif
        !           209:            error = tsleep(&locked_queue_count, PCATCH | PUSER, "buffers",
        !           210:                hz * LFS_BUFWAIT);
        !           211:        }
        !           212: 
        !           213:        return (error);
        !           214: }

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