usr/src/sys/ufs/lfs/lfs_bio.c

/*
 * Copyright (c) 1991 Regents of the University of California.
 * All rights reserved.
 *
 * %sccs.include.redist.c%
 *
 *      @(#)lfs_bio.c   7.11 (Berkeley) %G%
 */

#include <sys/param.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/vnode.h>
#include <sys/resourcevar.h>
#include <sys/mount.h>

#include <ufs/ufs/quota.h>
#include <ufs/ufs/inode.h>
#include <ufs/ufs/ufsmount.h>

#include <ufs/lfs/lfs.h>
#include <ufs/lfs/lfs_extern.h>

/*
 * LFS block write function.
 *
 * XXX
 * No write cost accounting is done.
 * This is almost certainly wrong for synchronous operations and NFS.
 */
int     locked_queue_count;             /* XXX Count of locked-down buffers. */

int
lfs_bwrite (ap)
        struct vop_bwrite_args *ap;
{
        register struct buf *bp = ap->a_bp;
        int s;
#ifdef VERBOSE
printf("lfs_bwrite\n");
#endif
        /*
         * Set the delayed write flag and use reassignbuf to move the buffer
         * from the clean list to the dirty one.
         *
         * Set the B_LOCKED flag and unlock the buffer, causing brelse to move
         * the buffer onto the LOCKED free list.  This is necessary, otherwise
         * getnewbuf() would try to reclaim the buffers using bawrite, which
         * isn't going to work.
         */
        if (!(bp->b_flags & B_LOCKED)) {
                ++locked_queue_count;
                bp->b_flags |= B_DELWRI | B_LOCKED;
                bp->b_flags &= ~(B_READ | B_DONE | B_ERROR);
                s = splbio();
#define PMAP_BUG_FIX_HACK
#ifdef PMAP_BUG_FIX_HACK
                if (((struct ufsmount *)
                    (bp->b_vp->v_mount->mnt_data))->um_lfs->lfs_ivnode !=
                    bp->b_vp)
#endif
                reassignbuf(bp, bp->b_vp);
                splx(s);
        }
        brelse(bp);
        return (0);
}

/*
 * XXX
 * This routine flushes buffers out of the B_LOCKED queue when LFS has too
 * many locked down.  Eventually the pageout daemon will simply call LFS
 * when pages need to be reclaimed.  Note, we have one static count of locked
 * buffers, so we can't have more than a single file system.  To make this
 * work for multiple file systems, put the count into the mount structure.
 */
void
lfs_flush()
{
        register struct mount *mp;
        struct mount *omp;

        /* 1M in a 4K file system. */
        if (locked_queue_count < 256)
                return;
        mp = rootfs;
        do {
                /*
                 * The lock check below is to avoid races with mount
                 * and unmount.
                 */
                if (mp->mnt_stat.f_type == MOUNT_LFS &&
                    (mp->mnt_flag & (MNT_MLOCK|MNT_RDONLY|MNT_MPBUSY)) == 0 &&
                    !vfs_busy(mp)) {
                        /*
                         * We set the queue to 0 here because we are about to
                         * write all the dirty buffers we have.  If more come
                         * in while we're writing the segment, they may not
                         * get written, so we want the count to reflect these
                         * new writes after the segwrite completes.
                         */
                        locked_queue_count = 0;
                        lfs_segwrite(mp, 0);
                        omp = mp;
                        mp = mp->mnt_next;
                        vfs_unbusy(omp);
                } else
                        mp = mp->mnt_next;
        } while (mp != rootfs);
}