HAMMER 14/many - historical access cleanup, itimes, bug fixes.

[dragonfly.git] / sys / vfs / hammer / hammer_io.c

/*
 * Copyright (c) 2007 The DragonFly Project.  All rights reserved.
 * 
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@backplane.com>
 * 
 * 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.
 * 3. Neither the name of The DragonFly Project nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific, prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``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
 * COPYRIGHT HOLDERS OR CONTRIBUTORS 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.
 * 
 * $DragonFly: src/sys/vfs/hammer/hammer_io.c,v 1.11 2008/01/01 01:00:03 dillon Exp $
 */
/*
 * IO Primitives and buffer cache management
 *
 * All major data-tracking structures in HAMMER contain a struct hammer_io
 * which is used to manage their backing store.  We use filesystem buffers
 * for backing store and we leave them passively associated with their
 * HAMMER structures.
 *
 * If the kernel tries to release a passively associated buf which we cannot
 * yet let go we set B_LOCKED in the buffer and then actively released it
 * later when we can.
 */

#include "hammer.h"
#include <sys/fcntl.h>
#include <sys/nlookup.h>
#include <sys/buf.h>
#include <sys/buf2.h>

/*
 * Helper routine to disassociate a buffer cache buffer from an I/O
 * structure.
 */
static void
hammer_io_disassociate(union hammer_io_structure *io)
{
        struct buf *bp = io->io.bp;

        KKASSERT(io->io.released && io->io.modified == 0);
        LIST_INIT(&bp->b_dep);  /* clear the association */
        bp->b_ops = NULL;
        io->io.bp = NULL;
        bp->b_flags &= ~B_LOCKED;

        switch(io->io.type) {
        case HAMMER_STRUCTURE_VOLUME:
                io->volume.ondisk = NULL;
                io->volume.alist.meta = NULL;
                break;
        case HAMMER_STRUCTURE_SUPERCL:
                io->supercl.ondisk = NULL;
                io->supercl.alist.meta = NULL;
                break;
        case HAMMER_STRUCTURE_CLUSTER:
                io->cluster.ondisk = NULL;
                io->cluster.alist_master.meta = NULL;
                io->cluster.alist_btree.meta = NULL;
                io->cluster.alist_record.meta = NULL;
                io->cluster.alist_mdata.meta = NULL;
                break;
        case HAMMER_STRUCTURE_BUFFER:
                io->buffer.ondisk = NULL;
                io->buffer.alist.meta = NULL;
                break;
        }
}

/*
 * Mark a cluster as being closed.  This is done as late as possible,
 * only when we are asked to flush the cluster
 */
static void
hammer_close_cluster(hammer_cluster_t cluster)
{
        while (cluster->state == HAMMER_CLUSTER_ASYNC)
                tsleep(cluster, 0, "hmrdep", 0);
        if (cluster->state == HAMMER_CLUSTER_OPEN) {
                cluster->state = HAMMER_CLUSTER_IDLE;
                hammer_modify_cluster(cluster);
                cluster->ondisk->clu_flags &= ~HAMMER_CLUF_OPEN;
                hammer_modify_cluster_done(cluster);
                kprintf("CLOSE CLUSTER\n");
        }
}


/*
 * Load bp for a HAMMER structure.
 */
int
hammer_io_read(struct vnode *devvp, struct hammer_io *io)
{
        struct buf *bp;
        int error;

        if ((bp = io->bp) == NULL) {
                error = bread(devvp, io->offset, HAMMER_BUFSIZE, &io->bp);
                if (error == 0) {
                        bp = io->bp;
                        bp->b_ops = &hammer_bioops;
                        LIST_INSERT_HEAD(&bp->b_dep, &io->worklist, node);
                        BUF_KERNPROC(bp);
                }
                io->modified = 0;       /* no new modifications yet */
                io->released = 0;       /* we hold an active lock on bp */
        } else {
                error = 0;
        }
        return(error);
}

/*
 * Similar to hammer_io_read() but returns a zero'd out buffer instead.
 * vfs_bio_clrbuf() is kinda nasty, enforce serialization against background
 * I/O so we can call it.
 */
int
hammer_io_new(struct vnode *devvp, struct hammer_io *io)
{
        struct buf *bp;

        if ((bp = io->bp) == NULL) {
                io->bp = getblk(devvp, io->offset, HAMMER_BUFSIZE, 0, 0);
                bp = io->bp;
                bp->b_ops = &hammer_bioops;
                LIST_INSERT_HEAD(&bp->b_dep, &io->worklist, node);
                io->released = 0;       /* we hold an active lock on bp */
                BUF_KERNPROC(bp);
        } else {
                if (io->released) {
                        regetblk(bp);
                        BUF_KERNPROC(bp);
                        io->released = 0;
                }
        }
        io->modified = 1;
        vfs_bio_clrbuf(bp);
        return(0);
}

/*
 * This routine is called when a buffer within a cluster is modified.  We
 * mark the cluster open and immediately initiate asynchronous I/O.  Any
 * related hammer_buffer write I/O blocks until our async write completes.
 * This guarentees (inasmuch as the OS can) that the cluster recovery code
 * will see a cluster marked open if a crash occured while the filesystem
 * still had dirty buffers associated with that cluster.
 *
 * XXX
 */
void
hammer_io_notify_cluster(hammer_cluster_t cluster)
{
        struct hammer_io *io = &cluster->io;

        if (cluster->state == HAMMER_CLUSTER_IDLE) {
                hammer_lock_ex(&cluster->io.lock);
                if (cluster->state == HAMMER_CLUSTER_IDLE) {
                        if (io->released)
                                regetblk(io->bp);
                        else
                                io->released = 1;
                        kprintf("MARK CLUSTER OPEN\n");
                        cluster->ondisk->clu_flags |= HAMMER_CLUF_OPEN;
                        cluster->state = HAMMER_CLUSTER_ASYNC;
                        cluster->io.modified = 1;
                        bawrite(io->bp);
                }
                hammer_unlock(&cluster->io.lock);
        }
}

/*
 * This routine is called on the last reference to a hammer structure.
 * Regardless of the state io->modified must be cleared when we return.
 *
 * If flush is non-zero we have to completely disassociate the bp from the
 * structure (which may involve blocking).  Otherwise we can leave the bp
 * passively associated with the structure.
 *
 * The caller is holding io->lock exclusively.
 */
void
hammer_io_release(struct hammer_io *io, int flush)
{
        union hammer_io_structure *iou = (void *)io;
        hammer_cluster_t cluster;
        struct buf *bp;
        int modified;

        if ((bp = io->bp) != NULL) {
                /*
                 * If neither we nor the kernel want to flush the bp, we can
                 * stop here.  Make sure the bp is passively released
                 * before returning.  Even though we are still holding it,
                 * we want to be notified when the kernel wishes to flush
                 * it out so make sure B_DELWRI is properly set if we had
                 * made modifications.
                 */
                if (flush == 0 && (bp->b_flags & B_LOCKED) == 0) {
                        if ((bp->b_flags & B_DELWRI) == 0 && io->modified) {
                                if (io->released)
                                        regetblk(bp);
                                else
                                        io->released = 1;
                                io->modified = 0;
                                bdwrite(bp);
                        } else if (io->released == 0) {
                                /* buffer write state already synchronized */
                                io->modified = 0;
                                io->released = 1;
                                bqrelse(bp);
                        } else {
                                /* buffer write state already synchronized */
                                io->modified = 0;
                        }
                        return;
                }

                /*
                 * Either we want to flush the buffer or the kernel tried.
                 *
                 * If this is a hammer_buffer we may have to wait for the
                 * cluster header write to complete.
                 */
                if (iou->io.type == HAMMER_STRUCTURE_BUFFER &&
                    (io->modified || (bp->b_flags & B_DELWRI))) {
                        cluster = iou->buffer.cluster;
                        while (cluster->state == HAMMER_CLUSTER_ASYNC)
                                tsleep(iou->buffer.cluster, 0, "hmrdep", 0);
                }

                /*
                 * If we have an open cluster header, close it
                 */
                if (iou->io.type == HAMMER_STRUCTURE_CLUSTER) {
                        hammer_close_cluster(&iou->cluster);
                }

                /*
                 * Gain ownership of the buffer.  Nothing can take it away
                 * from the io structure while we have it locked, so we
                 * can safely reget.
                 *
                 * Once our thread owns the buffer we can disassociate it
                 * from the io structure.
                 */
                if (io->released)
                        regetblk(bp);
                else
                        io->released = 1;
                modified = io->modified;
                io->modified = 0;
                hammer_io_disassociate(iou);

                /*
                 * Now dispose of the buffer.  Someone tried to flush, so
                 * issue the I/O immediately.
                 */
                if (modified || (bp->b_flags & B_DELWRI))
                        bawrite(bp);
                else
                        bqrelse(bp);
        }
}

/*
 * Flush dirty data, if any.
 */
void
hammer_io_flush(struct hammer_io *io, struct hammer_sync_info *info)
{
        struct buf *bp;
        int error;

again:
        if ((bp = io->bp) == NULL)
                return;
        if (bp->b_flags & B_DELWRI)
                io->modified = 1;

        /*
         * We can't initiate a write while the buffer is being modified
         * by someone.
         */
        while (io->lock.modifying) {
                io->lock.wanted = 1;
                kprintf("DELAYING IO FLUSH BP %p TYPE %d REFS %d modifying %d\n",
                        bp, io->type, io->lock.refs, io->lock.modifying);
                tsleep(&io->lock, 0, "hmrfls", 0);
        }
        hammer_lock_ex(&io->lock);
        if (io->lock.modifying || io->bp == NULL) {
                hammer_unlock(&io->lock);
                goto again;
        }

        /*
         * Acquire ownership of the buffer cache buffer so we can flush it
         * out.
         */
        if (io->released) {
                if (io->modified == 0)
                        goto done;
                regetblk(bp);
        } else {
                io->released = 1;
        }

        /*
         * Return the bp to the system, issuing I/O if necessary.  The
         * system will issue a callback to us when it actually wants to
         * throw the bp away.
         */
        if (io->modified == 0) {
                bqrelse(bp);
        } else if (info->waitfor & MNT_WAIT) {
                io->modified = 0;
                error = bwrite(bp);
                if (error)
                        info->error = error;
        } else {
                io->modified = 0;
                bawrite(bp);
        }
done:
        hammer_unlock(&io->lock);
}

/*
 * Called prior to any modifications being made to ondisk data.  This
 * forces the caller to wait for any writes to complete.  We explicitly
 * avoid the write-modify race.
 *
 * This routine is only called on hammer structures which are already
 * actively referenced.
 */
void
hammer_io_intend_modify(struct hammer_io *io)
{
        KKASSERT(io->lock.refs != 0 && io->bp != NULL);
        if (io->released) {
                hammer_lock_ex(&io->lock);
                if (io->released) {
                        regetblk(io->bp);
                        BUF_KERNPROC(io->bp);
                        io->released = 0;
                }
                hammer_unlock(&io->lock);
        }
}

void
hammer_io_modify_done(struct hammer_io *io)
{
        KKASSERT(io->lock.modifying > 0);
        --io->lock.modifying;
        if (io->lock.wanted && io->lock.modifying == 0) {
                io->lock.wanted = 0;
                wakeup(&io->lock);
        }
}

/*
 * HAMMER_BIOOPS
 */

/*
 * Pre and post I/O callbacks.
 */
static void hammer_io_deallocate(struct buf *bp);

static void
hammer_io_start(struct buf *bp)
{
#if 0
        union hammer_io_structure *io = (void *)LIST_FIRST(&bp->b_dep);

        if (io->io.type == HAMMER_STRUCTURE_BUFFER) {
                while (io->buffer.cluster->io_in_progress) {
                        kprintf("hammer_io_start: wait for cluster\n");
                        tsleep(io->buffer.cluster, 0, "hmrdep", 0);
                        kprintf("hammer_io_start: wait for cluster done\n");
                }
        }
#endif
}

static void
hammer_io_complete(struct buf *bp)
{
        union hammer_io_structure *io = (void *)LIST_FIRST(&bp->b_dep);

        if (io->io.type == HAMMER_STRUCTURE_CLUSTER) {
                if (io->cluster.state == HAMMER_CLUSTER_ASYNC) {
                        io->cluster.state = HAMMER_CLUSTER_OPEN;
                        wakeup(&io->cluster);
                }
        }
}

/*
 * Callback from kernel when it wishes to deallocate a passively
 * associated structure.  This can only occur if the buffer is
 * passively associated with the structure.  The kernel has locked
 * the buffer.
 *
 * If we cannot disassociate we set B_LOCKED to prevent the buffer
 * from getting reused.
 */
static void
hammer_io_deallocate(struct buf *bp)
{
        union hammer_io_structure *io = (void *)LIST_FIRST(&bp->b_dep);

        /* XXX memory interlock, spinlock to sync cpus */

        /*
         * Since the kernel is passing us a locked buffer, the HAMMER
         * structure had better not believe it has a lock on the buffer.
         */
        KKASSERT(io->io.released);
        crit_enter();

        /*
         * First, ref the structure to prevent either the buffer or the
         * structure from going away or being unexpectedly flushed.
         */
        hammer_ref(&io->io.lock);

        /*
         * Buffers can have active references from cached hammer_node's,
         * even if those nodes are themselves passively cached.  Attempt
         * to clean them out.  This may not succeed.
         *
         * We have to do some magic with io.released because
         * hammer_io_intend_modify() can be called indirectly from the
         * flush code, otherwise we might panic with a recursive bp lock.
         */
        if (io->io.type == HAMMER_STRUCTURE_BUFFER &&
            hammer_lock_ex_try(&io->io.lock) == 0) {
                io->io.released = 0;
                hammer_flush_buffer_nodes(&io->buffer);
                KKASSERT(io->io.released == 0);
                io->io.released = 1;
                hammer_unlock(&io->io.lock);
        }

        if (hammer_islastref(&io->io.lock)) {
                /*
                 * If we are the only ref left we can disassociate the I/O.
                 * It had better still be in a released state because the
                 * kernel is holding a lock on the buffer.  Any passive
                 * modifications should have already been synchronized with
                 * the buffer.
                 */
                KKASSERT(io->io.modified == 0);
                hammer_io_disassociate(io);

                /*
                 * Perform final rights on the structure.  This can cause
                 * a chain reaction - e.g. last buffer -> last cluster ->
                 * last supercluster -> last volume.
                 */
                switch(io->io.type) {
                case HAMMER_STRUCTURE_VOLUME:
                        hammer_rel_volume(&io->volume, 1);
                        break;
                case HAMMER_STRUCTURE_SUPERCL:
                        hammer_rel_supercl(&io->supercl, 1);
                        break;
                case HAMMER_STRUCTURE_CLUSTER:
                        hammer_rel_cluster(&io->cluster, 1);
                        break;
                case HAMMER_STRUCTURE_BUFFER:
                        hammer_rel_buffer(&io->buffer, 1);
                        break;
                }
        } else {
                /*
                 * Otherwise tell the kernel not to destroy the buffer.
                 * 
                 * We have to unref the structure without performing any
                 * final rights to it to avoid a deadlock.
                 */
                bp->b_flags |= B_LOCKED;
                hammer_unref(&io->io.lock);
        }
        crit_exit();
}

static int
hammer_io_fsync(struct vnode *vp)
{
        return(0);
}

/*
 * NOTE: will not be called unless we tell the kernel about the
 * bioops.  Unused... we use the mount's VFS_SYNC instead.
 */
static int
hammer_io_sync(struct mount *mp)
{
        return(0);
}

static void
hammer_io_movedeps(struct buf *bp1, struct buf *bp2)
{
}

/*
 * I/O pre-check for reading and writing.  HAMMER only uses this for
 * B_CACHE buffers so checkread just shouldn't happen, but if it does
 * allow it.
 *
 * Writing is a different case.  We don't want the kernel to try to write
 * out a buffer that HAMMER may be modifying passively or which has a
 * dependancy.
 *
 * This code enforces the following write ordering: buffers, then cluster
 * headers, then volume headers.
 */
static int
hammer_io_checkread(struct buf *bp)
{
        return(0);
}

static int
hammer_io_checkwrite(struct buf *bp)
{
        union hammer_io_structure *iou = (void *)LIST_FIRST(&bp->b_dep);

        if (iou->io.type == HAMMER_STRUCTURE_BUFFER &&
            iou->buffer.cluster->state == HAMMER_CLUSTER_ASYNC) {
                /*
                 * Cannot write out a cluster buffer if the cluster header
                 * I/O opening the cluster has not completed.
                 */
                bp->b_flags |= B_LOCKED;
                return(-1);
        } else if (iou->io.lock.refs) {
                /*
                 * Cannot write out a bp if its associated buffer has active
                 * references.
                 */
                bp->b_flags |= B_LOCKED;
                return(-1);
        } else {
                /*
                 * We're good, but before we can let the kernel proceed we
                 * may have to make some adjustments.
                 *
                 * Since there are no refs on the io structure, HAMMER must
                 * have already synchronized its modify state with the bp
                 * so iou->io.modified should be 0.
                 */
                if (iou->io.type == HAMMER_STRUCTURE_CLUSTER)
                        hammer_close_cluster(&iou->cluster);
                hammer_io_disassociate(iou);
                return(0);
        }
}

/*
 * Return non-zero if the caller should flush the structure associated
 * with this io sub-structure.
 */
int
hammer_io_checkflush(struct hammer_io *io)
{
        if (io->bp == NULL || (io->bp->b_flags & B_LOCKED))
                return(1);
        return(0);
}

/*
 * Return non-zero if we wish to delay the kernel's attempt to flush
 * this buffer to disk.
 */
static int
hammer_io_countdeps(struct buf *bp, int n)
{
        return(0);
}

struct bio_ops hammer_bioops = {
        .io_start       = hammer_io_start,
        .io_complete    = hammer_io_complete,
        .io_deallocate  = hammer_io_deallocate,
        .io_fsync       = hammer_io_fsync,
        .io_sync        = hammer_io_sync,
        .io_movedeps    = hammer_io_movedeps,
        .io_countdeps   = hammer_io_countdeps,
        .io_checkread   = hammer_io_checkread,
        .io_checkwrite  = hammer_io_checkwrite,
};