Archipelago » qemu

/*

 * QEMU Enhanced Disk Format Table I/O

 *

 * Copyright IBM, Corp. 2010

 *

 * Authors:

 *  Stefan Hajnoczi   <stefanha@linux.vnet.ibm.com>

 *  Anthony Liguori   <aliguori@us.ibm.com>

 *

 * This work is licensed under the terms of the GNU LGPL, version 2 or later.

 * See the COPYING.LIB file in the top-level directory.

 *

 */

#include "trace.h"

#include "qemu/sockets.h" /* for EINPROGRESS on Windows */

#include "qed.h"

typedef struct {

    GenericCB gencb;

    BDRVQEDState *s;

    QEDTable *table;

    struct iovec iov;

    QEMUIOVector qiov;

} QEDReadTableCB;

static void qed_read_table_cb(void *opaque, int ret)

{

    QEDReadTableCB *read_table_cb = opaque;

    QEDTable *table = read_table_cb->table;

    int noffsets = read_table_cb->qiov.size / sizeof(uint64_t);

    int i;

    /* Handle I/O error */

    if (ret) {

        goto out;

    }

    /* Byteswap offsets */

    for (i = 0; i < noffsets; i++) {

        table->offsets[i] = le64_to_cpu(table->offsets[i]);

    }

out:

    /* Completion */

    trace_qed_read_table_cb(read_table_cb->s, read_table_cb->table, ret);

    gencb_complete(&read_table_cb->gencb, ret);

}

static void qed_read_table(BDRVQEDState *s, uint64_t offset, QEDTable *table,

                           BlockDriverCompletionFunc *cb, void *opaque)

{

    QEDReadTableCB *read_table_cb = gencb_alloc(sizeof(*read_table_cb),

                                                cb, opaque);

    QEMUIOVector *qiov = &read_table_cb->qiov;

    trace_qed_read_table(s, offset, table);

    read_table_cb->s = s;

    read_table_cb->table = table;

    read_table_cb->iov.iov_base = table->offsets,

    read_table_cb->iov.iov_len = s->header.cluster_size * s->header.table_size,

    qemu_iovec_init_external(qiov, &read_table_cb->iov, 1);

    bdrv_aio_readv(s->bs->file, offset / BDRV_SECTOR_SIZE, qiov,

                   qiov->size / BDRV_SECTOR_SIZE,

                   qed_read_table_cb, read_table_cb);

}

typedef struct {

    GenericCB gencb;

    BDRVQEDState *s;

    QEDTable *orig_table;

    QEDTable *table;

    bool flush;             /* flush after write? */

    struct iovec iov;

    QEMUIOVector qiov;

} QEDWriteTableCB;

static void qed_write_table_cb(void *opaque, int ret)

{

    QEDWriteTableCB *write_table_cb = opaque;

    trace_qed_write_table_cb(write_table_cb->s,

                             write_table_cb->orig_table,

                             write_table_cb->flush,

                             ret);

    if (ret) {

        goto out;

    }

    if (write_table_cb->flush) {

        /* We still need to flush first */

        write_table_cb->flush = false;

        bdrv_aio_flush(write_table_cb->s->bs, qed_write_table_cb,

                       write_table_cb);

        return;

    }

out:

    qemu_vfree(write_table_cb->table);

    gencb_complete(&write_table_cb->gencb, ret);

}

/**

 * Write out an updated part or all of a table

 *

 * @s:          QED state

 * @offset:     Offset of table in image file, in bytes

 * @table:      Table

 * @index:      Index of first element

 * @n:          Number of elements

 * @flush:      Whether or not to sync to disk

 * @cb:         Completion function

 * @opaque:     Argument for completion function

 */

static void qed_write_table(BDRVQEDState *s, uint64_t offset, QEDTable *table,

                            unsigned int index, unsigned int n, bool flush,

                            BlockDriverCompletionFunc *cb, void *opaque)

{

    QEDWriteTableCB *write_table_cb;

    unsigned int sector_mask = BDRV_SECTOR_SIZE / sizeof(uint64_t) - 1;

    unsigned int start, end, i;

    size_t len_bytes;

    trace_qed_write_table(s, offset, table, index, n);

    /* Calculate indices of the first and one after last elements */

    start = index & ~sector_mask;

    end = (index + n + sector_mask) & ~sector_mask;

    len_bytes = (end - start) * sizeof(uint64_t);

    write_table_cb = gencb_alloc(sizeof(*write_table_cb), cb, opaque);

    write_table_cb->s = s;

    write_table_cb->orig_table = table;

    write_table_cb->flush = flush;

    write_table_cb->table = qemu_blockalign(s->bs, len_bytes);

    write_table_cb->iov.iov_base = write_table_cb->table->offsets;

    write_table_cb->iov.iov_len = len_bytes;

    qemu_iovec_init_external(&write_table_cb->qiov, &write_table_cb->iov, 1);

    /* Byteswap table */

    for (i = start; i < end; i++) {

        uint64_t le_offset = cpu_to_le64(table->offsets[i]);

        write_table_cb->table->offsets[i - start] = le_offset;

    }

    /* Adjust for offset into table */

    offset += start * sizeof(uint64_t);

    bdrv_aio_writev(s->bs->file, offset / BDRV_SECTOR_SIZE,

                    &write_table_cb->qiov,

                    write_table_cb->qiov.size / BDRV_SECTOR_SIZE,

                    qed_write_table_cb, write_table_cb);

}

/**

 * Propagate return value from async callback

 */

static void qed_sync_cb(void *opaque, int ret)

{

    *(int *)opaque = ret;

}

int qed_read_l1_table_sync(BDRVQEDState *s)

{

    int ret = -EINPROGRESS;

    qed_read_table(s, s->header.l1_table_offset,

                   s->l1_table, qed_sync_cb, &ret);

    while (ret == -EINPROGRESS) {

        qemu_aio_wait();

    }

    return ret;

}

void qed_write_l1_table(BDRVQEDState *s, unsigned int index, unsigned int n,

                        BlockDriverCompletionFunc *cb, void *opaque)

{

    BLKDBG_EVENT(s->bs->file, BLKDBG_L1_UPDATE);

    qed_write_table(s, s->header.l1_table_offset,

                    s->l1_table, index, n, false, cb, opaque);

}

int qed_write_l1_table_sync(BDRVQEDState *s, unsigned int index,

                            unsigned int n)

{

    int ret = -EINPROGRESS;

    qed_write_l1_table(s, index, n, qed_sync_cb, &ret);

    while (ret == -EINPROGRESS) {

        qemu_aio_wait();

    }

    return ret;

}

typedef struct {

    GenericCB gencb;

    BDRVQEDState *s;

    uint64_t l2_offset;

    QEDRequest *request;

} QEDReadL2TableCB;

static void qed_read_l2_table_cb(void *opaque, int ret)

{

    QEDReadL2TableCB *read_l2_table_cb = opaque;

    QEDRequest *request = read_l2_table_cb->request;

    BDRVQEDState *s = read_l2_table_cb->s;

    CachedL2Table *l2_table = request->l2_table;

    uint64_t l2_offset = read_l2_table_cb->l2_offset;

    if (ret) {

        /* can't trust loaded L2 table anymore */

        qed_unref_l2_cache_entry(l2_table);

        request->l2_table = NULL;

    } else {

        l2_table->offset = l2_offset;

        qed_commit_l2_cache_entry(&s->l2_cache, l2_table);

        /* This is guaranteed to succeed because we just committed the entry

         * to the cache.

         */

        request->l2_table = qed_find_l2_cache_entry(&s->l2_cache, l2_offset);

        assert(request->l2_table != NULL);

    }

    gencb_complete(&read_l2_table_cb->gencb, ret);

}

void qed_read_l2_table(BDRVQEDState *s, QEDRequest *request, uint64_t offset,

                       BlockDriverCompletionFunc *cb, void *opaque)

{

    QEDReadL2TableCB *read_l2_table_cb;

    qed_unref_l2_cache_entry(request->l2_table);

    /* Check for cached L2 entry */

    request->l2_table = qed_find_l2_cache_entry(&s->l2_cache, offset);

    if (request->l2_table) {

        cb(opaque, 0);

        return;

    }

    request->l2_table = qed_alloc_l2_cache_entry(&s->l2_cache);

    request->l2_table->table = qed_alloc_table(s);

    read_l2_table_cb = gencb_alloc(sizeof(*read_l2_table_cb), cb, opaque);

    read_l2_table_cb->s = s;

    read_l2_table_cb->l2_offset = offset;

    read_l2_table_cb->request = request;

    BLKDBG_EVENT(s->bs->file, BLKDBG_L2_LOAD);

    qed_read_table(s, offset, request->l2_table->table,

                   qed_read_l2_table_cb, read_l2_table_cb);

}

int qed_read_l2_table_sync(BDRVQEDState *s, QEDRequest *request, uint64_t offset)

{

    int ret = -EINPROGRESS;

    qed_read_l2_table(s, request, offset, qed_sync_cb, &ret);

    while (ret == -EINPROGRESS) {

        qemu_aio_wait();

    }

    return ret;

}

void qed_write_l2_table(BDRVQEDState *s, QEDRequest *request,

                        unsigned int index, unsigned int n, bool flush,

                        BlockDriverCompletionFunc *cb, void *opaque)

{

    BLKDBG_EVENT(s->bs->file, BLKDBG_L2_UPDATE);

    qed_write_table(s, request->l2_table->offset,

                    request->l2_table->table, index, n, flush, cb, opaque);

}

int qed_write_l2_table_sync(BDRVQEDState *s, QEDRequest *request,

                            unsigned int index, unsigned int n, bool flush)

{

    int ret = -EINPROGRESS;

    qed_write_l2_table(s, request, index, n, flush, qed_sync_cb, &ret);

    while (ret == -EINPROGRESS) {

        qemu_aio_wait();

    }

    return ret;

}