qcow: Avoid direct AIO callback
bdrv_aio_* must not call the callback before returning to its caller. In qcow, this could happen in some error cases. This starts the real requests processing in a BH to avoid this situation. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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42496d6240
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b11a24dee6
58
block/qcow.c
58
block/qcow.c
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@ -496,6 +496,8 @@ typedef struct QCowAIOCB {
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uint64_t cluster_offset;
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uint8_t *cluster_data;
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struct iovec hd_iov;
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bool is_write;
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QEMUBH *bh;
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QEMUIOVector hd_qiov;
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BlockDriverAIOCB *hd_aiocb;
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} QCowAIOCB;
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@ -525,6 +527,8 @@ static QCowAIOCB *qcow_aio_setup(BlockDriverState *bs,
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acb->hd_aiocb = NULL;
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acb->sector_num = sector_num;
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acb->qiov = qiov;
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acb->is_write = is_write;
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if (qiov->niov > 1) {
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acb->buf = acb->orig_buf = qemu_blockalign(bs, qiov->size);
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if (is_write)
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@ -538,6 +542,38 @@ static QCowAIOCB *qcow_aio_setup(BlockDriverState *bs,
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return acb;
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}
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static void qcow_aio_read_cb(void *opaque, int ret);
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static void qcow_aio_write_cb(void *opaque, int ret);
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static void qcow_aio_rw_bh(void *opaque)
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{
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QCowAIOCB *acb = opaque;
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qemu_bh_delete(acb->bh);
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acb->bh = NULL;
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if (acb->is_write) {
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qcow_aio_write_cb(opaque, 0);
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} else {
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qcow_aio_read_cb(opaque, 0);
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}
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}
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static int qcow_schedule_bh(QEMUBHFunc *cb, QCowAIOCB *acb)
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{
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if (acb->bh) {
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return -EIO;
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}
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acb->bh = qemu_bh_new(cb, acb);
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if (!acb->bh) {
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return -EIO;
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}
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qemu_bh_schedule(acb->bh);
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return 0;
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}
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static void qcow_aio_read_cb(void *opaque, int ret)
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{
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QCowAIOCB *acb = opaque;
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@ -640,12 +676,21 @@ static BlockDriverAIOCB *qcow_aio_readv(BlockDriverState *bs,
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BlockDriverCompletionFunc *cb, void *opaque)
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{
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QCowAIOCB *acb;
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int ret;
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acb = qcow_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, 0);
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if (!acb)
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return NULL;
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qcow_aio_read_cb(acb, 0);
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ret = qcow_schedule_bh(qcow_aio_rw_bh, acb);
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if (ret < 0) {
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if (acb->qiov->niov > 1) {
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qemu_vfree(acb->orig_buf);
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}
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qemu_aio_release(acb);
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return NULL;
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}
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return &acb->common;
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}
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@ -725,6 +770,7 @@ static BlockDriverAIOCB *qcow_aio_writev(BlockDriverState *bs,
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{
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BDRVQcowState *s = bs->opaque;
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QCowAIOCB *acb;
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int ret;
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s->cluster_cache_offset = -1; /* disable compressed cache */
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@ -733,7 +779,15 @@ static BlockDriverAIOCB *qcow_aio_writev(BlockDriverState *bs,
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return NULL;
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qcow_aio_write_cb(acb, 0);
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ret = qcow_schedule_bh(qcow_aio_rw_bh, acb);
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if (ret < 0) {
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if (acb->qiov->niov > 1) {
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qemu_vfree(acb->orig_buf);
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}
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qemu_aio_release(acb);
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return NULL;
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}
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return &acb->common;
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}
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