Since xen_disk now always copies data to and from a guest there is no need to maintain a vector entry corresponding to every page of a request. This means there is less per-request state to maintain so the ioreq structure can shrink significantly.
Signed-off-by: Paul Durrant <paul.durr...@citrix.com> --- Cc: Stefano Stabellini <sstabell...@kernel.org> Cc: Anthony Perard <anthony.per...@citrix.com> Cc: Kevin Wolf <kw...@redhat.com> Cc: Max Reitz <mre...@redhat.com> --- hw/block/xen_disk.c | 103 ++++++++++++++++------------------------------------ 1 file changed, 31 insertions(+), 72 deletions(-) diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c index 8f4e229..6d737fd 100644 --- a/hw/block/xen_disk.c +++ b/hw/block/xen_disk.c @@ -46,13 +46,10 @@ struct ioreq { /* parsed request */ off_t start; QEMUIOVector v; + void *buf; + size_t size; int presync; - uint32_t domids[BLKIF_MAX_SEGMENTS_PER_REQUEST]; - uint32_t refs[BLKIF_MAX_SEGMENTS_PER_REQUEST]; - void *page[BLKIF_MAX_SEGMENTS_PER_REQUEST]; - void *pages; - /* aio status */ int aio_inflight; int aio_errors; @@ -110,13 +107,10 @@ static void ioreq_reset(struct ioreq *ioreq) memset(&ioreq->req, 0, sizeof(ioreq->req)); ioreq->status = 0; ioreq->start = 0; + ioreq->buf = NULL; + ioreq->size = 0; ioreq->presync = 0; - memset(ioreq->domids, 0, sizeof(ioreq->domids)); - memset(ioreq->refs, 0, sizeof(ioreq->refs)); - memset(ioreq->page, 0, sizeof(ioreq->page)); - ioreq->pages = NULL; - ioreq->aio_inflight = 0; ioreq->aio_errors = 0; @@ -139,7 +133,7 @@ static struct ioreq *ioreq_start(struct XenBlkDev *blkdev) ioreq = g_malloc0(sizeof(*ioreq)); ioreq->blkdev = blkdev; blkdev->requests_total++; - qemu_iovec_init(&ioreq->v, BLKIF_MAX_SEGMENTS_PER_REQUEST); + qemu_iovec_init(&ioreq->v, 1); } else { /* get one from freelist */ ioreq = QLIST_FIRST(&blkdev->freelist); @@ -184,7 +178,6 @@ static void ioreq_release(struct ioreq *ioreq, bool finish) static int ioreq_parse(struct ioreq *ioreq) { struct XenBlkDev *blkdev = ioreq->blkdev; - uintptr_t mem; size_t len; int i; @@ -231,14 +224,10 @@ static int ioreq_parse(struct ioreq *ioreq) goto err; } - ioreq->domids[i] = blkdev->xendev.dom; - ioreq->refs[i] = ioreq->req.seg[i].gref; - - mem = ioreq->req.seg[i].first_sect * blkdev->file_blk; len = (ioreq->req.seg[i].last_sect - ioreq->req.seg[i].first_sect + 1) * blkdev->file_blk; - qemu_iovec_add(&ioreq->v, (void*)mem, len); + ioreq->size += len; } - if (ioreq->start + ioreq->v.size > blkdev->file_size) { + if (ioreq->start + ioreq->size > blkdev->file_size) { xen_pv_printf(&blkdev->xendev, 0, "error: access beyond end of file\n"); goto err; } @@ -249,85 +238,55 @@ err: return -1; } -static void ioreq_free_copy_buffers(struct ioreq *ioreq) -{ - int i; - - for (i = 0; i < ioreq->v.niov; i++) { - ioreq->page[i] = NULL; - } - - qemu_vfree(ioreq->pages); -} - -static int ioreq_init_copy_buffers(struct ioreq *ioreq) -{ - int i; - - if (ioreq->v.niov == 0) { - return 0; - } - - ioreq->pages = qemu_memalign(XC_PAGE_SIZE, ioreq->v.niov * XC_PAGE_SIZE); - - for (i = 0; i < ioreq->v.niov; i++) { - ioreq->page[i] = ioreq->pages + i * XC_PAGE_SIZE; - ioreq->v.iov[i].iov_base = ioreq->page[i]; - } - - return 0; -} - static int ioreq_grant_copy(struct ioreq *ioreq) { - xengnttab_handle *gnt = ioreq->blkdev->xendev.gnttabdev; + struct XenBlkDev *blkdev = ioreq->blkdev; + xengnttab_handle *gnt = blkdev->xendev.gnttabdev; + void *virt = ioreq->buf; xengnttab_grant_copy_segment_t segs[BLKIF_MAX_SEGMENTS_PER_REQUEST]; - int i, count, rc; - int64_t file_blk = ioreq->blkdev->file_blk; - - if (ioreq->v.niov == 0) { - return 0; - } + int i, rc; + int64_t file_blk = blkdev->file_blk; - count = ioreq->v.niov; - - for (i = 0; i < count; i++) { + for (i = 0; i < ioreq->req.nr_segments; i++) { if (ioreq->req.operation == BLKIF_OP_READ) { segs[i].flags = GNTCOPY_dest_gref; - segs[i].dest.foreign.ref = ioreq->refs[i]; - segs[i].dest.foreign.domid = ioreq->domids[i]; + segs[i].dest.foreign.ref = ioreq->req.seg[i].gref; + segs[i].dest.foreign.domid = blkdev->xendev.dom; segs[i].dest.foreign.offset = ioreq->req.seg[i].first_sect * file_blk; - segs[i].source.virt = ioreq->v.iov[i].iov_base; + segs[i].source.virt = virt; } else { segs[i].flags = GNTCOPY_source_gref; - segs[i].source.foreign.ref = ioreq->refs[i]; - segs[i].source.foreign.domid = ioreq->domids[i]; + segs[i].source.foreign.ref = ioreq->req.seg[i].gref; + segs[i].source.foreign.domid = blkdev->xendev.dom; segs[i].source.foreign.offset = ioreq->req.seg[i].first_sect * file_blk; - segs[i].dest.virt = ioreq->v.iov[i].iov_base; + segs[i].dest.virt = virt; } segs[i].len = (ioreq->req.seg[i].last_sect - ioreq->req.seg[i].first_sect + 1) * file_blk; + virt += segs[i].len; } - rc = xengnttab_grant_copy(gnt, count, segs); + rc = xengnttab_grant_copy(gnt, ioreq->req.nr_segments, segs); if (rc) { - xen_pv_printf(&ioreq->blkdev->xendev, 0, + xen_pv_printf(&blkdev->xendev, 0, "failed to copy data %d\n", rc); ioreq->aio_errors++; return -1; } - for (i = 0; i < count; i++) { + for (i = 0; i < ioreq->req.nr_segments; i++) { if (segs[i].status != GNTST_okay) { - xen_pv_printf(&ioreq->blkdev->xendev, 3, + xen_pv_printf(&blkdev->xendev, 3, "failed to copy data %d for gref %d, domid %d\n", - segs[i].status, ioreq->refs[i], ioreq->domids[i]); + segs[i].status, ioreq->req.seg[i].gref, + blkdev->xendev.dom); ioreq->aio_errors++; rc = -1; } } + qemu_iovec_add(&ioreq->v, ioreq->buf, ioreq->size); return rc; } @@ -362,14 +321,14 @@ static void qemu_aio_complete(void *opaque, int ret) if (ret == 0) { ioreq_grant_copy(ioreq); } - ioreq_free_copy_buffers(ioreq); + qemu_vfree(ioreq->buf); break; case BLKIF_OP_WRITE: case BLKIF_OP_FLUSH_DISKCACHE: if (!ioreq->req.nr_segments) { break; } - ioreq_free_copy_buffers(ioreq); + qemu_vfree(ioreq->buf); break; default: break; @@ -437,12 +396,12 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq) { struct XenBlkDev *blkdev = ioreq->blkdev; - ioreq_init_copy_buffers(ioreq); + ioreq->buf = qemu_memalign(XC_PAGE_SIZE, ioreq->size); if (ioreq->req.nr_segments && (ioreq->req.operation == BLKIF_OP_WRITE || ioreq->req.operation == BLKIF_OP_FLUSH_DISKCACHE) && ioreq_grant_copy(ioreq)) { - ioreq_free_copy_buffers(ioreq); + qemu_vfree(ioreq->buf); goto err; } -- 2.1.4