From 5f5aa9ae86ff5d78c7c558f9883cf6e47e475730 Mon Sep 17 00:00:00 2001 From: Olaf Hering Date: Thu, 30 Jan 2014 16:02:18 +0100 Subject: [PATCH] xen_disk: add discard support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Implement discard support for xen_disk. It makes use of the existing discard code in qemu. The discard support is enabled unconditionally. The tool stack may provide a property "discard-enable" in the backend node to optionally disable discard support. This is helpful in case the backing file was intentionally created non-sparse to avoid fragmentation. Signed-off-by: Olaf Hering Signed-off-by: Andreas Färber --- hw/block/xen_blkif.h | 12 ++++++++++++ hw/block/xen_disk.c | 34 ++++++++++++++++++++++++++++++++++ 2 files changed, 46 insertions(+) diff --git a/hw/block/xen_blkif.h b/hw/block/xen_blkif.h index c0f4136..711b692 100644 --- a/hw/block/xen_blkif.h +++ b/hw/block/xen_blkif.h @@ -79,6 +79,12 @@ static inline void blkif_get_x86_32_req(blkif_request_t *dst, blkif_x86_32_reque dst->handle = src->handle; dst->id = src->id; dst->sector_number = src->sector_number; + if (src->operation == BLKIF_OP_DISCARD) { + struct blkif_request_discard *s = (void *)src; + struct blkif_request_discard *d = (void *)dst; + d->nr_sectors = s->nr_sectors; + return; + } if (n > src->nr_segments) n = src->nr_segments; for (i = 0; i < n; i++) @@ -94,6 +100,12 @@ static inline void blkif_get_x86_64_req(blkif_request_t *dst, blkif_x86_64_reque dst->handle = src->handle; dst->id = src->id; dst->sector_number = src->sector_number; + if (src->operation == BLKIF_OP_DISCARD) { + struct blkif_request_discard *s = (void *)src; + struct blkif_request_discard *d = (void *)dst; + d->nr_sectors = s->nr_sectors; + return; + } if (n > src->nr_segments) n = src->nr_segments; for (i = 0; i < n; i++) diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c index bc061e6..989a90f 100644 --- a/hw/block/xen_disk.c +++ b/hw/block/xen_disk.c @@ -114,6 +114,7 @@ struct XenBlkDev { int requests_finished; /* Persistent grants extension */ + gboolean feature_discard; gboolean feature_persistent; GTree *persistent_gnts; unsigned int persistent_gnt_count; @@ -253,6 +254,8 @@ static int ioreq_parse(struct ioreq *ioreq) case BLKIF_OP_WRITE: ioreq->prot = PROT_READ; /* from memory */ break; + case BLKIF_OP_DISCARD: + return 0; default: xen_be_printf(&blkdev->xendev, 0, "error: unknown operation (%d)\n", ioreq->req.operation); @@ -532,6 +535,17 @@ static int ioreq_runio_qemu_aio(struct ioreq *ioreq) &ioreq->v, ioreq->v.size / BLOCK_SIZE, qemu_aio_complete, ioreq); break; + case BLKIF_OP_DISCARD: + { + struct blkif_request_discard *discard_req = (void *)&ioreq->req; + bdrv_acct_start(blkdev->bs, &ioreq->acct, + discard_req->nr_sectors * BLOCK_SIZE, BDRV_ACCT_WRITE); + ioreq->aio_inflight++; + bdrv_aio_discard(blkdev->bs, + discard_req->sector_number, discard_req->nr_sectors, + qemu_aio_complete, ioreq); + break; + } default: /* unknown operation (shouldn't happen -- parse catches this) */ goto err; @@ -710,6 +724,21 @@ static void blk_alloc(struct XenDevice *xendev) } } +static void blk_parse_discard(struct XenBlkDev *blkdev) +{ + int enable; + + blkdev->feature_discard = true; + + if (xenstore_read_be_int(&blkdev->xendev, "discard-enable", &enable) == 0) { + blkdev->feature_discard = !!enable; + } + + if (blkdev->feature_discard) { + xenstore_write_be_int(&blkdev->xendev, "feature-discard", 1); + } +} + static int blk_init(struct XenDevice *xendev) { struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev); @@ -777,6 +806,8 @@ static int blk_init(struct XenDevice *xendev) xenstore_write_be_int(&blkdev->xendev, "feature-persistent", 1); xenstore_write_be_int(&blkdev->xendev, "info", info); + blk_parse_discard(blkdev); + g_free(directiosafe); return 0; @@ -812,6 +843,9 @@ static int blk_connect(struct XenDevice *xendev) qflags |= BDRV_O_RDWR; readonly = false; } + if (blkdev->feature_discard) { + qflags |= BDRV_O_UNMAP; + } /* init qemu block driver */ index = (blkdev->xendev.dev - 202 * 256) / 16;