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162 lines
5.6 KiB
162 lines
5.6 KiB
From 74aaa42e1f25309a163acd00083ecbbc186fbb47 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
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<marmarek@invisiblethingslab.com>
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Date: Wed, 16 Dec 2015 06:07:14 +0100
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Subject: [PATCH 13/13] xen-blkfront: prepare request locally, only then put it
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on the shared ring
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Organization: Invisible Things Lab
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Cc: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
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Do not reuse data which theoretically might be already modified by the
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backend. This is mostly about private copy of the request
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(info->shadow[id].req) - make sure the request saved there is really the
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one just filled.
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This is part of XSA155.
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CC: stable@vger.kernel.org
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Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
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---
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drivers/block/xen-blkfront.c | 56 ++++++++++++++++++++++++--------------------
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1 file changed, 30 insertions(+), 26 deletions(-)
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diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
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index 5d7eb04..514cf18 100644
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--- a/drivers/block/xen-blkfront.c
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+++ b/drivers/block/xen-blkfront.c
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@@ -463,27 +463,29 @@ static int blkif_ioctl(struct block_devi
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static int blkif_queue_discard_req(struct request *req)
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{
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struct blkfront_info *info = req->rq_disk->private_data;
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- struct blkif_request *ring_req;
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+ struct blkif_request ring_req = { };
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unsigned long id;
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/* Fill out a communications ring structure. */
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- ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
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id = get_id_from_freelist(info);
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info->shadow[id].request = req;
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- ring_req->operation = BLKIF_OP_DISCARD;
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- ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
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- ring_req->u.discard.id = id;
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- ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
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+ ring_req.operation = BLKIF_OP_DISCARD;
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+ ring_req.u.discard.nr_sectors = blk_rq_sectors(req);
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+ ring_req.u.discard.id = id;
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+ ring_req.u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
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if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
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- ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
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+ ring_req.u.discard.flag = BLKIF_DISCARD_SECURE;
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else
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- ring_req->u.discard.flag = 0;
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+ ring_req.u.discard.flag = 0;
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+ /* make the request available to the backend */
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+ *RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt) = ring_req;
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+ wmb();
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info->ring.req_prod_pvt++;
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/* Keep a private copy so we can reissue requests when recovering. */
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- info->shadow[id].req = *ring_req;
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+ info->shadow[id].req = ring_req;
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return 0;
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}
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@@ -573,7 +575,7 @@ static void blkif_setup_rw_req_grant(uns
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static int blkif_queue_rw_req(struct request *req)
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{
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struct blkfront_info *info = req->rq_disk->private_data;
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- struct blkif_request *ring_req;
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+ struct blkif_request ring_req = { };
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unsigned long id;
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int i;
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struct setup_rw_req setup = {
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@@ -435,7 +435,6 @@
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new_persistent_gnts = 0;
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/* Fill out a communications ring structure. */
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- ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
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id = get_id_from_freelist(info);
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info->shadow[id].request = req;
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@@ -632,7 +633,7 @@ static int blkif_queue_rw_req(struct req
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for_each_sg(info->shadow[id].sg, sg, num_sg, i)
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num_grant += gnttab_count_grant(sg->offset, sg->length);
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- ring_req->u.rw.id = id;
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+ ring_req.u.rw.id = id;
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info->shadow[id].num_sg = num_sg;
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if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST) {
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/*
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@@ -640,16 +641,16 @@ static int blkif_queue_rw_req(struct req
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* BLKIF_OP_WRITE
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*/
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BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA));
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- ring_req->operation = BLKIF_OP_INDIRECT;
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- ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
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+ ring_req.operation = BLKIF_OP_INDIRECT;
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+ ring_req.u.indirect.indirect_op = rq_data_dir(req) ?
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BLKIF_OP_WRITE : BLKIF_OP_READ;
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- ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
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- ring_req->u.indirect.handle = info->handle;
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- ring_req->u.indirect.nr_segments = num_grant;
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+ ring_req.u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
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+ ring_req.u.indirect.handle = info->handle;
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+ ring_req.u.indirect.nr_segments = num_grant;
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} else {
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- ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
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- ring_req->u.rw.handle = info->handle;
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- ring_req->operation = rq_data_dir(req) ?
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+ ring_req.u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
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+ ring_req.u.rw.handle = info->handle;
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+ ring_req.operation = rq_data_dir(req) ?
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BLKIF_OP_WRITE : BLKIF_OP_READ;
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if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
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/*
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@@ -662,21 +663,21 @@ static int blkif_queue_rw_req(struct req
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switch (info->feature_flush &
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((REQ_FLUSH|REQ_FUA))) {
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case REQ_FLUSH|REQ_FUA:
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- ring_req->operation =
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+ ring_req.operation =
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BLKIF_OP_WRITE_BARRIER;
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break;
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case REQ_FLUSH:
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- ring_req->operation =
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+ ring_req.operation =
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BLKIF_OP_FLUSH_DISKCACHE;
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break;
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default:
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- ring_req->operation = 0;
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+ ring_req.operation = 0;
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}
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}
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- ring_req->u.rw.nr_segments = num_grant;
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+ ring_req.u.rw.nr_segments = num_grant;
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}
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- setup.ring_req = ring_req;
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+ setup.ring_req = &ring_req;
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setup.id = id;
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for_each_sg(info->shadow[id].sg, sg, num_sg, i) {
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BUG_ON(sg->offset + sg->length > PAGE_SIZE);
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@@ -698,10 +699,13 @@ static int blkif_queue_rw_req(struct req
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if (setup.segments)
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kunmap_atomic(setup.segments);
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+ /* make the request available to the backend */
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+ *RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt) = ring_req;
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+ wmb();
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info->ring.req_prod_pvt++;
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/* Keep a private copy so we can reissue requests when recovering. */
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- info->shadow[id].req = *ring_req;
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+ info->shadow[id].req = ring_req;
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if (new_persistent_gnts)
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gnttab_free_grant_references(setup.gref_head);
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