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Blame SOURCES/kvm-vmdk-Only-read-cid-from-image-file-when-opening.patch

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From 5bd906f28072f5d071705801cc1dd2e9084057bc Mon Sep 17 00:00:00 2001
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From: Max Reitz <mreitz@redhat.com>
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Date: Wed, 6 Nov 2013 16:53:43 +0100
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Subject: [PATCH 86/87] vmdk: Only read cid from image file when opening
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RH-Author: Max Reitz <mreitz@redhat.com>
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Message-id: <1383756824-6921-21-git-send-email-mreitz@redhat.com>
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Patchwork-id: 55575
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O-Subject: [RHEL-7.0 qemu-kvm PATCH v2 20/21] vmdk: Only read cid from image file when opening
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Bugzilla: 980771
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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RH-Acked-by: Jeffrey Cody <jcody@redhat.com>
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From: Fam Zheng <famz@redhat.com>
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BZ: 980771
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Previously cid of parent is parsed from image file for every IO request.
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We already have L1/L2 cache and don't have assumption that parent image
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can be updated behind us, so remove this to get more efficiency.
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The parent CID is checked only for once after opening.
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Signed-off-by: Fam Zheng <famz@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit c338b6ad609699cf352c8dd6338360b7e3895ad0)
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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---
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 block/vmdk.c | 8 +++-----
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 1 file changed, 3 insertions(+), 5 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/vmdk.c |    8 +++-----
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 1 files changed, 3 insertions(+), 5 deletions(-)
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diff --git a/block/vmdk.c b/block/vmdk.c
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index ccbb0c9..8bef9f2 100644
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--- a/block/vmdk.c
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+++ b/block/vmdk.c
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@@ -112,6 +112,7 @@ typedef struct BDRVVmdkState {
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     CoMutex lock;
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     uint64_t desc_offset;
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     bool cid_updated;
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+    bool cid_checked;
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     uint32_t parent_cid;
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     int num_extents;
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     /* Extent array with num_extents entries, ascend ordered by address */
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@@ -197,8 +198,6 @@ static int vmdk_probe(const uint8_t *buf, int buf_size, const char *filename)
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     }
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 }
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-#define CHECK_CID 1
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-
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 #define SECTOR_SIZE 512
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 #define DESC_SIZE (20 * SECTOR_SIZE)    /* 20 sectors of 512 bytes each */
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 #define BUF_SIZE 4096
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@@ -301,19 +300,18 @@ static int vmdk_write_cid(BlockDriverState *bs, uint32_t cid)
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 static int vmdk_is_cid_valid(BlockDriverState *bs)
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 {
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-#ifdef CHECK_CID
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     BDRVVmdkState *s = bs->opaque;
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     BlockDriverState *p_bs = bs->backing_hd;
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     uint32_t cur_pcid;
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-    if (p_bs) {
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+    if (!s->cid_checked && p_bs) {
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         cur_pcid = vmdk_read_cid(p_bs, 0);
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         if (s->parent_cid != cur_pcid) {
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             /* CID not valid */
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             return 0;
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         }
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     }
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-#endif
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+    s->cid_checked = true;
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     /* CID valid */
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     return 1;
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 }
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-- 
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1.7.1
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