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From 35538bdb46122fdf90ca869df29869b8aeaefa09 Mon Sep 17 00:00:00 2001
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From: Stefan Hajnoczi <stefanha@redhat.com>
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Date: Tue, 25 Mar 2014 14:23:42 +0100
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Subject: [PATCH 35/49] dmg: drop broken bdrv_pread() loop
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <1395753835-7591-36-git-send-email-kwolf@redhat.com>
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Patchwork-id: n/a
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O-Subject: [virt-devel] [EMBARGOED RHEL-7.0 qemu-kvm PATCH 35/48] dmg: drop broken bdrv_pread() loop
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Bugzilla: 1066691
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RH-Acked-by: Jeff Cody <jcody@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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From: Stefan Hajnoczi <stefanha@redhat.com>
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Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1066691
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Upstream status: Series embargoed
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It is not necessary to check errno for EINTR and the block layer does
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not produce short reads. Therefore we can drop the loop that attempts
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to read a compressed chunk.
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The loop is buggy because it incorrectly adds the transferred bytes
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twice:
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do {
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ret = bdrv_pread(...);
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i += ret;
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} while (ret >= 0 && ret + i < s->lengths[chunk]);
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Luckily we can drop the loop completely and perform a single
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bdrv_pread().
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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---
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block/dmg.c | 15 ++-------------
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1 files changed, 2 insertions(+), 13 deletions(-)
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diff --git a/block/dmg.c b/block/dmg.c
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index f4f3e8e..1cc5426 100644
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--- a/block/dmg.c
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+++ b/block/dmg.c
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@@ -298,21 +298,10 @@ static inline int dmg_read_chunk(BlockDriverState *bs, int sector_num)
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s->current_chunk = s->n_chunks;
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switch (s->types[chunk]) {
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case 0x80000005: { /* zlib compressed */
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- int i;
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-
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/* we need to buffer, because only the chunk as whole can be
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* inflated. */
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- i = 0;
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- do {
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- ret = bdrv_pread(bs->file, s->offsets[chunk] + i,
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- s->compressed_chunk + i,
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- s->lengths[chunk] - i);
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- if (ret < 0 && errno == EINTR) {
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- ret = 0;
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- }
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- i += ret;
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- } while (ret >= 0 && ret + i < s->lengths[chunk]);
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-
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+ ret = bdrv_pread(bs->file, s->offsets[chunk],
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+ s->compressed_chunk, s->lengths[chunk]);
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if (ret != s->lengths[chunk]) {
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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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