From: Avi Kivity <avi@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: [Qemu-devel] [PATCH +stable] block: don't attempt to merge overlapping requests
Date: Tue, 18 May 2010 20:18:44 +0300 [thread overview]
Message-ID: <1274203124-14318-1-git-send-email-avi@redhat.com> (raw)
The block multiwrite code pretends to be able to merge overlapping requests,
but doesn't do so in fact. This leads to I/O errors (for example on mkfs
of a large virtio disk).
Signed-off-by: Avi Kivity <avi@redhat.com>
---
block.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/block.c b/block.c
index 48305b7..0e44e26 100644
--- a/block.c
+++ b/block.c
@@ -1956,8 +1956,8 @@ static int multiwrite_merge(BlockDriverState *bs, BlockRequest *reqs,
int64_t oldreq_last = reqs[outidx].sector + reqs[outidx].nb_sectors;
// This handles the cases that are valid for all block drivers, namely
- // exactly sequential writes and overlapping writes.
- if (reqs[i].sector <= oldreq_last) {
+ // exactly sequential writes
+ if (reqs[i].sector == oldreq_last) {
merge = 1;
}
--
1.6.6.1
next reply other threads:[~2010-05-18 17:19 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-18 17:18 Avi Kivity [this message]
2010-05-18 19:22 ` [Qemu-devel] Re: [PATCH +stable] block: don't attempt to merge overlapping requests Stefan Hajnoczi
2010-05-18 19:37 ` Stefan Hajnoczi
2010-05-18 19:41 ` Michael Tokarev
2010-05-18 20:19 ` Stefan Hajnoczi
2010-05-19 8:09 ` Avi Kivity
2010-05-19 9:01 ` Stefan Hajnoczi
2010-05-19 9:06 ` Avi Kivity
2010-05-19 9:23 ` Stefan Hajnoczi
2010-05-19 9:31 ` Christoph Hellwig
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