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[Qemu-devel] [STABLE][PATCH 02/10] block: avoid creating too large iovec
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [STABLE][PATCH 02/10] block: avoid creating too large iovecs in multiwrite_merge |
Date: |
Fri, 9 Apr 2010 11:46:20 +0200 |
From: Christoph Hellwig <address@hidden>
If we go over the maximum number of iovecs support by syscall we get
back EINVAL from the kernel which translate to I/O errors for the guest.
Add a MAX_IOV defintion for platforms that don't have it. For now we use
the same 1024 define that's used on Linux and various other platforms,
but until the windows block backend implements some kind of vectored I/O
it doesn't matter.
Signed-off-by: Christoph Hellwig <address@hidden>
Signed-off-by: Anthony Liguori <address@hidden>
(cherry picked from commit e2a305fb13ff0f5cf6ff805555aaa90a5ed5954c)
Signed-off-by: Kevin Wolf <address@hidden>
---
block.c | 4 ++++
qemu-common.h | 4 ++++
2 files changed, 8 insertions(+), 0 deletions(-)
diff --git a/block.c b/block.c
index 97af3f5..9697dc9 100644
--- a/block.c
+++ b/block.c
@@ -1669,6 +1669,10 @@ static int multiwrite_merge(BlockDriverState *bs,
BlockRequest *reqs,
merge = bs->drv->bdrv_merge_requests(bs, &reqs[outidx], &reqs[i]);
}
+ if (reqs[outidx].qiov->niov + reqs[i].qiov->niov + 1 > IOV_MAX) {
+ merge = 0;
+ }
+
if (merge) {
size_t size;
QEMUIOVector *qiov = qemu_mallocz(sizeof(*qiov));
diff --git a/qemu-common.h b/qemu-common.h
index d96060a..a23afbc 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -54,6 +54,10 @@ struct iovec {
void *iov_base;
size_t iov_len;
};
+/*
+ * Use the same value as Linux for now.
+ */
+#define IOV_MAX 1024
#else
#include <sys/uio.h>
#endif
--
1.6.6.1
- [Qemu-devel] [STABLE][PULL 00/10] Patches for 0.12.4, Kevin Wolf, 2010/04/09
- [Qemu-devel] [STABLE][PATCH 01/10] json-parser: Fix segfault on malformed input, Kevin Wolf, 2010/04/09
- [Qemu-devel] [STABLE][PATCH 02/10] block: avoid creating too large iovecs in multiwrite_merge,
Kevin Wolf <=
- [Qemu-devel] [STABLE][PATCH 05/10] scsi-disk: fix buffer overflow, Kevin Wolf, 2010/04/09
- [Qemu-devel] [STABLE][PATCH 06/10] block: Fix multiwrite error handling, Kevin Wolf, 2010/04/09
- [Qemu-devel] [STABLE][PATCH 03/10] qcow2: Factor next_refcount_table_size out, Kevin Wolf, 2010/04/09
- [Qemu-devel] [STABLE][PATCH 04/10] qcow2: Rewrite alloc_refcount_block/grow_refcount_table, Kevin Wolf, 2010/04/09
- [Qemu-devel] [STABLE][PATCH 10/10] qcow2: Remove request from in-flight list after error, Kevin Wolf, 2010/04/09
- [Qemu-devel] [STABLE][PATCH 09/10] qcow2: Don't ignore immediate read/write failures, Kevin Wolf, 2010/04/09
- [Qemu-devel] [STABLE][PATCH 08/10] block: Fix multiwrite memory leak in error case, Kevin Wolf, 2010/04/09
- [Qemu-devel] [STABLE][PATCH 07/10] block: Fix error code in multiwrite for immediate failures, Kevin Wolf, 2010/04/09
- Re: [Qemu-devel] [STABLE][PULL 00/10] Patches for 0.12.4, Aurelien Jarno, 2010/04/09