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[Qemu-stable] [PATCH v2] block/vdi: Add locking for parallel requests
From: |
Max Reitz |
Subject: |
[Qemu-stable] [PATCH v2] block/vdi: Add locking for parallel requests |
Date: |
Fri, 27 Feb 2015 09:05:47 -0500 |
Concurrently modifying the bmap does not seem to be a good idea; this patch adds
a lock for it. See https://bugs.launchpad.net/qemu/+bug/1422307 for what
can go wrong without.
Cc: qemu-stable <address@hidden>
Signed-off-by: Max Reitz <address@hidden>
---
v2:
- Make the mutex cover vdi_co_write() completely [Kevin]
- Add a TODO comment [Kevin]
---
block/vdi.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/block/vdi.c b/block/vdi.c
index 74030c6..f5f42ef 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -51,6 +51,7 @@
#include "qemu-common.h"
#include "block/block_int.h"
+#include "block/coroutine.h"
#include "qemu/module.h"
#include "migration/migration.h"
@@ -196,6 +197,8 @@ typedef struct {
/* VDI header (converted to host endianness). */
VdiHeader header;
+ CoMutex bmap_lock;
+
Error *migration_blocker;
} BDRVVdiState;
@@ -498,6 +501,8 @@ static int vdi_open(BlockDriverState *bs, QDict *options,
int flags,
goto fail_free_bmap;
}
+ qemu_co_mutex_init(&s->bmap_lock);
+
/* Disable migration when vdi images are used */
error_set(&s->migration_blocker,
QERR_BLOCK_FORMAT_FEATURE_NOT_SUPPORTED,
@@ -607,6 +612,9 @@ static int vdi_co_write(BlockDriverState *bs,
logout("\n");
+ /* TODO: Figure out why this is necessary */
+ qemu_co_mutex_lock(&s->bmap_lock);
+
while (ret >= 0 && nb_sectors > 0) {
block_index = sector_num / s->block_sectors;
sector_in_block = sector_num % s->block_sectors;
@@ -656,6 +664,7 @@ static int vdi_co_write(BlockDriverState *bs,
logout("finished data write\n");
if (ret < 0) {
+ qemu_co_mutex_unlock(&s->bmap_lock);
return ret;
}
@@ -674,6 +683,7 @@ static int vdi_co_write(BlockDriverState *bs,
block = NULL;
if (ret < 0) {
+ qemu_co_mutex_unlock(&s->bmap_lock);
return ret;
}
@@ -690,6 +700,7 @@ static int vdi_co_write(BlockDriverState *bs,
ret = bdrv_write(bs->file, offset, base, n_sectors);
}
+ qemu_co_mutex_unlock(&s->bmap_lock);
return ret;
}
--
2.1.0
- [Qemu-stable] [PATCH v2] block/vdi: Add locking for parallel requests,
Max Reitz <=
- Re: [Qemu-stable] [PATCH v2] block/vdi: Add locking for parallel requests, Stefan Hajnoczi, 2015/02/27
- Re: [Qemu-stable] [PATCH v2] block/vdi: Add locking for parallel requests, Max Reitz, 2015/02/27
- Re: [Qemu-stable] [Qemu-devel] [PATCH v2] block/vdi: Add locking for parallel requests, Stefan Weil, 2015/02/27
- Re: [Qemu-stable] [Qemu-devel] [PATCH v2] block/vdi: Add locking for parallel requests, Max Reitz, 2015/02/27
- Re: [Qemu-stable] [Qemu-devel] [PATCH v2] block/vdi: Add locking for parallel requests, Stefan Weil, 2015/02/27
- Re: [Qemu-stable] [Qemu-devel] [PATCH v2] block/vdi: Add locking for parallel requests, Stefan Weil, 2015/02/27
- Re: [Qemu-stable] [Qemu-devel] [PATCH v2] block/vdi: Add locking for parallel requests, Max Reitz, 2015/02/27
- Re: [Qemu-stable] [Qemu-devel] [PATCH v2] block/vdi: Add locking for parallel requests, Stefan Weil, 2015/02/27
- Re: [Qemu-stable] [Qemu-devel] [PATCH v2] block/vdi: Add locking for parallel requests, Max Reitz, 2015/02/27
- Re: [Qemu-stable] [Qemu-devel] [PATCH v2] block/vdi: Add locking for parallel requests, Max Reitz, 2015/02/27