[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH] block/vdi: Fix locking for parallel requests
From: |
Max Reitz |
Subject: |
[Qemu-devel] [PATCH] block/vdi: Fix locking for parallel requests |
Date: |
Tue, 17 Feb 2015 16:33:39 -0500 |
Concurrently modifying the bmap is not a good idea; this patch adds a
lock for it. See https://bugs.launchpad.net/qemu/+bug/1422307 for what
can go wrong without.
Signed-off-by: Max Reitz <address@hidden>
---
block/vdi.c | 23 ++++++++++++++++++++---
1 file changed, 20 insertions(+), 3 deletions(-)
diff --git a/block/vdi.c b/block/vdi.c
index 74030c6..c5ff428 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,
@@ -619,6 +624,9 @@ static int vdi_co_write(BlockDriverState *bs,
n_sectors, sector_num);
/* prepare next AIO request */
+ if (!block) {
+ qemu_co_mutex_lock(&s->bmap_lock);
+ }
bmap_entry = le32_to_cpu(s->bmap[block_index]);
if (!VDI_IS_ALLOCATED(bmap_entry)) {
/* Allocate new block and write to it. */
@@ -641,9 +649,13 @@ static int vdi_co_write(BlockDriverState *bs,
(s->block_sectors - n_sectors - sector_in_block) *
SECTOR_SIZE);
ret = bdrv_write(bs->file, offset, block, s->block_sectors);
} else {
- uint64_t offset = s->header.offset_data / SECTOR_SIZE +
- (uint64_t)bmap_entry * s->block_sectors +
- sector_in_block;
+ uint64_t offset;
+
+ qemu_co_mutex_unlock(&s->bmap_lock);
+
+ offset = s->header.offset_data / SECTOR_SIZE +
+ (uint64_t)bmap_entry * s->block_sectors +
+ sector_in_block;
ret = bdrv_write(bs->file, offset, buf, n_sectors);
}
@@ -656,6 +668,9 @@ static int vdi_co_write(BlockDriverState *bs,
logout("finished data write\n");
if (ret < 0) {
+ if (block) {
+ qemu_co_mutex_unlock(&s->bmap_lock);
+ }
return ret;
}
@@ -688,6 +703,8 @@ static int vdi_co_write(BlockDriverState *bs,
logout("will write %u block map sectors starting from entry %u\n",
n_sectors, bmap_first);
ret = bdrv_write(bs->file, offset, base, n_sectors);
+
+ qemu_co_mutex_unlock(&s->bmap_lock);
}
return ret;
--
2.1.0
- [Qemu-devel] [PATCH] block/vdi: Fix locking for parallel requests,
Max Reitz <=