Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
---
block.c | 6 ++++--
block/io.c | 8 ++++----
blockdev.c | 2 +-
include/block/block_int.h | 11 ++++++-----
4 files changed, 15 insertions(+), 12 deletions(-)
diff --git a/block.c b/block.c
index 50ba264..f6066ef 100644
--- a/block.c
+++ b/block.c
@@ -1260,7 +1260,9 @@ static int bdrv_open_common(BlockDriverState *bs,
BlockBackend *file,
goto fail_opts;
}
- assert(bs->copy_on_read == 0); /* bdrv_new() and bdrv_close() make it so */
+ /* bdrv_new() and bdrv_close() make it so */
+ assert(atomic_read(&bs->copy_on_read) == 0);
+
if (bs->open_flags & BDRV_O_COPY_ON_READ) {
if (!bs->read_only) {
bdrv_enable_copy_on_read(bs);
@@ -3023,7 +3025,7 @@ static void bdrv_close(BlockDriverState *bs)
g_free(bs->opaque);
bs->opaque = NULL;
- bs->copy_on_read = 0;
+ atomic_set(&bs->copy_on_read, 0);
bs->backing_file[0] = '\0';
bs->backing_format[0] = '\0';
bs->total_sectors = 0;
diff --git a/block/io.c b/block/io.c
index fdd7485..80a3a8c 100644
--- a/block/io.c
+++ b/block/io.c
@@ -129,13 +129,13 @@ void bdrv_refresh_limits(BlockDriverState *bs, Error
**errp)
*/
void bdrv_enable_copy_on_read(BlockDriverState *bs)
{
- bs->copy_on_read++;
+ atomic_inc(&bs->copy_on_read);
}
void bdrv_disable_copy_on_read(BlockDriverState *bs)
{
- assert(bs->copy_on_read > 0);
- bs->copy_on_read--;
+ int old = atomic_fetch_dec(&bs->copy_on_read);
+ assert(old >= 1);
}
/* Check if any requests are in-flight (including throttled requests) */
@@ -1157,7 +1157,7 @@ int coroutine_fn bdrv_co_preadv(BdrvChild *child,
bdrv_inc_in_flight(bs);
/* Don't do copy-on-read if we read data before write operation */
- if (bs->copy_on_read && !(flags & BDRV_REQ_NO_SERIALISING)) {
+ if (atomic_read(&bs->copy_on_read) && !(flags & BDRV_REQ_NO_SERIALISING)) {
flags |= BDRV_REQ_COPY_ON_READ;
}
diff --git a/blockdev.c b/blockdev.c
index c63f4e8..a2fa9f7 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -1791,7 +1791,7 @@ static void external_snapshot_commit(BlkActionState
*common)
/* We don't need (or want) to use the transactional
* bdrv_reopen_multiple() across all the entries at once, because we
* don't want to abort all of them if one of them fails the reopen */
- if (!state->old_bs->copy_on_read) {
+ if (!atomic_read(&state->old_bs->copy_on_read)) {
bdrv_reopen(state->old_bs, state->old_bs->open_flags & ~BDRV_O_RDWR,
NULL);
}
diff --git a/include/block/block_int.h b/include/block/block_int.h
index 8d3724c..c71492a 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -595,11 +595,6 @@ struct BlockDriverState {
/* Protected by AioContext lock */
- /* If true, copy read backing sectors into image. Can be >1 if more
- * than one client has requested copy-on-read.
- */
- int copy_on_read;
-
/* If we are reading a disk image, give its size in sectors.
* Generally read-only; it is written to by load_vmstate and save_vmstate,
* but the block layer is quiescent during those.
@@ -633,6 +628,12 @@ struct BlockDriverState {
QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps;
+ /* If true, copy read backing sectors into image. Can be >1 if more
+ * than one client has requested copy-on-read. Accessed with atomic
+ * ops.
+ */
+ int copy_on_read;
+
/* do we need to tell the quest if we have a volatile write cache? */
int enable_write_cache;
--
1.8.3.1
