diff --git a/block/copy-before-write.c b/block/copy-before-write.c
index c83c9c7c46f25ea2d0651f6b8683b8afba9b441c..a8a06fdc09b6a9e2dcdfe82f54c74179fb367ced 100644
--- a/block/copy-before-write.c
+++ b/block/copy-before-write.c
@@ -33,12 +33,37 @@
#include "block/block-copy.h"
#include "block/copy-before-write.h"
+#include "block/reqlist.h"
#include "qapi/qapi-visit-block-core.h"
typedef struct BDRVCopyBeforeWriteState {
BlockCopyState *bcs;
BdrvChild *target;
+
+ /*
+ * @lock: protects access to @access_bitmap, @done_bitmap and
+ * @frozen_read_reqs
+ */
+ CoMutex lock;
+
+ /*
+ * @access_bitmap: represents areas allowed for reading by fleecing user.
+ * Reading from non-dirty areas leads to -EACCES.
+ */
+ BdrvDirtyBitmap *access_bitmap;
+
+ /*
+ * @done_bitmap: represents areas that was successfully copied to @target by
+ * copy-before-write operations.
+ */
+ BdrvDirtyBitmap *done_bitmap;
+
+ /*
+ * @frozen_read_reqs: current read requests for fleecing user in bs->file
+ * node. These areas must not be rewritten by guest.
+ */
+ BlockReqList frozen_read_reqs;
} BDRVCopyBeforeWriteState;
static coroutine_fn int cbw_co_preadv(
@@ -48,10 +73,20 @@ static coroutine_fn int cbw_co_preadv(
return bdrv_co_preadv(bs->file, offset, bytes, qiov, flags);
}
+/*
+ * Do copy-before-write operation.
+ *
+ * On failure guest request must be failed too.
+ *
+ * On success, we also wait for all in-flight fleecing read requests in source
+ * node, and it's guaranteed that after cbw_do_copy_before_write() successful
+ * return there are no such requests and they will never appear.
+ */
static coroutine_fn int cbw_do_copy_before_write(BlockDriverState *bs,
uint64_t offset, uint64_t bytes, BdrvRequestFlags flags)
{
BDRVCopyBeforeWriteState *s = bs->opaque;
+ int ret;
uint64_t off, end;
int64_t cluster_size = block_copy_cluster_size(s->bcs);
@@ -62,7 +97,17 @@ static coroutine_fn int cbw_do_copy_before_write(BlockDriverState *bs,
off = QEMU_ALIGN_DOWN(offset, cluster_size);
end = QEMU_ALIGN_UP(offset + bytes, cluster_size);
- return block_copy(s->bcs, off, end - off, true);
+ ret = block_copy(s->bcs, off, end - off, true);
+ if (ret < 0) {
+ return ret;
+ }
+
+ WITH_QEMU_LOCK_GUARD(&s->lock) {
+ bdrv_set_dirty_bitmap(s->done_bitmap, off, end - off);
+ reqlist_wait_all(&s->frozen_read_reqs, off, end - off, &s->lock);
+ }
+
+ return 0;
}
static int coroutine_fn cbw_co_pdiscard(BlockDriverState *bs,
@@ -110,6 +155,142 @@ static int coroutine_fn cbw_co_flush(BlockDriverState *bs)
return bdrv_co_flush(bs->file->bs);
}
+/*
+ * If @offset not accessible - return NULL.
+ *
+ * Otherwise, set @pnum to some bytes that accessible from @file (@file is set
+ * to bs->file or to s->target). Return newly allocated BlockReq object that
+ * should be than passed to cbw_snapshot_read_unlock().
+ *
+ * It's guaranteed that guest writes will not interact in the region until
+ * cbw_snapshot_read_unlock() called.
+ */
+static BlockReq *cbw_snapshot_read_lock(BlockDriverState *bs,
+ int64_t offset, int64_t bytes,
+ int64_t *pnum, BdrvChild **file)
+{
+ BDRVCopyBeforeWriteState *s = bs->opaque;
+ BlockReq *req = g_new(BlockReq, 1);
+ bool done;
+
+ QEMU_LOCK_GUARD(&s->lock);
+
+ if (bdrv_dirty_bitmap_next_zero(s->access_bitmap, offset, bytes) != -1) {
+ g_free(req);
+ return NULL;
+ }
+
+ done = bdrv_dirty_bitmap_status(s->done_bitmap, offset, bytes, pnum);
+ if (done) {
+ /*
+ * Special invalid BlockReq, that is handled in
+ * cbw_snapshot_read_unlock(). We don't need to lock something to read
+ * from s->target.
+ */
+ *req = (BlockReq) {.offset = -1, .bytes = -1};
+ *file = s->target;
+ } else {
+ reqlist_init_req(&s->frozen_read_reqs, req, offset, bytes);
+ *file = bs->file;
+ }
+
+ return req;
+}
+
+static void cbw_snapshot_read_unlock(BlockDriverState *bs, BlockReq *req)
+{
+ BDRVCopyBeforeWriteState *s = bs->opaque;
+
+ if (req->offset == -1 && req->bytes == -1) {
+ g_free(req);
+ return;
+ }
+
+ QEMU_LOCK_GUARD(&s->lock);
+
+ reqlist_remove_req(req);
+ g_free(req);
+}
+
+static coroutine_fn int
+cbw_co_preadv_snapshot(BlockDriverState *bs, int64_t offset, int64_t bytes,
+ QEMUIOVector *qiov, size_t qiov_offset)
+{
+ BlockReq *req;
+ BdrvChild *file;
+ int ret;
+
+ /* TODO: upgrade to async loop using AioTask */
+ while (bytes) {
+ int64_t cur_bytes;
+
+ req = cbw_snapshot_read_lock(bs, offset, bytes, &cur_bytes, &file);
+ if (!req) {
+ return -EACCES;
+ }
+
+ ret = bdrv_co_preadv_part(file, offset, cur_bytes,
+ qiov, qiov_offset, 0);
+ cbw_snapshot_read_unlock(bs, req);
+ if (ret < 0) {
+ return ret;
+ }
+
+ bytes -= cur_bytes;
+ offset += cur_bytes;
+ qiov_offset += cur_bytes;
+ }
+
+ return 0;
+}
+
+static int coroutine_fn
+cbw_co_snapshot_block_status(BlockDriverState *bs,
+ bool want_zero, int64_t offset, int64_t bytes,
+ int64_t *pnum, int64_t *map,
+ BlockDriverState **file)
+{
+ BDRVCopyBeforeWriteState *s = bs->opaque;
+ BlockReq *req;
+ int ret;
+ int64_t cur_bytes;
+ BdrvChild *child;
+
+ req = cbw_snapshot_read_lock(bs, offset, bytes, &cur_bytes, &child);
+ if (!req) {
+ return -EACCES;
+ }
+
+ ret = bdrv_block_status(child->bs, offset, cur_bytes, pnum, map, file);
+ if (child == s->target) {
+ /*
+ * We refer to s->target only for areas that we've written to it.
+ * And we can not report unallocated blocks in s->target: this will
+ * break generic block-status-above logic, that will go to
+ * copy-before-write filtered child in this case.
+ */
+ assert(ret & BDRV_BLOCK_ALLOCATED);
+ }
+
+ cbw_snapshot_read_unlock(bs, req);
+
+ return ret;
+}
+
+static int coroutine_fn cbw_co_pdiscard_snapshot(BlockDriverState *bs,
+ int64_t offset, int64_t bytes)
+{
+ BDRVCopyBeforeWriteState *s = bs->opaque;
+
+ WITH_QEMU_LOCK_GUARD(&s->lock) {
+ bdrv_reset_dirty_bitmap(s->access_bitmap, offset, bytes);
+ }
+
+ block_copy_reset(s->bcs, offset, bytes);
+
+ return bdrv_co_pdiscard(s->target, offset, bytes);
+}
+
static void cbw_refresh_filename(BlockDriverState *bs)
{
pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
@@ -194,6 +375,7 @@ static int cbw_open(BlockDriverState *bs, QDict *options, int flags,
{
BDRVCopyBeforeWriteState *s = bs->opaque;
BdrvDirtyBitmap *bitmap = NULL;
+ int64_t cluster_size;
bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY,
@@ -225,6 +407,27 @@ static int cbw_open(BlockDriverState *bs, QDict *options, int flags,
return -EINVAL;
}
+ cluster_size = block_copy_cluster_size(s->bcs);
+
+ s->done_bitmap = bdrv_create_dirty_bitmap(bs, cluster_size, NULL, errp);
+ if (!s->done_bitmap) {
+ return -EINVAL;
+ }
+ bdrv_disable_dirty_bitmap(s->done_bitmap);
+
+ /* s->access_bitmap starts equal to bcs bitmap */
+ s->access_bitmap = bdrv_create_dirty_bitmap(bs, cluster_size, NULL, errp);
+ if (!s->access_bitmap) {
+ return -EINVAL;
+ }
+ bdrv_disable_dirty_bitmap(s->access_bitmap);
+ bdrv_dirty_bitmap_merge_internal(s->access_bitmap,
+ block_copy_dirty_bitmap(s->bcs), NULL,
+ true);
+
+ qemu_co_mutex_init(&s->lock);
+ QLIST_INIT(&s->frozen_read_reqs);
+
return 0;
}
@@ -232,6 +435,9 @@ static void cbw_close(BlockDriverState *bs)
{
BDRVCopyBeforeWriteState *s = bs->opaque;
+ bdrv_release_dirty_bitmap(s->access_bitmap);
+ bdrv_release_dirty_bitmap(s->done_bitmap);
+
block_copy_state_free(s->bcs);
s->bcs = NULL;
}
@@ -249,6 +455,10 @@ BlockDriver bdrv_cbw_filter = {
.bdrv_co_pdiscard = cbw_co_pdiscard,
.bdrv_co_flush = cbw_co_flush,
+ .bdrv_co_preadv_snapshot = cbw_co_preadv_snapshot,
+ .bdrv_co_pdiscard_snapshot = cbw_co_pdiscard_snapshot,
+ .bdrv_co_snapshot_block_status = cbw_co_snapshot_block_status,
+
.bdrv_refresh_filename = cbw_refresh_filename,
.bdrv_child_perm = cbw_child_perm,
diff --git a/tests/qemu-iotests/257.out b/tests/qemu-iotests/257.out
index 50cbd8e882bcf70a6160c41b0567619bd974b14a..aa76131ca91b91c6ab6bdda82b3bd5991131bfd6 100644
--- a/tests/qemu-iotests/257.out
+++ b/tests/qemu-iotests/257.out
@@ -106,6 +106,22 @@ write -P0x67 0x3fe0000 0x20000
{"return": ""}
{
"bitmaps": {
+ "backup-top": [
+ {
+ "busy": false,
+ "count": 67108864,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ },
+ {
+ "busy": false,
+ "count": 458752,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ }
+ ],
"drive0": [
{
"busy": false,
@@ -566,6 +582,22 @@ write -P0x67 0x3fe0000 0x20000
{"return": ""}
{
"bitmaps": {
+ "backup-top": [
+ {
+ "busy": false,
+ "count": 67108864,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ },
+ {
+ "busy": false,
+ "count": 458752,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ }
+ ],
"drive0": [
{
"busy": false,
@@ -819,6 +851,22 @@ write -P0x67 0x3fe0000 0x20000
{"return": ""}
{
"bitmaps": {
+ "backup-top": [
+ {
+ "busy": false,
+ "count": 67108864,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ },
+ {
+ "busy": false,
+ "count": 458752,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ }
+ ],
"drive0": [
{
"busy": false,
@@ -1279,6 +1327,22 @@ write -P0x67 0x3fe0000 0x20000
{"return": ""}
{
"bitmaps": {
+ "backup-top": [
+ {
+ "busy": false,
+ "count": 67108864,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ },
+ {
+ "busy": false,
+ "count": 458752,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ }
+ ],
"drive0": [
{
"busy": false,
@@ -1532,6 +1596,22 @@ write -P0x67 0x3fe0000 0x20000
{"return": ""}
{
"bitmaps": {
+ "backup-top": [
+ {
+ "busy": false,
+ "count": 67108864,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ },
+ {
+ "busy": false,
+ "count": 458752,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ }
+ ],
"drive0": [
{
"busy": false,
@@ -1992,6 +2072,22 @@ write -P0x67 0x3fe0000 0x20000
{"return": ""}
{
"bitmaps": {
+ "backup-top": [
+ {
+ "busy": false,
+ "count": 67108864,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ },
+ {
+ "busy": false,
+ "count": 458752,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ }
+ ],
"drive0": [
{
"busy": false,
@@ -2245,6 +2341,22 @@ write -P0x67 0x3fe0000 0x20000
{"return": ""}
{
"bitmaps": {
+ "backup-top": [
+ {
+ "busy": false,
+ "count": 67108864,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ },
+ {
+ "busy": false,
+ "count": 458752,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ }
+ ],
"drive0": [
{
"busy": false,
@@ -2705,6 +2817,22 @@ write -P0x67 0x3fe0000 0x20000
{"return": ""}
{
"bitmaps": {
+ "backup-top": [
+ {
+ "busy": false,
+ "count": 67108864,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ },
+ {
+ "busy": false,
+ "count": 458752,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ }
+ ],
"drive0": [
{
"busy": false,
@@ -2958,6 +3086,22 @@ write -P0x67 0x3fe0000 0x20000
{"return": ""}
{
"bitmaps": {
+ "backup-top": [
+ {
+ "busy": false,
+ "count": 67108864,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ },
+ {
+ "busy": false,
+ "count": 458752,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ }
+ ],
"drive0": [
{
"busy": false,
@@ -3418,6 +3562,22 @@ write -P0x67 0x3fe0000 0x20000
{"return": ""}
{
"bitmaps": {
+ "backup-top": [
+ {
+ "busy": false,
+ "count": 67108864,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ },
+ {
+ "busy": false,
+ "count": 458752,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ }
+ ],
"drive0": [
{
"busy": false,
@@ -3671,6 +3831,22 @@ write -P0x67 0x3fe0000 0x20000
{"return": ""}
{
"bitmaps": {
+ "backup-top": [
+ {
+ "busy": false,
+ "count": 67108864,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ },
+ {
+ "busy": false,
+ "count": 458752,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ }
+ ],
"drive0": [
{
"busy": false,
@@ -4131,6 +4307,22 @@ write -P0x67 0x3fe0000 0x20000
{"return": ""}
{
"bitmaps": {
+ "backup-top": [
+ {
+ "busy": false,
+ "count": 67108864,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ },
+ {
+ "busy": false,
+ "count": 458752,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ }
+ ],
"drive0": [
{
"busy": false,
@@ -4384,6 +4576,22 @@ write -P0x67 0x3fe0000 0x20000
{"return": ""}
{
"bitmaps": {
+ "backup-top": [
+ {
+ "busy": false,
+ "count": 67108864,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ },
+ {
+ "busy": false,
+ "count": 458752,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ }
+ ],
"drive0": [
{
"busy": false,
@@ -4844,6 +5052,22 @@ write -P0x67 0x3fe0000 0x20000
{"return": ""}
{
"bitmaps": {
+ "backup-top": [
+ {
+ "busy": false,
+ "count": 67108864,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ },
+ {
+ "busy": false,
+ "count": 458752,
+ "granularity": 65536,
+ "persistent": false,
+ "recording": false
+ }
+ ],
"drive0": [
{
"busy": false,