Merge remote-tracking branch 'remotes/cody/tags/block-pull-request' into staging

# gpg: Signature made Fri 25 Sep 2015 16:47:31 BST using RSA key ID C0DE3057
# gpg: Good signature from "Jeffrey Cody <jcody@redhat.com>"
# gpg:                 aka "Jeffrey Cody <jeff@codyprime.org>"
# gpg:                 aka "Jeffrey Cody <codyprime@gmail.com>"

* remotes/cody/tags/block-pull-request:
  sheepdog: refine discard support
  sheepdog: use per AIOCB dirty indexes for non overlapping requests
  Backup: don't do copy-on-read in before_write_notifier
  block: Introduce a new API bdrv_co_no_copy_on_readv()
  sheepdog: add reopen support
  block/nfs: cache allocated filesize for read-only files
  block/nfs: fix calculation of allocated file size

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

6 files changed, 200 insertions, 48 deletions

diff --git a/block/backup.c b/block/backup.c
index 965654d521..5696431711 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -89,7 +89,8 @@ static void cow_request_end(CowRequest *req)
 
 static int coroutine_fn backup_do_cow(BlockDriverState *bs,
                                       int64_t sector_num, int nb_sectors,
-                                      bool *error_is_read)
+                                      bool *error_is_read,
+                                      bool is_write_notifier)
 {
     BackupBlockJob *job = (BackupBlockJob *)bs->job;
     CowRequest cow_request;
@@ -129,8 +130,14 @@ static int coroutine_fn backup_do_cow(BlockDriverState *bs,
         iov.iov_len = n * BDRV_SECTOR_SIZE;
         qemu_iovec_init_external(&bounce_qiov, &iov, 1);
 
-        ret = bdrv_co_readv(bs, start * BACKUP_SECTORS_PER_CLUSTER, n,
-                            &bounce_qiov);
+        if (is_write_notifier) {
+            ret = bdrv_co_no_copy_on_readv(bs,
+                                           start * BACKUP_SECTORS_PER_CLUSTER,
+                                           n, &bounce_qiov);
+        } else {
+            ret = bdrv_co_readv(bs, start * BACKUP_SECTORS_PER_CLUSTER, n,
+                                &bounce_qiov);
+        }
         if (ret < 0) {
             trace_backup_do_cow_read_fail(job, start, ret);
             if (error_is_read) {
@@ -190,7 +197,7 @@ static int coroutine_fn backup_before_write_notify(
     assert((req->offset & (BDRV_SECTOR_SIZE - 1)) == 0);
     assert((req->bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
 
-    return backup_do_cow(req->bs, sector_num, nb_sectors, NULL);
+    return backup_do_cow(req->bs, sector_num, nb_sectors, NULL, true);
 }
 
 static void backup_set_speed(BlockJob *job, int64_t speed, Error **errp)
@@ -303,7 +310,8 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
                     return ret;
                 }
                 ret = backup_do_cow(bs, cluster * BACKUP_SECTORS_PER_CLUSTER,
-                                    BACKUP_SECTORS_PER_CLUSTER, &error_is_read);
+                                    BACKUP_SECTORS_PER_CLUSTER, &error_is_read,
+                                    false);
                 if ((ret < 0) &&
                     backup_error_action(job, error_is_read, -ret) ==
                     BLOCK_ERROR_ACTION_REPORT) {
@@ -408,7 +416,7 @@ static void coroutine_fn backup_run(void *opaque)
             }
             /* FULL sync mode we copy the whole drive. */
             ret = backup_do_cow(bs, start * BACKUP_SECTORS_PER_CLUSTER,
-                    BACKUP_SECTORS_PER_CLUSTER, &error_is_read);
+                    BACKUP_SECTORS_PER_CLUSTER, &error_is_read, false);
             if (ret < 0) {
                 /* Depending on error action, fail now or retry cluster */
                 BlockErrorAction action =
diff --git a/block/io.c b/block/io.c
index d4bc83b33b..94e18e6a9d 100644
--- a/block/io.c
+++ b/block/io.c
@@ -932,7 +932,8 @@ static int coroutine_fn bdrv_co_do_preadv(BlockDriverState *bs,
         return ret;
     }
 
-    if (bs->copy_on_read) {
+    /* Don't do copy-on-read if we read data before write operation */
+    if (bs->copy_on_read && !(flags & BDRV_REQ_NO_COPY_ON_READ)) {
         flags |= BDRV_REQ_COPY_ON_READ;
     }
 
@@ -1001,6 +1002,15 @@ int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
     return bdrv_co_do_readv(bs, sector_num, nb_sectors, qiov, 0);
 }
 
+int coroutine_fn bdrv_co_no_copy_on_readv(BlockDriverState *bs,
+    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
+{
+    trace_bdrv_co_no_copy_on_readv(bs, sector_num, nb_sectors);
+
+    return bdrv_co_do_readv(bs, sector_num, nb_sectors, qiov,
+                            BDRV_REQ_NO_COPY_ON_READ);
+}
+
 int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs,
     int64_t sector_num, int nb_sectors, QEMUIOVector *qiov)
 {
diff --git a/block/nfs.c b/block/nfs.c
index c026ff6883..887a98e3fc 100644
--- a/block/nfs.c
+++ b/block/nfs.c
@@ -43,6 +43,7 @@ typedef struct NFSClient {
     int events;
     bool has_zero_init;
     AioContext *aio_context;
+    blkcnt_t st_blocks;
 } NFSClient;
 
 typedef struct NFSRPC {
@@ -374,6 +375,7 @@ static int64_t nfs_client_open(NFSClient *client, const char *filename,
     }
 
     ret = DIV_ROUND_UP(st.st_size, BDRV_SECTOR_SIZE);
+    client->st_blocks = st.st_blocks;
     client->has_zero_init = S_ISREG(st.st_mode);
     goto out;
 fail:
@@ -464,6 +466,11 @@ static int64_t nfs_get_allocated_file_size(BlockDriverState *bs)
     NFSRPC task = {0};
     struct stat st;
 
+    if (bdrv_is_read_only(bs) &&
+        !(bs->open_flags & BDRV_O_NOCACHE)) {
+        return client->st_blocks * 512;
+    }
+
     task.st = &st;
     if (nfs_fstat_async(client->context, client->fh, nfs_co_generic_cb,
                         &task) != 0) {
@@ -475,7 +482,7 @@ static int64_t nfs_get_allocated_file_size(BlockDriverState *bs)
         aio_poll(client->aio_context, true);
     }
 
-    return (task.ret < 0 ? task.ret : st.st_blocks * st.st_blksize);
+    return (task.ret < 0 ? task.ret : st.st_blocks * 512);
 }
 
 static int nfs_file_truncate(BlockDriverState *bs, int64_t offset)
@@ -484,6 +491,34 @@ static int nfs_file_truncate(BlockDriverState *bs, int64_t offset)
     return nfs_ftruncate(client->context, client->fh, offset);
 }
 
+/* Note that this will not re-establish a connection with the NFS server
+ * - it is effectively a NOP.  */
+static int nfs_reopen_prepare(BDRVReopenState *state,
+                              BlockReopenQueue *queue, Error **errp)
+{
+    NFSClient *client = state->bs->opaque;
+    struct stat st;
+    int ret = 0;
+
+    if (state->flags & BDRV_O_RDWR && bdrv_is_read_only(state->bs)) {
+        error_setg(errp, "Cannot open a read-only mount as read-write");
+        return -EACCES;
+    }
+
+    /* Update cache for read-only reopens */
+    if (!(state->flags & BDRV_O_RDWR)) {
+        ret = nfs_fstat(client->context, client->fh, &st);
+        if (ret < 0) {
+            error_setg(errp, "Failed to fstat file: %s",
+                       nfs_get_error(client->context));
+            return ret;
+        }
+        client->st_blocks = st.st_blocks;
+    }
+
+    return 0;
+}
+
 static BlockDriver bdrv_nfs = {
     .format_name                    = "nfs",
     .protocol_name                  = "nfs",
@@ -499,6 +534,7 @@ static BlockDriver bdrv_nfs = {
     .bdrv_file_open                 = nfs_file_open,
     .bdrv_close                     = nfs_file_close,
     .bdrv_create                    = nfs_file_create,
+    .bdrv_reopen_prepare            = nfs_reopen_prepare,
 
     .bdrv_co_readv                  = nfs_co_readv,
     .bdrv_co_writev                 = nfs_co_writev,
diff --git a/block/sheepdog.c b/block/sheepdog.c
index 67ca788d5c..e7e58b782c 100644
--- a/block/sheepdog.c
+++ b/block/sheepdog.c
@@ -28,7 +28,6 @@
 #define SD_OP_READ_OBJ       0x02
 #define SD_OP_WRITE_OBJ      0x03
 /* 0x04 is used internally by Sheepdog */
-#define SD_OP_DISCARD_OBJ    0x05
 
 #define SD_OP_NEW_VDI        0x11
 #define SD_OP_LOCK_VDI       0x12
@@ -318,7 +317,7 @@ enum AIOCBState {
     AIOCB_DISCARD_OBJ,
 };
 
-#define AIOCBOverwrapping(x, y)                                 \
+#define AIOCBOverlapping(x, y)                                 \
     (!(x->max_affect_data_idx < y->min_affect_data_idx          \
        || y->max_affect_data_idx < x->min_affect_data_idx))
 
@@ -342,6 +341,15 @@ struct SheepdogAIOCB {
     uint32_t min_affect_data_idx;
     uint32_t max_affect_data_idx;
 
+    /*
+     * The difference between affect_data_idx and dirty_data_idx:
+     * affect_data_idx represents range of index of all request types.
+     * dirty_data_idx represents range of index updated by COW requests.
+     * dirty_data_idx is used for updating an inode object.
+     */
+    uint32_t min_dirty_data_idx;
+    uint32_t max_dirty_data_idx;
+
     QLIST_ENTRY(SheepdogAIOCB) aiocb_siblings;
 };
 
@@ -351,9 +359,6 @@ typedef struct BDRVSheepdogState {
 
     SheepdogInode inode;
 
-    uint32_t min_dirty_data_idx;
-    uint32_t max_dirty_data_idx;
-
     char name[SD_MAX_VDI_LEN];
     bool is_snapshot;
     uint32_t cache_flags;
@@ -373,10 +378,15 @@ typedef struct BDRVSheepdogState {
     QLIST_HEAD(inflight_aio_head, AIOReq) inflight_aio_head;
     QLIST_HEAD(failed_aio_head, AIOReq) failed_aio_head;
 
-    CoQueue overwrapping_queue;
+    CoQueue overlapping_queue;
     QLIST_HEAD(inflight_aiocb_head, SheepdogAIOCB) inflight_aiocb_head;
 } BDRVSheepdogState;
 
+typedef struct BDRVSheepdogReopenState {
+    int fd;
+    int cache_flags;
+} BDRVSheepdogReopenState;
+
 static const char * sd_strerror(int err)
 {
     int i;
@@ -556,6 +566,9 @@ static SheepdogAIOCB *sd_aio_setup(BlockDriverState *bs, QEMUIOVector *qiov,
     acb->max_affect_data_idx = (acb->sector_num * BDRV_SECTOR_SIZE +
                               acb->nb_sectors * BDRV_SECTOR_SIZE) / object_size;
 
+    acb->min_dirty_data_idx = UINT32_MAX;
+    acb->max_dirty_data_idx = 0;
+
     return acb;
 }
 
@@ -819,8 +832,8 @@ static void coroutine_fn aio_read_response(void *opaque)
              */
             if (rsp.result == SD_RES_SUCCESS) {
                 s->inode.data_vdi_id[idx] = s->inode.vdi_id;
-                s->max_dirty_data_idx = MAX(idx, s->max_dirty_data_idx);
-                s->min_dirty_data_idx = MIN(idx, s->min_dirty_data_idx);
+                acb->max_dirty_data_idx = MAX(idx, acb->max_dirty_data_idx);
+                acb->min_dirty_data_idx = MIN(idx, acb->min_dirty_data_idx);
             }
         }
         break;
@@ -847,10 +860,6 @@ static void coroutine_fn aio_read_response(void *opaque)
             rsp.result = SD_RES_SUCCESS;
             s->discard_supported = false;
             break;
-        case SD_RES_SUCCESS:
-            idx = data_oid_to_idx(aio_req->oid);
-            s->inode.data_vdi_id[idx] = 0;
-            break;
         default:
             break;
         }
@@ -1165,7 +1174,13 @@ static void coroutine_fn add_aio_request(BDRVSheepdogState *s, AIOReq *aio_req,
         hdr.flags = SD_FLAG_CMD_WRITE | flags;
         break;
     case AIOCB_DISCARD_OBJ:
-        hdr.opcode = SD_OP_DISCARD_OBJ;
+        hdr.opcode = SD_OP_WRITE_OBJ;
+        hdr.flags = SD_FLAG_CMD_WRITE | flags;
+        s->inode.data_vdi_id[data_oid_to_idx(oid)] = 0;
+        offset = offsetof(SheepdogInode,
+                          data_vdi_id[data_oid_to_idx(oid)]);
+        oid = vid_to_vdi_oid(s->inode.vdi_id);
+        wlen = datalen = sizeof(uint32_t);
         break;
     }
 
@@ -1466,13 +1481,11 @@ static int sd_open(BlockDriverState *bs, QDict *options, int flags,
     }
 
     memcpy(&s->inode, buf, sizeof(s->inode));
-    s->min_dirty_data_idx = UINT32_MAX;
-    s->max_dirty_data_idx = 0;
 
     bs->total_sectors = s->inode.vdi_size / BDRV_SECTOR_SIZE;
     pstrcpy(s->name, sizeof(s->name), vdi);
     qemu_co_mutex_init(&s->lock);
-    qemu_co_queue_init(&s->overwrapping_queue);
+    qemu_co_queue_init(&s->overlapping_queue);
     qemu_opts_del(opts);
     g_free(buf);
     return 0;
@@ -1486,6 +1499,68 @@ out:
     return ret;
 }
 
+static int sd_reopen_prepare(BDRVReopenState *state, BlockReopenQueue *queue,
+                             Error **errp)
+{
+    BDRVSheepdogState *s = state->bs->opaque;
+    BDRVSheepdogReopenState *re_s;
+    int ret = 0;
+
+    re_s = state->opaque = g_new0(BDRVSheepdogReopenState, 1);
+
+    re_s->cache_flags = SD_FLAG_CMD_CACHE;
+    if (state->flags & BDRV_O_NOCACHE) {
+        re_s->cache_flags = SD_FLAG_CMD_DIRECT;
+    }
+
+    re_s->fd = get_sheep_fd(s, errp);
+    if (re_s->fd < 0) {
+        ret = re_s->fd;
+        return ret;
+    }
+
+    return ret;
+}
+
+static void sd_reopen_commit(BDRVReopenState *state)
+{
+    BDRVSheepdogReopenState *re_s = state->opaque;
+    BDRVSheepdogState *s = state->bs->opaque;
+
+    if (s->fd) {
+        aio_set_fd_handler(s->aio_context, s->fd, NULL, NULL, NULL);
+        closesocket(s->fd);
+    }
+
+    s->fd = re_s->fd;
+    s->cache_flags = re_s->cache_flags;
+
+    g_free(state->opaque);
+    state->opaque = NULL;
+
+    return;
+}
+
+static void sd_reopen_abort(BDRVReopenState *state)
+{
+    BDRVSheepdogReopenState *re_s = state->opaque;
+    BDRVSheepdogState *s = state->bs->opaque;
+
+    if (re_s == NULL) {
+        return;
+    }
+
+    if (re_s->fd) {
+        aio_set_fd_handler(s->aio_context, re_s->fd, NULL, NULL, NULL);
+        closesocket(re_s->fd);
+    }
+
+    g_free(state->opaque);
+    state->opaque = NULL;
+
+    return;
+}
+
 static int do_sd_create(BDRVSheepdogState *s, uint32_t *vdi_id, int snapshot,
                         Error **errp)
 {
@@ -1922,16 +1997,16 @@ static void coroutine_fn sd_write_done(SheepdogAIOCB *acb)
     AIOReq *aio_req;
     uint32_t offset, data_len, mn, mx;
 
-    mn = s->min_dirty_data_idx;
-    mx = s->max_dirty_data_idx;
+    mn = acb->min_dirty_data_idx;
+    mx = acb->max_dirty_data_idx;
     if (mn <= mx) {
         /* we need to update the vdi object. */
         offset = sizeof(s->inode) - sizeof(s->inode.data_vdi_id) +
             mn * sizeof(s->inode.data_vdi_id[0]);
         data_len = (mx - mn + 1) * sizeof(s->inode.data_vdi_id[0]);
 
-        s->min_dirty_data_idx = UINT32_MAX;
-        s->max_dirty_data_idx = 0;
+        acb->min_dirty_data_idx = UINT32_MAX;
+        acb->max_dirty_data_idx = 0;
 
         iov.iov_base = &s->inode;
         iov.iov_len = sizeof(s->inode);
@@ -2140,7 +2215,9 @@ static int coroutine_fn sd_co_rw_vector(void *p)
         }
 
         aio_req = alloc_aio_req(s, acb, oid, len, offset, flags, create,
-                                old_oid, done);
+                                old_oid,
+                                acb->aiocb_type == AIOCB_DISCARD_OBJ ?
+                                0 : done);
         QLIST_INSERT_HEAD(&s->inflight_aio_head, aio_req, aio_siblings);
 
         add_aio_request(s, aio_req, acb->qiov->iov, acb->qiov->niov,
@@ -2157,12 +2234,12 @@ out:
     return 1;
 }
 
-static bool check_overwrapping_aiocb(BDRVSheepdogState *s, SheepdogAIOCB *aiocb)
+static bool check_overlapping_aiocb(BDRVSheepdogState *s, SheepdogAIOCB *aiocb)
 {
     SheepdogAIOCB *cb;
 
     QLIST_FOREACH(cb, &s->inflight_aiocb_head, aiocb_siblings) {
-        if (AIOCBOverwrapping(aiocb, cb)) {
+        if (AIOCBOverlapping(aiocb, cb)) {
             return true;
         }
     }
@@ -2191,15 +2268,15 @@ static coroutine_fn int sd_co_writev(BlockDriverState *bs, int64_t sector_num,
     acb->aiocb_type = AIOCB_WRITE_UDATA;
 
 retry:
-    if (check_overwrapping_aiocb(s, acb)) {
-        qemu_co_queue_wait(&s->overwrapping_queue);
+    if (check_overlapping_aiocb(s, acb)) {
+        qemu_co_queue_wait(&s->overlapping_queue);
         goto retry;
     }
 
     ret = sd_co_rw_vector(acb);
     if (ret <= 0) {
         QLIST_REMOVE(acb, aiocb_siblings);
-        qemu_co_queue_restart_all(&s->overwrapping_queue);
+        qemu_co_queue_restart_all(&s->overlapping_queue);
         qemu_aio_unref(acb);
         return ret;
     }
@@ -2207,7 +2284,7 @@ retry:
     qemu_coroutine_yield();
 
     QLIST_REMOVE(acb, aiocb_siblings);
-    qemu_co_queue_restart_all(&s->overwrapping_queue);
+    qemu_co_queue_restart_all(&s->overlapping_queue);
 
     return acb->ret;
 }
@@ -2224,15 +2301,15 @@ static coroutine_fn int sd_co_readv(BlockDriverState *bs, int64_t sector_num,
     acb->aio_done_func = sd_finish_aiocb;
 
 retry:
-    if (check_overwrapping_aiocb(s, acb)) {
-        qemu_co_queue_wait(&s->overwrapping_queue);
+    if (check_overlapping_aiocb(s, acb)) {
+        qemu_co_queue_wait(&s->overlapping_queue);
         goto retry;
     }
 
     ret = sd_co_rw_vector(acb);
     if (ret <= 0) {
         QLIST_REMOVE(acb, aiocb_siblings);
-        qemu_co_queue_restart_all(&s->overwrapping_queue);
+        qemu_co_queue_restart_all(&s->overlapping_queue);
         qemu_aio_unref(acb);
         return ret;
     }
@@ -2240,7 +2317,7 @@ retry:
     qemu_coroutine_yield();
 
     QLIST_REMOVE(acb, aiocb_siblings);
-    qemu_co_queue_restart_all(&s->overwrapping_queue);
+    qemu_co_queue_restart_all(&s->overlapping_queue);
     return acb->ret;
 }
 
@@ -2576,28 +2653,36 @@ static coroutine_fn int sd_co_discard(BlockDriverState *bs, int64_t sector_num,
                                       int nb_sectors)
 {
     SheepdogAIOCB *acb;
-    QEMUIOVector dummy;
     BDRVSheepdogState *s = bs->opaque;
     int ret;
+    QEMUIOVector discard_iov;
+    struct iovec iov;
+    uint32_t zero = 0;
 
     if (!s->discard_supported) {
             return 0;
     }
 
-    acb = sd_aio_setup(bs, &dummy, sector_num, nb_sectors);
+    memset(&discard_iov, 0, sizeof(discard_iov));
+    memset(&iov, 0, sizeof(iov));
+    iov.iov_base = &zero;
+    iov.iov_len = sizeof(zero);
+    discard_iov.iov = &iov;
+    discard_iov.niov = 1;
+    acb = sd_aio_setup(bs, &discard_iov, sector_num, nb_sectors);
     acb->aiocb_type = AIOCB_DISCARD_OBJ;
     acb->aio_done_func = sd_finish_aiocb;
 
 retry:
-    if (check_overwrapping_aiocb(s, acb)) {
-        qemu_co_queue_wait(&s->overwrapping_queue);
+    if (check_overlapping_aiocb(s, acb)) {
+        qemu_co_queue_wait(&s->overlapping_queue);
         goto retry;
     }
 
     ret = sd_co_rw_vector(acb);
     if (ret <= 0) {
         QLIST_REMOVE(acb, aiocb_siblings);
-        qemu_co_queue_restart_all(&s->overwrapping_queue);
+        qemu_co_queue_restart_all(&s->overlapping_queue);
         qemu_aio_unref(acb);
         return ret;
     }
@@ -2605,7 +2690,7 @@ retry:
     qemu_coroutine_yield();
 
     QLIST_REMOVE(acb, aiocb_siblings);
-    qemu_co_queue_restart_all(&s->overwrapping_queue);
+    qemu_co_queue_restart_all(&s->overlapping_queue);
 
     return acb->ret;
 }
@@ -2702,6 +2787,9 @@ static BlockDriver bdrv_sheepdog = {
     .instance_size  = sizeof(BDRVSheepdogState),
     .bdrv_needs_filename = true,
     .bdrv_file_open = sd_open,
+    .bdrv_reopen_prepare    = sd_reopen_prepare,
+    .bdrv_reopen_commit     = sd_reopen_commit,
+    .bdrv_reopen_abort      = sd_reopen_abort,
     .bdrv_close     = sd_close,
     .bdrv_create    = sd_create,
     .bdrv_has_zero_init = bdrv_has_zero_init_1,
@@ -2735,6 +2823,9 @@ static BlockDriver bdrv_sheepdog_tcp = {
     .instance_size  = sizeof(BDRVSheepdogState),
     .bdrv_needs_filename = true,
     .bdrv_file_open = sd_open,
+    .bdrv_reopen_prepare    = sd_reopen_prepare,
+    .bdrv_reopen_commit     = sd_reopen_commit,
+    .bdrv_reopen_abort      = sd_reopen_abort,
     .bdrv_close     = sd_close,
     .bdrv_create    = sd_create,
     .bdrv_has_zero_init = bdrv_has_zero_init_1,
@@ -2768,6 +2859,9 @@ static BlockDriver bdrv_sheepdog_unix = {
     .instance_size  = sizeof(BDRVSheepdogState),
     .bdrv_needs_filename = true,
     .bdrv_file_open = sd_open,
+    .bdrv_reopen_prepare    = sd_reopen_prepare,
+    .bdrv_reopen_commit     = sd_reopen_commit,
+    .bdrv_reopen_abort      = sd_reopen_abort,
     .bdrv_close     = sd_close,
     .bdrv_create    = sd_create,
     .bdrv_has_zero_init = bdrv_has_zero_init_1,
diff --git a/include/block/block.h b/include/block/block.h
index ef67353108..2dd66300ed 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -51,15 +51,16 @@ typedef struct BlockFragInfo {
 } BlockFragInfo;
 
 typedef enum {
-    BDRV_REQ_COPY_ON_READ = 0x1,
-    BDRV_REQ_ZERO_WRITE   = 0x2,
+    BDRV_REQ_COPY_ON_READ       = 0x1,
+    BDRV_REQ_ZERO_WRITE         = 0x2,
     /* The BDRV_REQ_MAY_UNMAP flag is used to indicate that the block driver
      * is allowed to optimize a write zeroes request by unmapping (discarding)
      * blocks if it is guaranteed that the result will read back as
      * zeroes. The flag is only passed to the driver if the block device is
      * opened with BDRV_O_UNMAP.
      */
-    BDRV_REQ_MAY_UNMAP    = 0x4,
+    BDRV_REQ_MAY_UNMAP          = 0x4,
+    BDRV_REQ_NO_COPY_ON_READ    = 0x8,
 } BdrvRequestFlags;
 
 typedef struct BlockSizes {
@@ -252,6 +253,8 @@ int coroutine_fn bdrv_co_readv(BlockDriverState *bs, int64_t sector_num,
     int nb_sectors, QEMUIOVector *qiov);
 int coroutine_fn bdrv_co_copy_on_readv(BlockDriverState *bs,
     int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
+int coroutine_fn bdrv_co_no_copy_on_readv(BlockDriverState *bs,
+    int64_t sector_num, int nb_sectors, QEMUIOVector *qiov);
 int coroutine_fn bdrv_co_writev(BlockDriverState *bs, int64_t sector_num,
     int nb_sectors, QEMUIOVector *qiov);
 /*
diff --git a/trace-events b/trace-events
index 25c53e0c7c..a70ea9c3ae 100644
--- a/trace-events
+++ b/trace-events
@@ -69,6 +69,7 @@ bdrv_aio_write_zeroes(void *bs, int64_t sector_num, int nb_sectors, int flags, v
 bdrv_lock_medium(void *bs, bool locked) "bs %p locked %d"
 bdrv_co_readv(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d"
 bdrv_co_copy_on_readv(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d"
+bdrv_co_no_copy_on_readv(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d"
 bdrv_co_writev(void *bs, int64_t sector_num, int nb_sector) "bs %p sector_num %"PRId64" nb_sectors %d"
 bdrv_co_write_zeroes(void *bs, int64_t sector_num, int nb_sector, int flags) "bs %p sector_num %"PRId64" nb_sectors %d flags %#x"
 bdrv_co_io_em(void *bs, int64_t sector_num, int nb_sectors, int is_write, void *acb) "bs %p sector_num %"PRId64" nb_sectors %d is_write %d acb %p"