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

# gpg: Signature made Thu Jul  2 10:10:39 2015 BST using RSA key ID 81AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"

* remotes/stefanha/tags/block-pull-request:
  block: remove redundant check before g_slist_find()
  block/nfs: limit maximum readahead size to 1MB
  block/iscsi: restore compatiblity with libiscsi 1.9.0
  iotests: Use event_wait in wait_ready
  qemu-iotests: Add test case for mirror with unmap
  qemu-iotests: Make block job methods common
  block: Remove bdrv_reset_dirty
  block: Fix dirty bitmap in bdrv_co_discard
  mirror: Do zero write on target if sectors not allocated
  qmp: Add optional bool "unmap" to drive-mirror
  block: Add bdrv_get_block_status_above
  timer: Use a single definition of NSEC_PER_SEC for the whole codebase
  timer: Move NANOSECONDS_PER_SECONDS to timer.h
  blockdev: no need to drain+flush in hmp_drive_del
  qapi: Rename 'dirty-bitmap' mode to 'incremental'
  qcow2: Handle EAGAIN returned from update_refcount
  block/iscsi: add support for request timeouts

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

31 files changed, 353 insertions, 170 deletions

diff --git a/block.c b/block.c
index 81233be..7e130cc 100644
--- a/block.c
+++ b/block.c
@@ -3528,18 +3528,6 @@ void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector,
     }
 }
 
-void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
-                      int nr_sectors)
-{
-    BdrvDirtyBitmap *bitmap;
-    QLIST_FOREACH(bitmap, &bs->dirty_bitmaps, list) {
-        if (!bdrv_dirty_bitmap_enabled(bitmap)) {
-            continue;
-        }
-        hbitmap_reset(bitmap->bitmap, cur_sector, nr_sectors);
-    }
-}
-
 /**
  * Advance an HBitmapIter to an arbitrary offset.
  */
diff --git a/block/backup.c b/block/backup.c
index 4a1af68..d3c7d9f 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -38,7 +38,7 @@ typedef struct CowRequest {
 typedef struct BackupBlockJob {
     BlockJob common;
     BlockDriverState *target;
-    /* bitmap for sync=dirty-bitmap */
+    /* bitmap for sync=incremental */
     BdrvDirtyBitmap *sync_bitmap;
     MirrorSyncMode sync_mode;
     RateLimit limit;
@@ -365,7 +365,7 @@ static void coroutine_fn backup_run(void *opaque)
             qemu_coroutine_yield();
             job->common.busy = true;
         }
-    } else if (job->sync_mode == MIRROR_SYNC_MODE_DIRTY_BITMAP) {
+    } else if (job->sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
         ret = backup_run_incremental(job);
     } else {
         /* Both FULL and TOP SYNC_MODE's require copying.. */
@@ -497,10 +497,10 @@ void backup_start(BlockDriverState *bs, BlockDriverState *target,
         return;
     }
 
-    if (sync_mode == MIRROR_SYNC_MODE_DIRTY_BITMAP) {
+    if (sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
         if (!sync_bitmap) {
             error_setg(errp, "must provide a valid bitmap name for "
-                             "\"dirty-bitmap\" sync mode");
+                             "\"incremental\" sync mode");
             return;
         }
 
@@ -535,7 +535,7 @@ void backup_start(BlockDriverState *bs, BlockDriverState *target,
     job->on_target_error = on_target_error;
     job->target = target;
     job->sync_mode = sync_mode;
-    job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_DIRTY_BITMAP ?
+    job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_INCREMENTAL ?
                        sync_bitmap : NULL;
     job->common.len = len;
     job->common.co = qemu_coroutine_create(backup_run);
diff --git a/block/io.c b/block/io.c
index e295992..305e0d9 100644
--- a/block/io.c
+++ b/block/io.c
@@ -283,7 +283,7 @@ void bdrv_drain_all(void)
         }
         aio_context_release(aio_context);
 
-        if (!aio_ctxs || !g_slist_find(aio_ctxs, aio_context)) {
+        if (!g_slist_find(aio_ctxs, aio_context)) {
             aio_ctxs = g_slist_prepend(aio_ctxs, aio_context);
         }
     }
@@ -1531,28 +1531,54 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
     return ret;
 }
 
-/* Coroutine wrapper for bdrv_get_block_status() */
-static void coroutine_fn bdrv_get_block_status_co_entry(void *opaque)
+static int64_t coroutine_fn bdrv_co_get_block_status_above(BlockDriverState *bs,
+        BlockDriverState *base,
+        int64_t sector_num,
+        int nb_sectors,
+        int *pnum)
+{
+    BlockDriverState *p;
+    int64_t ret = 0;
+
+    assert(bs != base);
+    for (p = bs; p != base; p = p->backing_hd) {
+        ret = bdrv_co_get_block_status(p, sector_num, nb_sectors, pnum);
+        if (ret < 0 || ret & BDRV_BLOCK_ALLOCATED) {
+            break;
+        }
+        /* [sector_num, pnum] unallocated on this layer, which could be only
+         * the first part of [sector_num, nb_sectors].  */
+        nb_sectors = MIN(nb_sectors, *pnum);
+    }
+    return ret;
+}
+
+/* Coroutine wrapper for bdrv_get_block_status_above() */
+static void coroutine_fn bdrv_get_block_status_above_co_entry(void *opaque)
 {
     BdrvCoGetBlockStatusData *data = opaque;
-    BlockDriverState *bs = data->bs;
 
-    data->ret = bdrv_co_get_block_status(bs, data->sector_num, data->nb_sectors,
-                                         data->pnum);
+    data->ret = bdrv_co_get_block_status_above(data->bs, data->base,
+                                               data->sector_num,
+                                               data->nb_sectors,
+                                               data->pnum);
     data->done = true;
 }
 
 /*
- * Synchronous wrapper around bdrv_co_get_block_status().
+ * Synchronous wrapper around bdrv_co_get_block_status_above().
  *
- * See bdrv_co_get_block_status() for details.
+ * See bdrv_co_get_block_status_above() for details.
  */
-int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num,
-                              int nb_sectors, int *pnum)
+int64_t bdrv_get_block_status_above(BlockDriverState *bs,
+                                    BlockDriverState *base,
+                                    int64_t sector_num,
+                                    int nb_sectors, int *pnum)
 {
     Coroutine *co;
     BdrvCoGetBlockStatusData data = {
         .bs = bs,
+        .base = base,
         .sector_num = sector_num,
         .nb_sectors = nb_sectors,
         .pnum = pnum,
@@ -1561,11 +1587,11 @@ int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num,
 
     if (qemu_in_coroutine()) {
         /* Fast-path if already in coroutine context */
-        bdrv_get_block_status_co_entry(&data);
+        bdrv_get_block_status_above_co_entry(&data);
     } else {
         AioContext *aio_context = bdrv_get_aio_context(bs);
 
-        co = qemu_coroutine_create(bdrv_get_block_status_co_entry);
+        co = qemu_coroutine_create(bdrv_get_block_status_above_co_entry);
         qemu_coroutine_enter(co, &data);
         while (!data.done) {
             aio_poll(aio_context, true);
@@ -1574,6 +1600,14 @@ int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num,
     return data.ret;
 }
 
+int64_t bdrv_get_block_status(BlockDriverState *bs,
+                              int64_t sector_num,
+                              int nb_sectors, int *pnum)
+{
+    return bdrv_get_block_status_above(bs, bs->backing_hd,
+                                       sector_num, nb_sectors, pnum);
+}
+
 int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num,
                                    int nb_sectors, int *pnum)
 {
@@ -2378,8 +2412,6 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
         return -EPERM;
     }
 
-    bdrv_reset_dirty(bs, sector_num, nb_sectors);
-
     /* Do nothing if disabled.  */
     if (!(bs->open_flags & BDRV_O_UNMAP)) {
         return 0;
@@ -2389,6 +2421,8 @@ int coroutine_fn bdrv_co_discard(BlockDriverState *bs, int64_t sector_num,
         return 0;
     }
 
+    bdrv_set_dirty(bs, sector_num, nb_sectors);
+
     max_discard = MIN_NON_ZERO(bs->bl.max_discard, BDRV_REQUEST_MAX_SECTORS);
     while (nb_sectors > 0) {
         int ret;
diff --git a/block/iscsi.c b/block/iscsi.c
index 49cee4d..5002916 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -70,6 +70,7 @@ typedef struct IscsiLun {
     bool dpofua;
     bool has_write_same;
     bool force_next_flush;
+    bool request_timed_out;
 } IscsiLun;
 
 typedef struct IscsiTask {
@@ -100,7 +101,8 @@ typedef struct IscsiAIOCB {
 #endif
 } IscsiAIOCB;
 
-#define EVENT_INTERVAL 250
+/* libiscsi uses time_t so its enough to process events every second */
+#define EVENT_INTERVAL 1000
 #define NOP_INTERVAL 5000
 #define MAX_NOP_FAILURES 3
 #define ISCSI_CMD_RETRIES ARRAY_SIZE(iscsi_retry_times)
@@ -167,6 +169,19 @@ static inline unsigned exp_random(double mean)
     return -mean * log((double)rand() / RAND_MAX);
 }
 
+/* SCSI_STATUS_TASK_SET_FULL and SCSI_STATUS_TIMEOUT were introduced
+ * in libiscsi 1.10.0 as part of an enum. The LIBISCSI_API_VERSION
+ * macro was introduced in 1.11.0. So use the API_VERSION macro as
+ * a hint that the macros are defined and define them ourselves
+ * otherwise to keep the required libiscsi version at 1.9.0 */
+#if !defined(LIBISCSI_API_VERSION)
+#define QEMU_SCSI_STATUS_TASK_SET_FULL  0x28
+#define QEMU_SCSI_STATUS_TIMEOUT        0x0f000002
+#else
+#define QEMU_SCSI_STATUS_TASK_SET_FULL  SCSI_STATUS_TASK_SET_FULL
+#define QEMU_SCSI_STATUS_TIMEOUT        SCSI_STATUS_TIMEOUT
+#endif
+
 static void
 iscsi_co_generic_cb(struct iscsi_context *iscsi, int status,
                         void *command_data, void *opaque)
@@ -187,13 +202,19 @@ iscsi_co_generic_cb(struct iscsi_context *iscsi, int status,
                 iTask->do_retry = 1;
                 goto out;
             }
-            /* status 0x28 is SCSI_TASK_SET_FULL. It was first introduced
-             * in libiscsi 1.10.0. Hardcode this value here to avoid
-             * the need to bump the libiscsi requirement to 1.10.0 */
-            if (status == SCSI_STATUS_BUSY || status == 0x28) {
+            if (status == SCSI_STATUS_BUSY ||
+                status == QEMU_SCSI_STATUS_TIMEOUT ||
+                status == QEMU_SCSI_STATUS_TASK_SET_FULL) {
                 unsigned retry_time =
                     exp_random(iscsi_retry_times[iTask->retries - 1]);
-                error_report("iSCSI Busy/TaskSetFull (retry #%u in %u ms): %s",
+                if (status == QEMU_SCSI_STATUS_TIMEOUT) {
+                    /* make sure the request is rescheduled AFTER the
+                     * reconnect is initiated */
+                    retry_time = EVENT_INTERVAL * 2;
+                    iTask->iscsilun->request_timed_out = true;
+                }
+                error_report("iSCSI Busy/TaskSetFull/TimeOut"
+                             " (retry #%u in %u ms): %s",
                              iTask->retries, retry_time,
                              iscsi_get_error(iscsi));
                 aio_timer_init(iTask->iscsilun->aio_context,
@@ -277,20 +298,26 @@ iscsi_set_events(IscsiLun *iscsilun)
                            iscsilun);
         iscsilun->events = ev;
     }
-
-    /* newer versions of libiscsi may return zero events. In this
-     * case start a timer to ensure we are able to return to service
-     * once this situation changes. */
-    if (!ev) {
-        timer_mod(iscsilun->event_timer,
-                  qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + EVENT_INTERVAL);
-    }
 }
 
-static void iscsi_timed_set_events(void *opaque)
+static void iscsi_timed_check_events(void *opaque)
 {
     IscsiLun *iscsilun = opaque;
+
+    /* check for timed out requests */
+    iscsi_service(iscsilun->iscsi, 0);
+
+    if (iscsilun->request_timed_out) {
+        iscsilun->request_timed_out = false;
+        iscsi_reconnect(iscsilun->iscsi);
+    }
+
+    /* newer versions of libiscsi may return zero events. Ensure we are able
+     * to return to service once this situation changes. */
     iscsi_set_events(iscsilun);
+
+    timer_mod(iscsilun->event_timer,
+              qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + EVENT_INTERVAL);
 }
 
 static void
@@ -1093,16 +1120,37 @@ static char *parse_initiator_name(const char *target)
     return iscsi_name;
 }
 
+static int parse_timeout(const char *target)
+{
+    QemuOptsList *list;
+    QemuOpts *opts;
+    const char *timeout;
+
+    list = qemu_find_opts("iscsi");
+    if (list) {
+        opts = qemu_opts_find(list, target);
+        if (!opts) {
+            opts = QTAILQ_FIRST(&list->head);
+        }
+        if (opts) {
+            timeout = qemu_opt_get(opts, "timeout");
+            if (timeout) {
+                return atoi(timeout);
+            }
+        }
+    }
+
+    return 0;
+}
+
 static void iscsi_nop_timed_event(void *opaque)
 {
     IscsiLun *iscsilun = opaque;
 
-    if (iscsi_get_nops_in_flight(iscsilun->iscsi) > MAX_NOP_FAILURES) {
+    if (iscsi_get_nops_in_flight(iscsilun->iscsi) >= MAX_NOP_FAILURES) {
         error_report("iSCSI: NOP timeout. Reconnecting...");
-        iscsi_reconnect(iscsilun->iscsi);
-    }
-
-    if (iscsi_nop_out_async(iscsilun->iscsi, NULL, NULL, 0, NULL) != 0) {
+        iscsilun->request_timed_out = true;
+    } else if (iscsi_nop_out_async(iscsilun->iscsi, NULL, NULL, 0, NULL) != 0) {
         error_report("iSCSI: failed to sent NOP-Out. Disabling NOP messages.");
         return;
     }
@@ -1260,10 +1308,13 @@ static void iscsi_attach_aio_context(BlockDriverState *bs,
     timer_mod(iscsilun->nop_timer,
               qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + NOP_INTERVAL);
 
-    /* Prepare a timer for a delayed call to iscsi_set_events */
+    /* Set up a timer for periodic calls to iscsi_set_events and to
+     * scan for command timeout */
     iscsilun->event_timer = aio_timer_new(iscsilun->aio_context,
                                           QEMU_CLOCK_REALTIME, SCALE_MS,
-                                          iscsi_timed_set_events, iscsilun);
+                                          iscsi_timed_check_events, iscsilun);
+    timer_mod(iscsilun->event_timer,
+              qemu_clock_get_ms(QEMU_CLOCK_REALTIME) + EVENT_INTERVAL);
 }
 
 static void iscsi_modesense_sync(IscsiLun *iscsilun)
@@ -1318,7 +1369,7 @@ static int iscsi_open(BlockDriverState *bs, QDict *options, int flags,
     QemuOpts *opts;
     Error *local_err = NULL;
     const char *filename;
-    int i, ret = 0;
+    int i, ret = 0, timeout = 0;
 
     opts = qemu_opts_create(&runtime_opts, NULL, 0, &error_abort);
     qemu_opts_absorb_qdict(opts, options, &local_err);
@@ -1388,6 +1439,16 @@ static int iscsi_open(BlockDriverState *bs, QDict *options, int flags,
         goto out;
     }
 
+    /* timeout handling is broken in libiscsi before 1.15.0 */
+    timeout = parse_timeout(iscsi_url->target);
+#if defined(LIBISCSI_API_VERSION) && LIBISCSI_API_VERSION >= 20150621
+    iscsi_set_timeout(iscsi, timeout);
+#else
+    if (timeout) {
+        error_report("iSCSI: ignoring timeout value for libiscsi <1.15.0");
+    }
+#endif
+
     if (iscsi_full_connect_sync(iscsi, iscsi_url->portal, iscsi_url->lun) != 0) {
         error_setg(errp, "iSCSI: Failed to connect to LUN : %s",
             iscsi_get_error(iscsi));
@@ -1736,6 +1797,10 @@ static QemuOptsList qemu_iscsi_opts = {
             .name = "initiator-name",
             .type = QEMU_OPT_STRING,
             .help = "Initiator iqn name to use when connecting",
+        },{
+            .name = "timeout",
+            .type = QEMU_OPT_NUMBER,
+            .help = "Request timeout in seconds (default 0 = no timeout)",
         },
         { /* end of list */ }
     },
diff --git a/block/mirror.c b/block/mirror.c
index 048e452..8888cea 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -58,6 +58,7 @@ typedef struct MirrorBlockJob {
     int in_flight;
     int sectors_in_flight;
     int ret;
+    bool unmap;
 } MirrorBlockJob;
 
 typedef struct MirrorOp {
@@ -164,6 +165,8 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
     int64_t end, sector_num, next_chunk, next_sector, hbitmap_next_sector;
     uint64_t delay_ns = 0;
     MirrorOp *op;
+    int pnum;
+    int64_t ret;
 
     s->sector_num = hbitmap_iter_next(&s->hbi);
     if (s->sector_num < 0) {
@@ -290,8 +293,22 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
     s->in_flight++;
     s->sectors_in_flight += nb_sectors;
     trace_mirror_one_iteration(s, sector_num, nb_sectors);
-    bdrv_aio_readv(source, sector_num, &op->qiov, nb_sectors,
-                   mirror_read_complete, op);
+
+    ret = bdrv_get_block_status_above(source, NULL, sector_num,
+                                      nb_sectors, &pnum);
+    if (ret < 0 || pnum < nb_sectors ||
+            (ret & BDRV_BLOCK_DATA && !(ret & BDRV_BLOCK_ZERO))) {
+        bdrv_aio_readv(source, sector_num, &op->qiov, nb_sectors,
+                       mirror_read_complete, op);
+    } else if (ret & BDRV_BLOCK_ZERO) {
+        bdrv_aio_write_zeroes(s->target, sector_num, op->nb_sectors,
+                              s->unmap ? BDRV_REQ_MAY_UNMAP : 0,
+                              mirror_write_complete, op);
+    } else {
+        assert(!(ret & BDRV_BLOCK_DATA));
+        bdrv_aio_discard(s->target, sector_num, op->nb_sectors,
+                         mirror_write_complete, op);
+    }
     return delay_ns;
 }
 
@@ -652,6 +669,7 @@ static void mirror_start_job(BlockDriverState *bs, BlockDriverState *target,
                              int64_t buf_size,
                              BlockdevOnError on_source_error,
                              BlockdevOnError on_target_error,
+                             bool unmap,
                              BlockCompletionFunc *cb,
                              void *opaque, Error **errp,
                              const BlockJobDriver *driver,
@@ -686,6 +704,7 @@ static void mirror_start_job(BlockDriverState *bs, BlockDriverState *target,
     s->base = base;
     s->granularity = granularity;
     s->buf_size = MAX(buf_size, granularity);
+    s->unmap = unmap;
 
     s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp);
     if (!s->dirty_bitmap) {
@@ -704,21 +723,22 @@ void mirror_start(BlockDriverState *bs, BlockDriverState *target,
                   int64_t speed, uint32_t granularity, int64_t buf_size,
                   MirrorSyncMode mode, BlockdevOnError on_source_error,
                   BlockdevOnError on_target_error,
+                  bool unmap,
                   BlockCompletionFunc *cb,
                   void *opaque, Error **errp)
 {
     bool is_none_mode;
     BlockDriverState *base;
 
-    if (mode == MIRROR_SYNC_MODE_DIRTY_BITMAP) {
-        error_setg(errp, "Sync mode 'dirty-bitmap' not supported");
+    if (mode == MIRROR_SYNC_MODE_INCREMENTAL) {
+        error_setg(errp, "Sync mode 'incremental' not supported");
         return;
     }
     is_none_mode = mode == MIRROR_SYNC_MODE_NONE;
     base = mode == MIRROR_SYNC_MODE_TOP ? bs->backing_hd : NULL;
     mirror_start_job(bs, target, replaces,
                      speed, granularity, buf_size,
-                     on_source_error, on_target_error, cb, opaque, errp,
+                     on_source_error, on_target_error, unmap, cb, opaque, errp,
                      &mirror_job_driver, is_none_mode, base);
 }
 
@@ -766,7 +786,7 @@ void commit_active_start(BlockDriverState *bs, BlockDriverState *base,
 
     bdrv_ref(base);
     mirror_start_job(bs, base, NULL, speed, 0, 0,
-                     on_error, on_error, cb, opaque, &local_err,
+                     on_error, on_error, false, cb, opaque, &local_err,
                      &commit_active_job_driver, false, base);
     if (local_err) {
         error_propagate(errp, local_err);
diff --git a/block/nfs.c b/block/nfs.c
index ca9e24e..c026ff6 100644
--- a/block/nfs.c
+++ b/block/nfs.c
@@ -35,6 +35,8 @@
 #include "sysemu/sysemu.h"
 #include <nfsc/libnfs.h>
 
+#define QEMU_NFS_MAX_READAHEAD_SIZE 1048576
+
 typedef struct NFSClient {
     struct nfs_context *context;
     struct nfsfh *fh;
@@ -327,6 +329,11 @@ static int64_t nfs_client_open(NFSClient *client, const char *filename,
             nfs_set_tcp_syncnt(client->context, val);
 #ifdef LIBNFS_FEATURE_READAHEAD
         } else if (!strcmp(qp->p[i].name, "readahead")) {
+            if (val > QEMU_NFS_MAX_READAHEAD_SIZE) {
+                error_report("NFS Warning: Truncating NFS readahead"
+                             " size to %d", QEMU_NFS_MAX_READAHEAD_SIZE);
+                val = QEMU_NFS_MAX_READAHEAD_SIZE;
+            }
             nfs_set_readahead(client->context, val);
 #endif
         } else {
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 0632fc3..b0ee42d 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -940,19 +940,21 @@ int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
     }
 
     free_in_cluster = s->cluster_size - offset_into_cluster(s, offset);
-    if (!offset || free_in_cluster < size) {
-        int64_t new_cluster = alloc_clusters_noref(bs, s->cluster_size);
-        if (new_cluster < 0) {
-            return new_cluster;
-        }
+    do {
+        if (!offset || free_in_cluster < size) {
+            int64_t new_cluster = alloc_clusters_noref(bs, s->cluster_size);
+            if (new_cluster < 0) {
+                return new_cluster;
+            }
 
-        if (!offset || ROUND_UP(offset, s->cluster_size) != new_cluster) {
-            offset = new_cluster;
+            if (!offset || ROUND_UP(offset, s->cluster_size) != new_cluster) {
+                offset = new_cluster;
+            }
         }
-    }
 
-    assert(offset);
-    ret = update_refcount(bs, offset, size, 1, false, QCOW2_DISCARD_NEVER);
+        assert(offset);
+        ret = update_refcount(bs, offset, size, 1, false, QCOW2_DISCARD_NEVER);
+    } while (ret == -EAGAIN);
     if (ret < 0) {
         return ret;
     }
diff --git a/blockdev.c b/blockdev.c
index b354676..7fee519 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2167,9 +2167,6 @@ void hmp_drive_del(Monitor *mon, const QDict *qdict)
         return;
     }
 
-    /* quiesce block driver; prevent further io */
-    bdrv_drain_all();
-    bdrv_flush(bs);
     bdrv_close(bs);
 
     /* if we have a device attached to this BlockDriverState
@@ -2658,6 +2655,7 @@ void qmp_drive_mirror(const char *device, const char *target,
                       bool has_buf_size, int64_t buf_size,
                       bool has_on_source_error, BlockdevOnError on_source_error,
                       bool has_on_target_error, BlockdevOnError on_target_error,
+                      bool has_unmap, bool unmap,
                       Error **errp)
 {
     BlockBackend *blk;
@@ -2689,6 +2687,9 @@ void qmp_drive_mirror(const char *device, const char *target,
     if (!has_buf_size) {
         buf_size = DEFAULT_MIRROR_BUF_SIZE;
     }
+    if (!has_unmap) {
+        unmap = true;
+    }
 
     if (granularity != 0 && (granularity < 512 || granularity > 1048576 * 64)) {
         error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "granularity",
@@ -2830,6 +2831,7 @@ void qmp_drive_mirror(const char *device, const char *target,
                  has_replaces ? replaces : NULL,
                  speed, granularity, buf_size, sync,
                  on_source_error, on_target_error,
+                 unmap,
                  block_job_cb, bs, &local_err);
     if (local_err != NULL) {
         bdrv_unref(target_bs);
diff --git a/docs/bitmaps.md b/docs/bitmaps.md
index f066b48..fa87f07 100644
--- a/docs/bitmaps.md
+++ b/docs/bitmaps.md
@@ -210,7 +210,7 @@ full backup as a backing image.
         "bitmap": "bitmap0",
         "target": "incremental.0.img",
         "format": "qcow2",
-        "sync": "dirty-bitmap",
+        "sync": "incremental",
         "mode": "existing"
       }
     }
@@ -235,7 +235,7 @@ full backup as a backing image.
         "bitmap": "bitmap0",
         "target": "incremental.1.img",
         "format": "qcow2",
-        "sync": "dirty-bitmap",
+        "sync": "incremental",
         "mode": "existing"
       }
     }
@@ -275,7 +275,7 @@ full backup as a backing image.
         "bitmap": "bitmap0",
         "target": "incremental.0.img",
         "format": "qcow2",
-        "sync": "dirty-bitmap",
+        "sync": "incremental",
         "mode": "existing"
       }
     }
@@ -308,7 +308,7 @@ full backup as a backing image.
         "bitmap": "bitmap0",
         "target": "incremental.0.img",
         "format": "qcow2",
-        "sync": "dirty-bitmap",
+        "sync": "incremental",
         "mode": "existing"
       }
     }
diff --git a/hmp.c b/hmp.c
index 070aaf8..dcc66f1 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1061,7 +1061,7 @@ void hmp_drive_mirror(Monitor *mon, const QDict *qdict)
                      false, NULL, false, NULL,
                      full ? MIRROR_SYNC_MODE_FULL : MIRROR_SYNC_MODE_TOP,
                      true, mode, false, 0, false, 0, false, 0,
-                     false, 0, false, 0, &err);
+                     false, 0, false, 0, false, true, &err);
     hmp_handle_error(mon, &err);
 }
 
diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
index 99db56c..2a4b8e1 100644
--- a/hw/ppc/ppc.c
+++ b/hw/ppc/ppc.c
@@ -51,8 +51,6 @@
 #  define LOG_TB(...) do { } while (0)
 #endif
 
-#define NSEC_PER_SEC    1000000000LL
-
 static void cpu_ppc_tb_stop (CPUPPCState *env);
 static void cpu_ppc_tb_start (CPUPPCState *env);
 
diff --git a/hw/ppc/spapr_rtc.c b/hw/ppc/spapr_rtc.c
index 83eb7c1..9da3746 100644
--- a/hw/ppc/spapr_rtc.c
+++ b/hw/ppc/spapr_rtc.c
@@ -26,6 +26,7 @@
  *
  */
 #include "cpu.h"
+#include "qemu/timer.h"
 #include "sysemu/sysemu.h"
 #include "hw/ppc/spapr.h"
 #include "qapi-event.h"
@@ -40,8 +41,6 @@ struct sPAPRRTCState {
     int64_t ns_offset;
 };
 
-#define NSEC_PER_SEC    1000000000LL
-
 void spapr_rtc_read(DeviceState *dev, struct tm *tm, uint32_t *ns)
 {
     sPAPRRTCState *rtc = SPAPR_RTC(dev);
diff --git a/hw/timer/mc146818rtc.c b/hw/timer/mc146818rtc.c
index 2e3ffc8..954c34d 100644
--- a/hw/timer/mc146818rtc.c
+++ b/hw/timer/mc146818rtc.c
@@ -48,7 +48,6 @@
 # define DPRINTF_C(format, ...)      do { } while (0)
 #endif
 
-#define NSEC_PER_SEC    1000000000LL
 #define SEC_PER_MIN     60
 #define MIN_PER_HOUR    60
 #define SEC_PER_HOUR    3600
diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
index d4d7547..d7cd40b 100644
--- a/hw/usb/hcd-ehci.c
+++ b/hw/usb/hcd-ehci.c
@@ -32,7 +32,7 @@
 #include "trace.h"
 
 #define FRAME_TIMER_FREQ 1000
-#define FRAME_TIMER_NS   (1000000000 / FRAME_TIMER_FREQ)
+#define FRAME_TIMER_NS   (NSEC_PER_SEC / FRAME_TIMER_FREQ)
 #define UFRAME_TIMER_NS  (FRAME_TIMER_NS / 8)
 
 #define NB_MAXINTRATE    8        // Max rate at which controller issues ints
diff --git a/include/block/block.h b/include/block/block.h
index 07bb724..06e4137 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -372,6 +372,10 @@ bool bdrv_unallocated_blocks_are_zero(BlockDriverState *bs);
 bool bdrv_can_write_zeroes_with_unmap(BlockDriverState *bs);
 int64_t bdrv_get_block_status(BlockDriverState *bs, int64_t sector_num,
                               int nb_sectors, int *pnum);
+int64_t bdrv_get_block_status_above(BlockDriverState *bs,
+                                    BlockDriverState *base,
+                                    int64_t sector_num,
+                                    int nb_sectors, int *pnum);
 int bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num, int nb_sectors,
                       int *pnum);
 int bdrv_is_allocated_above(BlockDriverState *top, BlockDriverState *base,
diff --git a/include/block/block_int.h b/include/block/block_int.h
index b0476fc..8996baf 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -612,6 +612,7 @@ void commit_active_start(BlockDriverState *bs, BlockDriverState *base,
  * @mode: Whether to collapse all images in the chain to the target.
  * @on_source_error: The action to take upon error reading from the source.
  * @on_target_error: The action to take upon error writing to the target.
+ * @unmap: Whether to unmap target where source sectors only contain zeroes.
  * @cb: Completion function for the job.
  * @opaque: Opaque pointer value passed to @cb.
  * @errp: Error object.
@@ -626,6 +627,7 @@ void mirror_start(BlockDriverState *bs, BlockDriverState *target,
                   int64_t speed, uint32_t granularity, int64_t buf_size,
                   MirrorSyncMode mode, BlockdevOnError on_source_error,
                   BlockdevOnError on_target_error,
+                  bool unmap,
                   BlockCompletionFunc *cb,
                   void *opaque, Error **errp);
 
@@ -635,7 +637,7 @@ void mirror_start(BlockDriverState *bs, BlockDriverState *target,
  * @target: Block device to write to.
  * @speed: The maximum speed, in bytes per second, or 0 for unlimited.
  * @sync_mode: What parts of the disk image should be copied to the destination.
- * @sync_bitmap: The dirty bitmap if sync_mode is MIRROR_SYNC_MODE_DIRTY_BITMAP.
+ * @sync_bitmap: The dirty bitmap if sync_mode is MIRROR_SYNC_MODE_INCREMENTAL.
  * @on_source_error: The action to take upon error reading from the source.
  * @on_target_error: The action to take upon error writing to the target.
  * @cb: Completion function for the job.
@@ -660,7 +662,5 @@ bool blk_dev_is_medium_locked(BlockBackend *blk);
 void blk_dev_resize_cb(BlockBackend *blk);
 
 void bdrv_set_dirty(BlockDriverState *bs, int64_t cur_sector, int nr_sectors);
-void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
-                      int nr_sectors);
 
 #endif /* BLOCK_INT_H */
diff --git a/include/qemu/throttle.h b/include/qemu/throttle.h
index 5af76f0..995b2d5 100644
--- a/include/qemu/throttle.h
+++ b/include/qemu/throttle.h
@@ -29,8 +29,6 @@
 #include "qemu-common.h"
 #include "qemu/timer.h"
 
-#define NANOSECONDS_PER_SECOND  1000000000.0
-
 typedef enum {
     THROTTLE_BPS_TOTAL,
     THROTTLE_BPS_READ,
diff --git a/include/qemu/timer.h b/include/qemu/timer.h
index 9e4f90f..4dda20b 100644
--- a/include/qemu/timer.h
+++ b/include/qemu/timer.h
@@ -5,6 +5,8 @@
 #include "qemu-common.h"
 #include "qemu/notify.h"
 
+#define NSEC_PER_SEC 1000000000LL
+
 /* timers */
 
 #define SCALE_MS 1000000
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 5a368f6..7b2efb8 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -536,12 +536,12 @@
 #
 # @none: only copy data written from now on
 #
-# @dirty-bitmap: only copy data described by the dirty bitmap. Since: 2.4
+# @incremental: only copy data described by the dirty bitmap. Since: 2.4
 #
 # Since: 1.3
 ##
 { 'enum': 'MirrorSyncMode',
-  'data': ['top', 'full', 'none', 'dirty-bitmap'] }
+  'data': ['top', 'full', 'none', 'incremental'] }
 
 ##
 # @BlockJobType:
@@ -724,8 +724,8 @@
 #
 # @speed: #optional the maximum speed, in bytes per second
 #
-# @bitmap: #optional the name of dirty bitmap if sync is "dirty-bitmap".
-#          Must be present if sync is "dirty-bitmap", must NOT be present
+# @bitmap: #optional the name of dirty bitmap if sync is "incremental".
+#          Must be present if sync is "incremental", must NOT be present
 #          otherwise. (Since 2.4)
 #
 # @on-source-error: #optional the action to take on an error on the source,
@@ -975,6 +975,11 @@
 # @on-target-error: #optional the action to take on an error on the target,
 #                   default 'report' (no limitations, since this applies to
 #                   a different block device than @device).
+# @unmap: #optional Whether to try to unmap target sectors where source has
+#         only zero. If true, and target unallocated sectors will read as zero,
+#         target image sectors will be unmapped; otherwise, zeroes will be
+#         written. Both will result in identical contents.
+#         Default is true. (Since 2.4)
 #
 # Returns: nothing on success
 #          If @device is not a valid block device, DeviceNotFound
@@ -987,7 +992,8 @@
             'sync': 'MirrorSyncMode', '*mode': 'NewImageMode',
             '*speed': 'int', '*granularity': 'uint32',
             '*buf-size': 'int', '*on-source-error': 'BlockdevOnError',
-            '*on-target-error': 'BlockdevOnError' } }
+            '*on-target-error': 'BlockdevOnError',
+            '*unmap': 'bool' } }
 
 ##
 # @BlockDirtyBitmap
diff --git a/qemu-options.hx b/qemu-options.hx
index e6e3895..7b8efbf 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2294,6 +2294,10 @@ By default qemu will use the iSCSI initiator-name
 'iqn.2008-11.org.linux-kvm[:<name>]' but this can also be set from the command
 line or a configuration file.
 
+Since version Qemu 2.4 it is possible to specify a iSCSI request timeout to detect
+stalled requests and force a reestablishment of the session. The timeout
+is specified in seconds. The default is 0 which means no timeout. Libiscsi
+1.15.0 or greater is required for this feature.
 
 Example (without authentication):
 @example
@@ -2321,6 +2325,7 @@ DEF("iscsi", HAS_ARG, QEMU_OPTION_iscsi,
     "-iscsi [user=user][,password=password]\n"
     "       [,header-digest=CRC32C|CR32C-NONE|NONE-CRC32C|NONE\n"
     "       [,initiator-name=initiator-iqn][,id=target-iqn]\n"
+    "       [,timeout=timeout]\n"
     "                iSCSI session parameters\n", QEMU_ARCH_ALL)
 STEXI
 
diff --git a/qmp-commands.hx b/qmp-commands.hx
index a05d25f..e1bcc60 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -1137,10 +1137,10 @@ Arguments:
             (json-string, optional)
 - "sync": what parts of the disk image should be copied to the destination;
   possibilities include "full" for all the disk, "top" for only the sectors
-  allocated in the topmost image, "dirty-bitmap" for only the dirty sectors in
+  allocated in the topmost image, "incremental" for only the dirty sectors in
   the bitmap, or "none" to only replicate new I/O (MirrorSyncMode).
-- "bitmap": dirty bitmap name for sync==dirty-bitmap. Must be present if sync
-            is "dirty-bitmap", must NOT be present otherwise.
+- "bitmap": dirty bitmap name for sync==incremental. Must be present if sync
+            is "incremental", must NOT be present otherwise.
 - "mode": whether and how QEMU should create a new image
           (NewImageMode, optional, default 'absolute-paths')
 - "speed": the maximum speed, in bytes per second (json-int, optional)
@@ -1503,6 +1503,7 @@ EQMP
         .args_type  = "sync:s,device:B,target:s,speed:i?,mode:s?,format:s?,"
                       "node-name:s?,replaces:s?,"
                       "on-source-error:s?,on-target-error:s?,"
+                      "unmap:b?,"
                       "granularity:i?,buf-size:i?",
         .mhandler.cmd_new = qmp_marshal_input_drive_mirror,
     },
@@ -1542,6 +1543,8 @@ Arguments:
   (BlockdevOnError, default 'report')
 - "on-target-error": the action to take on an error on the target
   (BlockdevOnError, default 'report')
+- "unmap": whether the target sectors should be discarded where source has only
+  zeroes. (json-bool, optional, default true)
 
 The default value of the granularity is the image cluster size clamped
 between 4096 and 65536, if the image format defines one.  If the format
diff --git a/tests/qemu-iotests/041 b/tests/qemu-iotests/041
index 59a8f73..3d46ed7 100755
--- a/tests/qemu-iotests/041
+++ b/tests/qemu-iotests/041
@@ -34,38 +34,8 @@ quorum_img3 = os.path.join(iotests.test_dir, 'quorum3.img')
 quorum_repair_img = os.path.join(iotests.test_dir, 'quorum_repair.img')
 quorum_snapshot_file = os.path.join(iotests.test_dir, 'quorum_snapshot.img')
 
-class ImageMirroringTestCase(iotests.QMPTestCase):
-    '''Abstract base class for image mirroring test cases'''
 
-    def wait_ready(self, drive='drive0'):
-        '''Wait until a block job BLOCK_JOB_READY event'''
-        ready = False
-        while not ready:
-            for event in self.vm.get_qmp_events(wait=True):
-                if event['event'] == 'BLOCK_JOB_READY':
-                    self.assert_qmp(event, 'data/type', 'mirror')
-                    self.assert_qmp(event, 'data/device', drive)
-                    ready = True
-
-    def wait_ready_and_cancel(self, drive='drive0'):
-        self.wait_ready(drive=drive)
-        event = self.cancel_and_wait(drive=drive)
-        self.assertEquals(event['event'], 'BLOCK_JOB_COMPLETED')
-        self.assert_qmp(event, 'data/type', 'mirror')
-        self.assert_qmp(event, 'data/offset', event['data']['len'])
-
-    def complete_and_wait(self, drive='drive0', wait_ready=True):
-        '''Complete a block job and wait for it to finish'''
-        if wait_ready:
-            self.wait_ready(drive=drive)
-
-        result = self.vm.qmp('block-job-complete', device=drive)
-        self.assert_qmp(result, 'return', {})
-
-        event = self.wait_until_completed(drive=drive)
-        self.assert_qmp(event, 'data/type', 'mirror')
-
-class TestSingleDrive(ImageMirroringTestCase):
+class TestSingleDrive(iotests.QMPTestCase):
     image_len = 1 * 1024 * 1024 # MB
 
     def setUp(self):
@@ -221,17 +191,9 @@ class TestSingleDriveUnalignedLength(TestSingleDrive):
     test_small_buffer2 = None
     test_large_cluster = None
 
-class TestMirrorNoBacking(ImageMirroringTestCase):
+class TestMirrorNoBacking(iotests.QMPTestCase):
     image_len = 2 * 1024 * 1024 # MB
 
-    def complete_and_wait(self, drive='drive0', wait_ready=True):
-        iotests.create_image(target_backing_img, TestMirrorNoBacking.image_len)
-        return ImageMirroringTestCase.complete_and_wait(self, drive, wait_ready)
-
-    def compare_images(self, img1, img2):
-        iotests.create_image(target_backing_img, TestMirrorNoBacking.image_len)
-        return iotests.compare_images(img1, img2)
-
     def setUp(self):
         iotests.create_image(backing_img, TestMirrorNoBacking.image_len)
         qemu_img('create', '-f', iotests.imgfmt, '-o', 'backing_file=%s' % backing_img, test_img)
@@ -242,7 +204,10 @@ class TestMirrorNoBacking(ImageMirroringTestCase):
         self.vm.shutdown()
         os.remove(test_img)
         os.remove(backing_img)
-        os.remove(target_backing_img)
+        try:
+            os.remove(target_backing_img)
+        except:
+            pass
         os.remove(target_img)
 
     def test_complete(self):
@@ -257,7 +222,7 @@ class TestMirrorNoBacking(ImageMirroringTestCase):
         result = self.vm.qmp('query-block')
         self.assert_qmp(result, 'return[0]/inserted/file', target_img)
         self.vm.shutdown()
-        self.assertTrue(self.compare_images(test_img, target_img),
+        self.assertTrue(iotests.compare_images(test_img, target_img),
                         'target image does not match source after mirroring')
 
     def test_cancel(self):
@@ -272,7 +237,7 @@ class TestMirrorNoBacking(ImageMirroringTestCase):
         result = self.vm.qmp('query-block')
         self.assert_qmp(result, 'return[0]/inserted/file', test_img)
         self.vm.shutdown()
-        self.assertTrue(self.compare_images(test_img, target_img),
+        self.assertTrue(iotests.compare_images(test_img, target_img),
                         'target image does not match source after mirroring')
 
     def test_large_cluster(self):
@@ -283,7 +248,6 @@ class TestMirrorNoBacking(ImageMirroringTestCase):
                         %(TestMirrorNoBacking.image_len), target_backing_img)
         qemu_img('create', '-f', iotests.imgfmt, '-o', 'cluster_size=%d,backing_file=%s'
                         % (TestMirrorNoBacking.image_len, target_backing_img), target_img)
-        os.remove(target_backing_img)
 
         result = self.vm.qmp('drive-mirror', device='drive0', sync='full',
                              mode='existing', target=target_img)
@@ -293,10 +257,10 @@ class TestMirrorNoBacking(ImageMirroringTestCase):
         result = self.vm.qmp('query-block')
         self.assert_qmp(result, 'return[0]/inserted/file', target_img)
         self.vm.shutdown()
-        self.assertTrue(self.compare_images(test_img, target_img),
+        self.assertTrue(iotests.compare_images(test_img, target_img),
                         'target image does not match source after mirroring')
 
-class TestMirrorResized(ImageMirroringTestCase):
+class TestMirrorResized(iotests.QMPTestCase):
     backing_len = 1 * 1024 * 1024 # MB
     image_len = 2 * 1024 * 1024 # MB
 
@@ -344,7 +308,7 @@ class TestMirrorResized(ImageMirroringTestCase):
         self.assertTrue(iotests.compare_images(test_img, target_img),
                         'target image does not match source after mirroring')
 
-class TestReadErrors(ImageMirroringTestCase):
+class TestReadErrors(iotests.QMPTestCase):
     image_len = 2 * 1024 * 1024 # MB
 
     # this should be a multiple of twice the default granularity
@@ -498,7 +462,7 @@ new_state = "1"
         self.assert_no_active_block_jobs()
         self.vm.shutdown()
 
-class TestWriteErrors(ImageMirroringTestCase):
+class TestWriteErrors(iotests.QMPTestCase):
     image_len = 2 * 1024 * 1024 # MB
 
     # this should be a multiple of twice the default granularity
@@ -624,7 +588,7 @@ new_state = "1"
         self.assert_no_active_block_jobs()
         self.vm.shutdown()
 
-class TestSetSpeed(ImageMirroringTestCase):
+class TestSetSpeed(iotests.QMPTestCase):
     image_len = 80 * 1024 * 1024 # MB
 
     def setUp(self):
@@ -690,7 +654,7 @@ class TestSetSpeed(ImageMirroringTestCase):
 
         self.wait_ready_and_cancel()
 
-class TestUnbackedSource(ImageMirroringTestCase):
+class TestUnbackedSource(iotests.QMPTestCase):
     image_len = 2 * 1024 * 1024 # MB
 
     def setUp(self):
@@ -731,7 +695,7 @@ class TestUnbackedSource(ImageMirroringTestCase):
         self.complete_and_wait()
         self.assert_no_active_block_jobs()
 
-class TestRepairQuorum(ImageMirroringTestCase):
+class TestRepairQuorum(iotests.QMPTestCase):
     """ This class test quorum file repair using drive-mirror.
         It's mostly a fork of TestSingleDrive """
     image_len = 1 * 1024 * 1024 # MB
diff --git a/tests/qemu-iotests/124 b/tests/qemu-iotests/124
index 8abce2f..9ccd118 100644
--- a/tests/qemu-iotests/124
+++ b/tests/qemu-iotests/124
@@ -187,7 +187,7 @@ class TestIncrementalBackup(iotests.QMPTestCase):
 
         target = self.prepare_backup(bitmap, parent)
         res = self.do_qmp_backup(device=bitmap.drive['id'],
-                                 sync='dirty-bitmap', bitmap=bitmap.name,
+                                 sync='incremental', bitmap=bitmap.name,
                                  format=bitmap.drive['fmt'], target=target,
                                  mode='existing')
         if not res:
@@ -325,7 +325,7 @@ class TestIncrementalBackup(iotests.QMPTestCase):
         self.assert_no_active_block_jobs()
         self.files.append(self.err_img)
         result = self.vm.qmp('drive-backup', device=self.drives[0]['id'],
-                             sync='dirty-bitmap', format=self.drives[0]['fmt'],
+                             sync='incremental', format=self.drives[0]['fmt'],
                              target=self.err_img)
         self.assert_qmp(result, 'error/class', 'GenericError')
 
@@ -334,7 +334,7 @@ class TestIncrementalBackup(iotests.QMPTestCase):
         self.assert_no_active_block_jobs()
         self.files.append(self.err_img)
         result = self.vm.qmp('drive-backup', device=self.drives[0]['id'],
-                             sync='dirty-bitmap', bitmap='unknown',
+                             sync='incremental', bitmap='unknown',
                              format=self.drives[0]['fmt'], target=self.err_img)
         self.assert_qmp(result, 'error/class', 'GenericError')
 
diff --git a/tests/qemu-iotests/132 b/tests/qemu-iotests/132
new file mode 100644
index 0000000..f53ef6e
--- /dev/null
+++ b/tests/qemu-iotests/132
@@ -0,0 +1,59 @@
+#!/usr/bin/env python
+#
+# Test mirror with unmap
+#
+# Copyright (C) 2015 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import time
+import os
+import iotests
+from iotests import qemu_img, qemu_io
+
+test_img = os.path.join(iotests.test_dir, 'test.img')
+target_img = os.path.join(iotests.test_dir, 'target.img')
+
+class TestSingleDrive(iotests.QMPTestCase):
+    image_len = 2 * 1024 * 1024 # MB
+
+    def setUp(self):
+        # Write data to the image so we can compare later
+        qemu_img('create', '-f', iotests.imgfmt, test_img, str(TestSingleDrive.image_len))
+        qemu_io('-f', iotests.imgfmt, '-c', 'write -P0x5d 0 2M', test_img)
+
+        self.vm = iotests.VM().add_drive(test_img, 'discard=unmap')
+        self.vm.launch()
+
+    def tearDown(self):
+        self.vm.shutdown()
+        os.remove(test_img)
+        try:
+            os.remove(target_img)
+        except OSError:
+            pass
+
+    def test_mirror_discard(self):
+        result = self.vm.qmp('drive-mirror', device='drive0', sync='full',
+                             target=target_img)
+        self.assert_qmp(result, 'return', {})
+        self.vm.hmp_qemu_io('drive0', 'discard 0 64k')
+        self.complete_and_wait('drive0')
+        self.vm.shutdown()
+        self.assertTrue(iotests.compare_images(test_img, target_img),
+                        'target image does not match source after mirroring')
+
+if __name__ == '__main__':
+    iotests.main(supported_fmts=['raw', 'qcow2'])
diff --git a/tests/qemu-iotests/132.out b/tests/qemu-iotests/132.out
new file mode 100644
index 0000000..ae1213e
--- /dev/null
+++ b/tests/qemu-iotests/132.out
@@ -0,0 +1,5 @@
+.
+----------------------------------------------------------------------
+Ran 1 tests
+
+OK
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 4597fc1..6206765 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -131,4 +131,5 @@
 129 rw auto quick
 130 rw auto quick
 131 rw auto quick
+132 rw auto quick
 134 rw auto quick
diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index 04a294d..8615b10 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -326,6 +326,29 @@ class QMPTestCase(unittest.TestCase):
         self.assert_no_active_block_jobs()
         return event
 
+    def wait_ready(self, drive='drive0'):
+        '''Wait until a block job BLOCK_JOB_READY event'''
+        f = {'data': {'type': 'mirror', 'device': drive } }
+        event = self.vm.event_wait(name='BLOCK_JOB_READY', match=f)
+
+    def wait_ready_and_cancel(self, drive='drive0'):
+        self.wait_ready(drive=drive)
+        event = self.cancel_and_wait(drive=drive)
+        self.assertEquals(event['event'], 'BLOCK_JOB_COMPLETED')
+        self.assert_qmp(event, 'data/type', 'mirror')
+        self.assert_qmp(event, 'data/offset', event['data']['len'])
+
+    def complete_and_wait(self, drive='drive0', wait_ready=True):
+        '''Complete a block job and wait for it to finish'''
+        if wait_ready:
+            self.wait_ready(drive=drive)
+
+        result = self.vm.qmp('block-job-complete', device=drive)
+        self.assert_qmp(result, 'return', {})
+
+        event = self.wait_until_completed(drive=drive)
+        self.assert_qmp(event, 'data/type', 'mirror')
+
 def notrun(reason):
     '''Skip this test suite'''
     # Each test in qemu-iotests has a number ("seq")
diff --git a/tests/rtl8139-test.c b/tests/rtl8139-test.c
index 4e0bf02..3bff0e3 100644
--- a/tests/rtl8139-test.c
+++ b/tests/rtl8139-test.c
@@ -12,6 +12,7 @@
 #include "libqtest.h"
 #include "libqos/pci-pc.h"
 #include "qemu/osdep.h"
+#include "qemu/timer.h"
 #include "qemu-common.h"
 
 /* Tests only initialization so far. TODO: Replace with functional tests */
@@ -20,7 +21,6 @@ static void nop(void)
 }
 
 #define CLK 33000000
-#define NS_PER_SEC 1000000000ULL
 
 static QPCIBus *pcibus;
 static QPCIDevice *dev;
@@ -86,7 +86,7 @@ static void test_timer(void)
         fatal("time too big %u\n", curr);
     }
     for (cnt = 0; ; ) {
-        clock_step(1 * NS_PER_SEC);
+        clock_step(1 * NSEC_PER_SEC);
         prev = curr;
         curr = in_Timer();
 
@@ -125,7 +125,7 @@ static void test_timer(void)
     out_IntrStatus(0x4000);
     curr = in_Timer();
     out_TimerInt(curr + 0.5 * CLK);
-    clock_step(1 * NS_PER_SEC);
+    clock_step(1 * NSEC_PER_SEC);
     out_Timer(0);
     if ((in_IntrStatus() & 0x4000) == 0) {
         fatal("we should have an interrupt here!\n");
@@ -137,7 +137,7 @@ static void test_timer(void)
     out_IntrStatus(0x4000);
     curr = in_Timer();
     out_TimerInt(curr + 0.5 * CLK);
-    clock_step(1 * NS_PER_SEC);
+    clock_step(1 * NSEC_PER_SEC);
     out_TimerInt(0);
     if ((in_IntrStatus() & 0x4000) == 0) {
         fatal("we should have an interrupt here!\n");
@@ -148,7 +148,7 @@ static void test_timer(void)
     next = curr + 5.0 * CLK;
     out_TimerInt(next);
     for (cnt = 0; ; ) {
-        clock_step(1 * NS_PER_SEC);
+        clock_step(1 * NSEC_PER_SEC);
         prev = curr;
         curr = in_Timer();
         diff = (curr-prev) & 0xffffffffu;
diff --git a/tests/test-throttle.c b/tests/test-throttle.c
index 0168445..33b6b95 100644
--- a/tests/test-throttle.c
+++ b/tests/test-throttle.c
@@ -40,19 +40,19 @@ static void test_leak_bucket(void)
     bkt.level = 1.5;
 
     /* leak an op work of time */
-    throttle_leak_bucket(&bkt, NANOSECONDS_PER_SECOND / 150);
+    throttle_leak_bucket(&bkt, NSEC_PER_SEC / 150);
     g_assert(bkt.avg == 150);
     g_assert(bkt.max == 15);
     g_assert(double_cmp(bkt.level, 0.5));
 
     /* leak again emptying the bucket */
-    throttle_leak_bucket(&bkt, NANOSECONDS_PER_SECOND / 150);
+    throttle_leak_bucket(&bkt, NSEC_PER_SEC / 150);
     g_assert(bkt.avg == 150);
     g_assert(bkt.max == 15);
     g_assert(double_cmp(bkt.level, 0));
 
     /* check that the bucket level won't go lower */
-    throttle_leak_bucket(&bkt, NANOSECONDS_PER_SECOND / 150);
+    throttle_leak_bucket(&bkt, NSEC_PER_SEC / 150);
     g_assert(bkt.avg == 150);
     g_assert(bkt.max == 15);
     g_assert(double_cmp(bkt.level, 0));
@@ -90,7 +90,7 @@ static void test_compute_wait(void)
     bkt.level = 15.5;
     wait = throttle_compute_wait(&bkt);
     /* time required to do half an operation */
-    result = (int64_t)  NANOSECONDS_PER_SECOND / 150 / 2;
+    result = (int64_t)  NSEC_PER_SEC / 150 / 2;
     g_assert(wait == result);
 }
 
diff --git a/tests/wdt_ib700-test.c b/tests/wdt_ib700-test.c
index 513a533..10a5472 100644
--- a/tests/wdt_ib700-test.c
+++ b/tests/wdt_ib700-test.c
@@ -11,8 +11,7 @@
 #include <string.h>
 #include "libqtest.h"
 #include "qemu/osdep.h"
-
-#define NS_PER_SEC 1000000000ULL
+#include "qemu/timer.h"
 
 static void qmp_check_no_event(void)
 {
@@ -41,29 +40,29 @@ static QDict *qmp_get_event(const char *name)
 
 static QDict *ib700_program_and_wait(QTestState *s)
 {
-    clock_step(NS_PER_SEC * 40);
+    clock_step(NSEC_PER_SEC * 40);
     qmp_check_no_event();
 
     /* 2 second limit */
     outb(0x443, 14);
 
     /* Ping */
-    clock_step(NS_PER_SEC);
+    clock_step(NSEC_PER_SEC);
     qmp_check_no_event();
     outb(0x443, 14);
 
     /* Disable */
-    clock_step(NS_PER_SEC);
+    clock_step(NSEC_PER_SEC);
     qmp_check_no_event();
     outb(0x441, 1);
-    clock_step(3 * NS_PER_SEC);
+    clock_step(3 * NSEC_PER_SEC);
     qmp_check_no_event();
 
     /* Enable and let it fire */
     outb(0x443, 13);
-    clock_step(3 * NS_PER_SEC);
+    clock_step(3 * NSEC_PER_SEC);
     qmp_check_no_event();
-    clock_step(2 * NS_PER_SEC);
+    clock_step(2 * NSEC_PER_SEC);
     return qmp_get_event("WATCHDOG");
 }
 
diff --git a/util/throttle.c b/util/throttle.c
index 706c131..ec70476 100644
--- a/util/throttle.c
+++ b/util/throttle.c
@@ -36,7 +36,7 @@ void throttle_leak_bucket(LeakyBucket *bkt, int64_t delta_ns)
     double leak;
 
     /* compute how much to leak */
-    leak = (bkt->avg * (double) delta_ns) / NANOSECONDS_PER_SECOND;
+    leak = (bkt->avg * (double) delta_ns) / NSEC_PER_SEC;
 
     /* make the bucket leak */
     bkt->level = MAX(bkt->level - leak, 0);
@@ -72,7 +72,7 @@ static void throttle_do_leak(ThrottleState *ts, int64_t now)
  */
 static int64_t throttle_do_compute_wait(double limit, double extra)
 {
-    double wait = extra * NANOSECONDS_PER_SECOND;
+    double wait = extra * NSEC_PER_SEC;
     wait /= limit;
     return wait;
 }