mirror: add support for on-source-error/on-target-error

Error management is important for mirroring; otherwise, an error on the
target (even something as "innocent" as ENOSPC) requires to start again
with a full copy.  Similar to on_read_error/on_write_error, two separate
knobs are provided for on_source_error (reads) and on_target_error (writes).
The default is 'report' for both.

The 'ignore' policy will leave the sector dirty, so that it will be
retried later.  Thus, it will not cause corruption.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 73 insertions, 21 deletions

diff --git a/block/mirror.c b/block/mirror.c
index 6320f6a..d6618a4 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -32,13 +32,28 @@ typedef struct MirrorBlockJob {
     RateLimit limit;
     BlockDriverState *target;
     MirrorSyncMode mode;
+    BlockdevOnError on_source_error, on_target_error;
     bool synced;
     bool should_complete;
     int64_t sector_num;
     uint8_t *buf;
 } MirrorBlockJob;
 
-static int coroutine_fn mirror_iteration(MirrorBlockJob *s)
+static BlockErrorAction mirror_error_action(MirrorBlockJob *s, bool read,
+                                            int error)
+{
+    s->synced = false;
+    if (read) {
+        return block_job_error_action(&s->common, s->common.bs,
+                                      s->on_source_error, true, error);
+    } else {
+        return block_job_error_action(&s->common, s->target,
+                                      s->on_target_error, false, error);
+    }
+}
+
+static int coroutine_fn mirror_iteration(MirrorBlockJob *s,
+                                         BlockErrorAction *p_action)
 {
     BlockDriverState *source = s->common.bs;
     BlockDriverState *target = s->target;
@@ -60,9 +75,21 @@ static int coroutine_fn mirror_iteration(MirrorBlockJob *s)
     trace_mirror_one_iteration(s, s->sector_num, nb_sectors);
     ret = bdrv_co_readv(source, s->sector_num, nb_sectors, &qiov);
     if (ret < 0) {
-        return ret;
+        *p_action = mirror_error_action(s, true, -ret);
+        goto fail;
+    }
+    ret = bdrv_co_writev(target, s->sector_num, nb_sectors, &qiov);
+    if (ret < 0) {
+        *p_action = mirror_error_action(s, false, -ret);
+        s->synced = false;
+        goto fail;
     }
-    return bdrv_co_writev(target, s->sector_num, nb_sectors, &qiov);
+    return 0;
+
+fail:
+    /* Try again later.  */
+    bdrv_set_dirty(source, s->sector_num, nb_sectors);
+    return ret;
 }
 
 static void coroutine_fn mirror_run(void *opaque)
@@ -117,8 +144,9 @@ static void coroutine_fn mirror_run(void *opaque)
 
         cnt = bdrv_get_dirty_count(bs);
         if (cnt != 0) {
-            ret = mirror_iteration(s);
-            if (ret < 0) {
+            BlockErrorAction action = BDRV_ACTION_REPORT;
+            ret = mirror_iteration(s, &action);
+            if (ret < 0 && action == BDRV_ACTION_REPORT) {
                 goto immediate_exit;
             }
             cnt = bdrv_get_dirty_count(bs);
@@ -129,23 +157,25 @@ static void coroutine_fn mirror_run(void *opaque)
             trace_mirror_before_flush(s);
             ret = bdrv_flush(s->target);
             if (ret < 0) {
-                goto immediate_exit;
-            }
-
-            /* We're out of the streaming phase.  From now on, if the job
-             * is cancelled we will actually complete all pending I/O and
-             * report completion.  This way, block-job-cancel will leave
-             * the target in a consistent state.
-             */
-            s->common.offset = end * BDRV_SECTOR_SIZE;
-            if (!s->synced) {
-                block_job_ready(&s->common);
-                s->synced = true;
+                if (mirror_error_action(s, false, -ret) == BDRV_ACTION_REPORT) {
+                    goto immediate_exit;
+                }
+            } else {
+                /* We're out of the streaming phase.  From now on, if the job
+                 * is cancelled we will actually complete all pending I/O and
+                 * report completion.  This way, block-job-cancel will leave
+                 * the target in a consistent state.
+                 */
+                s->common.offset = end * BDRV_SECTOR_SIZE;
+                if (!s->synced) {
+                    block_job_ready(&s->common);
+                    s->synced = true;
+                }
+
+                should_complete = s->should_complete ||
+                    block_job_is_cancelled(&s->common);
+                cnt = bdrv_get_dirty_count(bs);
             }
-
-            should_complete = s->should_complete ||
-                block_job_is_cancelled(&s->common);
-            cnt = bdrv_get_dirty_count(bs);
         }
 
         if (cnt == 0 && should_complete) {
@@ -197,6 +227,7 @@ static void coroutine_fn mirror_run(void *opaque)
 immediate_exit:
     g_free(s->buf);
     bdrv_set_dirty_tracking(bs, false);
+    bdrv_iostatus_disable(s->target);
     if (s->should_complete && ret == 0) {
         if (bdrv_get_flags(s->target) != bdrv_get_flags(s->common.bs)) {
             bdrv_reopen(s->target, bdrv_get_flags(s->common.bs), NULL);
@@ -219,6 +250,13 @@ static void mirror_set_speed(BlockJob *job, int64_t speed, Error **errp)
     ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME);
 }
 
+static void mirror_iostatus_reset(BlockJob *job)
+{
+    MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
+
+    bdrv_iostatus_reset(s->target);
+}
+
 static void mirror_complete(BlockJob *job, Error **errp)
 {
     MirrorBlockJob *s = container_of(job, MirrorBlockJob, common);
@@ -245,25 +283,39 @@ static BlockJobType mirror_job_type = {
     .instance_size = sizeof(MirrorBlockJob),
     .job_type      = "mirror",
     .set_speed     = mirror_set_speed,
+    .iostatus_reset= mirror_iostatus_reset,
     .complete      = mirror_complete,
 };
 
 void mirror_start(BlockDriverState *bs, BlockDriverState *target,
                   int64_t speed, MirrorSyncMode mode,
+                  BlockdevOnError on_source_error,
+                  BlockdevOnError on_target_error,
                   BlockDriverCompletionFunc *cb,
                   void *opaque, Error **errp)
 {
     MirrorBlockJob *s;
 
+    if ((on_source_error == BLOCKDEV_ON_ERROR_STOP ||
+         on_source_error == BLOCKDEV_ON_ERROR_ENOSPC) &&
+        !bdrv_iostatus_is_enabled(bs)) {
+        error_set(errp, QERR_INVALID_PARAMETER, "on-source-error");
+        return;
+    }
+
     s = block_job_create(&mirror_job_type, bs, speed, cb, opaque, errp);
     if (!s) {
         return;
     }
 
+    s->on_source_error = on_source_error;
+    s->on_target_error = on_target_error;
     s->target = target;
     s->mode = mode;
     bdrv_set_dirty_tracking(bs, true);
     bdrv_set_enable_write_cache(s->target, true);
+    bdrv_set_on_error(s->target, on_target_error, on_target_error);
+    bdrv_iostatus_enable(s->target);
     s->common.co = qemu_coroutine_create(mirror_run);
     trace_mirror_start(bs, s, s->common.co, opaque);
     qemu_coroutine_enter(s->common.co, s);