From f27835b1c21b80477e828ed82c5afd764e6f90ca Mon Sep 17 00:00:00 2001

From: John Snow <jsnow@redhat.com>

Date: Mon, 10 Sep 2018 18:17:53 +0200

Subject: [PATCH 15/25] block/mirror: conservative mirror_exit refactor

RH-Author: John Snow <jsnow@redhat.com>

Message-id: <20180910181803.11781-16-jsnow@redhat.com>

Patchwork-id: 82105

O-Subject: [RHEL-7.6 qemu-kvm-rhev PATCH 15/25] block/mirror: conservative mirror_exit refactor

Bugzilla: 1626061

RH-Acked-by: Max Reitz <mreitz@redhat.com>

RH-Acked-by: Jeffrey Cody <jcody@redhat.com>

RH-Acked-by: Kevin Wolf <kwolf@redhat.com>

For purposes of minimum code movement, refactor the mirror_exit

callback to use the post-finalization callbacks in a trivial way.

Signed-off-by: John Snow <jsnow@redhat.com>

Message-id: 20180906130225.5118-7-jsnow@redhat.com

Reviewed-by: Jeff Cody <jcody@redhat.com>

Reviewed-by: Max Reitz <mreitz@redhat.com>

[mreitz: Added comment for the mirror_exit() function]

Signed-off-by: Max Reitz <mreitz@redhat.com>

(cherry picked from commit 9fd426955da4239af7690c92b387fff0502aca84)

Signed-off-by: John Snow <jsnow@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

Conflicts:

    block/mirror.c: context conflict on job properties

---

 block/mirror.c | 44 +++++++++++++++++++++++++++++++++-----------

 1 file changed, 33 insertions(+), 11 deletions(-)

diff --git a/block/mirror.c b/block/mirror.c

index 1945000..313e6e9 100644

--- a/block/mirror.c

+++ b/block/mirror.c

@@ -71,6 +71,7 @@ typedef struct MirrorBlockJob {

     int target_cluster_size;

     int max_iov;

     bool initial_zeroing_ongoing;

+    bool prepared;

 } MirrorBlockJob;

 typedef struct MirrorOp {

@@ -480,7 +481,12 @@ static void mirror_wait_for_all_io(MirrorBlockJob *s)

     }

 }

-static void mirror_exit(Job *job)

+/**

+ * mirror_exit_common: handle both abort() and prepare() cases.

+ * for .prepare, returns 0 on success and -errno on failure.

+ * for .abort cases, denoted by abort = true, MUST return 0.

+ */

+static int mirror_exit_common(Job *job)

 {

     MirrorBlockJob *s = container_of(job, MirrorBlockJob, common.job);

     BlockJob *bjob = &s->common;

@@ -489,7 +495,13 @@ static void mirror_exit(Job *job)

     BlockDriverState *target_bs = blk_bs(s->target);

     BlockDriverState *mirror_top_bs = s->mirror_top_bs;

     Error *local_err = NULL;

-    int ret = job->ret;

+    bool abort = job->ret < 0;

+    int ret = 0;

+

+    if (s->prepared) {

+        return 0;

+    }

+    s->prepared = true;

     bdrv_release_dirty_bitmap(src, s->dirty_bitmap);

@@ -514,7 +526,7 @@ static void mirror_exit(Job *job)

      * required before it could become a backing file of target_bs. */

     bdrv_child_try_set_perm(mirror_top_bs->backing, 0, BLK_PERM_ALL,

                             &error_abort);

-    if (ret == 0 && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) {

+    if (!abort && s->backing_mode == MIRROR_SOURCE_BACKING_CHAIN) {

         BlockDriverState *backing = s->is_none_mode ? src : s->base;

         if (backing_bs(target_bs) != backing) {

             bdrv_set_backing_hd(target_bs, backing, &local_err);

@@ -530,11 +542,8 @@ static void mirror_exit(Job *job)

         aio_context_acquire(replace_aio_context);

     }

-    if (s->should_complete && ret == 0) {

-        BlockDriverState *to_replace = src;

-        if (s->to_replace) {

-            to_replace = s->to_replace;

-        }

+    if (s->should_complete && !abort) {

+        BlockDriverState *to_replace = s->to_replace ?: src;

         if (bdrv_get_flags(target_bs) != bdrv_get_flags(to_replace)) {

             bdrv_reopen(target_bs, bdrv_get_flags(to_replace), NULL);

@@ -581,7 +590,18 @@ static void mirror_exit(Job *job)

     bdrv_unref(mirror_top_bs);

     bdrv_unref(src);

-    job->ret = ret;

+    return ret;

+}

+

+static int mirror_prepare(Job *job)

+{

+    return mirror_exit_common(job);

+}

+

+static void mirror_abort(Job *job)

+{

+    int ret = mirror_exit_common(job);

+    assert(ret == 0);

 }

 static void mirror_throttle(MirrorBlockJob *s)

@@ -986,7 +1006,8 @@ static const BlockJobDriver mirror_job_driver = {

         .user_resume            = block_job_user_resume,

         .drain                  = block_job_drain,

         .run                    = mirror_run,

-        .exit                   = mirror_exit,

+        .prepare                = mirror_prepare,

+        .abort                  = mirror_abort,

         .pause                  = mirror_pause,

         .complete               = mirror_complete,

     },

@@ -1002,7 +1023,8 @@ static const BlockJobDriver commit_active_job_driver = {

         .user_resume            = block_job_user_resume,

         .drain                  = block_job_drain,

         .run                    = mirror_run,

-        .exit                   = mirror_exit,

+        .prepare                = mirror_prepare,

+        .abort                  = mirror_abort,

         .pause                  = mirror_pause,

         .complete               = mirror_complete,

     },

-- 

1.8.3.1