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From: Kevin Wolf <kwolf@redhat.com>
To: qemu-block@nongnu.org
Cc: kwolf@redhat.com, mreitz@redhat.com, jcody@redhat.com,
	famz@redhat.com, qemu-devel@nongnu.org
Subject: [Qemu-devel] [PATCH v2 29/43] block: BdrvChildRole.attach/detach() callbacks
Date: Mon, 27 Feb 2017 21:09:30 +0100	[thread overview]
Message-ID: <1488226184-9044-30-git-send-email-kwolf@redhat.com> (raw)
In-Reply-To: <1488226184-9044-1-git-send-email-kwolf@redhat.com>

Backing files are somewhat special compared to other kinds of children
because they are attached and detached using bdrv_set_backing_hd()
rather than the normal set of functions, which does a few more things
like setting backing blockers, toggling the BDRV_O_NO_BACKING flag,
setting parent_bs->backing_file, etc.

These special features are a reason why change_parent_backing_link()
can't handle backing files yet. With abstracting the additional features
into .attach/.detach callbacks, we get a step closer to a function that
can actually deal with this.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
---
 block.c                   | 94 +++++++++++++++++++++++++++++------------------
 include/block/block_int.h |  3 ++
 2 files changed, 62 insertions(+), 35 deletions(-)

diff --git a/block.c b/block.c
index 7926c6c..86567a8 100644
--- a/block.c
+++ b/block.c
@@ -807,6 +807,57 @@ const BdrvChildRole child_format = {
     .drained_end     = bdrv_child_cb_drained_end,
 };
 
+static void bdrv_backing_attach(BdrvChild *c)
+{
+    BlockDriverState *parent = c->opaque;
+    BlockDriverState *backing_hd = c->bs;
+
+    assert(!parent->backing_blocker);
+    error_setg(&parent->backing_blocker,
+               "node is used as backing hd of '%s'",
+               bdrv_get_device_or_node_name(parent));
+
+    parent->open_flags &= ~BDRV_O_NO_BACKING;
+    pstrcpy(parent->backing_file, sizeof(parent->backing_file),
+            backing_hd->filename);
+    pstrcpy(parent->backing_format, sizeof(parent->backing_format),
+            backing_hd->drv ? backing_hd->drv->format_name : "");
+
+    bdrv_op_block_all(backing_hd, parent->backing_blocker);
+    /* Otherwise we won't be able to commit or stream */
+    bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET,
+                    parent->backing_blocker);
+    bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM,
+                    parent->backing_blocker);
+    /*
+     * We do backup in 3 ways:
+     * 1. drive backup
+     *    The target bs is new opened, and the source is top BDS
+     * 2. blockdev backup
+     *    Both the source and the target are top BDSes.
+     * 3. internal backup(used for block replication)
+     *    Both the source and the target are backing file
+     *
+     * In case 1 and 2, neither the source nor the target is the backing file.
+     * In case 3, we will block the top BDS, so there is only one block job
+     * for the top BDS and its backing chain.
+     */
+    bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE,
+                    parent->backing_blocker);
+    bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET,
+                    parent->backing_blocker);
+}
+
+static void bdrv_backing_detach(BdrvChild *c)
+{
+    BlockDriverState *parent = c->opaque;
+
+    assert(parent->backing_blocker);
+    bdrv_op_unblock_all(c->bs, parent->backing_blocker);
+    error_free(parent->backing_blocker);
+    parent->backing_blocker = NULL;
+}
+
 /*
  * Returns the options and flags that bs->backing should get, based on the
  * given options and flags for the parent BDS
@@ -833,6 +884,8 @@ static void bdrv_backing_options(int *child_flags, QDict *child_options,
 
 const BdrvChildRole child_backing = {
     .get_parent_desc = bdrv_child_get_parent_desc,
+    .attach          = bdrv_backing_attach,
+    .detach          = bdrv_backing_detach,
     .inherit_options = bdrv_backing_options,
     .drained_begin   = bdrv_child_cb_drained_begin,
     .drained_end     = bdrv_child_cb_drained_end,
@@ -1672,6 +1725,9 @@ static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs)
         if (old_bs->quiesce_counter && child->role->drained_end) {
             child->role->drained_end(child);
         }
+        if (child->role->detach) {
+            child->role->detach(child);
+        }
         QLIST_REMOVE(child, next_parent);
         bdrv_update_perm(old_bs);
     }
@@ -1684,6 +1740,9 @@ static void bdrv_replace_child(BdrvChild *child, BlockDriverState *new_bs)
             child->role->drained_begin(child);
         }
         bdrv_update_perm(new_bs);
+        if (child->role->attach) {
+            child->role->attach(child);
+        }
     }
 }
 
@@ -1821,52 +1880,17 @@ void bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd)
     }
 
     if (bs->backing) {
-        assert(bs->backing_blocker);
-        bdrv_op_unblock_all(bs->backing->bs, bs->backing_blocker);
         bdrv_unref_child(bs, bs->backing);
-    } else if (backing_hd) {
-        error_setg(&bs->backing_blocker,
-                   "node is used as backing hd of '%s'",
-                   bdrv_get_device_or_node_name(bs));
     }
 
     if (!backing_hd) {
-        error_free(bs->backing_blocker);
-        bs->backing_blocker = NULL;
         bs->backing = NULL;
         goto out;
     }
     /* FIXME Error handling */
     bs->backing = bdrv_attach_child(bs, backing_hd, "backing", &child_backing,
                                     &error_abort);
-    bs->open_flags &= ~BDRV_O_NO_BACKING;
-    pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_hd->filename);
-    pstrcpy(bs->backing_format, sizeof(bs->backing_format),
-            backing_hd->drv ? backing_hd->drv->format_name : "");
 
-    bdrv_op_block_all(backing_hd, bs->backing_blocker);
-    /* Otherwise we won't be able to commit or stream */
-    bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_COMMIT_TARGET,
-                    bs->backing_blocker);
-    bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_STREAM,
-                    bs->backing_blocker);
-    /*
-     * We do backup in 3 ways:
-     * 1. drive backup
-     *    The target bs is new opened, and the source is top BDS
-     * 2. blockdev backup
-     *    Both the source and the target are top BDSes.
-     * 3. internal backup(used for block replication)
-     *    Both the source and the target are backing file
-     *
-     * In case 1 and 2, neither the source nor the target is the backing file.
-     * In case 3, we will block the top BDS, so there is only one block job
-     * for the top BDS and its backing chain.
-     */
-    bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_SOURCE,
-                    bs->backing_blocker);
-    bdrv_op_unblock(backing_hd, BLOCK_OP_TYPE_BACKUP_TARGET,
-                    bs->backing_blocker);
 out:
     bdrv_refresh_limits(bs, NULL);
 }
diff --git a/include/block/block_int.h b/include/block/block_int.h
index a0d9328..a5c704b 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -472,6 +472,9 @@ struct BdrvChildRole {
      */
     void (*drained_begin)(BdrvChild *child);
     void (*drained_end)(BdrvChild *child);
+
+    void (*attach)(BdrvChild *child);
+    void (*detach)(BdrvChild *child);
 };
 
 extern const BdrvChildRole child_file;
-- 
1.8.3.1

  parent reply	other threads:[~2017-02-27 20:11 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-27 20:09 [Qemu-devel] [PATCH v2 00/43] New op blocker system, part 1 Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 01/43] block: Add op blocker permission constants Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 02/43] block: Add Error argument to bdrv_attach_child() Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 03/43] block: Let callers request permissions when attaching a child node Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 04/43] block: Involve block drivers in permission granting Kevin Wolf
2017-02-28  8:18   ` Fam Zheng
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 05/43] block: Default .bdrv_child_perm() for filter drivers Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 06/43] block: Request child permissions in " Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 07/43] block: Default .bdrv_child_perm() for format drivers Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 08/43] block: Request child permissions in " Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 09/43] vvfat: Implement .bdrv_child_perm() Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 10/43] block: Require .bdrv_child_perm() with child nodes Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 11/43] block: Request real permissions in bdrv_attach_child() Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 12/43] block: Add permissions to BlockBackend Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 13/43] block: Add permissions to blk_new() Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 14/43] block: Add error parameter to blk_insert_bs() Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 15/43] block: Add BDRV_O_RESIZE for blk_new_open() Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 16/43] block: Request real permissions in blk_new_open() Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 17/43] block: Allow error return in BlockDevOps.change_media_cb() Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 18/43] hw/block: Request permissions Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 19/43] hw/block: Introduce share-rw qdev property Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 20/43] blockjob: Add permissions to block_job_create() Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 21/43] block: Add BdrvChildRole.get_parent_desc() Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 22/43] block: Include details on permission errors in message Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 23/43] block: Add BdrvChildRole.stay_at_node Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 24/43] blockjob: Add permissions to block_job_add_bdrv() Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 25/43] commit: Use real permissions in commit block job Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 26/43] commit: Use real permissions for HMP 'commit' Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 27/43] backup: Use real permissions in backup block job Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 28/43] block: Fix pending requests check in bdrv_append() Kevin Wolf
2017-02-27 20:09 ` Kevin Wolf [this message]
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 30/43] block: Allow backing file links in change_parent_backing_link() Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 31/43] mirror: Use real permissions in mirror/active commit block job Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 32/43] stream: Use real permissions in streaming " Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 33/43] mirror: Add filter-node-name to blockdev-mirror Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 34/43] commit: Add filter-node-name to block-commit Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 35/43] hmp: Request permissions in qemu-io Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 36/43] migration/block: Use real permissions Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 37/43] nbd/server: Use real permissions for NBD exports Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 38/43] tests: Remove FIXME comments Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 39/43] block: Pass BdrvChild to bdrv_aligned_preadv/pwritev and copy-on-read Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 40/43] block: Assertions for write permissions Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 41/43] block: Assertions for resize permission Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 42/43] block: Add Error parameter to bdrv_set_backing_hd() Kevin Wolf
2017-02-27 20:09 ` [Qemu-devel] [PATCH v2 43/43] block: Add Error parameter to bdrv_append() Kevin Wolf

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