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[Qemu-devel] [PATCH 25/35] block: set device_list.tqe_prev to NULL on BD
From: |
Michael Roth |
Subject: |
[Qemu-devel] [PATCH 25/35] block: set device_list.tqe_prev to NULL on BDS removal |
Date: |
Mon, 21 Mar 2016 12:28:23 -0500 |
From: Jeff Cody <address@hidden>
This fixes a regression introduced with commit 3f09bfbc7. Multiple
bugs arise in conjunction with live snapshots and mirroring operations
(which include active layer commit).
After a live snapshot occurs, the active layer and the base layer both
have a non-NULL tqe_prev field in the device_list, although the base
node's tqe_prev field points to a NULL entry. This non-NULL tqe_prev
field occurs after the bdrv_append() in the external snapshot calls
change_parent_backing_link().
In change_parent_backing_link(), when the previous active layer is
removed from device_list, the device_list.tqe_prev pointer is not
set to NULL.
The operating scheme in the block layer is to indicate that a BDS belongs
in the bdrv_states device_list iff the device_list.tqe_prev pointer
is non-NULL.
This patch does two things:
1.) Introduces a new block layer helper bdrv_device_remove() to remove a
BDS from the device_list, and
2.) uses that new API, which also fixes the regression once used in
change_parent_backing_link().
Signed-off-by: Jeff Cody <address@hidden>
Message-id: address@hidden
Reviewed-by: Max Reitz <address@hidden>
Signed-off-by: Max Reitz <address@hidden>
(cherry picked from commit f8aa905a4fec89863c82de4186352447d851871e)
Signed-off-by: Michael Roth <address@hidden>
---
block.c | 24 ++++++++++++++----------
blockdev.c | 3 +--
include/block/block.h | 1 +
3 files changed, 16 insertions(+), 12 deletions(-)
diff --git a/block.c b/block.c
index 3a7324b..3c172dd 100644
--- a/block.c
+++ b/block.c
@@ -1976,21 +1976,25 @@ void bdrv_close_all(void)
}
}
+/* Note that bs->device_list.tqe_prev is initially null,
+ * and gets set to non-null by QTAILQ_INSERT_TAIL(). Establish
+ * the useful invariant "bs in bdrv_states iff bs->tqe_prev" by
+ * resetting it to null on remove. */
+void bdrv_device_remove(BlockDriverState *bs)
+{
+ QTAILQ_REMOVE(&bdrv_states, bs, device_list);
+ bs->device_list.tqe_prev = NULL;
+}
+
/* make a BlockDriverState anonymous by removing from bdrv_state and
* graph_bdrv_state list.
Also, NULL terminate the device_name to prevent double remove */
void bdrv_make_anon(BlockDriverState *bs)
{
- /*
- * Take care to remove bs from bdrv_states only when it's actually
- * in it. Note that bs->device_list.tqe_prev is initially null,
- * and gets set to non-null by QTAILQ_INSERT_TAIL(). Establish
- * the useful invariant "bs in bdrv_states iff bs->tqe_prev" by
- * resetting it to null on remove.
- */
+ /* Take care to remove bs from bdrv_states only when it's actually
+ * in it. */
if (bs->device_list.tqe_prev) {
- QTAILQ_REMOVE(&bdrv_states, bs, device_list);
- bs->device_list.tqe_prev = NULL;
+ bdrv_device_remove(bs);
}
if (bs->node_name[0] != '\0') {
QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list);
@@ -2031,7 +2035,7 @@ static void change_parent_backing_link(BlockDriverState
*from,
if (!to->device_list.tqe_prev) {
QTAILQ_INSERT_BEFORE(from, to, device_list);
}
- QTAILQ_REMOVE(&bdrv_states, from, device_list);
+ bdrv_device_remove(from);
}
}
diff --git a/blockdev.c b/blockdev.c
index 7c81f48..e20e0c1 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -2394,8 +2394,7 @@ void qmp_x_blockdev_remove_medium(const char *device,
Error **errp)
/* This follows the convention established by bdrv_make_anon() */
if (bs->device_list.tqe_prev) {
- QTAILQ_REMOVE(&bdrv_states, bs, device_list);
- bs->device_list.tqe_prev = NULL;
+ bdrv_device_remove(bs);
}
blk_remove_bs(blk);
diff --git a/include/block/block.h b/include/block/block.h
index 3477328..d83d420 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -196,6 +196,7 @@ int bdrv_create(BlockDriver *drv, const char* filename,
int bdrv_create_file(const char *filename, QemuOpts *opts, Error **errp);
BlockDriverState *bdrv_new_root(void);
BlockDriverState *bdrv_new(void);
+void bdrv_device_remove(BlockDriverState *bs);
void bdrv_make_anon(BlockDriverState *bs);
void bdrv_swap(BlockDriverState *bs_new, BlockDriverState *bs_old);
void bdrv_append(BlockDriverState *bs_new, BlockDriverState *bs_top);
--
1.9.1
- [Qemu-devel] [PATCH 19/35] block/raw-posix: avoid bogus fixup for cylinders on DASD disks, (continued)
- [Qemu-devel] [PATCH 19/35] block/raw-posix: avoid bogus fixup for cylinders on DASD disks, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 01/35] ehci: make idt processing more robust, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 21/35] s390x/css: fix control flags during csch, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 15/35] net/filter: fix nf->netdev_id leak, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 16/35] net: ne2000: check ring buffer control registers, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 24/35] qmp: Fix reference-counting of qnull on empty output visit, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 23/35] cpus: use broadcast on qemu_pause_cond, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 20/35] s390x/ioinst: set type and len for SEI response, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 27/35] e1000: eliminate infinite loops on out-of-bounds transfer start, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 26/35] block: qemu-iotests - add test for snapshot, commit, snapshot bug, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 25/35] block: set device_list.tqe_prev to NULL on BDS removal,
Michael Roth <=
- [Qemu-devel] [PATCH 29/35] hw/virtio: fix double use of a virtio flag, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 32/35] vhost-user: don't merge regions with different fds, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 30/35] hw/virtio: group virtio flags into an enum, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 31/35] fw_cfg: unbreak migration compatibility for 2.4 and earlier machines, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 22/35] fw_cfg: avoid calculating invalid current entry pointer, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 34/35] quorum: Fix crash in quorum_aio_cb(), Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 33/35] target-arm: Make reserved ranges in ID_AA64* spaces RAZ, not UNDEF, Michael Roth, 2016/03/21
- [Qemu-devel] [PATCH 28/35] spapr: skip configuration section during migration of older machines, Michael Roth, 2016/03/21