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author | Jeff Cody <jcody@redhat.com> | 2016-02-01 20:33:10 -0500 |
---|---|---|
committer | Michael Roth <mdroth@linux.vnet.ibm.com> | 2016-03-17 16:51:48 -0500 |
commit | a375e0b03ee3438924b24a45e61ee189ec9361db (patch) | |
tree | 38d61a6edfcf4eb45369a47959b9db996be2bb47 | |
parent | a38a283fc707b404544c491e32c4adc94e4788c6 (diff) | |
download | qemu-a375e0b03ee3438924b24a45e61ee189ec9361db.zip qemu-a375e0b03ee3438924b24a45e61ee189ec9361db.tar.gz qemu-a375e0b03ee3438924b24a45e61ee189ec9361db.tar.bz2 |
block: set device_list.tqe_prev to NULL on BDS removal
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 <jcody@redhat.com>
Message-id: 0cd51e11c0666c04ddb7c05293fe94afeb551e89.1454376655.git.jcody@redhat.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
(cherry picked from commit f8aa905a4fec89863c82de4186352447d851871e)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
-rw-r--r-- | block.c | 24 | ||||
-rw-r--r-- | blockdev.c | 3 | ||||
-rw-r--r-- | include/block/block.h | 1 |
3 files changed, 16 insertions, 12 deletions
@@ -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); } } @@ -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); |