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[Qemu-devel] [PATCH v2 2/8] block: Introduce op_blockers to BlockDriverS
From: |
Fam Zheng |
Subject: |
[Qemu-devel] [PATCH v2 2/8] block: Introduce op_blockers to BlockDriverState |
Date: |
Fri, 23 May 2014 21:29:42 +0800 |
BlockDriverState.op_blockers is an array of lists with BLOCK_OP_TYPE_MAX
elements. Each list is a list of blockers of an operation type
(BlockOpType), that marks this BDS as currently blocked for a certain
type of operation with reason errors stored in the list. The rule of
usage is:
* BDS user who wants to take an operation should check if there's any
blocker of the type with bdrv_op_is_blocked().
* BDS user who wants to block certain types of operation, should call
bdrv_op_block (or bdrv_op_block_all to block all types of operations,
which is similar to the existing bdrv_set_in_use()).
* A blocker is only referenced by op_blockers, so the lifecycle is
managed by caller, and shouldn't be lost until unblock, so typically
a caller does these:
- Allocate a blocker with error_setg or similar, call bdrv_op_block()
to block some operations.
- Hold the blocker, do his job.
- Unblock operations that it blocked, with the same reason pointer
passed to bdrv_op_unblock().
- Release the blocker with error_free().
Signed-off-by: Fam Zheng <address@hidden>
Reviewed-by: Benoit Canet <address@hidden>
Reviewed-by: Jeff Cody <address@hidden>
Reviewed-by: Stefan Hajnoczi <address@hidden>
---
block.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++
include/block/block.h | 7 +++++
include/block/block_int.h | 5 ++++
3 files changed, 88 insertions(+)
diff --git a/block.c b/block.c
index 40c5e1a..589c6e3 100644
--- a/block.c
+++ b/block.c
@@ -335,6 +335,7 @@ void bdrv_register(BlockDriver *bdrv)
BlockDriverState *bdrv_new(const char *device_name, Error **errp)
{
BlockDriverState *bs;
+ int i;
if (bdrv_find(device_name)) {
error_setg(errp, "Device with id '%s' already exists",
@@ -353,6 +354,9 @@ BlockDriverState *bdrv_new(const char *device_name, Error
**errp)
if (device_name[0] != '\0') {
QTAILQ_INSERT_TAIL(&bdrv_states, bs, device_list);
}
+ for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
+ QLIST_INIT(&bs->op_blockers[i]);
+ }
bdrv_iostatus_disable(bs);
notifier_list_init(&bs->close_notifiers);
notifier_with_return_list_init(&bs->before_write_notifiers);
@@ -1952,6 +1956,8 @@ static void bdrv_move_feature_fields(BlockDriverState
*bs_dest,
pstrcpy(bs_dest->device_name, sizeof(bs_dest->device_name),
bs_src->device_name);
bs_dest->device_list = bs_src->device_list;
+ memcpy(bs_dest->op_blockers, bs_src->op_blockers,
+ sizeof(bs_dest->op_blockers));
}
/*
@@ -5325,6 +5331,76 @@ void bdrv_unref(BlockDriverState *bs)
}
}
+struct BdrvOpBlocker {
+ Error *reason;
+ QLIST_ENTRY(BdrvOpBlocker) list;
+};
+
+bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp)
+{
+ BdrvOpBlocker *blocker;
+ assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
+ if (!QLIST_EMPTY(&bs->op_blockers[op])) {
+ blocker = QLIST_FIRST(&bs->op_blockers[op]);
+ if (errp) {
+ error_setg(errp, "Device '%s' is busy: %s",
+ bs->device_name, error_get_pretty(blocker->reason));
+ }
+ return true;
+ }
+ return false;
+}
+
+void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason)
+{
+ BdrvOpBlocker *blocker;
+ assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
+
+ blocker = g_malloc0(sizeof(BdrvOpBlocker));
+ blocker->reason = reason;
+ QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list);
+}
+
+void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason)
+{
+ BdrvOpBlocker *blocker, *next;
+ assert((int) op >= 0 && op < BLOCK_OP_TYPE_MAX);
+ QLIST_FOREACH_SAFE(blocker, &bs->op_blockers[op], list, next) {
+ if (blocker->reason == reason) {
+ QLIST_REMOVE(blocker, list);
+ g_free(blocker);
+ }
+ }
+}
+
+void bdrv_op_block_all(BlockDriverState *bs, Error *reason)
+{
+ int i;
+ for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
+ bdrv_op_block(bs, i, reason);
+ }
+}
+
+void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason)
+{
+ int i;
+ for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
+ bdrv_op_unblock(bs, i, reason);
+ }
+}
+
+bool bdrv_op_blocker_is_empty(BlockDriverState *bs)
+{
+ int i;
+
+ for (i = 0; i < BLOCK_OP_TYPE_MAX; i++) {
+ if (!QLIST_EMPTY(&bs->op_blockers[i])) {
+ return false;
+ }
+ }
+ return true;
+}
+
void bdrv_set_in_use(BlockDriverState *bs, int in_use)
{
assert(bs->in_use != in_use);
diff --git a/include/block/block.h b/include/block/block.h
index cc4cc16..7f0448c 100644
--- a/include/block/block.h
+++ b/include/block/block.h
@@ -475,6 +475,13 @@ void bdrv_unref(BlockDriverState *bs);
void bdrv_set_in_use(BlockDriverState *bs, int in_use);
int bdrv_in_use(BlockDriverState *bs);
+bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp);
+void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason);
+void bdrv_op_unblock(BlockDriverState *bs, BlockOpType op, Error *reason);
+void bdrv_op_block_all(BlockDriverState *bs, Error *reason);
+void bdrv_op_unblock_all(BlockDriverState *bs, Error *reason);
+bool bdrv_op_blocker_is_empty(BlockDriverState *bs);
+
#ifdef CONFIG_LINUX_AIO
int raw_get_aio_fd(BlockDriverState *bs);
#else
diff --git a/include/block/block_int.h b/include/block/block_int.h
index b8cc926..fdf2a7d 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -270,6 +270,8 @@ typedef struct BlockLimits {
size_t opt_mem_alignment;
} BlockLimits;
+typedef struct BdrvOpBlocker BdrvOpBlocker;
+
/*
* Note: the function bdrv_append() copies and swaps contents of
* BlockDriverStates, so if you add new fields to this struct, please
@@ -360,6 +362,9 @@ struct BlockDriverState {
QLIST_HEAD(, BdrvTrackedRequest) tracked_requests;
+ /* operation blockers */
+ QLIST_HEAD(, BdrvOpBlocker) op_blockers[BLOCK_OP_TYPE_MAX];
+
/* long-running background operation */
BlockJob *job;
--
1.9.2
- [Qemu-devel] [PATCH v2 0/8] block: Drop in_use with op blocker, Fam Zheng, 2014/05/23
- [Qemu-devel] [PATCH v2 1/8] block: Add BlockOpType enum, Fam Zheng, 2014/05/23
- [Qemu-devel] [PATCH v2 2/8] block: Introduce op_blockers to BlockDriverState,
Fam Zheng <=
- [Qemu-devel] [PATCH v2 3/8] block: Replace in_use with operation blocker, Fam Zheng, 2014/05/23
- [Qemu-devel] [PATCH v2 4/8] block: Move op_blocker check from block_job_create to its caller, Fam Zheng, 2014/05/23
- [Qemu-devel] [PATCH v2 5/8] block: Add bdrv_set_backing_hd(), Fam Zheng, 2014/05/23
- [Qemu-devel] [PATCH v2 6/8] block: Use bdrv_set_backing_hd everywhere, Fam Zheng, 2014/05/23
- [Qemu-devel] [PATCH v2 7/8] block: Add backing_blocker in BlockDriverState, Fam Zheng, 2014/05/23
- [Qemu-devel] [PATCH v2 8/8] block: Drop redundant bdrv_refresh_limits, Fam Zheng, 2014/05/23
- Re: [Qemu-devel] [PATCH v2 0/8] block: Drop in_use with op blocker, Stefan Hajnoczi, 2014/05/23