| Message ID | 1394436370-8908-3-git-send-email-famz@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Mon, Mar 10, 2014 at 03:25:58PM +0800, Fam Zheng wrote: > 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(). Is there a reason to assume there will be atypical usages that don't follow these steps? If not, could the Error reason resource be allocated inside the block() operation if non-NULL, and freed inside the unblock() operations? > > Signed-off-by: Fam Zheng <famz@redhat.com> > Reviewed-by: Benoit Canet <benoit@irqsave.net> > --- > block.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++ > include/block/block.h | 7 +++++ > include/block/block_int.h | 5 ++++ > 3 files changed, 87 insertions(+) > > diff --git a/block.c b/block.c > index f1ef4b0..56a4433 100644 > --- a/block.c > +++ b/block.c > @@ -335,6 +335,7 @@ void bdrv_register(BlockDriver *bdrv) > BlockDriverState *bdrv_new(const char *device_name) > { > BlockDriverState *bs; > + int i; > > bs = g_malloc0(sizeof(BlockDriverState)); > QLIST_INIT(&bs->dirty_bitmaps); > @@ -342,6 +343,9 @@ BlockDriverState *bdrv_new(const char *device_name) > 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); > @@ -1853,6 +1857,8 @@ 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)); > } > > /* > @@ -5151,6 +5157,75 @@ 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) { > + *errp = error_copy(blocker->reason); > + } The blocker assignment could be moved inside the if bracket (just an observation, not a request) Reviewed-by: Jeff Cody <jcody@redhat.com> > + 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 8820735..4874e2a 100644 > --- a/include/block/block.h > +++ b/include/block/block.h > @@ -474,6 +474,13 @@ 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 0bcf1c9..4e558d0 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 > @@ -361,6 +363,9 @@ struct BlockDriverState { > > QLIST_HEAD(, BdrvTrackedRequest) tracked_requests; > > + /* operation blockers */ > + QLIST_HEAD(, BdrvOpBlocker) op_blockers[BLOCK_OP_TYPE_MAX]; > + > /* long-running background operation */ > BlockJob *job; > > -- > 1.9.0 > >
On Sun, 04/06 19:49, Jeff Cody wrote: > On Mon, Mar 10, 2014 at 03:25:58PM +0800, Fam Zheng wrote: > > 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(). > > Is there a reason to assume there will be atypical usages that don't > follow these steps? If not, could the Error reason resource be > allocated inside the block() operation if non-NULL, and freed inside > the unblock() operations? Could work as well. It's just that the current interface is following the style of migration blocker. Thanks, Fam
diff --git a/block.c b/block.c index f1ef4b0..56a4433 100644 --- a/block.c +++ b/block.c @@ -335,6 +335,7 @@ void bdrv_register(BlockDriver *bdrv) BlockDriverState *bdrv_new(const char *device_name) { BlockDriverState *bs; + int i; bs = g_malloc0(sizeof(BlockDriverState)); QLIST_INIT(&bs->dirty_bitmaps); @@ -342,6 +343,9 @@ BlockDriverState *bdrv_new(const char *device_name) 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); @@ -1853,6 +1857,8 @@ 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)); } /* @@ -5151,6 +5157,75 @@ 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) { + *errp = error_copy(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 8820735..4874e2a 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -474,6 +474,13 @@ 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 0bcf1c9..4e558d0 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 @@ -361,6 +363,9 @@ struct BlockDriverState { QLIST_HEAD(, BdrvTrackedRequest) tracked_requests; + /* operation blockers */ + QLIST_HEAD(, BdrvOpBlocker) op_blockers[BLOCK_OP_TYPE_MAX]; + /* long-running background operation */ BlockJob *job;
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 <famz@redhat.com> Reviewed-by: Benoit Canet <benoit@irqsave.net> --- block.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++ include/block/block.h | 7 +++++ include/block/block_int.h | 5 ++++ 3 files changed, 87 insertions(+)