| Message ID | 1399858555-9672-4-git-send-email-famz@redhat.com |
|---|---|
| State | New |
| Headers | show |
Fam Zheng <famz@redhat.com> writes: > 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> > Reviewed-by: Jeff Cody <jcody@redhat.com> > --- > 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 b749d31..32338ca 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); > @@ -1907,6 +1911,8 @@ 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)); > } > > /* > @@ -5269,6 +5275,75 @@ 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); Space between cast and its operand is unusual. Please don't respin just for that. > + 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)); Please consider g_new0(), but don't respin just for that. > + blocker->reason = reason; > + QLIST_INSERT_HEAD(&bs->op_blockers[op], blocker, list); > +} [...]
Am 19.05.2014 um 16:10 hat Markus Armbruster geschrieben: > Fam Zheng <famz@redhat.com> writes: > > > 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> > > Reviewed-by: Jeff Cody <jcody@redhat.com> > > --- > > 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 b749d31..32338ca 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); > > @@ -1907,6 +1911,8 @@ 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)); > > } > > > > /* > > @@ -5269,6 +5275,75 @@ 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); > > Space between cast and its operand is unusual. Please don't respin just > for that. That was a surprising statement for me. Do you have an idea how to grep for casts? I tried '*)' just in order to find _some_ examples of casts, and there doesn't seem to be a clear winner. But if there is one, it appears to be the version with space. (I won't reject patches with either style.) Kevin
On Mon, May 19, 2014 at 04:37:52PM +0200, Kevin Wolf wrote: > Am 19.05.2014 um 16:10 hat Markus Armbruster geschrieben: > > Fam Zheng <famz@redhat.com> writes: > > > > > 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> > > > Reviewed-by: Jeff Cody <jcody@redhat.com> > > > --- > > > 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 b749d31..32338ca 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); > > > @@ -1907,6 +1911,8 @@ 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)); > > > } > > > > > > /* > > > @@ -5269,6 +5275,75 @@ 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); > > > > Space between cast and its operand is unusual. Please don't respin just > > for that. > > That was a surprising statement for me. Do you have an idea how to grep > for casts? I tried '*)' just in order to find _some_ examples of casts, > and there doesn't seem to be a clear winner. But if there is one, it > appears to be the version with space. > > (I won't reject patches with either style.) > This just searches for pointer casts - it isn't perfect, but pretty decent if you just want to get a sampling: grep -E "\([a-zA-Z0-9_]+[\\*\ ]+\)" * -rHnI
Jeff Cody <jcody@redhat.com> writes: > On Mon, May 19, 2014 at 04:37:52PM +0200, Kevin Wolf wrote: >> Am 19.05.2014 um 16:10 hat Markus Armbruster geschrieben: >> > Fam Zheng <famz@redhat.com> writes: [...] >> > > diff --git a/block.c b/block.c >> > > index b749d31..32338ca 100644 >> > > --- a/block.c >> > > +++ b/block.c [...] >> > > @@ -5269,6 +5275,75 @@ 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); >> > >> > Space between cast and its operand is unusual. Please don't respin just >> > for that. >> >> That was a surprising statement for me. Do you have an idea how to grep >> for casts? I tried '*)' just in order to find _some_ examples of casts, >> and there doesn't seem to be a clear winner. But if there is one, it >> appears to be the version with space. >> >> (I won't reject patches with either style.) >> > > This just searches for pointer casts - it isn't perfect, but pretty > decent if you just want to get a sampling: > > grep -E "\([a-zA-Z0-9_]+[\\*\ ]+\)" * -rHnI Challenge! I used $ gdb -batch -ex "info types" qemu-system-x86_64 | sed -n 's/^typedef .* \([^ ]*\);/\1/p' types | sort -u to find typedef names, turned them into a regexp, and topped it off with one matching predefined scalar types. Let that be T. I git-grepped for -E '\((T) *\**\)', and found too many sizeof(T), QLIST_ENTRY(T) and such, so I filtered out the hits where the last non-space letter before the (T) is a letter. This passed visual muster, although it's of course neither 100% complete nor 100% correct. Close enough. This gave me roughly 6000 probable casts. >75% are not followed by space. In block-land (as defined by MAINTAINERS), it's close to 80%. Three thirds majority may not quite qualify for "clear winner" in matters of code formatting. I dislike space between cast and operand because the cast operator has a high operator precedence.
diff --git a/block.c b/block.c index b749d31..32338ca 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); @@ -1907,6 +1911,8 @@ 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)); } /* @@ -5269,6 +5275,75 @@ 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 ac3a69b..5db028d 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -468,6 +468,13 @@ 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 9ffcb69..78662d5 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;
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> Reviewed-by: Jeff Cody <jcody@redhat.com> --- block.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++ include/block/block.h | 7 +++++ include/block/block_int.h | 5 ++++ 3 files changed, 87 insertions(+)