From: Emanuele Giuseppe Esposito <eespo...@redhat.com> BlockDriver->bdrv_getlength is categorized as IO callback, and it currently doesn't run in a coroutine. We should let it take a graph rdlock since the callback traverses the block nodes graph, which however is only possible in a coroutine.
Therefore turn it into a co_wrapper to move the actual function into a coroutine where the lock can be taken. Because now this function creates a new coroutine and polls, we need to take the AioContext lock where it is missing, for the only reason that internally co_wrapper calls AIO_WAIT_WHILE and it expects to release the AioContext lock. This is especially messy when a co_wrapper creates a coroutine and polls in bdrv_open_driver, because this function has so many callers in so many context that it can easily lead to deadlocks. Therefore the new rule for bdrv_open_driver is that the caller must always hold the AioContext lock of the given bs (except if it is a coroutine), because the function calls bdrv_refresh_total_sectors() which is now a co_wrapper. Once the rwlock is ultimated and placed in every place it needs to be, we will poll using AIO_WAIT_WHILE_UNLOCKED and remove the AioContext lock. Signed-off-by: Emanuele Giuseppe Esposito <eespo...@redhat.com> Signed-off-by: Kevin Wolf <kw...@redhat.com> --- include/block/block-io.h | 8 ++++++-- include/block/block_int-common.h | 2 +- include/block/block_int-io.h | 5 ++++- include/sysemu/block-backend-io.h | 10 ++++++++-- block.c | 26 +++++++++++++++++++++----- block/block-backend.c | 10 ++++++---- block/commit.c | 4 ++-- block/mirror.c | 4 ++-- hw/scsi/scsi-disk.c | 5 +++++ tests/unit/test-block-iothread.c | 3 +++ block/meson.build | 1 + 11 files changed, 59 insertions(+), 19 deletions(-) diff --git a/include/block/block-io.h b/include/block/block-io.h index 3bf201f7f4..fe1fa339be 100644 --- a/include/block/block-io.h +++ b/include/block/block-io.h @@ -73,8 +73,12 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child, int64_t offset, bool exact, PreallocMode prealloc, BdrvRequestFlags flags, Error **errp); -int64_t bdrv_nb_sectors(BlockDriverState *bs); -int64_t bdrv_getlength(BlockDriverState *bs); +int64_t coroutine_fn bdrv_co_nb_sectors(BlockDriverState *bs); +int64_t co_wrapper_mixed bdrv_nb_sectors(BlockDriverState *bs); + +int64_t coroutine_fn bdrv_co_getlength(BlockDriverState *bs); +int64_t co_wrapper_mixed bdrv_getlength(BlockDriverState *bs); + int64_t bdrv_get_allocated_file_size(BlockDriverState *bs); BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts, BlockDriverState *in_bs, Error **errp); diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h index adccb4e540..0e705e08f4 100644 --- a/include/block/block_int-common.h +++ b/include/block/block_int-common.h @@ -684,7 +684,7 @@ struct BlockDriver { int coroutine_fn (*bdrv_co_truncate)(BlockDriverState *bs, int64_t offset, bool exact, PreallocMode prealloc, BdrvRequestFlags flags, Error **errp); - int64_t (*bdrv_getlength)(BlockDriverState *bs); + int64_t coroutine_fn (*bdrv_getlength)(BlockDriverState *bs); int64_t (*bdrv_get_allocated_file_size)(BlockDriverState *bs); BlockMeasureInfo *(*bdrv_measure)(QemuOpts *opts, BlockDriverState *in_bs, Error **errp); diff --git a/include/block/block_int-io.h b/include/block/block_int-io.h index 6b285fb520..d1559a501f 100644 --- a/include/block/block_int-io.h +++ b/include/block/block_int-io.h @@ -120,7 +120,10 @@ int coroutine_fn bdrv_co_copy_range_to(BdrvChild *src, int64_t src_offset, BdrvRequestFlags read_flags, BdrvRequestFlags write_flags); -int bdrv_refresh_total_sectors(BlockDriverState *bs, int64_t hint); +int coroutine_fn bdrv_co_refresh_total_sectors(BlockDriverState *bs, + int64_t hint); +int co_wrapper_mixed +bdrv_refresh_total_sectors(BlockDriverState *bs, int64_t hint); BdrvChild *bdrv_cow_child(BlockDriverState *bs); BdrvChild *bdrv_filter_child(BlockDriverState *bs); diff --git a/include/sysemu/block-backend-io.h b/include/sysemu/block-backend-io.h index d8cc8d74f5..8ad8854ecb 100644 --- a/include/sysemu/block-backend-io.h +++ b/include/sysemu/block-backend-io.h @@ -57,9 +57,15 @@ bool blk_is_inserted(BlockBackend *blk); bool blk_is_available(BlockBackend *blk); void blk_lock_medium(BlockBackend *blk, bool locked); void blk_eject(BlockBackend *blk, bool eject_flag); -int64_t blk_getlength(BlockBackend *blk); + +int64_t coroutine_fn blk_co_getlength(BlockBackend *blk); +int64_t co_wrapper_mixed blk_getlength(BlockBackend *blk); + void blk_get_geometry(BlockBackend *blk, uint64_t *nb_sectors_ptr); -int64_t blk_nb_sectors(BlockBackend *blk); + +int64_t coroutine_fn blk_co_nb_sectors(BlockBackend *blk); +int64_t co_wrapper_mixed blk_nb_sectors(BlockBackend *blk); + void *blk_try_blockalign(BlockBackend *blk, size_t size); void *blk_blockalign(BlockBackend *blk, size_t size); bool blk_is_writable(BlockBackend *blk); diff --git a/block.c b/block.c index fdcd06d05d..e1a8f7af4d 100644 --- a/block.c +++ b/block.c @@ -1034,7 +1034,8 @@ static int find_image_format(BlockBackend *file, const char *filename, * Set the current 'total_sectors' value * Return 0 on success, -errno on error. */ -int bdrv_refresh_total_sectors(BlockDriverState *bs, int64_t hint) +int coroutine_fn bdrv_co_refresh_total_sectors(BlockDriverState *bs, + int64_t hint) { BlockDriver *drv = bs->drv; IO_CODE(); @@ -1600,6 +1601,11 @@ out: g_free(gen_node_name); } +/* + * The caller must always hold @bs AioContext lock, because this function calls + * bdrv_refresh_total_sectors() which polls when called from non-coroutine + * context. + */ static int bdrv_open_driver(BlockDriverState *bs, BlockDriver *drv, const char *node_name, QDict *options, int open_flags, Error **errp) @@ -3795,6 +3801,10 @@ out: * The reference parameter may be used to specify an existing block device which * should be opened. If specified, neither options nor a filename may be given, * nor can an existing BDS be reused (that is, *pbs has to be NULL). + * + * The caller must always hold @filename AioContext lock, because this + * function eventually calls bdrv_refresh_total_sectors() which polls + * when called from non-coroutine context. */ static BlockDriverState *bdrv_open_inherit(const char *filename, const char *reference, @@ -4083,6 +4093,11 @@ close_and_fail: return NULL; } +/* + * The caller must always hold @filename AioContext lock, because this + * function eventually calls bdrv_refresh_total_sectors() which polls + * when called from non-coroutine context. + */ BlockDriverState *bdrv_open(const char *filename, const char *reference, QDict *options, int flags, Error **errp) { @@ -5799,7 +5814,7 @@ BlockMeasureInfo *bdrv_measure(BlockDriver *drv, QemuOpts *opts, /** * Return number of sectors on success, -errno on error. */ -int64_t bdrv_nb_sectors(BlockDriverState *bs) +int64_t coroutine_fn bdrv_co_nb_sectors(BlockDriverState *bs) { BlockDriver *drv = bs->drv; IO_CODE(); @@ -5808,7 +5823,7 @@ int64_t bdrv_nb_sectors(BlockDriverState *bs) return -ENOMEDIUM; if (drv->has_variable_length) { - int ret = bdrv_refresh_total_sectors(bs, bs->total_sectors); + int ret = bdrv_co_refresh_total_sectors(bs, bs->total_sectors); if (ret < 0) { return ret; } @@ -5820,11 +5835,12 @@ int64_t bdrv_nb_sectors(BlockDriverState *bs) * Return length in bytes on success, -errno on error. * The length is always a multiple of BDRV_SECTOR_SIZE. */ -int64_t bdrv_getlength(BlockDriverState *bs) +int64_t coroutine_fn bdrv_co_getlength(BlockDriverState *bs) { - int64_t ret = bdrv_nb_sectors(bs); + int64_t ret; IO_CODE(); + ret = bdrv_co_nb_sectors(bs); if (ret < 0) { return ret; } diff --git a/block/block-backend.c b/block/block-backend.c index 5a357f504a..0194d86113 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -1599,14 +1599,15 @@ BlockAIOCB *blk_aio_pwrite_zeroes(BlockBackend *blk, int64_t offset, flags | BDRV_REQ_ZERO_WRITE, cb, opaque); } -int64_t blk_getlength(BlockBackend *blk) +int64_t coroutine_fn blk_co_getlength(BlockBackend *blk) { IO_CODE(); + if (!blk_is_available(blk)) { return -ENOMEDIUM; } - return bdrv_getlength(blk_bs(blk)); + return bdrv_co_getlength(blk_bs(blk)); } void blk_get_geometry(BlockBackend *blk, uint64_t *nb_sectors_ptr) @@ -1619,14 +1620,15 @@ void blk_get_geometry(BlockBackend *blk, uint64_t *nb_sectors_ptr) } } -int64_t blk_nb_sectors(BlockBackend *blk) +int64_t coroutine_fn blk_co_nb_sectors(BlockBackend *blk) { IO_CODE(); + if (!blk_is_available(blk)) { return -ENOMEDIUM; } - return bdrv_nb_sectors(blk_bs(blk)); + return bdrv_co_nb_sectors(blk_bs(blk)); } BlockAIOCB *blk_aio_preadv(BlockBackend *blk, int64_t offset, diff --git a/block/commit.c b/block/commit.c index b346341767..41e3599281 100644 --- a/block/commit.c +++ b/block/commit.c @@ -123,13 +123,13 @@ static int coroutine_fn commit_run(Job *job, Error **errp) QEMU_AUTO_VFREE void *buf = NULL; int64_t len, base_len; - len = blk_getlength(s->top); + len = blk_co_getlength(s->top); if (len < 0) { return len; } job_progress_set_remaining(&s->common.job, len); - base_len = blk_getlength(s->base); + base_len = blk_co_getlength(s->base); if (base_len < 0) { return base_len; } diff --git a/block/mirror.c b/block/mirror.c index 251adc5ae0..c7d7ce2f8f 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -909,13 +909,13 @@ static int coroutine_fn mirror_run(Job *job, Error **errp) goto immediate_exit; } - s->bdev_length = bdrv_getlength(bs); + s->bdev_length = bdrv_co_getlength(bs); if (s->bdev_length < 0) { ret = s->bdev_length; goto immediate_exit; } - target_length = blk_getlength(s->target); + target_length = blk_co_getlength(s->target); if (target_length < 0) { ret = target_length; goto immediate_exit; diff --git a/hw/scsi/scsi-disk.c b/hw/scsi/scsi-disk.c index e493c28814..d4e360850f 100644 --- a/hw/scsi/scsi-disk.c +++ b/hw/scsi/scsi-disk.c @@ -2332,10 +2332,15 @@ static void scsi_disk_reset(DeviceState *dev) { SCSIDiskState *s = DO_UPCAST(SCSIDiskState, qdev.qdev, dev); uint64_t nb_sectors; + AioContext *ctx; scsi_device_purge_requests(&s->qdev, SENSE_CODE(RESET)); + ctx = blk_get_aio_context(s->qdev.conf.blk); + aio_context_acquire(ctx); blk_get_geometry(s->qdev.conf.blk, &nb_sectors); + aio_context_release(ctx); + nb_sectors /= s->qdev.blocksize / BDRV_SECTOR_SIZE; if (nb_sectors) { nb_sectors--; diff --git a/tests/unit/test-block-iothread.c b/tests/unit/test-block-iothread.c index 8ca5adec5e..e444aa707d 100644 --- a/tests/unit/test-block-iothread.c +++ b/tests/unit/test-block-iothread.c @@ -831,7 +831,10 @@ static void test_attach_second_node(void) qdict_put_str(options, "driver", "raw"); qdict_put_str(options, "file", "base"); + aio_context_acquire(ctx); filter = bdrv_open(NULL, NULL, options, BDRV_O_RDWR, &error_abort); + aio_context_release(ctx); + g_assert(blk_get_aio_context(blk) == ctx); g_assert(bdrv_get_aio_context(bs) == ctx); g_assert(bdrv_get_aio_context(filter) == ctx); diff --git a/block/meson.build b/block/meson.build index 90011a2805..3662852dc2 100644 --- a/block/meson.build +++ b/block/meson.build @@ -139,6 +139,7 @@ block_gen_c = custom_target('block-gen.c', input: files( '../include/block/block-io.h', '../include/block/dirty-bitmap.h', + '../include/block/block_int-io.h', '../include/block/block-global-state.h', '../include/sysemu/block-backend-io.h', 'coroutines.h' -- 2.38.1