Block drivers can implement this new operation .bdrv_lockf to actually lock the image in the protocol specific way.
Signed-off-by: Fam Zheng <f...@redhat.com> --- block.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++ include/block/block.h | 11 ++++++++- include/block/block_int.h | 5 ++++ 3 files changed, 74 insertions(+), 1 deletion(-) diff --git a/block.c b/block.c index 5f76f60..55a393f 100644 --- a/block.c +++ b/block.c @@ -859,6 +859,50 @@ out: g_free(gen_node_name); } +BdrvLockfCmd bdrv_get_locking_cmd(int flags) +{ + if (flags & BDRV_O_NO_LOCK) { + return BDRV_LOCKF_UNLOCK; + } else if (flags & BDRV_O_SHARED_LOCK) { + return BDRV_LOCKF_SHARED; + } else if (flags & BDRV_O_RDWR) { + return BDRV_LOCKF_EXCLUSIVE; + } else { + return BDRV_LOCKF_SHARED; + } +} + +static int bdrv_lock_unlock_image_do(BlockDriverState *bs, BdrvLockfCmd cmd) +{ + int ret; + + if (bs->cur_lock == cmd) { + return 0; + } else if (!bs->drv) { + return -ENOMEDIUM; + } else if (!bs->drv->bdrv_lockf) { + return 0; + } + ret = bs->drv->bdrv_lockf(bs, cmd); + if (ret == -ENOTSUP) { + /* Handle it the same way as !bs->drv->bdrv_lockf */ + ret = 0; + } else if (ret == 0) { + bs->cur_lock = cmd; + } + return ret; +} + +static int bdrv_lock_image(BlockDriverState *bs) +{ + return bdrv_lock_unlock_image_do(bs, bdrv_get_locking_cmd(bs->open_flags)); +} + +static int bdrv_unlock_image(BlockDriverState *bs) +{ + return bdrv_lock_unlock_image_do(bs, BDRV_LOCKF_UNLOCK); +} + static QemuOptsList bdrv_runtime_opts = { .name = "bdrv_common", .head = QTAILQ_HEAD_INITIALIZER(bdrv_runtime_opts.head), @@ -1025,6 +1069,16 @@ static int bdrv_open_common(BlockDriverState *bs, BdrvChild *file, goto free_and_fail; } + assert(!((open_flags & BDRV_O_NO_LOCK) && + (open_flags & BDRV_O_SHARED_LOCK))); + if (!(open_flags & (BDRV_O_NO_LOCK | BDRV_O_INACTIVE))) { + ret = bdrv_lock_image(bs); + if (ret) { + error_setg(errp, "Failed to lock image"); + goto free_and_fail; + } + } + ret = refresh_total_sectors(bs, bs->total_sectors); if (ret < 0) { error_setg_errno(errp, -ret, "Could not refresh total sector count"); @@ -2182,6 +2236,7 @@ static void bdrv_close(BlockDriverState *bs) if (bs->drv) { BdrvChild *child, *next; + bdrv_unlock_image(bs); bs->drv->bdrv_close(bs); bs->drv = NULL; @@ -3101,6 +3156,9 @@ void bdrv_invalidate_cache(BlockDriverState *bs, Error **errp) error_setg_errno(errp, -ret, "Could not refresh total sector count"); return; } + if (!(bs->open_flags & BDRV_O_NO_LOCK)) { + bdrv_lock_image(bs); + } } void bdrv_invalidate_cache_all(Error **errp) @@ -3143,6 +3201,7 @@ static int bdrv_inactivate_recurse(BlockDriverState *bs, } if (setting_flag) { + ret = bdrv_unlock_image(bs); bs->open_flags |= BDRV_O_INACTIVE; } return 0; diff --git a/include/block/block.h b/include/block/block.h index a14101b..9ceabcd 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -187,6 +187,15 @@ typedef enum BlockOpType { BLOCK_OP_TYPE_MAX, } BlockOpType; +typedef enum { + /* The values are ordered so that lower number implies higher restriction. + * Starting from 1 to make 0 an invalid value. + * */ + BDRV_LOCKF_EXCLUSIVE = 1, + BDRV_LOCKF_SHARED, + BDRV_LOCKF_UNLOCK, +} BdrvLockfCmd; + void bdrv_info_print(Monitor *mon, const QObject *data); void bdrv_info(Monitor *mon, QObject **ret_data); void bdrv_stats_print(Monitor *mon, const QObject *data); @@ -274,7 +283,7 @@ int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top, BlockDriverState *bdrv_find_overlay(BlockDriverState *active, BlockDriverState *bs); BlockDriverState *bdrv_find_base(BlockDriverState *bs); - +BdrvLockfCmd bdrv_get_locking_cmd(int flags); typedef struct BdrvCheckResult { int corruptions; diff --git a/include/block/block_int.h b/include/block/block_int.h index 47665be..448fa65 100644 --- a/include/block/block_int.h +++ b/include/block/block_int.h @@ -319,6 +319,10 @@ struct BlockDriver { Error **errp); void (*bdrv_del_child)(BlockDriverState *parent, BdrvChild *child, Error **errp); + /** + * Lock/unlock the image. + */ + int (*bdrv_lockf)(BlockDriverState *bs, BdrvLockfCmd cmd); QLIST_ENTRY(BlockDriver) list; }; @@ -528,6 +532,7 @@ struct BlockDriverState { unsigned io_plug_disabled; int quiesce_counter; + BdrvLockfCmd cur_lock; }; struct BlockBackendRootState { -- 2.7.4