From 3c3bc462adeb561f5dfdcbb84ae691c95ccef916 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Thu, 24 Sep 2020 17:27:06 +0200 Subject: [PATCH] block/export: Add block-export-del Implement a new QMP command block-export-del and make nbd-server-remove a wrapper around it. Signed-off-by: Kevin Wolf Reviewed-by: Max Reitz Message-Id: <20200924152717.287415-21-kwolf@redhat.com> Acked-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- block/export/export.c | 43 +++++++++++++++++++++++++++++++++- block/monitor/block-hmp-cmds.c | 4 ++-- blockdev-nbd.c | 25 +++++--------------- include/block/export.h | 1 + include/block/nbd.h | 1 - nbd/server.c | 14 ----------- qapi/block-export.json | 32 ++++++++++++++++++++----- 7 files changed, 77 insertions(+), 43 deletions(-) diff --git a/block/export/export.c b/block/export/export.c index 62699dfa05..d186beffe9 100644 --- a/block/export/export.c +++ b/block/export/export.c @@ -29,7 +29,7 @@ static const BlockExportDriver *blk_exp_drivers[] = { static QLIST_HEAD(, BlockExport) block_exports = QLIST_HEAD_INITIALIZER(block_exports); -static BlockExport *blk_exp_find(const char *id) +BlockExport *blk_exp_find(const char *id) { BlockExport *exp; @@ -143,12 +143,23 @@ void blk_exp_request_shutdown(BlockExport *exp) AioContext *aio_context = exp->ctx; aio_context_acquire(aio_context); + + /* + * If the user doesn't own the export any more, it is already shutting + * down. We must not call .request_shutdown and decrease the refcount a + * second time. + */ + if (!exp->user_owned) { + goto out; + } + exp->drv->request_shutdown(exp); assert(exp->user_owned); exp->user_owned = false; blk_exp_unref(exp); +out: aio_context_release(aio_context); } @@ -199,3 +210,33 @@ void qmp_block_export_add(BlockExportOptions *export, Error **errp) { blk_exp_add(export, errp); } + +void qmp_block_export_del(const char *id, + bool has_mode, BlockExportRemoveMode mode, + Error **errp) +{ + ERRP_GUARD(); + BlockExport *exp; + + exp = blk_exp_find(id); + if (exp == NULL) { + error_setg(errp, "Export '%s' is not found", id); + return; + } + if (!exp->user_owned) { + error_setg(errp, "Export '%s' is already shutting down", id); + return; + } + + if (!has_mode) { + mode = BLOCK_EXPORT_REMOVE_MODE_SAFE; + } + if (mode == BLOCK_EXPORT_REMOVE_MODE_SAFE && exp->refcount > 1) { + error_setg(errp, "export '%s' still in use", exp->id); + error_append_hint(errp, "Use mode='hard' to force client " + "disconnect\n"); + return; + } + + blk_exp_request_shutdown(exp); +} diff --git a/block/monitor/block-hmp-cmds.c b/block/monitor/block-hmp-cmds.c index db357cafcb..d15a2be827 100644 --- a/block/monitor/block-hmp-cmds.c +++ b/block/monitor/block-hmp-cmds.c @@ -476,8 +476,8 @@ void hmp_nbd_server_remove(Monitor *mon, const QDict *qdict) bool force = qdict_get_try_bool(qdict, "force", false); Error *err = NULL; - /* Rely on NBD_SERVER_REMOVE_MODE_SAFE being the default */ - qmp_nbd_server_remove(name, force, NBD_SERVER_REMOVE_MODE_HARD, &err); + /* Rely on BLOCK_EXPORT_REMOVE_MODE_SAFE being the default */ + qmp_nbd_server_remove(name, force, BLOCK_EXPORT_REMOVE_MODE_HARD, &err); hmp_handle_error(mon, err); } diff --git a/blockdev-nbd.c b/blockdev-nbd.c index 9efbaef8f7..4a9a1be571 100644 --- a/blockdev-nbd.c +++ b/blockdev-nbd.c @@ -307,31 +307,18 @@ fail: } void qmp_nbd_server_remove(const char *name, - bool has_mode, NbdServerRemoveMode mode, + bool has_mode, BlockExportRemoveMode mode, Error **errp) { - NBDExport *exp; - AioContext *aio_context; + BlockExport *exp; - if (!nbd_server) { - error_setg(errp, "NBD server not running"); + exp = blk_exp_find(name); + if (exp && exp->drv->type != BLOCK_EXPORT_TYPE_NBD) { + error_setg(errp, "Block export '%s' is not an NBD export", name); return; } - exp = nbd_export_find(name); - if (exp == NULL) { - error_setg(errp, "Export '%s' is not found", name); - return; - } - - if (!has_mode) { - mode = NBD_SERVER_REMOVE_MODE_SAFE; - } - - aio_context = nbd_export_aio_context(exp); - aio_context_acquire(aio_context); - nbd_export_remove(exp, mode, errp); - aio_context_release(aio_context); + qmp_block_export_del(name, has_mode, mode, errp); } void qmp_nbd_server_stop(Error **errp) diff --git a/include/block/export.h b/include/block/export.h index 4833947e89..ff54d35872 100644 --- a/include/block/export.h +++ b/include/block/export.h @@ -76,6 +76,7 @@ struct BlockExport { }; BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp); +BlockExport *blk_exp_find(const char *id); void blk_exp_ref(BlockExport *exp); void blk_exp_unref(BlockExport *exp); void blk_exp_request_shutdown(BlockExport *exp); diff --git a/include/block/nbd.h b/include/block/nbd.h index 0b9f3e5d4e..a4dc1f9e54 100644 --- a/include/block/nbd.h +++ b/include/block/nbd.h @@ -337,7 +337,6 @@ int nbd_export_new(BlockExport *blk_exp, BlockDriverState *bs, const char *bitmap, bool readonly, bool shared, bool writethrough, Error **errp); void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk); -void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp); AioContext *nbd_export_aio_context(NBDExport *exp); NBDExport *nbd_export_find(const char *name); diff --git a/nbd/server.c b/nbd/server.c index 22a1d66168..1a0e1db401 100644 --- a/nbd/server.c +++ b/nbd/server.c @@ -1669,20 +1669,6 @@ static void nbd_export_request_shutdown(BlockExport *blk_exp) blk_exp_unref(&exp->common); } -void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp) -{ - ERRP_GUARD(); - if (mode == NBD_SERVER_REMOVE_MODE_HARD || QTAILQ_EMPTY(&exp->clients)) { - nbd_export_request_shutdown(&exp->common); - return; - } - - assert(mode == NBD_SERVER_REMOVE_MODE_SAFE); - - error_setg(errp, "export '%s' still in use", exp->name); - error_append_hint(errp, "Use mode='hard' to force client disconnect\n"); -} - static void nbd_export_delete(BlockExport *blk_exp) { NBDExport *exp = container_of(blk_exp, NBDExport, common); diff --git a/qapi/block-export.json b/qapi/block-export.json index 658bdf05e1..3d22527c84 100644 --- a/qapi/block-export.json +++ b/qapi/block-export.json @@ -116,9 +116,9 @@ 'data': 'NbdServerAddOptions', 'boxed': true } ## -# @NbdServerRemoveMode: +# @BlockExportRemoveMode: # -# Mode for removing an NBD export. +# Mode for removing a block export. # # @safe: Remove export if there are no existing connections, fail otherwise. # @@ -134,16 +134,16 @@ # # Since: 2.12 ## -{'enum': 'NbdServerRemoveMode', 'data': ['safe', 'hard']} +{'enum': 'BlockExportRemoveMode', 'data': ['safe', 'hard']} ## # @nbd-server-remove: # # Remove NBD export by name. # -# @name: Export name. +# @name: Block export id. # -# @mode: Mode of command operation. See @NbdServerRemoveMode description. +# @mode: Mode of command operation. See @BlockExportRemoveMode description. # Default is 'safe'. # # Returns: error if @@ -154,7 +154,7 @@ # Since: 2.12 ## { 'command': 'nbd-server-remove', - 'data': {'name': 'str', '*mode': 'NbdServerRemoveMode'} } + 'data': {'name': 'str', '*mode': 'BlockExportRemoveMode'} } ## # @nbd-server-stop: @@ -213,3 +213,23 @@ ## { 'command': 'block-export-add', 'data': 'BlockExportOptions', 'boxed': true } + +## +# @block-export-del: +# +# Request to remove a block export. This drops the user's reference to the +# export, but the export may still stay around after this command returns until +# the shutdown of the export has completed. +# +# @id: Block export id. +# +# @mode: Mode of command operation. See @BlockExportRemoveMode description. +# Default is 'safe'. +# +# Returns: Error if the export is not found or @mode is 'safe' and the export +# is still in use (e.g. by existing client connections) +# +# Since: 5.2 +## +{ 'command': 'block-export-del', + 'data': { 'id': 'str', '*mode': 'BlockExportRemoveMode' } }