From 98292c61bc491b660c9fa2ccbdbb35131921ea65 Mon Sep 17 00:00:00 2001 From: Wen Congyang Date: Tue, 10 May 2016 15:36:38 +0800 Subject: [PATCH] quorum: implement bdrv_add_child() and bdrv_del_child() Signed-off-by: Wen Congyang Signed-off-by: zhanghailiang Signed-off-by: Gonglei Signed-off-by: Changlong Xie Message-id: 1462865799-19402-3-git-send-email-xiecl.fnst@cn.fujitsu.com Reviewed-by: Alberto Garcia Reviewed-by: Max Reitz Signed-off-by: Max Reitz --- block.c | 8 ++--- block/quorum.c | 78 +++++++++++++++++++++++++++++++++++++++++-- include/block/block.h | 4 +++ 3 files changed, 84 insertions(+), 6 deletions(-) diff --git a/block.c b/block.c index 0726dab8d0..18a497f69d 100644 --- a/block.c +++ b/block.c @@ -1174,10 +1174,10 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs, return child; } -static BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, - BlockDriverState *child_bs, - const char *child_name, - const BdrvChildRole *child_role) +BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, + BlockDriverState *child_bs, + const char *child_name, + const BdrvChildRole *child_role) { BdrvChild *child = bdrv_root_attach_child(child_bs, child_name, child_role); QLIST_INSERT_HEAD(&parent_bs->children, child, next); diff --git a/block/quorum.c b/block/quorum.c index 8f7c0992a2..1ec3511528 100644 --- a/block/quorum.c +++ b/block/quorum.c @@ -14,6 +14,7 @@ */ #include "qemu/osdep.h" +#include "qemu/cutils.h" #include "block/block_int.h" #include "qapi/qmp/qbool.h" #include "qapi/qmp/qdict.h" @@ -67,6 +68,9 @@ typedef struct QuorumVotes { typedef struct BDRVQuorumState { BdrvChild **children; /* children BlockDriverStates */ int num_children; /* children count */ + unsigned next_child_index; /* the index of the next child that should + * be added + */ int threshold; /* if less than threshold children reads gave the * same result a quorum error occurs. */ @@ -883,9 +887,9 @@ static int quorum_open(BlockDriverState *bs, QDict *options, int flags, ret = -EINVAL; goto exit; } - if (s->num_children < 2) { + if (s->num_children < 1) { error_setg(&local_err, - "Number of provided children must be greater than 1"); + "Number of provided children must be 1 or more"); ret = -EINVAL; goto exit; } @@ -949,6 +953,7 @@ static int quorum_open(BlockDriverState *bs, QDict *options, int flags, opened[i] = true; } + s->next_child_index = s->num_children; g_free(opened); goto exit; @@ -1005,6 +1010,72 @@ static void quorum_attach_aio_context(BlockDriverState *bs, } } +static void quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs, + Error **errp) +{ + BDRVQuorumState *s = bs->opaque; + BdrvChild *child; + char indexstr[32]; + int ret; + + assert(s->num_children <= INT_MAX / sizeof(BdrvChild *)); + if (s->num_children == INT_MAX / sizeof(BdrvChild *) || + s->next_child_index == UINT_MAX) { + error_setg(errp, "Too many children"); + return; + } + + ret = snprintf(indexstr, 32, "children.%u", s->next_child_index); + if (ret < 0 || ret >= 32) { + error_setg(errp, "cannot generate child name"); + return; + } + s->next_child_index++; + + bdrv_drained_begin(bs); + + /* We can safely add the child now */ + bdrv_ref(child_bs); + child = bdrv_attach_child(bs, child_bs, indexstr, &child_format); + s->children = g_renew(BdrvChild *, s->children, s->num_children + 1); + s->children[s->num_children++] = child; + + bdrv_drained_end(bs); +} + +static void quorum_del_child(BlockDriverState *bs, BdrvChild *child, + Error **errp) +{ + BDRVQuorumState *s = bs->opaque; + int i; + + for (i = 0; i < s->num_children; i++) { + if (s->children[i] == child) { + break; + } + } + + /* we have checked it in bdrv_del_child() */ + assert(i < s->num_children); + + if (s->num_children <= s->threshold) { + error_setg(errp, + "The number of children cannot be lower than the vote threshold %d", + s->threshold); + return; + } + + bdrv_drained_begin(bs); + + /* We can safely remove this child now */ + memmove(&s->children[i], &s->children[i + 1], + (s->num_children - i - 1) * sizeof(BdrvChild *)); + s->children = g_renew(BdrvChild *, s->children, --s->num_children); + bdrv_unref_child(bs, child); + + bdrv_drained_end(bs); +} + static void quorum_refresh_filename(BlockDriverState *bs, QDict *options) { BDRVQuorumState *s = bs->opaque; @@ -1059,6 +1130,9 @@ static BlockDriver bdrv_quorum = { .bdrv_detach_aio_context = quorum_detach_aio_context, .bdrv_attach_aio_context = quorum_attach_aio_context, + .bdrv_add_child = quorum_add_child, + .bdrv_del_child = quorum_del_child, + .is_filter = true, .bdrv_recurse_is_first_non_filter = quorum_recurse_is_first_non_filter, }; diff --git a/include/block/block.h b/include/block/block.h index c44d0a065c..b210832778 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -476,6 +476,10 @@ void bdrv_disable_copy_on_read(BlockDriverState *bs); void bdrv_ref(BlockDriverState *bs); void bdrv_unref(BlockDriverState *bs); void bdrv_unref_child(BlockDriverState *parent, BdrvChild *child); +BdrvChild *bdrv_attach_child(BlockDriverState *parent_bs, + BlockDriverState *child_bs, + const char *child_name, + const BdrvChildRole *child_role); bool bdrv_op_is_blocked(BlockDriverState *bs, BlockOpType op, Error **errp); void bdrv_op_block(BlockDriverState *bs, BlockOpType op, Error *reason);