On 16.02.2016 10:37, Changlong Xie wrote:
> From: Wen Congyang <we...@cn.fujitsu.com>
>
> Signed-off-by: Wen Congyang <we...@cn.fujitsu.com>
> Signed-off-by: zhanghailiang <zhang.zhanghaili...@huawei.com>
> Signed-off-by: Gonglei <arei.gong...@huawei.com>
> Signed-off-by: Changlong Xie <xiecl.f...@cn.fujitsu.com>
> ---
> block.c | 8 ++--
> block/quorum.c | 122
> +++++++++++++++++++++++++++++++++++++++++++++++++-
> include/block/block.h | 4 ++
> 3 files changed, 128 insertions(+), 6 deletions(-)
>
> diff --git a/block.c b/block.c
> index 08aa979..c3c9dc0 100644
> --- a/block.c
> +++ b/block.c
> @@ -1198,10 +1198,10 @@ static int bdrv_fill_options(QDict **options, const
> char *filename,
> return 0;
> }
>
> -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 = g_new(BdrvChild, 1);
> *child = (BdrvChild) {
> diff --git a/block/quorum.c b/block/quorum.c
> index a5ae4b8..e5a7e4f 100644
> --- a/block/quorum.c
> +++ b/block/quorum.c
> @@ -24,6 +24,7 @@
> #include "qapi/qmp/qstring.h"
> #include "qapi-event.h"
> #include "crypto/hash.h"
> +#include "qemu/bitmap.h"
>
> #define HASH_LENGTH 32
>
> @@ -81,6 +82,8 @@ typedef struct BDRVQuorumState {
> bool rewrite_corrupted;/* true if the driver must rewrite-on-read
> corrupted
> * block if Quorum is reached.
> */
> + unsigned long *index_bitmap;
> + int bsize;
>
> QuorumReadPattern read_pattern;
> } BDRVQuorumState;
> @@ -876,9 +879,9 @@ 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");
Side note: Actually, we could work with 0 children, too. Quorum would
then need to implement bdrv_is_inserted() and return false if there are
no children.
But that is something that can be implemented later on if the need arises.
> ret = -EINVAL;
> goto exit;
> }
> @@ -927,6 +930,7 @@ static int quorum_open(BlockDriverState *bs, QDict
> *options, int flags,
> /* allocate the children array */
> s->children = g_new0(BdrvChild *, s->num_children);
> opened = g_new0(bool, s->num_children);
> + s->index_bitmap = bitmap_new(s->num_children);
>
> for (i = 0; i < s->num_children; i++) {
> char indexstr[32];
> @@ -942,6 +946,8 @@ static int quorum_open(BlockDriverState *bs, QDict
> *options, int flags,
>
> opened[i] = true;
> }
> + bitmap_set(s->index_bitmap, 0, s->num_children);
> + s->bsize = s->num_children;
>
> g_free(opened);
> goto exit;
> @@ -998,6 +1004,115 @@ static void quorum_attach_aio_context(BlockDriverState
> *bs,
> }
> }
>
> +static int get_new_child_index(BDRVQuorumState *s)
> +{
> + int index;
> +
> + index = find_next_zero_bit(s->index_bitmap, s->bsize, 0);
> + if (index < s->bsize) {
> + return index;
> + }
> +
> + if ((s->bsize % BITS_PER_LONG) == 0) {
> + s->index_bitmap = bitmap_zero_extend(s->index_bitmap, s->bsize,
> + s->bsize + 1);
I think this function needs to be called unconditionally. Looking into
its implementation, its call to g_realloc() will not do anything (and it
will probably be pretty quick at that), but the following bitmap_clear()
will only clear the bits from old_nbits (s->bsize) to new_nbits
(s->bsize + 1).
Thus, if you only call this function every 32nd/64th child, only that
child's bit will be initialized to zero. All the rest is undefined.
You probably didn't notice because bitmap_new() returns a
zero-initialized bitmap, and thus you'd have to create around 64
children (on an x64 machine) to notice.
> + }
> +
> + return s->bsize++;
> +}
> +
> +static void remove_child_index(BDRVQuorumState *s, int index)
> +{
> + int last_index;
> + long new_len;
size_t would be the more appropriate type.
> +
> + assert(index < s->bsize);
> +
> + clear_bit(index, s->index_bitmap);
> + if (index < s->bsize - 1) {
> + /*
> + * The last bit is always set, and we don't clear
s/don't/didn't/
> + * the last bit.
> + */
> + return;
> + }
> +
> + last_index = find_last_bit(s->index_bitmap, s->bsize);
An assert(last_index < s->bsize); here wouldn't hurt.
(last_index == s->bsize would be the case if no bit is set in
s->index_bitmap anymore, which should be impossible.)
> + s->bsize = last_index + 1;
> + if (BITS_TO_LONGS(last_index + 1) == BITS_TO_LONGS(s->bsize)) {
> + return;
> + }
> +
> + new_len = BITS_TO_LONGS(last_index + 1) * sizeof(unsigned long);
s/last_index + 1/s->bsize/ looks better to me.
> + s->index_bitmap = g_realloc(s->index_bitmap, new_len);
> +}
> +
> +static void quorum_add_child(BlockDriverState *bs, BlockDriverState
> *child_bs,
> + Error **errp)
> +{
> + BDRVQuorumState *s = bs->opaque;
> + BdrvChild *child;
> + char indexstr[32];
> + int index, ret;
> +
> + index = get_new_child_index(s);
> + ret = snprintf(indexstr, 32, "children.%d", index);
> + if (ret < 0 || ret >= 32) {
> + error_setg(errp, "cannot generate child name");
> + return;
> + }
> +
> + bdrv_drain(bs);
> +
> + assert(s->num_children <= INT_MAX / sizeof(BdrvChild *));
> + if (s->num_children == INT_MAX / sizeof(BdrvChild *)) {
> + error_setg(errp, "Too many children");
> + return;
> + }
> + s->children = g_renew(BdrvChild *, s->children, s->num_children + 1);
> +
> + bdrv_ref(child_bs);
> + child = bdrv_attach_child(bs, child_bs, indexstr, &child_format);
> + s->children[s->num_children++] = child;
> + set_bit(index, s->index_bitmap);
> +}
> +
> +static void quorum_del_child(BlockDriverState *bs, BlockDriverState
> *child_bs,
> + Error **errp)
> +{
> + BDRVQuorumState *s = bs->opaque;
> + BdrvChild *child;
> + int i, index;
> +
> + for (i = 0; i < s->num_children; i++) {
> + if (s->children[i]->bs == child_bs) {
> + break;
> + }
> + }
> +
> + /* we have checked it in bdrv_del_child() */
> + assert(i < s->num_children);
> + child = s->children[i];
> +
> + if (s->num_children <= s->threshold) {
> + error_setg(errp,
> + "The number of children cannot be lower than the vote threshold
> %d",
> + s->threshold);
> + return;
> + }
> +
> + /* child->name is "children.%d" */
Optional: assert(!strncmp(child->name, "children.", 9));
> + index = atoi(child->name + 9);
Optional: Assert absence of an error:
unsigned long index;
char *endptr;
index = strtoul(child->name + 9, &endptr, 10);
assert(index >= 0 && !*endptr);
Max
> +
> + bdrv_drain(bs);
> + /* We can safely remove this child now */
> + memmove(&s->children[i], &s->children[i + 1],
> + (s->num_children - i - 1) * sizeof(void *));
> + s->children = g_renew(BdrvChild *, s->children, --s->num_children);
> + remove_child_index(s, index);
> + bdrv_unref_child(bs, child);
> +}
> +
> static void quorum_refresh_filename(BlockDriverState *bs, QDict *options)
> {
> BDRVQuorumState *s = bs->opaque;
> @@ -1053,6 +1168,9 @@ 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 ecde190..4b787d2 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -517,6 +517,10 @@ 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);
>
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