Re: [Qemu-devel] [Patch v8 2/3] quorum: implement bdrv_add_child() and bdrv_del_child()

[Li Zhijian]

On 11/27/2015 02:06 PM, Wen Congyang wrote:

Signed-off-by: Wen Congyang 
Signed-off-by: zhanghailiang 
Signed-off-by: Gonglei 
---
  block.c   |   8 ++--
  block/quorum.c| 124 +-
  include/block/block.h |   4 ++
  3 files changed, 130 insertions(+), 6 deletions(-)

diff --git a/block.c b/block.c
index 255a36e..bfc2be8 100644
--- a/block.c
+++ b/block.c
@@ -1196,10 +1196,10 @@ 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 2810e37..b7df14b 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -23,6 +23,7 @@
  #include "qapi/qmp/qstring.h"
  #include "qapi-event.h"
  #include "crypto/hash.h"
+#include "qemu/bitmap.h"

  #define HASH_LENGTH 32

@@ -80,6 +81,8 @@ 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;
@@ -875,9 +878,9 @@ 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(_err,
-   "Number of provided children must be greater than 1");
+   "Number of provided children must be 1 or more");
  ret = -EINVAL;
  goto exit;
  }
@@ -926,6 +929,7 @@ 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];
@@ -941,6 +945,8 @@ 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;
@@ -997,6 +1003,117 @@ 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);
+}
+
+return s->bsize++;
+}
+
+static void remove_child_index(BDRVQuorumState *s, int index)
+{
+int last_index;
+long new_len;
+
+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
+ * the last bit.
+ */
+return;
+}
+
+last_index = find_last_bit(s->index_bitmap, s->bsize);
+if (BITS_TO_LONGS(last_index + 1) == BITS_TO_LONGS(s->bsize)) {
+s->bsize = last_index + 1;
+return;
+}
+
+new_len = BITS_TO_LONGS(last_index + 1) * sizeof(unsigned long);
+s->index_bitmap = g_realloc(s->index_bitmap, new_len);
+s->bsize = last_index + 1;
+}
+
+static void quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs,
+ Error **errp)
+{
+BDRVQuorumState *s = bs->opaque;
+BdrvChild *child;
+char indexstr[32];
+int index = find_next_zero_bit(s->index_bitmap, s->bsize, 0);
+int ret;
+
+index = get_new_child_index(s);


double assignment of 'index', remove the first one pls

Thanks
Li


+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 = 

[Qemu-devel] [Patch v8 2/3] quorum: implement bdrv_add_child() and bdrv_del_child()

[Wen Congyang]

Signed-off-by: Wen Congyang 
Signed-off-by: zhanghailiang 
Signed-off-by: Gonglei 
---
 block.c   |   8 ++--
 block/quorum.c| 124 +-
 include/block/block.h |   4 ++
 3 files changed, 130 insertions(+), 6 deletions(-)

diff --git a/block.c b/block.c
index 255a36e..bfc2be8 100644
--- a/block.c
+++ b/block.c
@@ -1196,10 +1196,10 @@ 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 2810e37..b7df14b 100644
--- a/block/quorum.c
+++ b/block/quorum.c
@@ -23,6 +23,7 @@
 #include "qapi/qmp/qstring.h"
 #include "qapi-event.h"
 #include "crypto/hash.h"
+#include "qemu/bitmap.h"
 
 #define HASH_LENGTH 32
 
@@ -80,6 +81,8 @@ 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;
@@ -875,9 +878,9 @@ 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(_err,
-   "Number of provided children must be greater than 1");
+   "Number of provided children must be 1 or more");
 ret = -EINVAL;
 goto exit;
 }
@@ -926,6 +929,7 @@ 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];
@@ -941,6 +945,8 @@ 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;
@@ -997,6 +1003,117 @@ 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);
+}
+
+return s->bsize++;
+}
+
+static void remove_child_index(BDRVQuorumState *s, int index)
+{
+int last_index;
+long new_len;
+
+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
+ * the last bit.
+ */
+return;
+}
+
+last_index = find_last_bit(s->index_bitmap, s->bsize);
+if (BITS_TO_LONGS(last_index + 1) == BITS_TO_LONGS(s->bsize)) {
+s->bsize = last_index + 1;
+return;
+}
+
+new_len = BITS_TO_LONGS(last_index + 1) * sizeof(unsigned long);
+s->index_bitmap = g_realloc(s->index_bitmap, new_len);
+s->bsize = last_index + 1;
+}
+
+static void quorum_add_child(BlockDriverState *bs, BlockDriverState *child_bs,
+ Error **errp)
+{
+BDRVQuorumState *s = bs->opaque;
+BdrvChild *child;
+char indexstr[32];
+int index = find_next_zero_bit(s->index_bitmap, s->bsize, 0);
+int 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, _format);
+s->children[s->num_children++] = child;
+set_bit(index, s->index_bitmap);
+}
+
+static void