[Qemu-devel] [PATCH 06/23] block: Eliminate bdrv_states, use block_next() instead

[Markus Armbruster <armbru@redhat.com>]

Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 block.c                   | 43 +++++++++++++++++++------------------------
 block/block-backend.c     |  4 ++++
 include/block/block_int.h |  2 --
 3 files changed, 23 insertions(+), 26 deletions(-)

diff --git a/block.c b/block.c
index a6c03da..89f9cf0 100644
--- a/block.c
+++ b/block.c
@@ -24,6 +24,7 @@
 #include "config-host.h"
 #include "qemu-common.h"
 #include "trace.h"
+#include "sysemu/block-backend.h"
 #include "block/block_int.h"
 #include "block/blockjob.h"
 #include "qemu/module.h"
@@ -90,9 +91,6 @@ static void coroutine_fn bdrv_co_do_rw(void *opaque);
 static int coroutine_fn bdrv_co_do_write_zeroes(BlockDriverState *bs,
     int64_t sector_num, int nb_sectors, BdrvRequestFlags flags);
 
-static QTAILQ_HEAD(, BlockDriverState) bdrv_states =
-    QTAILQ_HEAD_INITIALIZER(bdrv_states);
-
 static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states =
     QTAILQ_HEAD_INITIALIZER(graph_bdrv_states);
 
@@ -355,9 +353,6 @@ BlockDriverState *bdrv_new_named(const char *device_name, Error **errp)
     bs = bdrv_new();
 
     pstrcpy(bs->device_name, sizeof(bs->device_name), device_name);
-    if (device_name[0] != '\0') {
-        QTAILQ_INSERT_TAIL(&bdrv_states, bs, device_list);
-    }
 
     return bs;
 }
@@ -1888,7 +1883,7 @@ void bdrv_close_all(void)
 {
     BlockDriverState *bs;
 
-    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
+    for (bs = bdrv_next(NULL); bs; bs = bdrv_next(bs)) {
         AioContext *aio_context = bdrv_get_aio_context(bs);
 
         aio_context_acquire(aio_context);
@@ -1939,7 +1934,7 @@ void bdrv_drain_all(void)
     while (busy) {
         busy = false;
 
-        QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
+        for (bs = bdrv_next(NULL); bs; bs = bdrv_next(bs)) {
             AioContext *aio_context = bdrv_get_aio_context(bs);
             bool bs_busy;
 
@@ -1960,9 +1955,6 @@ void bdrv_drain_all(void)
    Also, NULL terminate the device_name to prevent double remove */
 void bdrv_make_anon(BlockDriverState *bs)
 {
-    if (bs->device_name[0] != '\0') {
-        QTAILQ_REMOVE(&bdrv_states, bs, device_list);
-    }
     bs->device_name[0] = '\0';
     if (bs->node_name[0] != '\0') {
         QTAILQ_REMOVE(&graph_bdrv_states, bs, node_list);
@@ -2016,10 +2008,9 @@ static void bdrv_move_feature_fields(BlockDriverState *bs_dest,
     /* job */
     bs_dest->job                = bs_src->job;
 
-    /* keep the same entry in bdrv_states */
     pstrcpy(bs_dest->device_name, sizeof(bs_dest->device_name),
             bs_src->device_name);
-    bs_dest->device_list = bs_src->device_list;
+
     memcpy(bs_dest->op_blockers, bs_src->op_blockers,
            sizeof(bs_dest->op_blockers));
 }
@@ -2363,7 +2354,7 @@ int bdrv_commit_all(void)
 {
     BlockDriverState *bs;
 
-    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
+    for (bs = bdrv_next(NULL); bs; bs = bdrv_next(bs)) {
         AioContext *aio_context = bdrv_get_aio_context(bs);
 
         aio_context_acquire(aio_context);
@@ -3807,7 +3798,7 @@ BlockDriverState *bdrv_find(const char *name)
 {
     BlockDriverState *bs;
 
-    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
+    for (bs = bdrv_next(NULL); bs; bs = bdrv_next(bs)) {
         if (!strcmp(name, bs->device_name)) {
             return bs;
         }
@@ -3888,17 +3879,21 @@ bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base)
 
 BlockDriverState *bdrv_next(BlockDriverState *bs)
 {
-    if (!bs) {
-        return QTAILQ_FIRST(&bdrv_states);
-    }
-    return QTAILQ_NEXT(bs, device_list);
+    BlockBackend *blk;
+
+    for (blk = blk_next(bs ? bs->blk : NULL);
+         blk && !blk_bs(blk);
+         blk = blk_next(blk))
+        ;
+
+    return blk ? blk_bs(blk) : NULL;
 }
 
 void bdrv_iterate(void (*it)(void *opaque, BlockDriverState *bs), void *opaque)
 {
     BlockDriverState *bs;
 
-    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
+    for (bs = bdrv_next(NULL); bs; bs = bdrv_next(bs)) {
         it(opaque, bs);
     }
 }
@@ -3918,7 +3913,7 @@ int bdrv_flush_all(void)
     BlockDriverState *bs;
     int result = 0;
 
-    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
+    for (bs = bdrv_next(NULL); bs; bs = bdrv_next(bs)) {
         AioContext *aio_context = bdrv_get_aio_context(bs);
         int ret;
 
@@ -5065,7 +5060,7 @@ void bdrv_invalidate_cache_all(Error **errp)
     BlockDriverState *bs;
     Error *local_err = NULL;
 
-    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
+    for (bs = bdrv_next(NULL); bs; bs = bdrv_next(bs)) {
         AioContext *aio_context = bdrv_get_aio_context(bs);
 
         aio_context_acquire(aio_context);
@@ -5082,7 +5077,7 @@ void bdrv_clear_incoming_migration_all(void)
 {
     BlockDriverState *bs;
 
-    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
+    for (bs = bdrv_next(NULL); bs; bs = bdrv_next(bs)) {
         AioContext *aio_context = bdrv_get_aio_context(bs);
 
         aio_context_acquire(aio_context);
@@ -5918,7 +5913,7 @@ bool bdrv_is_first_non_filter(BlockDriverState *candidate)
     BlockDriverState *bs;
 
     /* walk down the bs forest recursively */
-    QTAILQ_FOREACH(bs, &bdrv_states, device_list) {
+    for (bs = bdrv_next(NULL); bs; bs = bdrv_next(bs)) {
         bool perm;
 
         /* try to recurse in this top level bs */
diff --git a/block/block-backend.c b/block/block-backend.c
index ae51f7f..c0876fa 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -191,6 +191,10 @@ BlockDriverState *blk_detach_bs(BlockBackend *blk)
 {
     BlockDriverState *bs = blk->bs;
 
+    /*
+     * Must bdrv_unref() before zapping bs->blk, or else
+     * bdrv_drain_all() will miss bs.
+     */
     if (bs) {
         bs->blk = NULL;
         blk->bs = NULL;
diff --git a/include/block/block_int.h b/include/block/block_int.h
index a04c852..d5de08b 100644
--- a/include/block/block_int.h
+++ b/include/block/block_int.h
@@ -396,8 +396,6 @@ struct BlockDriverState {
     QTAILQ_ENTRY(BlockDriverState) node_list;
     /* Device name is the name associated with the "drive" the guest sees */
     char device_name[32];
-    /* element of the list of "drives" the guest sees */
-    QTAILQ_ENTRY(BlockDriverState) device_list;
     QLIST_HEAD(, BdrvDirtyBitmap) dirty_bitmaps;
     int refcnt;
 
-- 
1.9.3