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block/export: Move refcount from NBDExport to BlockExport

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Having a refcount makes sense for all types of block exports. It is also
a prerequisite for keeping a list of all exports at the BlockExport
level.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200924152717.287415-14-kwolf@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2020-09-24 17:26:59 +02:00
parent dbc9e94a23
commit c69de1bef5
5 changed files with 64 additions and 43 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
block/export/export.c
View File

@ -49,6 +49,20 @@ BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
return drv->create(export, errp);
}
void blk_exp_ref(BlockExport *exp)
{
assert(exp->refcount > 0);
exp->refcount++;
}
void blk_exp_unref(BlockExport *exp)
{
assert(exp->refcount > 0);
if (--exp->refcount == 0) {
exp->drv->delete(exp);
}
}
void qmp_block_export_add(BlockExportOptions *export, Error **errp)
{
blk_exp_add(export, errp);

2
blockdev-nbd.c
View File

@ -236,7 +236,7 @@ BlockExport *nbd_export_create(BlockExportOptions *exp_args, Error **errp)
/* The list of named exports has a strong reference to this export now and
* our only way of accessing it is through nbd_export_find(), so we can drop
* the strong reference that is @exp. */
nbd_export_put(exp);
blk_exp_unref((BlockExport*) exp);
out:
aio_context_release(aio_context);

15
include/block/export.h
View File

@ -24,12 +24,27 @@ typedef struct BlockExportDriver {
/* Creates and starts a new block export */
BlockExport *(*create)(BlockExportOptions *, Error **);
/*
* Frees a removed block export. This function is only called after all
* references have been dropped.
*/
void (*delete)(BlockExport *);
} BlockExportDriver;
struct BlockExport {
const BlockExportDriver *drv;
/*
* Reference count for this block export. This includes strong references
* both from the owner (qemu-nbd or the monitor) and clients connected to
* the export.
*/
int refcount;
};
BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp);
void blk_exp_ref(BlockExport *exp);
void blk_exp_unref(BlockExport *exp);
#endif

2
include/block/nbd.h
View File

@ -338,8 +338,6 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
void nbd_export_set_on_eject_blk(BlockExport *exp, BlockBackend *blk);
void nbd_export_close(NBDExport *exp);
void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp);
void nbd_export_get(NBDExport *exp);
void nbd_export_put(NBDExport *exp);
AioContext *nbd_export_aio_context(NBDExport *exp);
NBDExport *nbd_export_find(const char *name);

74
nbd/server.c
View File

@ -83,7 +83,6 @@ struct NBDRequestData {
struct NBDExport {
BlockExport common;
int refcount;
BlockBackend *blk;
char *name;
@ -499,7 +498,7 @@ static int nbd_negotiate_handle_export_name(NBDClient *client, bool no_zeroes,
}
QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
nbd_export_get(client->exp);
blk_exp_ref(&client->exp->common);
nbd_check_meta_export(client);
return 0;
@ -707,7 +706,7 @@ static int nbd_negotiate_handle_info(NBDClient *client, Error **errp)
client->exp = exp;
client->check_align = check_align;
QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
nbd_export_get(client->exp);
blk_exp_ref(&client->exp->common);
nbd_check_meta_export(client);
rc = 1;
}
@ -1406,7 +1405,7 @@ void nbd_client_put(NBDClient *client)
g_free(client->tlsauthz);
if (client->exp) {
QTAILQ_REMOVE(&client->exp->clients, client, next);
nbd_export_put(client->exp);
blk_exp_unref(&client->exp->common);
}
g_free(client);
}
@ -1538,7 +1537,8 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
exp = g_new0(NBDExport, 1);
exp->common = (BlockExport) {
.drv = &blk_exp_nbd,
.drv = &blk_exp_nbd,
.refcount = 1,
};
/*
@ -1567,7 +1567,6 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
blk_set_enable_write_cache(blk, !writethrough);
blk_set_allow_aio_context_change(blk, true);
exp->refcount = 1;
QTAILQ_INIT(&exp->clients);
exp->blk = blk;
exp->name = g_strdup(name);
@ -1626,8 +1625,9 @@ NBDExport *nbd_export_new(BlockDriverState *bs,
exp->ctx = ctx;
blk_add_aio_context_notifier(blk, blk_aio_attached, blk_aio_detach, exp);
blk_exp_ref(&exp->common);
QTAILQ_INSERT_TAIL(&exports, exp, next);
nbd_export_get(exp);
return exp;
fail:
@ -1660,7 +1660,7 @@ void nbd_export_close(NBDExport *exp)
{
NBDClient *client, *next;
nbd_export_get(exp);
blk_exp_ref(&exp->common);
/*
* TODO: Should we expand QMP NbdServerRemoveNode enum to allow a
* close mode that stops advertising the export to new clients but
@ -1672,13 +1672,13 @@ void nbd_export_close(NBDExport *exp)
client_close(client, true);
}
if (exp->name) {
nbd_export_put(exp);
blk_exp_unref(&exp->common);
g_free(exp->name);
exp->name = NULL;
QTAILQ_REMOVE(&exports, exp, next);
QTAILQ_INSERT_TAIL(&closed_exports, exp, next);
}
nbd_export_put(exp);
blk_exp_unref(&exp->common);
}
void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp)
@ -1695,47 +1695,41 @@ void nbd_export_remove(NBDExport *exp, NbdServerRemoveMode mode, Error **errp)
error_append_hint(errp, "Use mode='hard' to force client disconnect\n");
}
void nbd_export_get(NBDExport *exp)
static void nbd_export_delete(BlockExport *blk_exp)
{
assert(exp->refcount > 0);
exp->refcount++;
}
NBDExport *exp = container_of(blk_exp, NBDExport, common);
void nbd_export_put(NBDExport *exp)
{
assert(exp->refcount > 0);
if (--exp->refcount == 0) {
assert(exp->name == NULL);
assert(QTAILQ_EMPTY(&exp->clients));
assert(exp->name == NULL);
assert(QTAILQ_EMPTY(&exp->clients));
g_free(exp->description);
exp->description = NULL;
g_free(exp->description);
exp->description = NULL;
if (exp->blk) {
if (exp->eject_notifier_blk) {
notifier_remove(&exp->eject_notifier);
blk_unref(exp->eject_notifier_blk);
}
blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
blk_aio_detach, exp);
blk_unref(exp->blk);
exp->blk = NULL;
if (exp->blk) {
if (exp->eject_notifier_blk) {
notifier_remove(&exp->eject_notifier);
blk_unref(exp->eject_notifier_blk);
}
if (exp->export_bitmap) {
bdrv_dirty_bitmap_set_busy(exp->export_bitmap, false);
g_free(exp->export_bitmap_context);
}
QTAILQ_REMOVE(&closed_exports, exp, next);
g_free(exp);
aio_wait_kick();
blk_remove_aio_context_notifier(exp->blk, blk_aio_attached,
blk_aio_detach, exp);
blk_unref(exp->blk);
exp->blk = NULL;
}
if (exp->export_bitmap) {
bdrv_dirty_bitmap_set_busy(exp->export_bitmap, false);
g_free(exp->export_bitmap_context);
}
QTAILQ_REMOVE(&closed_exports, exp, next);
g_free(exp);
aio_wait_kick();
}
const BlockExportDriver blk_exp_nbd = {
.type = BLOCK_EXPORT_TYPE_NBD,
.create = nbd_export_create,
.delete = nbd_export_delete,
};
void nbd_export_close_all(void)