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block: Mark bdrv_get_cumulative_perm() and callers GRAPH_RDLOCK

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The function reads the parents list, so it needs to hold the graph lock.

This happens to result in BlockDriver.bdrv_set_perm() to be called with
the graph lock held. For consistency, make it the same for all of the
BlockDriver callbacks for updating permissions and annotate the function
pointers with GRAPH_RDLOCK_PTR.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20230911094620.45040-15-kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2023-09-11 11:46:13 +02:00
parent 3804e3cf54
commit bce73bc25b
4 changed files with 40 additions and 14 deletions
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35
block.c
View file

@ -2320,7 +2320,7 @@ static void bdrv_child_set_perm(BdrvChild *c, uint64_t perm,
tran_add(tran, &bdrv_child_set_pem_drv, s);
}
static void bdrv_drv_set_perm_commit(void *opaque)
static void GRAPH_RDLOCK bdrv_drv_set_perm_commit(void *opaque)
{
BlockDriverState *bs = opaque;
uint64_t cumulative_perms, cumulative_shared_perms;
@ -2333,7 +2333,7 @@ static void bdrv_drv_set_perm_commit(void *opaque)
}
}
static void bdrv_drv_set_perm_abort(void *opaque)
static void GRAPH_RDLOCK bdrv_drv_set_perm_abort(void *opaque)
{
BlockDriverState *bs = opaque;
GLOBAL_STATE_CODE();
@ -2348,9 +2348,13 @@ TransactionActionDrv bdrv_drv_set_perm_drv = {
.commit = bdrv_drv_set_perm_commit,
};
static int bdrv_drv_set_perm(BlockDriverState *bs, uint64_t perm,
uint64_t shared_perm, Transaction *tran,
Error **errp)
/*
* After calling this function, the transaction @tran may only be completed
* while holding a reader lock for the graph.
*/
static int GRAPH_RDLOCK
bdrv_drv_set_perm(BlockDriverState *bs, uint64_t perm, uint64_t shared_perm,
Transaction *tran, Error **errp)
{
GLOBAL_STATE_CODE();
if (!bs->drv) {
@ -2457,9 +2461,13 @@ bdrv_replace_child_tran(BdrvChild *child, BlockDriverState *new_bs,
/*
* Refresh permissions in @bs subtree. The function is intended to be called
* after some graph modification that was done without permission update.
*
* After calling this function, the transaction @tran may only be completed
* while holding a reader lock for the graph.
*/
static int bdrv_node_refresh_perm(BlockDriverState *bs, BlockReopenQueue *q,
Transaction *tran, Error **errp)
static int GRAPH_RDLOCK
bdrv_node_refresh_perm(BlockDriverState *bs, BlockReopenQueue *q,
Transaction *tran, Error **errp)
{
BlockDriver *drv = bs->drv;
BdrvChild *c;
@ -2532,6 +2540,9 @@ static int bdrv_node_refresh_perm(BlockDriverState *bs, BlockReopenQueue *q,
/*
* @list is a product of bdrv_topological_dfs() (may be called several times) -
* a topologically sorted subgraph.
*
* After calling this function, the transaction @tran may only be completed
* while holding a reader lock for the graph.
*/
static int GRAPH_RDLOCK
bdrv_do_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran,
@ -2561,6 +2572,9 @@ bdrv_do_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran,
* @list is any list of nodes. List is completed by all subtrees and
* topologically sorted. It's not a problem if some node occurs in the @list
* several times.
*
* After calling this function, the transaction @tran may only be completed
* while holding a reader lock for the graph.
*/
static int GRAPH_RDLOCK
bdrv_list_refresh_perms(GSList *list, BlockReopenQueue *q, Transaction *tran,
@ -2623,7 +2637,12 @@ char *bdrv_perm_names(uint64_t perm)
}
/* @tran is allowed to be NULL. In this case no rollback is possible */
/*
* @tran is allowed to be NULL. In this case no rollback is possible.
*
* After calling this function, the transaction @tran may only be completed
* while holding a reader lock for the graph.
*/
static int GRAPH_RDLOCK
bdrv_refresh_perms(BlockDriverState *bs, Transaction *tran, Error **errp)
{

6
blockdev.c
View file

@ -1378,6 +1378,9 @@ static void external_snapshot_action(TransactionAction *action,
AioContext *aio_context;
uint64_t perm, shared;
/* TODO We'll eventually have to take a writer lock in this function */
GRAPH_RDLOCK_GUARD_MAINLOOP();
tran_add(tran, &external_snapshot_drv, state);
/* 'blockdev-snapshot' and 'blockdev-snapshot-sync' have similar
@ -2521,6 +2524,9 @@ void qmp_block_commit(const char *job_id, const char *device,
int job_flags = JOB_DEFAULT;
uint64_t top_perm, top_shared;
/* TODO We'll eventually have to take a writer lock in this function */
GRAPH_RDLOCK_GUARD_MAINLOOP();
if (!has_speed) {
speed = 0;
}

9
include/block/block_int-common.h
View file

@ -413,8 +413,8 @@ struct BlockDriver {
* If both conditions are met, 0 is returned. Otherwise, -errno is returned
* and errp is set to an error describing the conflict.
*/
int (*bdrv_check_perm)(BlockDriverState *bs, uint64_t perm,
uint64_t shared, Error **errp);
int GRAPH_RDLOCK_PTR (*bdrv_check_perm)(BlockDriverState *bs, uint64_t perm,
uint64_t shared, Error **errp);
/**
* Called to inform the driver that the set of cumulative set of used
@ -426,7 +426,8 @@ struct BlockDriver {
* This function is only invoked after bdrv_check_perm(), so block drivers
* may rely on preparations made in their .bdrv_check_perm implementation.
*/
void (*bdrv_set_perm)(BlockDriverState *bs, uint64_t perm, uint64_t shared);
void GRAPH_RDLOCK_PTR (*bdrv_set_perm)(
BlockDriverState *bs, uint64_t perm, uint64_t shared);
/*
* Called to inform the driver that after a previous bdrv_check_perm()
@ -436,7 +437,7 @@ struct BlockDriver {
* This function can be called even for nodes that never saw a
* bdrv_check_perm() call. It is a no-op then.
*/
void (*bdrv_abort_perm_update)(BlockDriverState *bs);
void GRAPH_RDLOCK_PTR (*bdrv_abort_perm_update)(BlockDriverState *bs);
/**
* Returns in @nperm and @nshared the permissions that the driver for @bs

4
include/block/block_int-global-state.h
View file

@ -204,8 +204,8 @@ BdrvChild *bdrv_root_attach_child(BlockDriverState *child_bs,
void *opaque, Error **errp);
void bdrv_root_unref_child(BdrvChild *child);
void bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
uint64_t *shared_perm);
void GRAPH_RDLOCK bdrv_get_cumulative_perm(BlockDriverState *bs, uint64_t *perm,
uint64_t *shared_perm);
/**
* Sets a BdrvChild's permissions. Avoid if the parent is a BDS; use