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block: Mark bdrv_set_backing_hd_drained() GRAPH_WRLOCK

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Instead of taking the writer lock internally, require callers to already
hold it when calling bdrv_set_backing_hd_drained(). Basically everthing
in the function needs the lock and its callers may already want to hold
the graph lock and so wouldn't be able to call functions that take it
internally.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231027155333.420094-14-kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2023-10-27 17:53:22 +02:00
parent 78a9c76eef
commit d0f9fd94d9
3 changed files with 8 additions and 5 deletions
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4
block.c
View file

@ -3557,7 +3557,6 @@ int bdrv_set_backing_hd_drained(BlockDriverState *bs,
if (bs->backing) {
assert(bs->backing->bs->quiesce_counter > 0);
}
bdrv_graph_wrlock(backing_hd);
ret = bdrv_set_backing_noperm(bs, backing_hd, tran, errp);
if (ret < 0) {
@ -3567,7 +3566,6 @@ int bdrv_set_backing_hd_drained(BlockDriverState *bs,
ret = bdrv_refresh_perms(bs, tran, errp);
out:
tran_finalize(tran, ret);
bdrv_graph_wrunlock();
return ret;
}
@ -3580,7 +3578,9 @@ int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
bdrv_ref(drain_bs);
bdrv_drained_begin(drain_bs);
bdrv_graph_wrlock(backing_hd);
ret = bdrv_set_backing_hd_drained(bs, backing_hd, errp);
bdrv_graph_wrunlock();
bdrv_drained_end(drain_bs);
bdrv_unref(drain_bs);

2
block/stream.c
View file

@ -99,7 +99,9 @@ static int stream_prepare(Job *job)
}
}
bdrv_graph_wrlock(base);
bdrv_set_backing_hd_drained(unfiltered_bs, base, &local_err);
bdrv_graph_wrunlock();
/*
* This call will do I/O, so the graph can change again from here on.

7
include/block/block-global-state.h
View file

@ -101,9 +101,10 @@ bdrv_co_open_blockdev_ref(BlockdevRef *ref, Error **errp);
int bdrv_set_backing_hd(BlockDriverState *bs, BlockDriverState *backing_hd,
Error **errp);
int bdrv_set_backing_hd_drained(BlockDriverState *bs,
BlockDriverState *backing_hd,
Error **errp);
int GRAPH_WRLOCK
bdrv_set_backing_hd_drained(BlockDriverState *bs, BlockDriverState *backing_hd,
Error **errp);
int bdrv_open_backing_file(BlockDriverState *bs, QDict *parent_options,
const char *bdref_key, Error **errp);