From 79bb76272763c090f2b1dae9519c516257241cac Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Fri, 27 Oct 2023 17:53:19 +0200 Subject: [PATCH] block: Mark bdrv_chain_contains() and callers GRAPH_RDLOCK This adds GRAPH_RDLOCK annotations to declare that callers of bdrv_chain_contains() need to hold a reader lock for the graph because it calls bdrv_filter_or_cow_bs(), which accesses bs->file/backing. Signed-off-by: Kevin Wolf Message-ID: <20231027155333.420094-11-kwolf@redhat.com> Reviewed-by: Eric Blake Signed-off-by: Kevin Wolf --- block.c | 1 - block/block-copy.c | 2 ++ blockdev.c | 48 +++++++++++++++++------------- include/block/block-global-state.h | 4 ++- 4 files changed, 32 insertions(+), 23 deletions(-) diff --git a/block.c b/block.c index dc1980ee42..bb322df7d8 100644 --- a/block.c +++ b/block.c @@ -6524,7 +6524,6 @@ bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base) { GLOBAL_STATE_CODE(); - GRAPH_RDLOCK_GUARD_MAINLOOP(); while (top && top != base) { top = bdrv_filter_or_cow_bs(top); diff --git a/block/block-copy.c b/block/block-copy.c index 6b2be3d204..9ee3dd7ef5 100644 --- a/block/block-copy.c +++ b/block/block-copy.c @@ -399,7 +399,9 @@ BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target, * For more information see commit f8d59dfb40bb and test * tests/qemu-iotests/222 */ + bdrv_graph_rdlock_main_loop(); is_fleecing = bdrv_chain_contains(target->bs, source->bs); + bdrv_graph_rdunlock_main_loop(); s = g_new(BlockCopyState, 1); *s = (BlockCopyState) { diff --git a/blockdev.c b/blockdev.c index 5f15ea3b1d..f04faf6373 100644 --- a/blockdev.c +++ b/blockdev.c @@ -2450,11 +2450,12 @@ void qmp_block_stream(const char *job_id, const char *device, aio_context = bdrv_get_aio_context(bs); aio_context_acquire(aio_context); + bdrv_graph_rdlock_main_loop(); if (base) { base_bs = bdrv_find_backing_image(bs, base); if (base_bs == NULL) { error_setg(errp, "Can't find '%s' in the backing chain", base); - goto out; + goto out_rdlock; } assert(bdrv_get_aio_context(base_bs) == aio_context); } @@ -2462,38 +2463,36 @@ void qmp_block_stream(const char *job_id, const char *device, if (base_node) { base_bs = bdrv_lookup_bs(NULL, base_node, errp); if (!base_bs) { - goto out; + goto out_rdlock; } if (bs == base_bs || !bdrv_chain_contains(bs, base_bs)) { error_setg(errp, "Node '%s' is not a backing image of '%s'", base_node, device); - goto out; + goto out_rdlock; } assert(bdrv_get_aio_context(base_bs) == aio_context); - bdrv_graph_rdlock_main_loop(); bdrv_refresh_filename(base_bs); - bdrv_graph_rdunlock_main_loop(); } if (bottom) { bottom_bs = bdrv_lookup_bs(NULL, bottom, errp); if (!bottom_bs) { - goto out; + goto out_rdlock; } if (!bottom_bs->drv) { error_setg(errp, "Node '%s' is not open", bottom); - goto out; + goto out_rdlock; } if (bottom_bs->drv->is_filter) { error_setg(errp, "Node '%s' is a filter, use a non-filter node " "as 'bottom'", bottom); - goto out; + goto out_rdlock; } if (!bdrv_chain_contains(bs, bottom_bs)) { error_setg(errp, "Node '%s' is not in a chain starting from '%s'", bottom, device); - goto out; + goto out_rdlock; } assert(bdrv_get_aio_context(bottom_bs) == aio_context); } @@ -2501,14 +2500,12 @@ void qmp_block_stream(const char *job_id, const char *device, /* * Check for op blockers in the whole chain between bs and base (or bottom) */ - bdrv_graph_rdlock_main_loop(); iter_end = bottom ? bdrv_filter_or_cow_bs(bottom_bs) : base_bs; for (iter = bs; iter && iter != iter_end; iter = bdrv_filter_or_cow_bs(iter)) { if (bdrv_op_is_blocked(iter, BLOCK_OP_TYPE_STREAM, errp)) { - bdrv_graph_rdunlock_main_loop(); - goto out; + goto out_rdlock; } } bdrv_graph_rdunlock_main_loop(); @@ -2540,6 +2537,11 @@ void qmp_block_stream(const char *job_id, const char *device, out: aio_context_release(aio_context); + return; + +out_rdlock: + bdrv_graph_rdunlock_main_loop(); + aio_context_release(aio_context); } void qmp_block_commit(const char *job_id, const char *device, @@ -3439,39 +3441,38 @@ void qmp_change_backing_file(const char *device, aio_context = bdrv_get_aio_context(bs); aio_context_acquire(aio_context); + bdrv_graph_rdlock_main_loop(); + image_bs = bdrv_lookup_bs(NULL, image_node_name, &local_err); if (local_err) { error_propagate(errp, local_err); - goto out; + goto out_rdlock; } if (!image_bs) { error_setg(errp, "image file not found"); - goto out; + goto out_rdlock; } - bdrv_graph_rdlock_main_loop(); if (bdrv_find_base(image_bs) == image_bs) { error_setg(errp, "not allowing backing file change on an image " "without a backing file"); - bdrv_graph_rdunlock_main_loop(); - goto out; + goto out_rdlock; } /* even though we are not necessarily operating on bs, we need it to * determine if block ops are currently prohibited on the chain */ if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_CHANGE, errp)) { - bdrv_graph_rdunlock_main_loop(); - goto out; + goto out_rdlock; } - bdrv_graph_rdunlock_main_loop(); /* final sanity check */ if (!bdrv_chain_contains(bs, image_bs)) { error_setg(errp, "'%s' and image file are not in the same chain", device); - goto out; + goto out_rdlock; } + bdrv_graph_rdunlock_main_loop(); /* if not r/w, reopen to make r/w */ ro = bdrv_is_read_only(image_bs); @@ -3499,6 +3500,11 @@ void qmp_change_backing_file(const char *device, out: aio_context_release(aio_context); + return; + +out_rdlock: + bdrv_graph_rdunlock_main_loop(); + aio_context_release(aio_context); } void qmp_blockdev_add(BlockdevOptions *options, Error **errp) diff --git a/include/block/block-global-state.h b/include/block/block-global-state.h index 545708c35a..9a33bd7ef9 100644 --- a/include/block/block-global-state.h +++ b/include/block/block-global-state.h @@ -199,7 +199,9 @@ XDbgBlockGraph * GRAPH_RDLOCK bdrv_get_xdbg_block_graph(Error **errp); BlockDriverState *bdrv_lookup_bs(const char *device, const char *node_name, Error **errp); -bool bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base); +bool GRAPH_RDLOCK +bdrv_chain_contains(BlockDriverState *top, BlockDriverState *base); + BlockDriverState *bdrv_next_node(BlockDriverState *bs); BlockDriverState *bdrv_next_all_states(BlockDriverState *bs); -- 2.39.2