btrfs: do not init a reloc root if we aren't relocating
[ Upstream commit 2abc726ab4
]
We previously were checking if the root had a dead root before accessing
root->reloc_root in order to avoid a use-after-free type bug. However
this scenario happens after we've unset the reloc control, so we would
have been saved if we'd simply checked for fs_info->reloc_control. At
this point during relocation we no longer need to be creating new reloc
roots, so simply move this check above the reloc_root checks to avoid
any future races and confusion.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
parent
98c921e6be
commit
c88596d593
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@ -1468,6 +1468,10 @@ int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
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int clear_rsv = 0;
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int ret;
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if (!rc || !rc->create_reloc_tree ||
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root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
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return 0;
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/*
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* The subvolume has reloc tree but the swap is finished, no need to
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* create/update the dead reloc tree
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@ -1481,10 +1485,6 @@ int btrfs_init_reloc_root(struct btrfs_trans_handle *trans,
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return 0;
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}
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if (!rc || !rc->create_reloc_tree ||
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root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID)
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return 0;
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if (!trans->reloc_reserved) {
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rsv = trans->block_rsv;
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trans->block_rsv = rc->block_rsv;
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@ -2336,6 +2336,18 @@ static noinline_for_stack int merge_reloc_root(struct reloc_control *rc,
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trans = NULL;
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goto out;
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}
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/*
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* At this point we no longer have a reloc_control, so we can't
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* depend on btrfs_init_reloc_root to update our last_trans.
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*
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* But that's ok, we started the trans handle on our
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* corresponding fs_root, which means it's been added to the
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* dirty list. At commit time we'll still call
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* btrfs_update_reloc_root() and update our root item
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* appropriately.
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*/
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reloc_root->last_trans = trans->transid;
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trans->block_rsv = rc->block_rsv;
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replaced = 0;
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