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Btrfs: fix racy system chunk allocation when setting block group ro
If while setting a block group read-only we end up allocating a system
chunk, through check_system_chunk(), we were not doing it while holding
the chunk mutex which is a problem if a concurrent chunk allocation is
happening, through do_chunk_alloc(), as it means both block groups can
end up using the same logical addresses and physical regions in the
device(s). So make sure we hold the chunk mutex.
Cc: stable@vger.kernel.org # 4.0+
Fixes: 2f0810880f
("btrfs: delete chunk allocation attemp when
setting block group ro")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
parent
2c2ed5aa01
commit
a96295965b
2 changed files with 3 additions and 0 deletions
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@ -8842,7 +8842,9 @@ int btrfs_set_block_group_ro(struct btrfs_root *root,
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out:
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if (cache->flags & BTRFS_BLOCK_GROUP_SYSTEM) {
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alloc_flags = update_block_group_flags(root, cache->flags);
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lock_chunks(root->fs_info->chunk_root);
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check_system_chunk(trans, root, alloc_flags);
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unlock_chunks(root->fs_info->chunk_root);
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}
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mutex_unlock(&root->fs_info->ro_block_group_mutex);
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@ -4625,6 +4625,7 @@ int btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
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{
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u64 chunk_offset;
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ASSERT(mutex_is_locked(&extent_root->fs_info->chunk_mutex));
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chunk_offset = find_next_chunk(extent_root->fs_info);
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return __btrfs_alloc_chunk(trans, extent_root, chunk_offset, type);
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}
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