Btrfs: fix data bytes_may_use underflow with fallocate due to failed quota reserve
When doing fallocate, we first add the range to the reserve_list and then reserve the quota. If quota reservation fails, we'll release all reserved parts of reserve_list. However, cur_offset is not updated to indicate that this range is already been inserted into the list. Therefore, the same range is freed twice. Once at list_for_each_entry loop, and once at the end of the function. This will result in WARN_ON on bytes_may_use when we free the remaining space. At the end, under the 'out' label we have a call to: btrfs_free_reserved_data_space(inode, data_reserved, alloc_start, alloc_end - cur_offset); The start offset, third argument, should be cur_offset. Everything from alloc_start to cur_offset was freed by the list_for_each_entry_safe_loop. Fixes: 18513091 ("btrfs: update btrfs_space_info's bytes_may_use timely") Reviewed-by: NFilipe Manana <fdmanana@suse.com> Signed-off-by: NRobbie Ko <robbieko@synology.com> Signed-off-by: NDavid Sterba <dsterba@suse.com>
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