Mo Zou, Haoran Ding, Dong Du, Ming Fu, Ronghui Gu, Haibo Chen
{"title":"使用并发关系逻辑和辅助程序来验证AtomFS文件系统","authors":"Mo Zou, Haoran Ding, Dong Du, Ming Fu, Ronghui Gu, Haibo Chen","doi":"10.1145/3341301.3359644","DOIUrl":null,"url":null,"abstract":"Concurrent file systems are pervasive but hard to correctly implement and formally verify due to nondeterministic interleavings. This paper presents AtomFS, the first formally-verified, fine-grained, concurrent file system, which provides linearizable interfaces to applications. The standard way to prove linearizability requires modeling linearization point of each operation---the moment when its effect becomes visible atomically to other threads. We observe that path inter-dependency, where one operation (like rename) breaks the path integrity of other operations, makes the linearization point external and thus poses a significant challenge to prove linearizability. To overcome the above challenge, this paper presents Concurrent Relational Logic with Helpers (CRL-H), a framework for building verified concurrent file systems. CRL-H is made powerful through two key contributions: (1) extending prior approaches using fixed linearization points with a helper mechanism where one operation of the thread can logically help other threads linearize their operations; (2) combining relational specifications and rely/guarantee conditions for relational and compositional reasoning. We have successfully applied CRL-H to verify the linearizability of AtomFS directly in C code. All the proofs are mechanized in Coq. Evaluations show that AtomFS speeds up file system workloads by utilizing fine-grained, multicore concurrency.","PeriodicalId":331561,"journal":{"name":"Proceedings of the 27th ACM Symposium on Operating Systems Principles","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2019-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"25","resultStr":"{\"title\":\"Using concurrent relational logic with helpers for verifying the AtomFS file system\",\"authors\":\"Mo Zou, Haoran Ding, Dong Du, Ming Fu, Ronghui Gu, Haibo Chen\",\"doi\":\"10.1145/3341301.3359644\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Concurrent file systems are pervasive but hard to correctly implement and formally verify due to nondeterministic interleavings. This paper presents AtomFS, the first formally-verified, fine-grained, concurrent file system, which provides linearizable interfaces to applications. The standard way to prove linearizability requires modeling linearization point of each operation---the moment when its effect becomes visible atomically to other threads. We observe that path inter-dependency, where one operation (like rename) breaks the path integrity of other operations, makes the linearization point external and thus poses a significant challenge to prove linearizability. To overcome the above challenge, this paper presents Concurrent Relational Logic with Helpers (CRL-H), a framework for building verified concurrent file systems. CRL-H is made powerful through two key contributions: (1) extending prior approaches using fixed linearization points with a helper mechanism where one operation of the thread can logically help other threads linearize their operations; (2) combining relational specifications and rely/guarantee conditions for relational and compositional reasoning. We have successfully applied CRL-H to verify the linearizability of AtomFS directly in C code. All the proofs are mechanized in Coq. Evaluations show that AtomFS speeds up file system workloads by utilizing fine-grained, multicore concurrency.\",\"PeriodicalId\":331561,\"journal\":{\"name\":\"Proceedings of the 27th ACM Symposium on Operating Systems Principles\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2019-10-27\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"25\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Proceedings of the 27th ACM Symposium on Operating Systems Principles\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1145/3341301.3359644\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Proceedings of the 27th ACM Symposium on Operating Systems Principles","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1145/3341301.3359644","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Using concurrent relational logic with helpers for verifying the AtomFS file system
Concurrent file systems are pervasive but hard to correctly implement and formally verify due to nondeterministic interleavings. This paper presents AtomFS, the first formally-verified, fine-grained, concurrent file system, which provides linearizable interfaces to applications. The standard way to prove linearizability requires modeling linearization point of each operation---the moment when its effect becomes visible atomically to other threads. We observe that path inter-dependency, where one operation (like rename) breaks the path integrity of other operations, makes the linearization point external and thus poses a significant challenge to prove linearizability. To overcome the above challenge, this paper presents Concurrent Relational Logic with Helpers (CRL-H), a framework for building verified concurrent file systems. CRL-H is made powerful through two key contributions: (1) extending prior approaches using fixed linearization points with a helper mechanism where one operation of the thread can logically help other threads linearize their operations; (2) combining relational specifications and rely/guarantee conditions for relational and compositional reasoning. We have successfully applied CRL-H to verify the linearizability of AtomFS directly in C code. All the proofs are mechanized in Coq. Evaluations show that AtomFS speeds up file system workloads by utilizing fine-grained, multicore concurrency.