The Texas Transactional File System (TxFS)

TxFS is a novel transactional file system that builds upon the file system’s atomic-update mechanism such as journaling. Though prior work has explored a number of transactional file systems, TxFS has a unique set of properties: a simple API, portability across different hardware, high performance, low complexity (by building on the journal), and full ACID transactions.

Please cite the following paper if you use TxFS: TxFS: Leveraging File-System Crash Consistency to Provide ACID Transactions. Yige Hu, Zhiting Zhu, Ian Neal, Youngjin Kwon, Tianyu Cheng, Vijay Chidambaram, and Emmett Witchel ATC 18. Bibtex

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In this repository

This repository includes two main components:

1. linux-3.18.22-mod. This contains the modified Linux kernel for TxFS.
   • fs/user_tx.c defines the system calls provided by TxFS;
   • fs/memlog contains TxFS's internal bookkeeping code;
   • fs/*_memlog.c contains TxFS's changes to the VFS layer;
   • fs/ext4/*_memlog.c contains TxFS's major changes to ext4;
   • fs/jbd2/transaction.c contains TxFS's changes to JBD2.
   • mm/filemap.c contains TxFS's changes to memory page accesses.
2. benchmark. Contains benchmarks used to evaluate TxFS (we have only released microbenchmarks).
   • syscall_wrapper contains a system call wrapper providing API calls fs_tx_begin/end/abort, and an example showing how to use the wrapper;
   • syscall contains a set of tests on the system calls supported by TxFS transactions;
   • multithread contains multi-threaded tests;
   • stress_test randomly executes file system operations with multiple threads.

Inside linux-3.18.22-mod, compiling the kernel follows the standard method of configure and make. To see examples of TxFS in action, check out the examples inside benchmark.

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Example

We present an example where two files file1 and file2 are modified atomically. For the sake of brevity, we do not show error cases.

ret = fs_tx_begin();
fd1 = open("file1.txt", O_RDWR | O_APPEND, 0644);
fd2 = open("file2.txt", O_RDWR | O_APPEND, 0644);
write(fd1, "foo\n", 4);
write(fd2, "bar\n", 4);
ret = ret = fs_tx_commit();

The user does not have to add any other code apart from fs_tx_begin() and fs_tx_commit(). Once fs_tx_commit returns successfully, reads of both files will include both foo and bar.

syscall_wrapper in the benchmmark directory has the more complete version of this example. You can find it here.

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Contact

Please contact us at yige@cs.utexas.edu with any questions. Drop us a note if you would like to use TxFS in your research.