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Update write up to reflect new test cases.

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This commit is contained in:
Frans Kaashoek 2019-08-17 12:33:32 -04:00
parent 5498ee2e92
commit e61377bf8a
1 changed files with 21 additions and 5 deletions
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labs/fs1.html
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@ -8,9 +8,9 @@
<h1>Lab: mount/umount</h1> <h1>Lab: mount/umount</h1>
<p>In this lab you will add support for mounting/unmounting of file <p>In this lab you will add support for mounting/unmounting of file
systems to xv6. This lab will expose you to many parts of the xv6 file systems to xv6. This lab will expose you to many parts of the xv6
system, including pathname lookup, inodes, logging, disk driver, file system, including pathname lookup, inodes, logging/recovery, disk
concurrency, etc. driver, concurrency, etc.
<p>Your job is modify xv6 so that your modified kernel passes the <p>Your job is modify xv6 so that your modified kernel passes the
tests in mounttest. You will have to implement two system tests in mounttest. You will have to implement two system
@ -181,10 +181,26 @@ add <tt>$(QEMUEXTRA)</tt> to the end of <tt>QEMUOPTS</tt>.
<h2>umount</h2> <h2>umount</h2>
<p>Once your kernel passes usertests and test0 of mounttest, implement <p>Once your kernel passes usertests and test0 of mounttest, implement
umount. Make sure your kernel can pass test1 of mounttest. umount. The main challenge is mount should fail if the file system
is still in use; that is, if there is an inode on the mounted device
that has a <tt>ref > 0</tt>. Furthermore, this test and unmounting
should be a atomic operation. (Hint: lock the inode cache.) Make
sure your kernel can pass test1 of mounttest.
<p>Test2 of mounttest stresses <namex> more; if you have done <p>Test2 of mounttest stresses <namex> more; if you have done
everything right above, your kernel may be able to pass it. everything right above, your kernel may be able to pass it. Test3
tests concurrent mount/unmounts with file creation.
<h2>crash safety</h2>
<p>One of the main goals of the file system is to provide crash
safety: if there is a power failure during a file system operation,
xv6 should recover correctly. It is difficult to introduce power
failure at the critical steps of logging; instead, we added a system
call that causes a kernel panic after committing an operation but
before installing the operation. Test4 with crashtest tests if your
xv6 recovers the mounted disk correctly.
</body> </body>
</html> </html>