X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=doc%2Ffilesys.texi;h=9075c9a5a3c2f113319b980fb205bba596d00b2a;hb=a96d2712f349629d7fe2186e2620f1704cbdee50;hp=a93481cca37da657cf8ec50890691e12f2d39dfe;hpb=73389b59f54bfed8eb0cb370a5ffec1223686a9e;p=pintos-anon

diff --git a/doc/filesys.texi b/doc/filesys.texi
index a93481c..9075c9a 100644
--- a/doc/filesys.texi
+++ b/doc/filesys.texi
@@ -25,6 +25,7 @@ to 5% extra credit if you do enable VM.
 
 @menu
 * File System New Code::        
+* Testing File System Persistence::  
 @end menu
 
 @node File System New Code
@@ -78,6 +79,35 @@ which you will remove.
 While most of your work will be in @file{filesys}, you should be
 prepared for interactions with all previous parts.
 
+@node Testing File System Persistence
+@subsection Testing File System Persistence
+
+By now, you should be familiar with the basic process of running the
+Pintos tests.  @xref{Testing}, for review, if necessary.
+
+Until now, each test invoked Pintos just once.  However, an important
+purpose of a file system is to ensure that data remains accessible from
+one boot to another.  Thus, the tests that are part of the file system
+project invoke Pintos a second time.  The second run combines all the
+files and directories in the file system into a single file, then copies
+that file out of the Pintos file system into the host (Unix) file
+system.
+
+The grading scripts check the file system's correctness based on the
+contents of the file copied out in the second run.  This means that your
+project will not pass any of the extended file system tests until the
+file system is implemented well enough to support @command{tar}, the
+Pintos user program that produces the file that is copied out.  The
+@command{tar} program is fairly demanding (it requires both extensible
+file and subdirectory support), so this will take some work.  Until
+then, you can ignore errors from @command{make check} regarding the
+extracted file system.
+
+Incidentally, as you may have surmised, the file format used for copying
+out the file system contents is the standard Unix ``tar'' format.  You
+can use the Unix @command{tar} program to examine them.  The tar file
+for test @var{t} is named @file{@var{t}.tar}.
+
 @node Project 4 Requirements
 @section Requirements
 
@@ -175,15 +205,19 @@ The directory separator character is forward slash (@samp{/}).
 You must also support special file names @file{.} and @file{..}, which
 have the same meanings as they do in Unix.
 
-Update the @code{remove} system call so that it can delete empty
-directories in addition to regular files.  Directories may only be
-deleted if they do not contain any files or subdirectories (other than
-@file{.} and @file{..}).
-
 Update the @code{open} system call so that it can also open directories.
 Of the existing system calls, only @code{close} needs to accept a file
 descriptor for a directory.
 
+Update the @code{remove} system call so that it can delete empty
+directories (other than the root) in addition to regular files.
+Directories may only be deleted if they do not contain any files or
+subdirectories (other than @file{.} and @file{..}).  You may decide
+whether to allow deletion of a directory that is open by a process or in
+use as a process's current working directory.  If it is allowed, then
+attempts to open files (including @file{.} and @file{..}) or create new
+files in a deleted directory must be disallowed.
+
 Implement the following new system calls:
 
 @deftypefn {System Call} bool chdir (const char *@var{dir})
@@ -225,8 +259,8 @@ false if it represents an ordinary file.
 @end deftypefn
 
 @deftypefn {System Call} int inumber (int @var{fd})
-Returns the @dfn{inode number} of the inode associated with @var{fd}.
-Applicable to file descriptors for both files and directories.
+Returns the @dfn{inode number} of the inode associated with @var{fd},
+which may represent an ordinary file or a directory.
 
 An inode number persistently identifies a file or directory.  It is
 unique during the file's existence.  In Pintos, the sector number of the
@@ -277,11 +311,8 @@ blocks back to disk.  The cache should also be written back to disk in
 @func{filesys_done}, so that halting Pintos flushes the cache.
 
 If you have @func{timer_sleep} from the first project working, write-behind is
-an excellent application.  If you're still using the base
-implementation of @func{timer_sleep}, be aware that it busy-waits, which
-is not acceptable here (or elsewhere).  If @func{timer_sleep}'s delays seem too
-short or too long, reread the explanation of the @option{-r} option to
-@command{pintos} (@pxref{Debugging versus Testing}).
+an excellent application.  Otherwise, you may implement a less general
+facility, but make sure that it does not exhibit busy-waiting.
 
 You should also implement @dfn{read-ahead}, that is,
 automatically fetch the next block of a file