Finish mkfs. Update readme.

README

@@ -1,50 +1,16 @@
-xv6 is a re-implementation of Dennis Ritchie's and Ken Thompson's Unix
-Version 6 (v6).  xv6 loosely follows the structure and style of v6,
-but is implemented for a modern x86-based multiprocessor using ANSI C.
 
-ACKNOWLEDGMENTS
+An implementation of a log-structured filesystem into xv6.
+Jon Morton, 2011.
 
-xv6 is inspired by John Lions's Commentary on UNIX 6th Edition (Peer
-to Peer Communications; ISBN: 1-57398-013-7; 1st edition (June 14,
-2000)). See also http://pdos.csail.mit.edu/6.828/2007/v6.html, which
-provides pointers to on-line resources for v6.
+current limitations:
+        - only one inode per block. this greatly simplifies the imap.
+        - the imap can only be one block long (1024 inodes).
 
-xv6 borrows code from the following sources:
-    JOS (asm.h, elf.h, mmu.h, bootasm.S, ide.c, console.c, and others)
-    Plan 9 (bootother.S, mp.h, mp.c, lapic.c)
-    FreeBSD (ioapic.c)
-    NetBSD (console.c)
+implementation order, as time allows:
+        [ ] mkfs
+        [ ] read-only lfs
+        [ ] segment writing
+        [ ] segment cleaning
 
-The following people made contributions:
-    Russ Cox (context switching, locking)
-    Cliff Frey (MP)
-    Xiao Yu (MP)
-    Nickolai Zeldovich
-    Austin Clements
+(original xv6 readme is in README.xv6)
 
-In addition, we are grateful for the patches contributed by Greg
-Price, Yandong Mao, and Hitoshi Mitake.
-
-The code in the files that constitute xv6 is
-Copyright 2006-2007 Frans Kaashoek, Robert Morris, and Russ Cox.
-
-ERROR REPORTS
-
-If you spot errors or have suggestions for improvement, please send
-email to Frans Kaashoek and Robert Morris (kaashoek,rtm@csail.mit.edu). 
-
-BUILDING AND RUNNING XV6
-
-To build xv6 on an x86 ELF machine (like Linux or FreeBSD), run "make".
-On non-x86 or non-ELF machines (like OS X, even on x86), you will
-need to install a cross-compiler gcc suite capable of producing x86 ELF
-binaries.  See http://pdos.csail.mit.edu/6.828/2007/tools.html.
-Then run "make TOOLPREFIX=i386-jos-elf-".
-
-To run xv6, you can use Bochs or QEMU, both PC simulators.
-Bochs makes debugging easier, but QEMU is much faster. 
-To run in Bochs, run "make bochs" and then type "c" at the bochs prompt.
-To run in QEMU, run "make qemu".
-
-To create a typeset version of the code, run "make xv6.pdf".  This
-requires the "mpage" utility.  See http://www.mesa.nl/pub/mpage/.

README.xv6

@@ -0,0 +1,50 @@
+xv6 is a re-implementation of Dennis Ritchie's and Ken Thompson's Unix
+Version 6 (v6).  xv6 loosely follows the structure and style of v6,
+but is implemented for a modern x86-based multiprocessor using ANSI C.
+
+ACKNOWLEDGMENTS
+
+xv6 is inspired by John Lions's Commentary on UNIX 6th Edition (Peer
+to Peer Communications; ISBN: 1-57398-013-7; 1st edition (June 14,
+2000)). See also http://pdos.csail.mit.edu/6.828/2007/v6.html, which
+provides pointers to on-line resources for v6.
+
+xv6 borrows code from the following sources:
+    JOS (asm.h, elf.h, mmu.h, bootasm.S, ide.c, console.c, and others)
+    Plan 9 (bootother.S, mp.h, mp.c, lapic.c)
+    FreeBSD (ioapic.c)
+    NetBSD (console.c)
+
+The following people made contributions:
+    Russ Cox (context switching, locking)
+    Cliff Frey (MP)
+    Xiao Yu (MP)
+    Nickolai Zeldovich
+    Austin Clements
+
+In addition, we are grateful for the patches contributed by Greg
+Price, Yandong Mao, and Hitoshi Mitake.
+
+The code in the files that constitute xv6 is
+Copyright 2006-2007 Frans Kaashoek, Robert Morris, and Russ Cox.
+
+ERROR REPORTS
+
+If you spot errors or have suggestions for improvement, please send
+email to Frans Kaashoek and Robert Morris (kaashoek,rtm@csail.mit.edu). 
+
+BUILDING AND RUNNING XV6
+
+To build xv6 on an x86 ELF machine (like Linux or FreeBSD), run "make".
+On non-x86 or non-ELF machines (like OS X, even on x86), you will
+need to install a cross-compiler gcc suite capable of producing x86 ELF
+binaries.  See http://pdos.csail.mit.edu/6.828/2007/tools.html.
+Then run "make TOOLPREFIX=i386-jos-elf-".
+
+To run xv6, you can use Bochs or QEMU, both PC simulators.
+Bochs makes debugging easier, but QEMU is much faster. 
+To run in Bochs, run "make bochs" and then type "c" at the bochs prompt.
+To run in QEMU, run "make qemu".
+
+To create a typeset version of the code, run "make xv6.pdf".  This
+requires the "mpage" utility.  See http://www.mesa.nl/pub/mpage/.

fs.h

@@ -5,13 +5,14 @@
 #define SEGSIZE 1024*1024 // 1mb
 
 typedef uint block_t;
+typedef uint inode_t;
 
 struct disk_superblock {
 	uint nsegs; // number of segments
 	uint segment; // checkpoint
-	block_t imap; // start block of imap
+	block_t imap; // imap block
 	uint ninodes;
-	uint blocks;
+	uint nblocks;
 };
 
 #define DISK_INODE_DATA 12 // size of disk_inode excluding addrs
@@ -48,4 +49,13 @@ struct disk_inode {
 
 #define IPB (BSIZE/sizeof(disk_inode));
 
+// Directory is a file containing a sequence of dirent structures.
+#define DIRSIZ 14
+
+struct dirent {
+  ushort inum;
+  char name[DIRSIZ];
+};
+
+
 #endif