commit d29f5ece8b534180076e2859dcc014b3c36b00cf
from: Russ Cox <rsc@swtch.com>
date: Sun Jun 01 12:47:06 2008 UTC

libdiskfs: ext2 revision 1 tweaks (Fazlul Shahriar)

commit - df1ee4e1af9340a8207535c5009ec289bf1ecda1
commit + d29f5ece8b534180076e2859dcc014b3c36b00cf
blob - afd952222c6cba995ea02827ae16aa7015b70be7
blob + b55f1eb3dadc4d18291f14212b1d1b77af23ffac
--- src/libdiskfs/ext2.c
+++ src/libdiskfs/ext2.c
@@ -275,7 +275,11 @@ ext2sync(Fsys *fsys)
 		/ super.blockspergroup;
 	fs->inospergroup = super.inospergroup;
 	fs->blockspergroup = super.blockspergroup;
-	fs->inosperblock = fs->blocksize / InodeSize;
+	if(super.revlevel >= 1)
+		fs->inosize = super.inosize;
+	else
+		fs->inosize = 128;
+	fs->inosperblock = fs->blocksize / fs->inosize;
 	if(fs->blocksize == SBOFF)
 		fs->groupaddr = 2;
 	else
@@ -336,7 +340,7 @@ handle2ino(Ext2 *fs, Nfs3Handle *h, u32int *pinum, Ino
 	addr = g.inodeaddr + ioff/fs->inosperblock;
 	if((b = diskread(fs->disk, fs->blocksize, (u64int)addr*fs->blocksize)) == nil)
 		return Nfs3ErrIo;
-	parseinode(ino, b->data+InodeSize*(ioff%fs->inosperblock));
+	parseinode(ino, b->data+fs->inosize*(ioff%fs->inosperblock));
 	blockput(b);
 	return Nfs3Ok;
 }
@@ -875,5 +879,8 @@ parsesuper(Super *s, uchar *p)
 	s->revlevel = l32(p+76);
 	s->defresuid = l16(p+80);
 	s->defresgid = l16(p+82);
-	/* 940 byte reserved */
+	s->firstino = l32(p+84);
+	s->inosize = l32(p+88);
+	s->blockgroupnr = l16(p+60);
+	/* 932 byte reserved */
 }
blob - 6109974d2b53a7571dd69fd8d19f561d44bcdaf9
blob + 7ddd400a94457930b7e37d45a6a32d297edb3bb6
--- src/libdiskfs/ext2.h
+++ src/libdiskfs/ext2.h
@@ -80,7 +80,12 @@ struct Super
 	u32int	revlevel;		/* Revision level */
 	u16int	defresuid;		/* Default uid for reserved blocks */
 	u16int	defresgid;		/* Default gid for reserved blocks */
-	u32int	reserved[235];	/* Padding to the end of the block */
+	
+	/* the following are only available with revlevel = 1 */
+	u32int	firstino;		/* First non-reserved inode */
+	u16int	inosize;		/* size of inode structure */
+	u16int	blockgroupnr;	/* block group # of this super block */
+	u32int	reserved[233];	/* Padding to the end of the block */
 };
 
 /*
@@ -122,10 +127,6 @@ struct Inode
 	u32int	diracl;	/* Directory ACL or high size bits */
 	u32int	faddr;		/* Fragment address */
 };
-enum
-{
-	InodeSize = 128
-};
 
 /*
  * Directory entry
@@ -153,6 +154,7 @@ struct Ext2
 	uint	inospergroup;
 	uint	blockspergroup;
 	uint	inosperblock;
+	uint	inosize;
 	uint	groupaddr;
 	uint	descperblock;
 	uint	firstblock;