[rfc, patch 2/3] larger block group descriptors

Alexandre Ratchov <[email protected]>
Newsgroups gmane.comp.file-systems.ext2.devel
Message-ID <[email protected]> 
make e2fsprogs-1.39 use variable length block group descriptors. mke2fs,
debugfs, dumpe2fs and fsck should work.

Index: e2fsprogs-1.39/lib/ext2fs/swapfs.c
===================================================================
--- e2fsprogs-1.39.orig/lib/ext2fs/swapfs.c	2006-06-07 13:49:36.000000000 +0200
+++ e2fsprogs-1.39/lib/ext2fs/swapfs.c	2006-06-07 13:50:04.000000000 +0200
@@ -60,6 +60,7 @@ void ext2fs_swap_super(struct ext2_super
 	sb->s_journal_inum = ext2fs_swab32(sb->s_journal_inum);
 	sb->s_journal_dev = ext2fs_swab32(sb->s_journal_dev);
 	sb->s_last_orphan = ext2fs_swab32(sb->s_last_orphan);
+	sb->s_desc_size = ext2fs_swab16(sb->s_desc_size);
 	sb->s_default_mount_opts = ext2fs_swab32(sb->s_default_mount_opts);
 	sb->s_first_meta_bg = ext2fs_swab32(sb->s_first_meta_bg);
 	sb->s_mkfs_time = ext2fs_swab32(sb->s_mkfs_time);
Index: e2fsprogs-1.39/lib/ext2fs/ext2fs.h
===================================================================
--- e2fsprogs-1.39.orig/lib/ext2fs/ext2fs.h	2006-06-07 13:49:36.000000000 +0200
+++ e2fsprogs-1.39/lib/ext2fs/ext2fs.h	2006-06-07 13:50:04.000000000 +0200
@@ -210,6 +210,7 @@ struct struct_ext2_filsys {
 	char *				device_name;
 	struct ext2_super_block	* 	super;
 	unsigned int			blocksize;
+	unsigned int			desc_size;
 	int				fragsize;
 	dgrp_t				group_desc_count;
 	unsigned long			desc_blocks;
@@ -453,12 +454,14 @@ typedef struct ext2_icount *ext2_icount_
 					 EXT2_FEATURE_INCOMPAT_COMPRESSION|\
 					 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV|\
 					 EXT2_FEATURE_INCOMPAT_META_BG|\
-					 EXT3_FEATURE_INCOMPAT_RECOVER)
+					 EXT3_FEATURE_INCOMPAT_RECOVER|\
+					 EXT3_FEATURE_INCOMPAT_DESC_SIZE)
 #else
 #define EXT2_LIB_FEATURE_INCOMPAT_SUPP	(EXT2_FEATURE_INCOMPAT_FILETYPE|\
 					 EXT3_FEATURE_INCOMPAT_JOURNAL_DEV|\
 					 EXT2_FEATURE_INCOMPAT_META_BG|\
-					 EXT3_FEATURE_INCOMPAT_RECOVER)
+					 EXT3_FEATURE_INCOMPAT_RECOVER|\
+					 EXT3_FEATURE_INCOMPAT_DESC_SIZE)
 #endif
 #define EXT2_LIB_FEATURE_RO_COMPAT_SUPP	(EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER|\
 					 EXT2_FEATURE_RO_COMPAT_LARGE_FILE)
Index: e2fsprogs-1.39/lib/ext2fs/openfs.c
===================================================================
--- e2fsprogs-1.39.orig/lib/ext2fs/openfs.c	2006-06-07 13:49:36.000000000 +0200
+++ e2fsprogs-1.39/lib/ext2fs/openfs.c	2006-06-07 13:50:04.000000000 +0200
@@ -39,7 +39,7 @@ blk_t ext2fs_descriptor_block_loc(ext2_f
 	    (i < fs->super->s_first_meta_bg))
 		return (group_block + i + 1);
 
-	bg = (fs->blocksize / sizeof (struct ext2_group_desc)) * i;
+	bg = (fs->blocksize / fs->desc_size) * i;
 	if (ext2fs_bg_has_super(fs, bg))
 		has_super = 1;
 	ret_blk = (fs->super->s_first_data_block + has_super + 
@@ -90,6 +90,7 @@ errcode_t ext2fs_open2(const char *name,
 	blk_t		group_block, blk;
 	char		*dest, *cp;
 	struct ext2_group_desc *gdp;
+	char		shadow_block[EXT2_MAX_BLOCK_SIZE];
 	
 	EXT2_CHECK_MAGIC(manager, EXT2_ET_MAGIC_IO_MANAGER);
 
@@ -232,6 +233,13 @@ errcode_t ext2fs_open2(const char *name,
 			goto cleanup;
 		}
 	}
+	
+	if (fs->super->s_feature_incompat & 
+	    EXT3_FEATURE_INCOMPAT_DESC_SIZE) {
+		fs->desc_size = EXT2_DESC_SIZE(fs->super);
+	} else {
+		fs->desc_size = EXT2_MIN_DESC_SIZE;
+	}
 	/*
 	 * Set the blocksize to the filesystem's blocksize.
 	 */
@@ -270,21 +278,22 @@ errcode_t ext2fs_open2(const char *name,
 		goto cleanup;
 	if (!group_block)
 		group_block = fs->super->s_first_data_block;
-	dest = (char *) fs->group_desc;
-	groups_per_block = fs->blocksize / sizeof(struct ext2_group_desc);
+	gdp = fs->group_desc;
+	groups_per_block = fs->blocksize / fs->desc_size;
 	for (i=0 ; i < fs->desc_blocks; i++) {
 		blk = ext2fs_descriptor_block_loc(fs, group_block, i);
-		retval = io_channel_read_blk(fs->io, blk, 1, dest);
+		retval = io_channel_read_blk(fs->io, blk, 1, shadow_block);
 		if (retval)
 			goto cleanup;
+		
+		for (j=0; j < groups_per_block; j++) {
+			*gdp = *(struct ext2_group_desc *)(shadow_block + j * fs->desc_size);
 #ifdef EXT2FS_ENABLE_SWAPFS
-		if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
-			gdp = (struct ext2_group_desc *) dest;
-			for (j=0; j < groups_per_block; j++)
-				ext2fs_swap_group_desc(gdp++);
-		}
+			if (fs->flags & EXT2_FLAG_SWAP_BYTES)
+					ext2fs_swap_group_desc(gdp);
 #endif
-		dest += fs->blocksize;
+			gdp++;
+		}
 	}
 
 	*ret_fs = fs;
Index: e2fsprogs-1.39/lib/ext2fs/closefs.c
===================================================================
--- e2fsprogs-1.39.orig/lib/ext2fs/closefs.c	2006-06-07 13:49:36.000000000 +0200
+++ e2fsprogs-1.39/lib/ext2fs/closefs.c	2006-06-07 13:50:04.000000000 +0200
@@ -81,7 +81,7 @@ int ext2fs_super_and_bgd_loc(ext2_filsys
 		super_blk = group_block;
 		numblocks--;
 	}
-	meta_bg_size = (fs->blocksize / sizeof (struct ext2_group_desc));
+	meta_bg_size = (fs->blocksize / fs->desc_size);
 	meta_bg = group / meta_bg_size;
 
 	if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
@@ -221,33 +221,34 @@ errcode_t ext2fs_flush(ext2_filsys fs)
 
 	fs->super->s_wtime = fs->now ? fs->now : time(NULL);
 	fs->super->s_block_group_nr = 0;
+
+	retval = ext2fs_get_mem((size_t)(fs->blocksize * fs->desc_blocks),
+				&group_shadow);
+	if (retval)
+		goto errout;
+	memset(group_shadow, 0, (size_t) fs->blocksize * fs->desc_blocks);
+
+	/* swap the group descriptors */
+	for (j=0, s=fs->group_desc, t=group_shadow;
+	     j < fs->group_desc_count; j++, s++) {
+		*t = *s;
+#ifdef EXT2FS_ENABLE_SWAPFS
+		if (fs->flags & EXT2_FLAG_SWAP_BYTES)
+			ext2fs_swap_group_desc(t);
+#endif
+		t = (struct ext2_group_desc *)((__u8 *)t + fs->desc_size);
+	}
+
 #ifdef EXT2FS_ENABLE_SWAPFS
 	if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
-		retval = EXT2_ET_NO_MEMORY;
 		retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &super_shadow);
 		if (retval)
 			goto errout;
-		retval = ext2fs_get_mem((size_t)(fs->blocksize *
-						 fs->desc_blocks),
-					&group_shadow);
-		if (retval)
-			goto errout;
-		memset(group_shadow, 0, (size_t) fs->blocksize *
-		       fs->desc_blocks);
-
-		/* swap the group descriptors */
-		for (j=0, s=fs->group_desc, t=group_shadow;
-		     j < fs->group_desc_count; j++, t++, s++) {
-			*t = *s;
-			ext2fs_swap_group_desc(t);
-		}
 	} else {
 		super_shadow = fs->super;
-		group_shadow = fs->group_desc;
 	}
 #else
 	super_shadow = fs->super;
-	group_shadow = fs->group_desc;
 #endif
 	
 	/*
Index: e2fsprogs-1.39/lib/ext2fs/ext2_fs.h
===================================================================
--- e2fsprogs-1.39.orig/lib/ext2fs/ext2_fs.h	2006-06-07 13:49:36.000000000 +0200
+++ e2fsprogs-1.39/lib/ext2fs/ext2_fs.h	2006-06-07 13:50:04.000000000 +0200
@@ -190,6 +190,9 @@ struct ext2_dx_countlimit {
 /*
  * Macro-instructions used to manage group descriptors
  */
+#define EXT2_MIN_DESC_SIZE		32
+#define EXT2_MAX_DESC_SIZE		EXT2_MIN_BLOCK_SIZE
+#define EXT2_DESC_SIZE(s)		(EXT2_SB(s)->s_desc_size)
 #define EXT2_BLOCKS_PER_GROUP(s)	(EXT2_SB(s)->s_blocks_per_group)
 #define EXT2_INODES_PER_GROUP(s)	(EXT2_SB(s)->s_inodes_per_group)
 #define EXT2_INODES_PER_BLOCK(s)	(EXT2_BLOCK_SIZE(s)/EXT2_INODE_SIZE(s))
@@ -200,7 +203,7 @@ struct ext2_dx_countlimit {
 #define EXT2_DESC_PER_BLOCK(s)		(EXT2_SB(s)->s_desc_per_block)
 #define EXT2_DESC_PER_BLOCK_BITS(s)	(EXT2_SB(s)->s_desc_per_block_bits)
 #else
-#define EXT2_DESC_PER_BLOCK(s)		(EXT2_BLOCK_SIZE(s) / sizeof (struct ext2_group_desc))
+#define EXT2_DESC_PER_BLOCK(s)		(EXT2_BLOCK_SIZE(s) / EXT2_DESC_SIZE(s))
 #endif
 
 /*
@@ -521,7 +524,7 @@ struct ext2_super_block {
 	__u32	s_hash_seed[4];		/* HTREE hash seed */
 	__u8	s_def_hash_version;	/* Default hash version to use */
 	__u8	s_jnl_backup_type; 	/* Default type of journal backup */
-	__u16	s_reserved_word_pad;
+	__u16	s_desc_size;		/* size of group descriptor */
 	__u32	s_default_mount_opts;
 	__u32	s_first_meta_bg;	/* First metablock group */
 	__u32	s_mkfs_time;		/* When the filesystem was created */
@@ -582,9 +585,9 @@ struct ext2_super_block {
 #define EXT3_FEATURE_INCOMPAT_RECOVER		0x0004 /* Needs recovery */
 #define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV	0x0008 /* Journal device */
 #define EXT2_FEATURE_INCOMPAT_META_BG		0x0010
+#define EXT3_FEATURE_INCOMPAT_DESC_SIZE		0x0020
 #define EXT3_FEATURE_INCOMPAT_EXTENTS		0x0040
 
-
 #define EXT2_FEATURE_COMPAT_SUPP	0
 #define EXT2_FEATURE_INCOMPAT_SUPP	(EXT2_FEATURE_INCOMPAT_FILETYPE)
 #define EXT2_FEATURE_RO_COMPAT_SUPP	(EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER| \
Index: e2fsprogs-1.39/lib/ext2fs/initialize.c
===================================================================
--- e2fsprogs-1.39.orig/lib/ext2fs/initialize.c	2006-06-07 13:49:36.000000000 +0200
+++ e2fsprogs-1.39/lib/ext2fs/initialize.c	2006-06-07 13:50:04.000000000 +0200
@@ -67,7 +67,7 @@ static unsigned int calc_reserved_gdt_bl
 {
 	struct ext2_super_block *sb = fs->super;
 	unsigned long bpg = sb->s_blocks_per_group;
-	unsigned int gdpb = fs->blocksize / sizeof(struct ext2_group_desc);
+	unsigned int gdpb = fs->blocksize / fs->desc_size;
 	unsigned long max_blocks = 0xffffffff;
 	unsigned long rsv_groups;
 	unsigned int rsv_gdb;
@@ -149,6 +149,7 @@ errcode_t ext2fs_initialize(const char *
 
 	set_field(s_log_block_size, 0);	/* default blocksize: 1024 bytes */
 	set_field(s_log_frag_size, 0); /* default fragsize: 1024 bytes */
+	set_field(s_desc_size, EXT2_MIN_DESC_SIZE);
 	set_field(s_first_data_block, super->s_log_block_size ? 0 : 1);
 	set_field(s_max_mnt_count, EXT2_DFL_MAX_MNT_COUNT);
 	set_field(s_errors, EXT2_ERRORS_DEFAULT);
@@ -178,6 +179,7 @@ errcode_t ext2fs_initialize(const char *
 
 	fs->blocksize = EXT2_BLOCK_SIZE(super);
 	fs->fragsize = EXT2_FRAG_SIZE(super);
+	fs->desc_size = EXT2_DESC_SIZE(super);
 	frags_per_block = fs->blocksize / fs->fragsize;
 
 	/* default: (fs->blocksize*8) blocks/group, up to 2^16 (GDT limit) */
Index: e2fsprogs-1.39/lib/e2p/ls.c
===================================================================
--- e2fsprogs-1.39.orig/lib/e2p/ls.c	2006-05-31 15:44:49.000000000 +0200
+++ e2fsprogs-1.39/lib/e2p/ls.c	2006-06-07 16:04:38.000000000 +0200
@@ -199,6 +199,7 @@ void list_super2(struct ext2_super_block
 	fprintf(f, "First block:              %u\n", sb->s_first_data_block);
 	fprintf(f, "Block size:               %u\n", EXT2_BLOCK_SIZE(sb));
 	fprintf(f, "Fragment size:            %u\n", EXT2_FRAG_SIZE(sb));
+	fprintf(f, "Descriptor size:          %u\n", EXT2_DESC_SIZE(sb));
 	if (sb->s_reserved_gdt_blocks)
 		fprintf(f, "Reserved GDT blocks:      %u\n", 
 			sb->s_reserved_gdt_blocks);
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