From: Theodore Ts'o <tytso@mit.edu>
Date: Sat, 4 Jun 2011 14:20:47 +0000 (-0400)
Subject: libext2fs: change fs->clustersize to fs->cluster_ratio_bits
X-Git-Tag: v1.42-WIP-0702~32^2~2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1da5ef707904cf99300a0fb36b9ae3b29dbc8bde;p=thirdparty%2Fe2fsprogs.git

libext2fs: change fs->clustersize to fs->cluster_ratio_bits

The log2 of the ratio of cluster size to block size is far more useful
than just storing the cluster size.  So make this change, and then
define basic utility macros: EXT2FS_CLUSTER_RATIO(),
EXT2FS_CLUSTER_MASK(), EXT2FS_B2C(), EXT2FS_C2B(), and
EXT2FS_NUM_B2C().

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 516eb1afc..5379422ba 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -195,7 +195,7 @@ struct struct_ext2_filsys {
 	char *				device_name;
 	struct ext2_super_block	* 	super;
 	unsigned int			blocksize;
-	int				clustersize;
+	int				cluster_ratio_bits;
 	dgrp_t				group_desc_count;
 	unsigned long			desc_blocks;
 	struct ext2_group_desc *	group_desc;
@@ -547,6 +547,17 @@ typedef struct ext2_icount *ext2_icount_t;
 #define EXT2_LIB_SOFTSUPP_INCOMPAT	(0)
 #define EXT2_LIB_SOFTSUPP_RO_COMPAT	(EXT4_FEATURE_RO_COMPAT_BIGALLOC)
 
+
+/* Translate a block number to a cluster number */
+#define EXT2FS_CLUSTER_RATIO(fs)	(1 << (fs)->cluster_ratio_bits)
+#define EXT2FS_CLUSTER_MASK(fs)		(EXT2FS_CLUSTER_RATIO(fs) - 1)
+#define EXT2FS_B2C(fs, blk)		((blk) >> (fs)->cluster_ratio_bits)
+/* Translate a cluster number to a block number */
+#define EXT2FS_C2B(fs, cluster)		((cluster) << (fs)->cluster_ratio_bits)
+/* Translate # of blks to # of clusters */
+#define EXT2FS_NUM_B2C(fs, blks)	(((blks) + EXT2FS_CLUSTER_MASK(fs)) >> \
+					 (fs)->cluster_ratio_bits)
+
 /*
  * function prototypes
  */
diff --git a/lib/ext2fs/initialize.c b/lib/ext2fs/initialize.c
index c109d08ed..b9d45aefc 100644
--- a/lib/ext2fs/initialize.c
+++ b/lib/ext2fs/initialize.c
@@ -178,7 +178,8 @@ errcode_t ext2fs_initialize(const char *name, int flags,
 	super->s_creator_os = CREATOR_OS;
 
 	fs->blocksize = EXT2_BLOCK_SIZE(super);
-	fs->clustersize = EXT2_CLUSTER_SIZE(super);
+	fs->cluster_ratio_bits = super->s_log_cluster_size -
+		super->s_log_block_size;
 
 	/* default: (fs->blocksize*8) blocks/group, up to 2^16 (GDT limit) */
 	set_field(s_blocks_per_group, fs->blocksize * 8);
diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
index f87c17170..a598ca04a 100644
--- a/lib/ext2fs/openfs.c
+++ b/lib/ext2fs/openfs.c
@@ -250,7 +250,13 @@ errcode_t ext2fs_open2(const char *name, const char *io_options,
 		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 		goto cleanup;
 	}
-	fs->clustersize = EXT2_CLUSTER_SIZE(fs->super);
+	fs->cluster_ratio_bits = fs->super->s_log_cluster_size -
+		fs->super->s_log_block_size;
+	if (EXT2_BLOCKS_PER_GROUP(fs->super) !=
+	    EXT2_CLUSTERS_PER_GROUP(fs->super) << fs->cluster_ratio_bits) {
+		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
+		goto cleanup;
+	}
 	fs->inode_blocks_per_group = ((EXT2_INODES_PER_GROUP(fs->super) *
 				       EXT2_INODE_SIZE(fs->super) +
 				       EXT2_BLOCK_SIZE(fs->super) - 1) /
diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index 9f28901ad..c46df6cec 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -619,9 +619,10 @@ static void show_stats(ext2_filsys fs)
 	if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 				       EXT4_FEATURE_RO_COMPAT_BIGALLOC))
 		printf(_("Cluster size=%u (log=%u)\n"),
-		       fs->clustersize, s->s_log_cluster_size);
+		       fs->blocksize << fs->cluster_ratio_bits,
+		       s->s_log_cluster_size);
 	else
-		printf(_("Fragment size=%u (log=%u)\n"), fs->clustersize,
+		printf(_("Fragment size=%u (log=%u)\n"), EXT2_CLUSTER_SIZE(s),
 		       s->s_log_cluster_size);
 	printf(_("Stride=%u blocks, Stripe width=%u blocks\n"),
 	       s->s_raid_stride, s->s_raid_stripe_width);