From: Darrick J. Wong <djwong@us.ibm.com>
Date: Mon, 30 Jul 2012 22:44:04 +0000 (-0400)
Subject: libext2fs: precompute FS UUID checksum seed
X-Git-Tag: v1.43-WIP-2012-09-22~65
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=4ffbe3afa9d05a28712c8f5c11b5b76be3dc99fc;p=thirdparty%2Fe2fsprogs.git

libext2fs: precompute FS UUID checksum seed

Precompute the FS UUID checksum seed that is used for all metadata
checksumming operations and store it in ext2_filsys.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---

diff --git a/e2fsck/super.c b/e2fsck/super.c
index 160991d6d..a5e8005b3 100644
--- a/e2fsck/super.c
+++ b/e2fsck/super.c
@@ -716,6 +716,7 @@ void check_super_block(e2fsck_t ctx)
 	if (!(ctx->options & E2F_OPT_READONLY) && uuid_is_null(sb->s_uuid)) {
 		if (fix_problem(ctx, PR_0_ADD_UUID, &pctx)) {
 			uuid_generate(sb->s_uuid);
+			ext2fs_init_csum_seed(fs);
 			fs->flags |= EXT2_FLAG_DIRTY;
 			fs->flags &= ~EXT2_FLAG_MASTER_SB_ONLY;
 		}
diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
index 0728999f7..ed8f0bd0a 100644
--- a/lib/ext2fs/ext2fs.h
+++ b/lib/ext2fs/ext2fs.h
@@ -271,6 +271,9 @@ struct struct_ext2_filsys {
 
 	/* progress operation functions */
 	struct ext2fs_progress_ops *progress_ops;
+
+	/* Precomputed FS UUID checksum for seeding other checksums */
+	__u32 csum_seed;
 };
 
 #if EXT2_FLAT_INCLUDES
@@ -1431,6 +1434,7 @@ extern errcode_t ext2fs_write_bb_FILE(ext2_badblocks_list bb_list,
 
 
 /* inline functions */
+extern void ext2fs_init_csum_seed(ext2_filsys fs);
 extern errcode_t ext2fs_get_mem(unsigned long size, void *ptr);
 extern errcode_t ext2fs_get_memalign(unsigned long size,
 				     unsigned long align, void *ptr);
@@ -1483,6 +1487,16 @@ extern int ext2fs_fstat(int fd, ext2fs_struct_stat *buf);
 
 #ifndef EXT2_CUSTOM_MEMORY_ROUTINES
 #include <string.h>
+_INLINE_ void ext2fs_init_csum_seed(ext2_filsys fs)
+{
+	if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
+					EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))
+		return;
+
+	fs->csum_seed = ext2fs_crc32c_le(~0, fs->super->s_uuid,
+					 sizeof(fs->super->s_uuid));
+}
+
 /*
  *  Allocate memory
  */
diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
index fbe9acdee..3675518f3 100644
--- a/lib/ext2fs/openfs.c
+++ b/lib/ext2fs/openfs.c
@@ -315,6 +315,8 @@ errcode_t ext2fs_open2(const char *name, const char *io_options,
 		retval = EXT2_ET_CORRUPT_SUPERBLOCK;
 		goto cleanup;
 	}
+	/* Precompute the FS UUID to seed other checksums */
+	ext2fs_init_csum_seed(fs);
 
 	/*
 	 * Read group descriptors
diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index 01b2111b0..94db901a9 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -2323,6 +2323,7 @@ int main (int argc, char *argv[])
 		}
 	} else
 		uuid_generate(fs->super->s_uuid);
+	ext2fs_init_csum_seed(fs);
 
 	/*
 	 * Initialize the directory index variables