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Message-ID: <20160213223738.25381.33873.stgit@birch.djwong.org>
Date: Sat, 13 Feb 2016 14:37:38 -0800
From: "Darrick J. Wong" <darrick.wong@...cle.com>
To: tytso@....edu, darrick.wong@...cle.com
Cc: linux-ext4@...r.kernel.org
Subject: [PATCH 2/9] tune2fs: allow user to turn on saving the checksum seed
Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
---
misc/tune2fs.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 60 insertions(+), 6 deletions(-)
diff --git a/misc/tune2fs.c b/misc/tune2fs.c
index 4d57399..f9e654f 100644
--- a/misc/tune2fs.c
+++ b/misc/tune2fs.c
@@ -149,7 +149,8 @@ static __u32 ok_features[3] = {
EXT4_FEATURE_INCOMPAT_FLEX_BG |
EXT4_FEATURE_INCOMPAT_MMP |
EXT4_FEATURE_INCOMPAT_64BIT |
- EXT4_FEATURE_INCOMPAT_ENCRYPT,
+ EXT4_FEATURE_INCOMPAT_ENCRYPT |
+ EXT4_FEATURE_INCOMPAT_CSUM_SEED,
/* R/O compat */
EXT2_FEATURE_RO_COMPAT_LARGE_FILE |
EXT4_FEATURE_RO_COMPAT_HUGE_FILE|
@@ -171,7 +172,8 @@ static __u32 clear_ok_features[3] = {
EXT2_FEATURE_INCOMPAT_FILETYPE |
EXT4_FEATURE_INCOMPAT_FLEX_BG |
EXT4_FEATURE_INCOMPAT_MMP |
- EXT4_FEATURE_INCOMPAT_64BIT,
+ EXT4_FEATURE_INCOMPAT_64BIT |
+ EXT4_FEATURE_INCOMPAT_CSUM_SEED,
/* R/O compat */
EXT2_FEATURE_RO_COMPAT_LARGE_FILE |
EXT4_FEATURE_RO_COMPAT_HUGE_FILE|
@@ -948,6 +950,15 @@ static errcode_t disable_uninit_bg(ext2_filsys fs, __u32 csum_feature_flag)
return 0;
}
+static void
+try_confirm_csum_seed_support(void)
+{
+ if (access("/sys/fs/ext4/features/metadata_csum_seed", R_OK))
+ fputs(_("WARNING: Could not confirm kernel support for "
+ "metadata_csum_seed.\n This requires Linux >= "
+ "v4.4.\n"), stderr);
+}
+
/*
* Update the feature set as provided by the user.
*/
@@ -1212,6 +1223,8 @@ mmp_error:
*/
old_features[E2P_FEATURE_RO_INCOMPAT] |=
EXT4_FEATURE_RO_COMPAT_GDT_CSUM;
+ fs->super->s_checksum_seed = 0;
+ ext2fs_clear_feature_csum_seed(fs->super);
}
if (FEATURE_ON(E2P_FEATURE_RO_INCOMPAT,
@@ -1294,6 +1307,37 @@ mmp_error:
EXT4_ENCRYPTION_MODE_AES_256_CTS;
}
+ if (FEATURE_ON(E2P_FEATURE_INCOMPAT,
+ EXT4_FEATURE_INCOMPAT_CSUM_SEED)) {
+ if (!ext2fs_has_feature_metadata_csum(sb)) {
+ fputs(_("Setting feature 'metadata_csum_seed' "
+ "is only supported\non filesystems with "
+ "the metadata_csum feature enabled.\n"),
+ stderr);
+ return 1;
+ }
+ try_confirm_csum_seed_support();
+ fs->super->s_checksum_seed = fs->csum_seed;
+ }
+
+ if (FEATURE_OFF(E2P_FEATURE_INCOMPAT,
+ EXT4_FEATURE_INCOMPAT_CSUM_SEED)) {
+ __le32 uuid_seed;
+
+ uuid_seed = ext2fs_crc32c_le(~0, fs->super->s_uuid,
+ sizeof(fs->super->s_uuid));
+ if (fs->super->s_checksum_seed != uuid_seed &&
+ (mount_flags & EXT2_MF_MOUNTED)) {
+ fputs(_("UUID has changed since enabling "
+ "metadata_csum. Filesystem must be unmounted "
+ "\nto safely rewrite all metadata to "
+ "match the new UUID.\n"), stderr);
+ return 1;
+ }
+
+ rewrite_checksums = 1;
+ }
+
if (sb->s_rev_level == EXT2_GOOD_OLD_REV &&
(sb->s_feature_compat || sb->s_feature_ro_compat ||
sb->s_feature_incompat))
@@ -2937,13 +2981,22 @@ retry_open:
if (ext2fs_has_group_desc_csum(fs)) {
/*
- * Changing the UUID requires rewriting all metadata,
- * which can race with a mounted fs. Don't allow that.
+ * Changing the UUID on a metadata_csum FS requires
+ * rewriting all metadata, which can race with a
+ * mounted fs. Don't allow that unless we're saving
+ * the checksum seed.
*/
- if ((mount_flags & EXT2_MF_MOUNTED) && !f_flag) {
+ if ((mount_flags & EXT2_MF_MOUNTED) &&
+ !ext2fs_has_feature_csum_seed(fs->super) &&
+ ext2fs_has_feature_metadata_csum(fs->super)) {
fputs(_("The UUID may only be "
"changed when the filesystem is "
"unmounted.\n"), stderr);
+ fputs(_("If you only use kernels newer than "
+ "v4.4, run 'tune2fs -O "
+ "metadata_csum_seed' and re-run this "
+ "command.\n"), stderr);
+ try_confirm_csum_seed_support();
exit(1);
}
if (check_fsck_needed(fs))
@@ -3005,7 +3058,8 @@ retry_open:
}
ext2fs_mark_super_dirty(fs);
- if (ext2fs_has_feature_metadata_csum(fs->super))
+ if (ext2fs_has_feature_metadata_csum(fs->super) &&
+ !ext2fs_has_feature_csum_seed(fs->super))
rewrite_checksums = 1;
}
--
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