ext4: make block group checksums use metadata_csum algorithm
metadata_csum supersedes uninit_bg. Convert the ROCOMPAT uninit_bg
flag check to a helper function that covers both, and make the
checksum calculation algorithm use either crc16 or the metadata_csum
chosen algorithm depending on which flag is set. Print a warning if
we try to mount a filesystem with both feature flags set.
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index f80c7e6..c18c596 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1952,43 +1952,69 @@
return 0;
}
-__le16 ext4_group_desc_csum(struct ext4_sb_info *sbi, __u32 block_group,
- struct ext4_group_desc *gdp)
+static __le16 ext4_group_desc_csum(struct ext4_sb_info *sbi, __u32 block_group,
+ struct ext4_group_desc *gdp)
{
+ int offset;
__u16 crc = 0;
+ __le32 le_group = cpu_to_le32(block_group);
- if (sbi->s_es->s_feature_ro_compat &
- cpu_to_le32(EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) {
- int offset = offsetof(struct ext4_group_desc, bg_checksum);
- __le32 le_group = cpu_to_le32(block_group);
+ if ((sbi->s_es->s_feature_ro_compat &
+ cpu_to_le32(EXT4_FEATURE_RO_COMPAT_METADATA_CSUM))) {
+ /* Use new metadata_csum algorithm */
+ __u16 old_csum;
+ __u32 csum32;
- crc = crc16(~0, sbi->s_es->s_uuid, sizeof(sbi->s_es->s_uuid));
- crc = crc16(crc, (__u8 *)&le_group, sizeof(le_group));
- crc = crc16(crc, (__u8 *)gdp, offset);
- offset += sizeof(gdp->bg_checksum); /* skip checksum */
- /* for checksum of struct ext4_group_desc do the rest...*/
- if ((sbi->s_es->s_feature_incompat &
- cpu_to_le32(EXT4_FEATURE_INCOMPAT_64BIT)) &&
- offset < le16_to_cpu(sbi->s_es->s_desc_size))
- crc = crc16(crc, (__u8 *)gdp + offset,
- le16_to_cpu(sbi->s_es->s_desc_size) -
- offset);
+ old_csum = gdp->bg_checksum;
+ gdp->bg_checksum = 0;
+ csum32 = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&le_group,
+ sizeof(le_group));
+ csum32 = ext4_chksum(sbi, csum32, (__u8 *)gdp,
+ sbi->s_desc_size);
+ gdp->bg_checksum = old_csum;
+
+ crc = csum32 & 0xFFFF;
+ goto out;
}
+ /* old crc16 code */
+ offset = offsetof(struct ext4_group_desc, bg_checksum);
+
+ crc = crc16(~0, sbi->s_es->s_uuid, sizeof(sbi->s_es->s_uuid));
+ crc = crc16(crc, (__u8 *)&le_group, sizeof(le_group));
+ crc = crc16(crc, (__u8 *)gdp, offset);
+ offset += sizeof(gdp->bg_checksum); /* skip checksum */
+ /* for checksum of struct ext4_group_desc do the rest...*/
+ if ((sbi->s_es->s_feature_incompat &
+ cpu_to_le32(EXT4_FEATURE_INCOMPAT_64BIT)) &&
+ offset < le16_to_cpu(sbi->s_es->s_desc_size))
+ crc = crc16(crc, (__u8 *)gdp + offset,
+ le16_to_cpu(sbi->s_es->s_desc_size) -
+ offset);
+
+out:
return cpu_to_le16(crc);
}
-int ext4_group_desc_csum_verify(struct ext4_sb_info *sbi, __u32 block_group,
+int ext4_group_desc_csum_verify(struct super_block *sb, __u32 block_group,
struct ext4_group_desc *gdp)
{
- if ((sbi->s_es->s_feature_ro_compat &
- cpu_to_le32(EXT4_FEATURE_RO_COMPAT_GDT_CSUM)) &&
- (gdp->bg_checksum != ext4_group_desc_csum(sbi, block_group, gdp)))
+ if (ext4_has_group_desc_csum(sb) &&
+ (gdp->bg_checksum != ext4_group_desc_csum(EXT4_SB(sb),
+ block_group, gdp)))
return 0;
return 1;
}
+void ext4_group_desc_csum_set(struct super_block *sb, __u32 block_group,
+ struct ext4_group_desc *gdp)
+{
+ if (!ext4_has_group_desc_csum(sb))
+ return;
+ gdp->bg_checksum = ext4_group_desc_csum(EXT4_SB(sb), block_group, gdp);
+}
+
/* Called at mount-time, super-block is locked */
static int ext4_check_descriptors(struct super_block *sb,
ext4_group_t *first_not_zeroed)
@@ -2043,7 +2069,7 @@
return 0;
}
ext4_lock_group(sb, i);
- if (!ext4_group_desc_csum_verify(sbi, i, gdp)) {
+ if (!ext4_group_desc_csum_verify(sb, i, gdp)) {
ext4_msg(sb, KERN_ERR, "ext4_check_descriptors: "
"Checksum for group %u failed (%u!=%u)",
i, le16_to_cpu(ext4_group_desc_csum(sbi, i,
@@ -3069,6 +3095,13 @@
goto cantfind_ext4;
sbi->s_kbytes_written = le64_to_cpu(es->s_kbytes_written);
+ /* Warn if metadata_csum and gdt_csum are both set. */
+ if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
+ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM) &&
+ EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
+ ext4_warning(sb, KERN_INFO "metadata_csum and uninit_bg are "
+ "redundant flags; please run fsck.");
+
/* Check for a known checksum algorithm */
if (!ext4_verify_csum_type(sb, es)) {
ext4_msg(sb, KERN_ERR, "VFS: Found ext4 filesystem with "
@@ -4400,7 +4433,7 @@
struct ext4_group_desc *gdp =
ext4_get_group_desc(sb, g, NULL);
- if (!ext4_group_desc_csum_verify(sbi, g, gdp)) {
+ if (!ext4_group_desc_csum_verify(sb, g, gdp)) {
ext4_msg(sb, KERN_ERR,
"ext4_remount: Checksum for group %u failed (%u!=%u)",
g, le16_to_cpu(ext4_group_desc_csum(sbi, g, gdp)),