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Subject[RFC v2 10/83] Add superblock integrity check.
Date
From: Andiry Xu <jix024@cs.ucsd.edu>

Repair broken primary superblock with redundant superblock.

Signed-off-by: Andiry Xu <jix024@cs.ucsd.edu>
---
fs/nova/super.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 102 insertions(+)

diff --git a/fs/nova/super.c b/fs/nova/super.c
index 552fe5d..e0e38ab 100644
--- a/fs/nova/super.c
+++ b/fs/nova/super.c
@@ -276,6 +276,21 @@ static bool nova_check_size(struct super_block *sb, unsigned long size)
return true;
}

+static inline int nova_check_super_checksum(struct super_block *sb)
+{
+ struct nova_sb_info *sbi = NOVA_SB(sb);
+ u32 crc = 0;
+
+ // Check CRC but skip c_sum, which is the 4 bytes at the beginning
+ crc = nova_crc32c(~0, (__u8 *)sbi->nova_sb + sizeof(__le32),
+ sizeof(struct nova_super_block) - sizeof(__le32));
+
+ if (sbi->nova_sb->s_sum == cpu_to_le32(crc))
+ return 0;
+ else
+ return 1;
+}
+
static inline void nova_sync_super(struct super_block *sb)
{
struct nova_sb_info *sbi = NOVA_SB(sb);
@@ -293,6 +308,34 @@ static inline void nova_sync_super(struct super_block *sb)
PERSISTENT_BARRIER();
}

+/* Update checksum for the DRAM copy */
+static inline void nova_update_super_crc(struct super_block *sb)
+{
+ struct nova_sb_info *sbi = NOVA_SB(sb);
+ u32 crc = 0;
+
+ sbi->nova_sb->s_wtime = cpu_to_le32(get_seconds());
+ sbi->nova_sb->s_sum = 0;
+ crc = nova_crc32c(~0, (__u8 *)sbi->nova_sb + sizeof(__le32),
+ sizeof(struct nova_super_block) - sizeof(__le32));
+ sbi->nova_sb->s_sum = cpu_to_le32(crc);
+}
+
+
+static inline void nova_update_mount_time(struct super_block *sb)
+{
+ struct nova_sb_info *sbi = NOVA_SB(sb);
+ u64 mnt_write_time;
+
+ mnt_write_time = (get_seconds() & 0xFFFFFFFF);
+ mnt_write_time = mnt_write_time | (mnt_write_time << 32);
+
+ sbi->nova_sb->s_mtime = cpu_to_le64(mnt_write_time);
+ nova_update_super_crc(sb);
+
+ nova_sync_super(sb);
+}
+
static struct nova_inode *nova_init(struct super_block *sb,
unsigned long size)
{
@@ -328,6 +371,7 @@ static struct nova_inode *nova_init(struct super_block *sb,
sbi->nova_sb->s_blocksize = cpu_to_le32(blocksize);
sbi->nova_sb->s_magic = cpu_to_le32(NOVA_SUPER_MAGIC);
sbi->nova_sb->s_epoch_id = 0;
+ nova_update_super_crc(sb);

nova_sync_super(sb);

@@ -369,6 +413,54 @@ static void nova_root_check(struct super_block *sb, struct nova_inode *root_pi)
nova_warn("root is not a directory!\n");
}

+/* Check super block magic and checksum */
+static int nova_check_super(struct super_block *sb,
+ struct nova_super_block *ps)
+{
+ struct nova_sb_info *sbi = NOVA_SB(sb);
+ int rc;
+
+ rc = memcpy_mcsafe(sbi->nova_sb, ps,
+ sizeof(struct nova_super_block));
+
+ if (rc < 0)
+ return rc;
+
+ if (le32_to_cpu(sbi->nova_sb->s_magic) != NOVA_SUPER_MAGIC)
+ return -EIO;
+
+ if (nova_check_super_checksum(sb))
+ return -EIO;
+
+ return 0;
+}
+
+static int nova_check_integrity(struct super_block *sb)
+{
+ struct nova_super_block *super = nova_get_super(sb);
+ struct nova_super_block *super_redund;
+ int rc;
+
+ super_redund = nova_get_redund_super(sb);
+
+ /* Do sanity checks on the superblock */
+ rc = nova_check_super(sb, super);
+ if (rc < 0) {
+ rc = nova_check_super(sb, super_redund);
+ if (rc < 0) {
+ nova_err(sb, "Can't find a valid nova partition\n");
+ return rc;
+ } else {
+ nova_warn("Error in super block: try to repair it with the other copy\n");
+ memcpy_to_pmem_nocache((void *)super, (void *)super_redund,
+ sizeof(struct nova_super_block));
+ PERSISTENT_BARRIER();
+ }
+ }
+
+ return 0;
+}
+
static int nova_fill_super(struct super_block *sb, void *data, int silent)
{
struct nova_sb_info *sbi = NULL;
@@ -446,6 +538,13 @@ static int nova_fill_super(struct super_block *sb, void *data, int silent)
goto setup_sb;
}

+ if (nova_check_integrity(sb) < 0) {
+ retval = -EINVAL;
+ nova_dbg("Memory contains invalid nova %x:%x\n",
+ le32_to_cpu(sbi->nova_sb->s_magic), NOVA_SUPER_MAGIC);
+ goto out;
+ }
+
blocksize = le32_to_cpu(sbi->nova_sb->s_blocksize);
nova_set_blocksize(sb, blocksize);

@@ -482,6 +581,9 @@ static int nova_fill_super(struct super_block *sb, void *data, int silent)
goto out;
}

+ if (!(sb->s_flags & MS_RDONLY))
+ nova_update_mount_time(sb);
+
retval = 0;
return retval;

--
2.7.4
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